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WO2008070568A2 - Appareil et procédé de dépôt électrochimique sur un substrat de cellule solaire - Google Patents

Appareil et procédé de dépôt électrochimique sur un substrat de cellule solaire Download PDF

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Publication number
WO2008070568A2
WO2008070568A2 PCT/US2007/086145 US2007086145W WO2008070568A2 WO 2008070568 A2 WO2008070568 A2 WO 2008070568A2 US 2007086145 W US2007086145 W US 2007086145W WO 2008070568 A2 WO2008070568 A2 WO 2008070568A2
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WIPO (PCT)
Prior art keywords
substrate
electrode
solar cell
conductive layer
electrolyte
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PCT/US2007/086145
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English (en)
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WO2008070568A3 (fr
Inventor
Sergey Lopatin
Nicolay Y. Kovarsky
David Eaglesham
John O. Dukovic
Charles Gay
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Applied Materials, Inc.
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Priority claimed from US11/566,202 external-priority patent/US7704352B2/en
Priority claimed from US11/566,201 external-priority patent/US20080128019A1/en
Application filed by Applied Materials, Inc. filed Critical Applied Materials, Inc.
Publication of WO2008070568A2 publication Critical patent/WO2008070568A2/fr
Publication of WO2008070568A3 publication Critical patent/WO2008070568A3/fr

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
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    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/20—Electrodes
    • H10F77/206—Electrodes for devices having potential barriers
    • H10F77/211—Electrodes for devices having potential barriers for photovoltaic cells
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    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
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    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
    • C23C28/3225—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only with at least one zinc-based layer
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    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
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    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/36—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including layers graded in composition or physical properties
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C25D17/001—Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C25D17/02—Tanks; Installations therefor
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    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C25D17/06—Suspending or supporting devices for articles to be coated
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/02—Electroplating of selected surface areas
    • C25D5/022—Electroplating of selected surface areas using masking means
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/08—Electroplating with moving electrolyte e.g. jet electroplating
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
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    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/48—After-treatment of electroplated surfaces
    • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • Embodiments of the present invention generally relate to the fabrication of photovoltaic cells.
  • Solar cells are photovoltaic devices that convert sunlight directly into electrical power.
  • the most common solar cell material is silicon, which is in the form of single or polycrystalline wafers. Because the amortized cost of forming a silicon- based solar cells to generate electricity is higher than the cost of generating electricity using traditional methods, there has been an effort to reduce the cost to form solar cells.
  • Figures 1A and 1 B schematically depicts a standard silicon solar cell 100 fabricated on a wafer 110.
  • the wafer 110 includes a p-type base region 101 , an n- type emitter region 102, and a p-n junction region 103 disposed therebetween.
  • An n-type region, or n-type semiconductor is formed by doping the semiconductor with certain types of elements ⁇ e.g., phosphorus (P), arsenic (As), or antimony (Sb)) in order to increase the number of negative charge carriers, i.e., electrons.
  • P phosphorus
  • As arsenic
  • Sb antimony
  • a p-type region is formed by the addition of trivalent atoms to the crystal lattice, resulting in a missing electron from one of the four covalent bonds normal for the silicon lattice.
  • the dopant atom can accept an electron from a neighboring atom's covalent bond to complete the fourth bond.
  • the dopant atom accepts an electron, causing the loss of half of one bond from the neighboring atom and resulting in the formation of a "hole".
  • the top contact structure is generally configured as widely-spaced thin metal lines, or fingers 104, that supply current to a larger bus bar 105.
  • the back contact 106 is generally not constrained to be formed in multiple thin metal lines, since it does not prevent incident light from striking solar cell 100.
  • Solar cell 100 is generally covered with a thin layer of dielectric material, such as Si 3 N 4 , to act as an anti-reflection coating 111 , or ARC, to minimize light reflection from the top surface of solar cell 100.
  • a solar cell In the interest of simplified assembly and higher efficiency of solar cells, a solar cell has been developed, wherein a plurality of holes is formed through the solar cell substrate and serves as vias for interconnection of the top contact structure to a backside conductor by using pins.
  • This solar cell design is referred to as a pin-up module, or PUM.
  • PUM pin-up module
  • One advantage of the PUM concept is the elimination of the busbars, such as bus bar 105 illustrated in Figure 1A, from covering the light- receiving side of the substrate, thereby increasing efficiency of the cell.
  • resistive losses are reduced because current produced by the solar cell is collected at holes equally spaced over the substrate rather than requiring some of the connections to extend across the surface of the solar cell. Further, resistive losses experienced by a PUM connected device will not increase as the solar cell surface area increases and, hence, larger solar cells may be manufactured without a loss in efficiency.
  • FIG. 1C is a partial schematic cross section of one example of a PUM cell 130 showing a contact 134.
  • PUM cell 130 Similar to a standard solar cell, such as solar cell 100, PUM cell 130 includes a single crystal silicon wafer 110 with a p-type base region 101 , an n-type emitter region 102, and a p-n junction region 103 disposed therebetween.
  • PUM cell 130 also includes a plurality of through-holes 131 , which are formed between the light-receiving surface 132 and the backside 133 of PUM cell 130.
  • the through-holes 131 allow the formation of contact 134 between the light-receiving surface 132 and the backside 133.
  • each through-hole 131 Disposed in each through-hole 131 is a contact 134, which includes a top contact structure 135 disposed on light- receiving surface 132, a backside contact 136 disposed on backside 133, and an interconnect 137, which fills through-hole 131 and electrically couples top contact structure 135 and backside contact 136.
  • An anti-reflective coating 107 may also be formed on light receiving surface 132 to minimize reflection of light energy therefrom.
  • a backside contact 139 completes the electrical circuit required for PUM cell 130 to produce a current by forming an ohmic contact with p-type base region 101 of the silicon wafer 110.
  • the fingers 104 ( Figure 1 B) or contact 134 ( Figure 1C) are in contact with the substrate are adapted to form an ohmic connection with doped region (e.g., n- type emitter region 102).
  • An ohmic contact is a region on a semiconductor device that has been prepared so that the current-voltage (I-V) curve of the device is linear and symmetric, i.e., there is no high resistance interface between the doped silicon region of the semiconductor device and the metal contact. Low-resistance, stable contacts are critical for the performance of the solar cell and reliability of the circuits formed in the solar cell fabrication process.
  • an annealing process of suitable temperature and duration is typically performed in order to produce the necessary low resistance metal suicide at the contact/semiconductor interface.
  • a backside contact completes the electrical circuit required for solar cell to produce a current by forming an ohmic contact with p-type base region of the substrate.
  • FIG. 1D illustrates a plan view of one example of a top contact structure 135 for a PUM cell, wherein the finger width and geometry have been optimized to maximize cell efficiency for the cell.
  • a top contact structure 135 for a PUM cell is configured as a grid electrode 138, which consists of a plurality of various width finger segments 135A.
  • the width of a particular finger segment 135A is selected as a function of the current to be carried by that finger segment 135A.
  • finger segments 135A are configured to branch as necessary to maintain finger spacing as a function of finger width. This minimizes resistance losses as well as shadowing by finger segments 135A.
  • the current carrying metal lines, or conductors are fabricated using a screen printing process in which a silver-containing paste is deposited in a desired pattern on a substrate surface and then annealed.
  • a screen printing process in which a silver-containing paste is deposited in a desired pattern on a substrate surface and then annealed.
  • the thin fingers of the conductors when formed by the screen printing process, may be discontinuous since the fingers formed using a metal paste do not always agglomerate into a continuous interconnecting line during the annealing process.
  • porosity present in the fingers formed during the agglomeration process results in greater resistive losses.
  • electrical shunts may be formed by diffusion of the metal (e.g., silver) from the contact into the p-type base region or on the surface of the substrate backside.
  • Shunts on the substrate backside are caused by poor definition of backside contacts such as waviness, and/or metal residue.
  • backside contacts such as waviness, and/or metal residue.
  • the act of screen printing the metal paste on the substrate surface can cause physical damage to the substrate.
  • silver-based paste is a relatively expensive material for forming conductive components of a solar cell.
  • One issue with the current method of forming metal interconnects using a screen printing process that utilizes a metal particle containing paste is that the process of forming the patterned features requires high temperature post-processing steps to densify the formed features and form a good electrical contact with the substrate surface. Due to the need to perform a high temperature sintering process the formed interconnect lines will have a high extrinsic stress created by the difference in thermal expansion of the substrate material and the metal lines. A high extrinsic stress, or even intrinsic stress, formed in the metal interconnect lines is an issue, since it can cause breakage of the formed metallized features, warping of the thin solar cell substrate, and/or delamination of the metallized features from the surface of the solar cell substrate.
  • the high temperature post processing step can also cause the material in the solar cell device to diffuse into unwanted regions of the device, thus causing device problems, such as an electrical short.
  • High temperature processes also limit the types of materials that can be used to form a solar cell due to the breakdown of certain materials at the high sintering temperatures.
  • screen printing processes also tend to be non-uniform, unreliable and often unrepeatable. Therefore, there is a need to form a low stress interconnect line that forms a strong bond to the surface of the substrate.
  • Another approach to forming very thin, robust current carrying metal lines on the surface of a solar cell substrate involves cutting grooves in the surface of the substrate with a laser.
  • the grooves are subsequently filled by an electroless plating method.
  • the laser-cut grooves are a source of macro- and micro-defects.
  • the laser-cut edge is not well defined, causing waviness on the finger edges, and the heat of the laser introduces defects into the silicon.
  • a process sequence is generally defined as the sequence of device fabrication steps, or process recipe steps, completed in one or more processing chambers that are used to form a solar cell.
  • a process sequence may generally contain various substrate (or wafer) fabrication processing steps.
  • the longest process recipe step will generally limit the throughput of the processing sequence, increase the CoO and possibly make a desirable processing sequence impractical. [0013] Therefore, there is a need for a system, a method and an apparatus that can process a substrate so that it can meet the required device performance goals and increase the system throughput and thus reduce the process sequence CoO. There is also a need for a low cost method of forming a contact structure for solar cells that have a low resistivity and clearly defined features.
  • Embodiments of the present invention generally provide an apparatus for forming a metal layer on a solar cell substrate, comprising a masking plate having a body, a first surface, a second surface and a plurality of apertures that extend through the body between the first surface and the second surface, a contact that is in communication with a first power supply, a thrust plate that is adapted to urge a metallized surface of a substrate against the contact and the first surface of the masking plate, an first electrode that is in electrical communication with the first power supply, wherein the first power supply is configured to electrically bias the first electrode relative to the contact, and an second electrode that is in electrical communication with a second power supply which is adapted to bias the second electrode relative to the contact or the first electrode.
  • Embodiments of the present invention may further provide an apparatus for forming a metal layer on a solar cell substrate, comprising a tank that has a processing region which is adapted to retain a volume of an electrolyte, an array of plating cells positioned in the processing region, wherein each plating cells in the array comprise a contact that is in communication with a power supply, a thrust plate that is adapted to urge a metallized surface of a substrate against the contact, and an electrode that is in electrical communication with a power supply.
  • Embodiments of the present invention may further provide an apparatus for forming a metal layer on a solar cell substrate, comprising a first tank that has a first processing region which is adapted to retain a volume of an electrolyte, a substrate holder assembly that is adapted hold two or more substrates, wherein the first substrate holder assembly comprises one or more contacts that is in electrical communication with a power supply, and a first actuator that is adapted to urge at least one of the one or more contacts against a metallized region formed on a surface of each of the two or more substrates to form an electrical connection, and a first electrode disposed in the first processing region of the first tank and is in electrical communication with a first power supply, wherein the first power supply is configured to electrically bias the first electrode relative to at least one of the one or more contacts.
  • Embodiments of the present invention may further provide an apparatus for forming a metal layer on a solar cell substrate, comprising a tank that has a processing region which is adapted to retain a volume of an electrolyte, a substrate holder assembly that is adapted hold one or more substrates, wherein the substrate holder assembly comprises one or more first contacts that are in electrical communication with a first power supply, one or more second contacts that are in electrical communication with a second power supply, and one or more actuators that are adapted to urge at least one of the one or more first contacts against a first metallized region formed on a first surface of each of the one or more substrates, and urge at least one of the one or more second contacts against a second metallized region formed on a second surface of each of the one or more substrates, a first electrode disposed in the processing region of the tank and is in electrical communication with a first power supply, wherein the first power supply is configured to electrically bias the first electrode relative to at least one of the one or more first contacts, and a
  • Embodiments of the present invention may further provide an apparatus for forming a metal layer on a solar cell substrate, comprising a substrate holder assembly that is adapted hold one or more substrates, wherein the first substrate holder assembly comprises one or more contacts, and one or more actuators that are adapted to urge at least one of the one or more contacts against a metallized region formed on a surface of each of the one or more substrates to form an electrical connection, a first processing chamber assembly comprising a first tank that has a first processing region which is adapted to retain a volume of an electrolyte, and a first electrode disposed in the first processing region of the first tank and is in electrical communication with a first power supply, wherein the first power supply is configured to electrically bias the first electrode relative to at least one of the one or more contacts in the substrate holder when it is positioned in the first processing region of the first tank, a second processing chamber assembly comprising a second tank that has a second processing region which is adapted to retain a volume of an electrolyte
  • Embodiments of the present invention may further provide an apparatus for forming a metal layer on a solar cell substrate, comprising a substrate holder assembly that is adapted hold one or more substrates, wherein the first substrate holder assembly comprises one or more contacts, and one or more actuators that are adapted to urge at least one of the one or more contacts against a metallized region formed on a surface of each of the one or more substrates to form an electrical connection, a tank that has a processing region which is adapted to retain a volume of an electrolyte, and a first electrode assembly disposed in the processing region of the tank, wherein the first electrode assembly comprises a first electrode that is in electrical communication with one or more power supplies, wherein one of the one or more power supplies is configured to electrically bias the first electrode relative to at least one of the one or more contacts in the substrate holder, and a second electrode that is in electrical communication with the one or more power supplies, wherein one of the one or more power supplies is configured to electrically bias the first electrode relative to at least one of
  • Embodiments of the present invention may further provide a method of forming a metal layer on a solar cell substrate, comprising disposing a first masking plate having a plurality of apertures formed therein over at least a portion of a seed layer formed on a first substrate, disposing a second masking plate having a plurality of apertures formed therein over at least a portion of a seed layer formed on a second substrate, contacting the seed layer formed on the first substrate with a first electrical contact, contacting the seed layer formed on the second substrate with a second electrical contact, and forming a first metal layer over the seed layer formed on the first and second substrates by immersing the first and second substrates, a first electrode and a second electrode in a first electrolyte and biasing the first electrical contact relative to the first electrode and the second electrical contact relative to the second electrode, wherein the first metal layer is simultaneously formed on the first and second substrates within the areas exposed by apertures formed in the first and the second masking plates.
  • Embodiments of the present invention may further provide a method of forming a metal layer on a solar cell substrate, comprising disposing a first surface of a masking plate over at least a portion of a seed layer formed on a substrate, wherein the masking plate has a plurality of apertures that are in communication with a first surface of the masking plate, contacting the seed layer formed on the substrate with one or more electrical contacts, forming a first metal layer over the seed layer formed on the substrate by immersing the substrate and a first electrode in an electrolyte and biasing the one or more electrical contacts relative to the first electrode using one or more power supplies, wherein the first metal layer is simultaneously formed on the substrate within the areas exposed by apertures formed in the first masking plate, and biasing a second electrode that is disposed in the electrolyte relative to the one or more electrical contacts or the first electrode while forming the first metal layer to vary the uniformity of the deposited first metal layer.
  • a method can be used to plate between 2 and 1000 substrates
  • Embodiments of the present invention may further provide a method of forming a solar cell device, comprising positioning a solar cell substrate in a first processing chamber, the solar cell substrate having a first region and a second region that comprise elements that are used to form a solar cell device, forming a first conductive layer on the first region and the second region in the first processing chamber, and forming a second conductive layer on the first conductive layer using an electrochemical plating process, wherein forming the second conductive layer comprises forming a first metal layer on at least a portion of the first conductive region, and forming a second metal layer on at least a portion of the second conductive region.
  • Embodiments of the present invention may further provide a method of forming a solar cell device, comprising positioning a solar cell substrate in a first processing chamber, the solar cell substrate having a first region and a second region that comprise elements that are used to form a solar cell device, forming a first conductive layer over a portion of the first region and the second region in the first processing chamber, and forming a second conductive layer over a portion of the first conductive layer using an electrochemical plating process, wherein forming the second conductive layer comprises disposing a masking plate having first surface and a plurality of apertures formed therein over at least a portion of the first conductive layer, wherein the plurality of apertures are in communication with a first surface, contacting the first conductive layer with an electrical contact, and forming the second conductive layer over the first conductive layer by immersing the substrate and an electrode in a first electrolyte and electrically biasing the electrical contact relative to the electrode, wherein the second metal layer is simultaneously formed within the areas exposed by aperture
  • Embodiments of the present invention may further provide a method of forming a solar cell device, comprising positioning a solar cell substrate in a first processing chamber, the solar cell substrate having a first region and a second region that comprise elements that are used to form a solar cell device, forming a first conductive layer over a portion of the first region and the second region in the first processing chamber, and forming a second conductive layer over a portion of the first conductive layer using an electrochemical plating process, wherein forming the second conductive layer comprises depositing a masking material over the first conductive layer, forming a plurality of apertures in the masking layer to expose desired regions of the first conductive layer, contacting the first conductive layer with an electrical contact, and forming the second metal layer over the first conductive layer by immersing the substrate and an electrode in a first electrolyte and electrically biasing the electrical contact relative to the electrode.
  • Figure 1A illustrates an isometric view of prior art solar cell containing a front side metallization interconnect pattern.
  • Figure 1 B illustrates a cross-sectional side view of a prior art solar cell shown in Figure 1A.
  • Figure 1 C illustrates a cross-sectional view of a prior art PUM type device.
  • Figure 1 D illustrates a plan view of a top contact structure of a PUM cell, wherein the finger width and geometry have been optimized to maximize cell efficiency.
  • Figure 2 illustrates a solar cell process sequence according to one embodiment described herein.
  • Figures 3A - 3F illustrate schematic cross-sectional views of a solar cell during different stages of the process sequence described in Figures 2.
  • Figure 4A illustrates a side cross-sectional view of an electrochemical processing chamber according to one embodiment described herein.
  • Figure 4B illustrates is an isometric view of various electrochemical processing chamber components according to one embodiment described herein.
  • Figure 4C illustrates is an isometric view of various electrochemical processing chamber components according to one embodiment described herein.
  • Figure 4D illustrates a side cross-sectional view of an electrochemical processing chamber according to one embodiment described herein.
  • Figures 5A-5F illustrate an isometric view of a substrate having an electrochemically deposited layer formed thereon according to one embodiment described herein.
  • Figure 6 illustrates a graph of the effect of temperature on deposition rate according to one embodiment described herein.
  • Figure 7A illustrates a side cross-sectional view of a batch electrochemical deposition chamber according to one embodiment described herein.
  • Figure 7B illustrates a plan view of a batch electrochemical deposition system according to one embodiment described herein.
  • Figure 7C illustrates an isometric view of a batch electrochemical deposition chamber according to one embodiment described herein.
  • Figure 7D illustrates a side cross-sectional view of a batch electrochemical deposition chamber according to one embodiment described herein.
  • Figure 7E illustrates an isometric view of a head assembly according to one embodiment described herein.
  • Figure 7F illustrates a close-up isometric view of the head assembly illustrated in Figure 7E according to one embodiment described herein.
  • Figure 7G illustrates a cross-sectional view of a batch electrochemical deposition system according to one embodiment described herein.
  • Figure 7H illustrates an isometric view of a batch electrochemical deposition system according to one embodiment described herein.
  • Figure 71 illustrates a plan view of a batch electrochemical deposition system according to one embodiment described herein.
  • Figure 8 illustrates a solar cell process sequence according to one embodiment described herein.
  • Figures 9A - 9E illustrate schematic cross-sectional views of a solar cell during different stages of the process sequence described in Figures 8.
  • Figure 10 illustrates a solar cell process sequence according to one embodiment described herein.
  • Figures 11A - 11 H illustrate schematic cross-sectional views of a solar cell during different stages of the process sequence described in Figures 10.
  • Embodiments of the invention contemplate the formation of a low cost solar cell using a novel high speed electroplating method and apparatus to form a metal contact structure having selectively formed metal lines using an electrochemical plating process.
  • the apparatus and methods described herein remove the need to perform one or more high temperature screen printing processes to form conductive features on the surface of a solar cell substrate.
  • Solar cell substrates that may benefit from the invention include substrates composed of single crystal silicon, multi-crystalline silicon, polycrystalline silicon, germanium (Ge), and gallium arsenide (GaAs), cadmium telluride (CdTe), cadmium sulfide (CdS), copper indium gallium selenide (CIGS), copper indium selenide (CuInSe 2 ), gallilium indium phosphide (GaInP 2 ), as well as heterojunction cells, such as GalnP/GaAs/Ge or ZnSe/GaAs/Ge substrates.
  • the solar cell substrates may be formed in a square, rectangular, circular or any other desirable shape.
  • the resistance of interconnects formed in a solar cell device greatly affects the efficiency of the solar cell. It is thus desirable to form a solar cell device that has a low resistance connection that is reliable and cost effective.
  • silver (Ag) interconnecting lines formed from a silver paste is one of the currently the preferred interconnecting method.
  • silver has a lower resistivity (e.g., 1.59 x10 "8 ohm-m) than other common metals such as copper (e.g., 1.7 x10 "8 ohm-m) and aluminum (e.g., 2.82 x10 "8 ohm-m) it costs orders of magnitude more than these other common metals.
  • the electroplated portions of the interconnecting layer may contain a substantially pure metal or a metal alloy layer containing copper (Cu), silver (Ag), gold (Au), tin (Sn), cobalt (Co), nickel (Ni), zinc (Zn), lead (Pb), palladium (Pd), and/or aluminum (Al).
  • the electroplated portion of the interconnect layer contains substantially pure copper or a copper alloy.
  • FIG. 2 illustrates a series of method steps 200 that are used to form metal contact structures on a solar cell device using the apparatus described herein.
  • the processes described below may be used to form a solar cell having interconnects formed using any conventional device interconnection style or technique.
  • this interconnect configuration is not intended to be limiting as to the scope of the invention, since other device configurations, such as PUM or multilayer buried contact structures (both contacts on one side), may be formed using the apparatus and methods described herein without varying from the basic scope of the invention.
  • Figures 3A-3E illustrate the various states of a metallized substrate 320 after each step of method steps 200 has been performed.
  • the method steps 200 start with step 202 in which a substrate 301 ( Figure 3A) is formed using conventional solar cell and/or semiconductor fabrication techniques.
  • the substrate 301 may be formed from single crystal or polycrystalline silicon materials.
  • Examples of these substrate fabrication process are the EFG process (Edge-defined Film-fed Growth) ⁇ e.g., US 5,106,763), the RGS (Ribbon Growth on Substrate) process ⁇ e.g., US 4,670,096, US 5,298,109, DE 4,105,910 A1) and the SSP ribbon process (Silicon Sheets from Powder) (e.g., US 5,336,335, US 5,496,446, US 6,111 ,191, and US 6,207,891).
  • EFG process Edge-defined Film-fed Growth
  • RGS Rabbon Growth on Substrate
  • SSP ribbon process Silicon Sheets from Powder
  • an n-type region 302 is disposed over the substrate 301 that has been doped with a p-type dopant.
  • the n-type region 302 can be formed using conventional chemical vapor deposition (CVD) process, by driving-in an n-type dopant using a diffusion furnace, or other similar doping or film deposition techniques.
  • the formed p-n junction will form a p-n junction region 303.
  • An arc layer 311 or antireflective coating, can be formed on the light-receiving surface 329 using a physical vapor deposition (PVD) or CVD technique.
  • PVD physical vapor deposition
  • an aperture 312 is formed in the arc layer 311 so that a metal line can directly contact the n-type region 302.
  • the apertures 312, as shown may formed in the arc layer 311 formed using a conventional lithography and wet or dry etching semiconductor processing techniques or by use of conventional laser drilling processes.
  • step 204 as shown in Figure 3C, a seed layer 321 is formed over desired regions of the substrate surface using a conventional selective deposition process, such as an electroless or selective CVD deposition process.
  • a conventional selective deposition process such as an electroless or selective CVD deposition process.
  • An example of electroless deposition process that may be used to grow a seed layer 321 on a doped silicon region is further described in the United States Patent Application Serial No. 11/385,047 [APPM 9916.02], filed 3/20/2006, United States Patent Application Serial No. 11/385,043 [APPM 9916.04], filed 3/20/2006, and United States Patent Application Serial No. 11/385,041 [APPM 10659], filed 3/20/2006, which are all incorporated by reference in their entirety.
  • the seed layer 321 may be selectively formed by use of an inkjet, rubber stamping, or any technique for the pattern wise deposition (i.e., printing) of a metal containing liquid or colloidal media on the surface of the substrate. After depositing the metal containing liquid or colloidal media on the surface of the substrate it is generally desirable to subsequently perform a thermal post treatment to remove any solvent and promote adhesion of the metal to the substrate surface.
  • An example of pattern wise deposition process that may be used to form a seed layer 321 on a region of a substrate is further described in the United States Patent Application Serial No. 11/530,003 [APPM 10254], filed 9/07/2006, which is incorporated by reference in its entirety.
  • the seed layer 321 is formed from a blanket seed layer 321 A ( Figure 3B), that is deposited over the complete surface of the substrate and then selective regions are removed using conventional masking and etching techniques to form the seed layer 321 ( Figure 3C) that has a desired pattern on the surface of the substrate.
  • a blanket seed layer 321 A may be deposited using a physical vapor deposition (PVD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), or atomic layer deposition (ALD) process.
  • the seed layer 321 may contain a pure metal, metal alloy or other conductive material.
  • the seed layer 321 contains one or more metals selected from the group consisting of nickel (Ni), cobalt (Co), titanium (Ti), tantalum (Ta), rhenium (Rh), molybdenum (Mo), tungsten (W), and ruthenium (Ru). It is desirable to select a deposition process and a metal that forms a good electrical contact, or ohmic contact, between the doped silicon region ⁇ e.g., n-type region 302) and the deposited seed layer 321.
  • the seed layer 321 is selected so that it acts as a barrier to the diffusion of a metal in the subsequently formed conductor 325 during subsequent processing steps.
  • the seed layer 321 may contain one or more metals or metal alloys selected from the group consisting of nickel (Ni), cobalt (Co), titanium (Ti), their suicides, titanium tungsten (TiW), titanium nitride (TiN), tantalum (Ta), tantalum nitride (TaN), molybdenum (Mo), tungsten (W), tungsten suicide (WSi), molybdenum suicide (MoSi), and ruthenium (Ru).
  • the thickness of the seed layer 321 may be between about 0.1 micrometers ( ⁇ m) and about 1 ⁇ m.
  • the seed layer 321 consists of at least two layers of metal that are used to promote adhesion to the surface of the substrate, act as a diffusion barrier, and/or promote the growth of a subsequently deposited metal layer 322 contained within the conductor 325 ( Figure 3D).
  • the seed layer 321 contains a first metal layer that is deposited on the substrate surface(s) and a second metal layer that contains copper. In this configuration the second layer is deposited over the first metal layer so that it can act as a seed on which an electrochemically deposited layer can be formed.
  • the first layer may contain one or more metals or metal alloys selected from the group consisting of nickel (Ni), cobalt (Co), titanium (Ti), titanium nitride (TiN), titanium tungsten (TiW), tantalum (Ta), tantalum nitride (TaN), molybdenum (Mo), tungsten (W), and ruthenium (Ru) that is deposited using an electroless deposition process, a conventional physical vapor deposition (PVD) process or a conventional chemical vapor deposition (CVD) process, and a second copper containing layer may be a substantially pure layer or an alloy that contains one or more metals selected from the group consisting of cobalt (Co), tin (Sn), silver (Ag), gold (Au), aluminum (Al), and nickel (Ni).
  • the second layer may be deposited using an electroless deposition process, a conventional physical vapor deposition (PVD) process or a conventional chemical vapor deposition (CVD
  • the conductor 325 elements are electrochemically deposited over desired regions of the seed layer 321 using a masking plate 410 that contains apertures 413 that preferentially allow the electrochemically deposited material to form therein.
  • the seed layer 321 is cathodically biased relative to an electrode 220 using a power supply 250, which causes the ions in an electrolyte to form a metal layer 322 on the exposed areas of the seed layer 321 created within the apertures 413.
  • the light-receiving side of the solar cell may have a metal pattern similar to the pattern shown in Figure 1 D, which is discussed above.
  • Figures 4A - 4D are cross-sectional views that illustrate various embodiments of a single substrate type electrochemical plating cell 400 that may be used to electrochemically deposit a metal layer on the seed layer 321 during step 206. While Figures 4A - 4D illustrate the substrate in a face-down configuration (e.g., seed layer 321 is facing down) this configuration is not intended to be limiting as to the scope of the invention, since the electrochemical plating cell 400 can be in any desirable orientation, such as face-up, vertically oriented or oriented at some desired angle relative to the horizontal without varying from the scope of the invention.
  • the electrochemical plating cell 400 generally contains a head assembly 405, an electrode 420, a power supply 450 and a plating cell 430.
  • the head assembly 405 may contain a thrust plate 414 and a masking plate 410 that is adapted to hold a metallized substrate 320 in a position relative to the electrode 420 during the electrochemical deposition.
  • an actuator 415 is used to urge the thrust plate 414 and metallized substrate 320 against electrical contacts 412 so that an electrical connection can be formed between a seed layer 321 formed on the surface of the metallized substrate 320 and the power supply 450 through the lead 451.
  • a masking plate 410 need not used.
  • a masking material can be used to allow a metal to be selectively formed on desired regions of the substrate surface.
  • a typical masking material may be a photoresist material that is patterned by conventional techniques.
  • the electrical contacts 412 are formed on a surface of the masking plate 410.
  • the electrical contacts 412 may be formed from separate and discrete conductive contacts (not shown), such as conventional conductive clips or conductive pins, that are nested within a recess formed in the masking plate 410 when the metallized substrate is being urged against the masking plate 410.
  • the electrical contacts ⁇ e.g., contacts 412) may be formed from a metal, such as platinum, gold, or nickel, or another conductive material, such as graphite, copper Cu, phosphorous doped copper (CuP), and platinum coated titanium (Pt/Ti).
  • the masking plate 410 is generally made of a dielectric material that has a plurality of apertures 413 formed therein that allow the electrolyte "A" to contact exposed regions on the substrate surface ⁇ e.g., exposed region 404). This configuration thus allows the preferential formation of an electrochemically deposited metal layer in the exposed regions 404 on the processing surface of the substrate when a cathodic bias of a sufficient magnitude is applied to the seed layer 321.
  • the masking plate 410 is made of glass, a plastic material, and/or a ceramic material that contains a plurality of apertures 413 that are formed in the masking plate 410 using conventional machining operations, such as laser cutting, milling, water-jet cutting, drilling, electro-discharge machining (EDM), wet etch, plasma etch, or stamping processes.
  • the masking plate 410 may be formed from Si ⁇ 2, polyimide, quartz, or other ceramic, plastic, glass, or polymeric material, for example.
  • the surface of the masking plate 410 that is in contact with the processing surface of the substrate contains a compliant material that is adapted to compensate for surface topography on the substrate surface and/or more actively prevent plating of on these covered surfaces.
  • Complaint materials may include polymeric materials ⁇ e.g., rubber materials) and polymeric materials that will not be chemically attacked by the electrolyte. The compliant materials may be soft enough to take-up variations in the topography of the substrate surface.
  • the plating cell 430 generally contains a cell body 431 and an electrode 420.
  • the cell body 431 comprises a plating region 435 and an electrolyte collection region 436 that contains an electrolyte ⁇ e.g., item "A") that is used to electrochemically deposit the metal layer on the substrate surface.
  • the electrode 420 is positioned in the lower portion of the plating region 435 and rests on, or is supported by, the features 434 formed in the cell body 431. In general, it is desirable to increase the surface area of the anode so that high current densities can applied to the electrode 420 relative to the seed layer 321 to increase the plating rate.
  • the electrode 420 is formed in a high- aspect-ratio configuration, which maximizes the surface of the electrode 420 to reduce the current density during the deposition process.
  • the electrode 420 may be formed in spiral shape to maximize the surface area of electrode 420.
  • the electrode 420 may have a plurality of holes, slots, or other features ⁇ e.g., item # 421) that allow fluid to pass therethrough and increase the surface area of the electrode.
  • the surface area of the electrode 420 is greater than about 2 to 10 times of the surface area of the cathode, or area of the metal is plated on the substrate surface.
  • a spiral shape is not intended to be limiting as to the scope of the invention, since any high surface area shape could be used herein, for example a wire mesh structure.
  • the electrode 420 can be formed so that it has a desired shape, such as square, rectangular, circular or oval.
  • the electrode 420 may be formed from material that is consumable ⁇ e.g., copper) during the electroplating reaction, but is more preferably formed from a non- consumable material.
  • a non-consumable electrode may be made of a conductive material that is not etched during the formation the metal layer 332, such as titanium coated copper, platinum coated copper, platinum coated titanium, or ruthenium coated titanium.
  • the plating apparatus, chamber and plating cell may also utilize a conveyor type design that continuously plate a number of substrates at one time, for example, between 25 and 1000 substrates.
  • the substrates in any of the processes described herein may be oriented in a horizontal, vertical or angled orientation relative to the horizontal during step 206.
  • the concentration metal ions near the cathode e.g., seed layer 321 surface
  • the diffusion boundary layer is strongly related to the hydrodynamic boundary layer. If the metal ion concentration is too low and/or the diffusion boundary layer is too large at a desired plating rate the limiting current (i L ) will be reached. The diffusion limited plating process created when the limiting current is reached, prevents the increase in plating rate by the application of more power ⁇ e.g., voltage) to the cathode (e.g., metallized substrate surface).
  • the hydrodynamic and diffusion boundary layers can be improved from a static flow case by directing a flow of the electrolyte to the metallized substrate surface during plating. In operation it is thus desirable to pump an electrolyte "A" from the electrolyte collection region 436 and then past the apertures 413 formed in the masking plate 410 to improve the diffusion boundary layer.
  • the pump 440 may be adapted to deliver the electrolyte from the collection region 436 across the electrode 420 and exposed region 404 and then over a weir 432 separating the plating region 435 and then back into the electrolyte collection region 436.
  • the pump 440 is adapted to deliver the electrolyte in a tangential path across the metallized substrate 320 from a nozzle 437. In this configuration the pump 440 is adapted to move the electrolyte from the collection region 436 and then across the exposed region 404 and then over a weir 432 separating the plating region 435 and then back into the electrolyte collection region 436.
  • the fluid motion created by the pump 440 in either configuration allows the replenishment of the electrolyte components at the exposed region 404 that is exposed at one end of the apertures 413.
  • to reduce the diffusion boundary layer it is desirable to rotate and/or move the metallized substrate 320 and head assembly 405 relative to the electrode 420 during step 206 by use of the actuator 415.
  • the electrochemical plating cell 400 also contains a diffusion plate 481 that is adapted to agitate the fluid near the metallized substrate surface.
  • the diffusion plate 481 is adapted to be move during the plating process by use of coupling shaft 483 and an actuator 482.
  • the moving diffusion plate 481 imparts motion to the electrolyte near the metallized substrate surface, which will reduce the diffusion boundary layer.
  • the diffusion plate 481 contains a plurality protrusions 485 ⁇ e.g., bumps, vanes) on the surface of the diffusion plate 481 to improve the fluid motion across the metallized substrate surface as the diffusion plate 481 is rotated. In cases where the diffusion plate 481 is rotated it may be desirable to use a circular shaped diffusion plate 481 (Figure 4C) rather than the rectangular shape shown in Figure 4B.
  • the actuator 482 is adapted to impart a vibrational motion to the diffuser plate 481 to help improve the diffusion boundary layer at the surface of the metallized substrate.
  • the diffusion plate 481 may have a plurality of holes 484 or pores that can be used to control and direct the flow of electrolyte towards the metallized substrate surface.
  • the diffusion plate 481 is formed from a porous plastic or porous ceramic material.
  • the fluid motion is achieved by the delivery of the electrolyte through a plurality of fluid jets that are oriented towards the metallized substrate surface, such as two or more of the nozzles ⁇ e.g., nozzle 437 in Figure 4D; only a single nozzle 437 is shown).
  • fluid motion is provided by the use of gas jets that deliver a gas into the solution that creates fluid movement due to the vertical motion of the injected gas bubbles due to the buoyancy of the gas in the electrolyte.
  • a dosing system 460 may be used in conjunction with the system controller 251 to control the concentration of the various chemicals found in the electrolyte over time.
  • the dosing system 460 generally includes one or more fluid delivery sources ⁇ e.g., reference numerals 461 , 462), a chemical analysis system 465 and a waste delivery system 464.
  • the waste delivery system 464 is adapted to remove a portion of the electrolyte from the plating cell 430 and deliver it to a waste collection system 463.
  • the fluid sources 461 , 462 are generally configured to deliver one or more of the chemicals to the electrolyte in the plating cell 430.
  • the fluid source 461 is adapted to deliver a powder ⁇ e.g., copper oxide powder) or metal ion containing solution ⁇ e.g., copper sulfate) to the electrolyte to replenish the metal ion concentration plated out during step 206 or step 208 when an inert anode is used.
  • the fluid sources 461 , 462 are adapted to deliver one or more of the chemicals found in the electrolyte that are discussed in conjunction with steps 206 or 208.
  • the chemical analysis system 465 may be an organic ⁇ e.g., Raman spectroscopy, CVS) and/or an inorganic chemical analyzer that are used to measure the properties and concentrations of the chemicals in the electrolyte solution at a desired time. Therefore, by use of the system controller 251 , the fluid sources 461 , 462, the waste delivery system 464, and the chemical analyzer 465, which can feed back the measured results to the system controller 251 , the chemical concentrations in the electrolyte can be controlled as a function of time.
  • the dosing system 460 may be used to perform a conventional "feed and bleed" type chemicals replenishment system.
  • an auxiliary electrode 454 is placed in a desirable position within the plating cell 430 to shape the electric field during the plating process and thus optimize the deposition uniformity of the deposited metal layer 322.
  • the electric field which is created between the biased seed layer 321 relative to the electrode 420, may have significant non-uniformities due to the non-optimal geometric and fluid dynamic characteristics of the plating cell that can be compensated for by use of the auxiliary electrode 454.
  • an auxiliary electrode 454 is positioned within plating region 435 below the diffuser plate 481.
  • the auxiliary electrode 454 is disposed within the electrolyte collection region 436 and thus is in electrical communication with the plating region 435 through the electrolyte flowing over the weir 432. In some cases it may be desirable to place the auxiliary electrode 454 above the diffuser plate 481 and closer to the substrate surface.
  • the auxiliary electrode 454 can be separately biased using a second power supply 453 that is controlled by the system controller 251.
  • An example of an exemplary auxiliary electrode design is further described in the commonly assigned United States Patent Application Serial No. 11/362,432, filed 2/24/2006, which is herein incorporated by reference.
  • Figure 4B illustrates an exploded isometric view of the head assembly 405, metallized substrate 320, diffusion plate 481 and electrode 420 portion of the electrochemical plating cell 400. While the metallized substrate 320 and plating cell 430 components illustrated in Figure 4B have a square shape, this configuration is not intended to limiting to scope of the invention.
  • the metallized substrate 320 is placed in contact with the masking plate 410 so that features 426 ( Figure 5A) can be formed on the exposed regions of the patterned features 425 of the seed layer 321 through the apertures ⁇ e.g., apertures 413A, 413B) formed in the masking plate 410.
  • the patterned features 425 are metallized regions of the seed layer 321 that have been deposited or formed in a desired pattern on the surface 429 of the metallized substrate 320. It should be noted that the apertures 413 formed in the masking plate 410 may be formed in any desirable shape and/or pattern. In one embodiment, the apertures 413 formed in the masking plate 410 may be a rectangular or a circular feature that is between about 100 ⁇ m and about 240 ⁇ m in size.
  • the apertures formed in the masking plate 410 may be a pattern features, for example grid lines or interdigitated grid lines that are between about 100 ⁇ m and about 240 ⁇ m wide and have a length that extends across the substrate surface, such as between about 100 ⁇ m and the length of the substrate in length.
  • the total exposed area on the surface of the substrate which is the sum of all of the cross-sectional areas of all of the apertures 413 at the contacting surface 418 of the masking plate 410, is between about 0.5% and about 100% of the surface area of the surface of the substrate that is in contact with the masking plate 410.
  • the total exposed area of the apertures that are in contact with the non-light-receiving surface, or backside, of the substrate is greater than about 70% of the surface area of the non-light-receiving surface of the substrate. In one embodiment, the total exposed area of the apertures that are in contact with the light-receiving surface of the substrate is less than about 30% of the surface area of the light-receiving surface of the substrate. Preferably, the total exposed area of the apertures that are in contact with the light- receiving surface of the substrate is less than about 10%.
  • the masking plate 410 must be thicker than the maximum electrochemical deposition thickness to allow the masking plate to be separated from the substrate after the deposition process has been performed. Typically, the masking plate may be between about 100 ⁇ m and about 1 cm thick.
  • Figure 4C is an exploded isometric view of the head assembly 405, metallized substrate 320, diffusion plate 481 and electrode 420 portion of the electrochemical plating cell 400 according to another embodiment of the invention.
  • Figure 4C is similar to Figure 4B except that the metallized substrate 320 and plating cell 430 components have a circular shape. This configuration may be useful where the metallized substrate 320 has a circular shape and/or it is desirable to rotate one or more of the components, such as the head assembly 405, metallized substrate 320, diffusion plate 481 and/or electrode 420.
  • Figures 5A and 5D are isometric views of a square and a circular metallized substrate 320 that contains a plurality of features 426 formed on certain regions of the patterned features 425 after step 206 has been performed.
  • a group of circular apertures 413A and slot shaped apertures 413B formed in the masking plate 410 are aligned to the patterned features 425 of the seed layer 321 so that features 426 having a desirable shape and thickness T ( Figure 5A and 5D) can be preferentially formed thereon.
  • the features 426 are formed by cathodically biasing the patterned features 425 using the power supply 450 and the contact(s) 452 so that the metal layer 322 can be grown to a desired thickness.
  • the thickness "t" of the features 426 that form the conductor 325 may be between about 20 ⁇ m and about 40 ⁇ m on the non-light-receiving side of the substrate and between about 1 ⁇ m to about 5 ⁇ m on the light-receiving surface of the substrate, which is hard to accomplish using conventional electroless, PVD and CVD techniques at an acceptable substrate throughput and/or desirable deposition thickness uniformity.
  • the conductor 325 thickness on the non-light-receiving side of the substrate may be between about 40 and about 70 ⁇ m, and on the light receiving side of the substrate the thickness may be between about 1 and about 20 ⁇ m thick.
  • Figures 5B and 5E are isometric views of a square and a circular metallized substrate 320 that contains a plurality of features 426 formed on a blanket seed layer 321 A formed after performing step 206 of the method steps 200.
  • a group of features 426 formed on selected areas of the blanket film 321 A that have a shape defined by the apertures (e.g., apertures 413A, 413B) and a thickness "t" set by the deposition rate and deposition time of electrochemical deposition process performed in step 206.
  • the features 426 may be formed on desirable regions of the blanket film 321 A by aligning the masking plate 410 to the metallized substrate 320.
  • Figures 5C and 5F are isometric views of a metallized substrate 320 that contains only the plurality of features 426 formed on the surface 429 of the metallized substrate 320 after an optional metal layer removal step is performed.
  • the optional metal layer removal step generally entails performing a conventional wet or dry etching step to remove any unwanted and/or excess metal on the surface 429 of the substrate, such as unused portions of the blanket seed layer 321 A ( Figures 5B or 5E) or unused portions of the patterned features 425 ( Figures 5A or 5D).
  • Conventional wet etching steps may use an acid or basic solution that is adapted to remove the unwanted and/or excess metal on the surface 429.
  • the system controller 251 is adapted to control the various components used to complete the electrochemical process performed in the electrochemical plating cell 400.
  • the system controller 251 is generally designed to facilitate the control and automation of the overall process chamber and typically includes a central processing unit (CPU) (not shown), memory (not shown), and support circuits (or I/O) (not shown).
  • the CPU may be one of any form of computer processors that are used in industrial settings for controlling various system functions, chamber processes and support hardware ⁇ e.g., detectors, robots, motors, gas sources hardware, etc.) and monitor the electrochemical plating cell processes ⁇ e.g., electrolyte temperature, power supply variables, chamber process time, I/O signals, etc.).
  • the memory is connected to the CPU, and may be one or more of a readily available memory, such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote.
  • Software instructions and data can be coded and stored within the memory for instructing the CPU.
  • the support circuits are also connected to the CPU for supporting the processor in a conventional manner.
  • the support circuits may include cache, power supplies, clock circuits, input/output circuitry, subsystems, and the like.
  • a program (or computer instructions) readable by the system controller 251 determines which tasks are performable on a substrate.
  • the program is software readable by the system controller 251 that includes code to perform tasks relating to monitoring and execution of the electrochemical process recipe tasks and various chamber process recipe steps.
  • one or more direct current (DC) and/or pulse plating waveforms are delivered to the seed layer 321 during the electrochemical deposition process to form the metal layer 322 that has desirable electrical and mechanical properties.
  • the applied bias may have a waveform that is DC and/or a series of pulses that may have a varying height, shape and duration to form the conductor 325.
  • a first waveform is applied to the seed layer 321 by use of a power supply 250 to cause some electrochemical activity at the surface of the seed layer.
  • the time average of the energy delivered by the application of the first waveform is cathodic and thus will deposit a metal on the surface of the seed layer 321.
  • concentration gradients of metal ions, additives or suppressors in the electrolyte "A" ( Figures 4A and 4D) in the proximity of the conductor 325 are affected by the polarity, sequencing, and durations of bias delivered to the surface of the substrate.
  • a deposition pulse during a pulse plating type process controls the deposition on the sidewall of the feature, while the dissolution pulse creates additional metal ions and thus, a concentration gradient of these ions, around the feature.
  • An example of a pulse plating process that may be used to form a metal feature on the substrate surface is further described in the co- pending United States Patent Application Serial No. 11/552,497 [APPM 11227], filed 10/24/2006 and entitled "Pulse Plating of a Low Stress Film on A Solar Cell Substrate", which is herein incorporated by reference in its entirety.
  • the temperature of the electrolyte is controlled within a range of about 18 0 C and about 85 °C, and preferably between about 30 °C and about 70°C to maximize the plating rate.
  • FIG. 6 illustrates a graph of the effect of temperature on maximum current density for two different electrolyte chemistries described in Example 1 and Example 2, shown below.
  • a conductor 325 that is defect free, has a low stress that can be rapidly deposited on the substrate surface.
  • the electrochemical process performed in the electrochemical plating cell 400 utilizes an electrolyte solution containing a metal ion source and an acid solution.
  • one or more additives such as an accelerator, a suppressor, a leveler, a surfactant, a brightener, or combinations thereof may be added to the electrolyte solution to help control the stress, grain size and uniformity of the electrochemically deposited metal layer(s).
  • the electrolyte can optionally contain an inorganic acid, (e.g., sulfuric acid, phosphoric acid or pyrophosphoric acid), various inorganic supporting salts, and other additives that may be used to improve the quality of plated surfaces ⁇ e.g., oxidizers, surfactants, brighteners, etc.).
  • an inorganic acid e.g., sulfuric acid, phosphoric acid or pyrophosphoric acid
  • various inorganic supporting salts e.g., various inorganic supporting salts
  • additives that may be used to improve the quality of plated surfaces ⁇ e.g., oxidizers, surfactants, brighteners, etc.
  • the metal ion source within the electrolyte solution used in step 206 in Figures 2 is a copper ion source.
  • the concentration of copper ions in the electrolyte may range from about 0.1 M to about 1.1 M, preferably from about 0.4 M to about 0.9 M.
  • Useful copper sources include copper sulfate (CuSO 4 ), copper chloride (CuCI 2 ), copper acetate (Cu(CO 2 CHs) 2 ), copper pyrophosphate (Cu 2 P 2 O 7 ), copper fluoroborate (Cu(BF 4 ) 2 ), derivatives thereof, hydrates thereof or combinations thereof.
  • the electrolyte composition can also be based on the alkaline copper plating baths (e.g., cyanide, glycerin, ammonia, etc) as well.
  • the electrolyte is an aqueous solution that contains between about 200 and 250 g/l of copper sulfate pentahydrate (CuSO 4 »5(H 2 O)), between about 40 and about 70 g/l of sulfuric acid (H 2 SO 4 ), and about 0.04 g/l of hydrochloric acid (HCI).
  • a low cost pH adjusting agent such as potassium hydroxide (KOH) or sodium hydroxide (NaOH) to form an inexpensive electrolyte that has a desirable pH to reduce the cost of ownership required to form a metal contact structure for a solar cell.
  • KOH potassium hydroxide
  • NaOH sodium hydroxide
  • a low acid chemistry is used to complete the high speed deposition process.
  • An example of some exemplary copper plating chemistries that may be used for high speed plating is further described in commonly assigned United States Patents 6,113,771 , 6,610,191 , 6,350,366, 6,436,267, and 6,544,399, which are all incorporated by reference in their entirety.
  • the electrolyte is an aqueous solution that contains between about 220 and 250 g/l of copper fluoroborate (Cu(BF 4 ) 2 ), between about 2 and about 15 g/l of tetrafluoroboric acid (HBF 4 ), and about 15 and about 16 g/l of boric acid (H 3 BO 3 ).
  • a pH adjusting agent such as potassium hydroxide (KOH), or sodium hydroxide (NaOH) to form an inexpensive electrolyte that has a desirable pH to reduce the cost of ownership required to form a metal contact structure for a solar cell.
  • TMAH tetramethylammonium hydroxide
  • the electrolyte is an aqueous solution that contains between about 60 and about 90 g/l of copper sulfate pentahydrate (CuSO 4 » 5(H 2 O)), between about 300 and about 330 g/l of potassium pyrophosphate (K 4 P 2 O 7 ), and about 10 to about 35 g/l of 5-sulfosalicylic acid dehydrate sodium salt (C 7 H 5 O 6 SNa » 2H 2 O).
  • CuSO 4 » 5(H 2 O) copper sulfate pentahydrate
  • K 4 P 2 O 7 potassium pyrophosphate
  • C 7 H 5 O 6 SNa » 2H 2 O 5-sulfosalicylic acid dehydrate sodium salt
  • a pH adjusting agent such as potassium hydroxide (KOH), or sodium hydroxide (NaOH) to form an inexpensive electrolyte that has a desirable pH to reduce the cost of ownership required to form a metal contact structure for a solar cell.
  • KOH potassium hydroxide
  • NaOH sodium hydroxide
  • TMAH tetramethylammonium hydroxide
  • the electrolyte is an aqueous solution that contains between about 30 and about 50 g/l of copper sulfate pentahydrate (CuSO 4 »5(H 2 O)), and between about 120 and about 180 g/l of sodium pyrophosphate decahydrate (Na 4 P 2 O 7 -IO(H 2 O)).
  • a pH adjusting agent such as potassium hydroxide (KOH), or sodium hydroxide (NaOH) to form an inexpensive electrolyte that has a desirable pH to reduce the cost of ownership required to form a metal contact structure for a solar cell.
  • TMAH tetramethylammonium hydroxide
  • a second metal ion to the primary metal ion containing electrolyte bath (e.g., copper ion containing bath) that will plate out or be incorporated in the growing electrochemically deposited layer or on the grain boundaries of the electrochemically deposited layer.
  • the formation of a metal layer that contains a percentage of a second element can be useful to reduce the intrinsic stress of the formed layer and/or improve its electrical and electromig ration properties.
  • a silver (Ag), nickel (Ni), zinc (Zn), or tin (Sn) metal ion source to a copper plating bath to form a copper alloy that has between about 1% and about 4% of the second metal in the deposited layer.
  • the metal ion source within the electrolyte solution used in step 206 in Figure 2 is a silver, tin, zinc or nickel ion source.
  • the concentration of silver, tin, zinc or nickel ions in the electrolyte may range from about 0.1 M to about 0.4M.
  • Useful nickel sources include nickel sulfate, nickel chloride, nickel acetate, nickel phosphate, derivatives thereof, hydrates thereof or combinations thereof.
  • an optional contact interface layer 323 is deposited over the surface of the metal layer 322 formed during step 206.
  • the contact interface layer 323 can be formed using an electrochemical deposition process, an electroless deposition process, a CVD deposition process, or other comparable deposition processes to form a good ohmic contact between the formed conductors 325 and an external interconnection bus (not shown) that is adapted to connect one or more solar cells together.
  • the contact interface layer 323 is formed from a metal that is different from the metal contained in the metal layer 322.
  • the contact interface layer 323 may be formed from a pure metal or metal alloy that contains metals, such as tin (Sn), silver (Ag), gold (Au), copper (Cu) or lead (Pb).
  • the thickness of the contact interface layer 323 may be between about 3 ⁇ m and about 7 ⁇ m. Forming a contact interface layer 323 having a thickness greater than 3 ⁇ m is generally hard to accomplish using conventional electroless, PVD and CVD techniques at an acceptable substrate throughput and/or desirable deposition thickness uniformity.
  • the contact interface layer 323 is formed by use of an electrochemical process. In some cases it is desirable to perform step 208 in the same electrochemical plating cell as step 206 was performed.
  • the seed layer 321 and metal layer 322 are cathodically biased relative to an electrode (e.g., electrode 420 in Figure 4A) using a power supply that causes the ions in an contact interface layer electrolyte, which is brought into contact with the seed layer 321 , metal layer 322 and the electrode, to plate the contact interface layer 323 on the surface of the seed layer 321 and/or metal layer 322.
  • the contact interface layer 323 is formed in the same electrochemical plating cell 400 as the metal layer 322 and the contact interface layer 323 contains one or more different elements than the metal layer 322 the electrolyte used to form the metal layer will need to be discarded and replaced with the new contact interface layer electrolyte to form the contact interface layer 323.
  • the contact interface layer 323 contains tin (Sn) and is deposited by use of an electrochemical deposition process.
  • concentration of tin ions in the contact interface layer electrolyte may range from about 0.1 M to about 1.1 M.
  • Useful tin sources include tin sulfate (SnSO 4 ), tin chloride (SnCI 2 ), and tin fluoroborate (Sn(BF 4 ) 2 ), derivatives thereof, hydrates thereof or combinations thereof.
  • the electrolyte can optionally contain an inorganic acid, ⁇ e.g., sulfuric acid, phosphoric acid or pyrophosphoric acid), various inorganic supporting salts, and other additives that may be used to improve the quality of plated surfaces (e.g., oxidizers, surfactants, brighteners, etc.).
  • the electrolyte composition can also be based on the alkaline tin plating baths ⁇ e.g., glycerin, ammonia, etc) as well.
  • the electrolyte may also contain methane-sulfonic acid (MSA).
  • the electrolyte is an aqueous solution that contains between about 200 and 250 g/l of tin sulfate pentahydrate (SnSO 4 »5(H 2 O)), between about 40 and 70 g/l of sulfuric acid (H 2 SO 4 ), and about 0.04 g/l of hydrochloric acid (HCI).
  • tin sulfate pentahydrate SnSO 4 »5(H 2 O)
  • H 2 SO 4 sulfuric acid
  • HCI hydrochloric acid
  • organic additives e.g., levelers, accelerators, suppressors
  • a low cost pH adjusting agent such as potassium hydroxide (KOH) or sodium hydroxide (NaOH) to form an inexpensive electrolyte that has a desirable pH to reduce the cost of ownership required to form a metal contact structure for a solar cell.
  • KOH potassium hydroxide
  • NaOH sodium hydroxide
  • TMAH tetramethylammonium hydroxide
  • inventions discussed above in conjunction with Figures 2- 5 can be used to form one or more of the conductors 325 on a surface of the substrate. While it is generally desirable to form all of the various contact structures used to form a solar cell device at one time, this is sometimes not possible due to various processing constraints. In some cases two metallization processes are required, for example, to form a front side contact, as shown in Figures 3A-3E, and a second metallization process to form a second contact on a different region of the metallized substrate 320, such as a backside contact 330 shown in Figure 3E.
  • the second metallization step can be used to form the backside contact 330 that is adapted to connect to an active region ⁇ e.g., p-type region in Figure 3A) of the solar cell device.
  • seed layer 331 can be formed using the process steps described above in conjunction with step 204 or other similar techniques.
  • a metal layer 332 and an interconnect layer 333 may be formed using the process steps described above in conjunction with steps 206 - 208 and Figures 2, 3D-3E and 4.
  • the total exposed area of the apertures 413 in the masking plate 410 ( Figures 4A-4D) used to form the backside contact on the substrate surface is between about 70% and about 99% of the surface area of the backside surface of the substrate.
  • FIG. 7A illustrates is a side cross-sectional view of a batch plating apparatus 701 that contains three plating cells 710 that are each adapted to plate one or more metal layers on a metallized substrate surface using the process steps described above ⁇ e.g., steps 206-208). While Figure 7A illustrates a batch plating apparatus 701 that contains three horizontally oriented plating cells 710, this configuration is not intended to be limiting as to the number plating cells that may be used to perform a batch type plating process or the angular orientation of the plating cells relative to each other or to the horizontal. In one aspect, two or more plating cells may be used to perform a batch plating process where two or more substrates are plated at once. In another aspect, the substrates are oriented vertically in the batch plating apparatus during the plating process.
  • the batch plating process is performed by immersing two or more plating cells 710 in a plating tank 751 and then biasing each of the metallized substrates relative to one or more electrodes.
  • each of the plating cells 710 may contain an electrode 420, power supply (e.g., item #s 450A-450C) and a head assembly 405 that is adapted to hold and retain the metallized substrate 320 during the plating process.
  • the plating cells 710 may each contain any of the components described above in conjunction with Figures 4A-4D.
  • the head assembly 405 may contain a thrust plate 414 that is used to urge the metallized substrate 320 against the electrical contacts 412 and masking plate 410 by use of an actuator (see Figure 4B).
  • the metallized substrates 320 are loaded into the head assemblies 405 of the respective plating cells 710 and then the plating cells 710 are immersed in the electrolyte "A" contained in the plating tank 751 so that a plating process can be performed.
  • the seed layer 321 on the surface of each of the metallized substrates 320 in each of the plating cells 710 are biased relative to the electrode 420 contained in the respective plating cell 710 using a power supply.
  • each electrode 420 in each plating cell 710 is biased independently from each other using a power supply, such as power supply 250A in the top most plating cell, power supply 250B in the middle plating cell 710 and power supply 250C in the lower plating cell 710.
  • a power supply such as power supply 250A in the top most plating cell, power supply 250B in the middle plating cell 710 and power supply 250C in the lower plating cell 710.
  • the electrolyte may be delivered to the region between the electrode 420 and the metallized substrate 320 using a fluid delivery system 441 that contains a pump 440.
  • FIG. 7B illustrates a plan view of a batch plating system 750 that contains an array of the batch plating apparatuses 701 illustrated in Figure 7A.
  • an array of plating cells 710 in each of the batch plating apparatuses 701 are immersed with an electrolyte retained in the plating tank 751 so that steps 206 or 208 can be performed.
  • an array of plating cells 710 in each of the batch plating apparatuses 701 are distributed around a spraying device 752 that is adapted to deliver a flow of electrolyte to a region between the electrode 420 and substrate 320 contained within each of the plating cells 710.
  • the spraying device 752 may connected to a pump (not shown) that is adapted to recirculate the electrolyte through the plating cells 710.
  • Figure 7I illustrates a plan view of a batch plating system 750 that contains an array of the batch plating apparatuses 701 illustrated in Figure 7A that are adapted to process circular type substrates.
  • FIG. 7C illustrates an isometric view of another embodiment of a batch plating system, hereafter batch plating system 760, which is adapted to plate multiple metallized substrates that are arrayed in horizontal orientation and immersed within an tank containing an electrolyte solution.
  • the head assembly 765 is adapted to retain a plurality of substrates in a desirable position relative to an electrode 420.
  • each of the metallized substrates 320 may be separately biased relative to the electrode 420 using one of the dedicated power supplies 450A-450C.
  • one or more masking plates (not shown) may be positioned against the surface of the substrates retained in the head assembly 765 to allow for a preferential deposition of desired regions on each of the substrates.
  • the electrode 420 may be formed from a plurality of electrodes that can be separately biased relative to a metallized substrate 320. While the metallized substrates in Figure 7C, are circular in shape this configuration is not intended to limiting as to the scope of invention described herein.
  • the plating apparatus, chamber and plating cell may also utilize a conveyor type design that continuously plate a number of substrates at one time, for example, between 25 and 1000 substrates.
  • the substrates in any of the processes described herein may be oriented in a horizontal, vertical or angled orientation relative to the horizontal during step 206.
  • Figures 7D-7F illustrate one embodiment of a batch plating chamber 780 that is adapted to plate both sides of multiple metallized substrates 320 that are immersed within an electrolyte tank 770.
  • the batch plating chamber 780 may be adapted to sequentially plate each side of multiple metallized substrates 320, or plate both sides of multiple metallized substrates 320 at the same time.
  • Figure 7D illustrates a side cross-sectional view of a batch plating chamber 780 that is adapted to deposit a metal layer on the surface of the metallized substrates 320 using steps 206 and/or 208, discussed above.
  • the batch plating chamber 780 generally contains a head assembly 776, one or more electrodes (e.g., reference numerals 771 , 772), an electrolyte tank 770, and one or more power supplies ⁇ e.g., reference numerals 775A, 775B) that are adapted to form one or more conductors 325 on a surface of the metallized substrate 320.
  • Figure 7D illustrates a batch plating chamber 780 that contains a plurality of vertically oriented metallized substrates, this configuration is not intended to be limiting as to the scope of the invention.
  • the substrates are oriented horizontally in the batch plating apparatus during the plating process.
  • Figure 7D illustrates an isometric view of the head assembly 776 that contains a plurality of cell assemblies 782 that are adapted to retain and preferentially form the conductors 325 on one or more surfaces of the plurality of metallized substrates 320 using an electrochemical plating process.
  • the cell assemblies 782 contain at least one masking plate assembly 779, an actuator 777, and a support frame 781 that are adapted to hold and make electrical contact to a conductive layer ⁇ e.g., seed layer 321) formed on one or more sides of the metallized substrates 320.
  • the head assembly 776 illustrated in Figure 7E, contains 20 cell assemblies 782 this configuration is not intended to be limiting to the scope of the invention, since the head assembly 766 could contain two or more cell assemblies 782 without varying from the scope of the invention described herein.
  • the cell assembly 782 contains between about 2 and about 1000 metallized substrates at one time.
  • the masking plate assemblies 779 may contain a plurality of masking plates 410 ( Figure 4A) that are held together by a supporting structure (not shown) that allows each of the masking plates 410 to contact a surface of a metallized substrate so that apertures 413 and contacts 412 ( Figure 4A) contained therein can be used to preferentially form the conductors 325 on a surface of each of the metallized substrates 320.
  • the masking plate assemblies 779 is a plate, or multiple plates, that are adapted to contact multiple metallized substrates 320 at one time so that apertures 413 formed therein can be used to preferentially form the conductors 325 on the surface of each of the metallized substrates 320.
  • Figure 7F illustrates a close-up partial section view of one cell assembly 782 that can be used to form a metal layer on the feature 425 through an aperture 413 formed in the masking plate assembly 779.
  • the contacts 412 ( Figure 4A) are electrically connected to portions of the support frame 781 so that a bias can be applied to each of the contacts in each of the cell assemblies 782 relative to one of the one or more electrodes 771 , 772 by use of a single electrical connection to a single power supply.
  • discrete electrical connections provided through the masking plate assembly 779 or support frame 781 to each of one or more of the contacts 412 in each of the cell assemblies 782 so that each of the one or more of the contacts 412 can be separately biased relative to one of the one or more electrodes 771 , 772 by use of different power supplies.
  • the electrolyte tank 770 generally contains a cell body 783 and one or more electrodes 771 , 772.
  • the cell body 783 comprises a plating region 784 and an electrolyte collection region 785 that contains an electrolyte (e.g., item "A") that is used to electrochemically deposit the metal layer on a conductive region formed on the substrate surface.
  • the electrode 771 , 772 are positioned vertically in the plating region 784 and are supported by one ore more of the walls of the cell body 783.
  • the electrodes 771 , 772 can be formed so that they have a desired shape, such as square, rectangular, circular or oval.
  • the electrodes 771 , 772 may be formed from material that is consumable (e.g., copper) during the electroplating reaction, but is more preferably formed from a non-consumable material.
  • a metallized substrate 320 is positioned in each of the cell assemblies 782 within the head assembly 776 so that electrical contacts (e.g., reference numerals 412 in Figures 4A-4D), found in each cell assembly 782, can be placed in contact with one or more conductive regions on the metallized substrate surface.
  • the metallized substrates 320 are positioned on the support frame 781 within each cell assembly 782 and then are clamped to the support frame 781 by use of the actuator 777 (e.g., air cylinder) contained in the head assembly 776 so that the masking plate assembly 779 and contacts 412 can contact the substrate surface.
  • the actuator 777 e.g., air cylinder
  • the metallized substrates are placed between opposing masking plate assemblies 779 and then clamped together by use of the actuator 777.
  • the head assembly 776 is immersed into the electrolyte contained in the electrolyte tank 770 so that a metal layer ⁇ e.g., reference numeral 322) can be formed on the conductive regions by biasing them relative to the one or more electrodes 771 , 772 using one or more of the power supplies 755A, 775B.
  • the electrolyte tank 770 may also contain a pump 778 may be adapted to deliver the electrolyte from the electrolyte collection region
  • the pump 778 is adapted to deliver electrolyte to a gap formed between the head assembly 776 and the electrodes 771 , 772 and then over a weir
  • the actuator 787 comprises an AC motor, piezoelectric device or other similar mechanical component that can impart motion to the head assembly 776.
  • Figure 7G illustrates a side cross-sectional view of a plating system 790 that contains two or more batch plating cells 780 that are positioned near each other so that the substrates positioned in the moveable head assembly 776 can be sequentially plated using different electrolytes or different plating parameters.
  • the head assembly 776 can be sequentially positioned in each of the batch plating cells 780 so that metal layers can be electrochemically deposited on the substrate surface by applying a bias to the individual substrates retained in the head assembly 776 relative to the electrodes 771 , 772 contained in the batch plating cells 780.
  • Figure 7G illustrates, one embodiment that contains three batch plating cells 780A-780C that each contain different electrolytes, such as A 1 , A 2 , and A 3 , respectively.
  • the actuator 787 is a device, such as a conventional robot, gantry crane or similar devices, which can be used to lift and transfer the head assembly 776 between the various batch plating cells 780.
  • a head assembly 776 that contains one or more metallized substrates 320 is immersed in the first batch plating cell 780A that contains a first electrolyte A 1 so that a first metal layer can be formed on the surface of the metallized substrates 320.
  • the one or more metallized substrates 320 contained in the head assembly 776 may be plated by biasing conductive features on the substrate surfaces relative to one or more of the electrodes 771 A, 772A positioned in the electrolyte A 1 using one or more of the power supplies 775A 1 , 775B 1 .
  • the head assembly 776 After depositing a desired amount of material on the surface of the substrates the head assembly 776 is transferred following path B 1 to an adjacent second batch plating cell 780B so that a second metal layer can be deposited on the surface of the metallized substrates.
  • the metallized substrates 320 contained in the head assembly 776 may be plated by biasing conductive features on the substrate surfaces relative to one or more of the electrodes 771 B, 772B positioned in the electrolyte A 2 using one or more of the power supplies 775A 2 , 775B 2 .
  • the head assembly 776 After depositing a second desired amount of material on the surface of the substrates the head assembly 776 is transferred following path B 2 to an adjacent third batch plating cell 780C so that a third metal layer can be deposited on the metallized substrate surface.
  • the metallized substrates 320 contained in the head assembly 776 may be plated by biasing conductive features on the substrate surfaces relative to one or more of the electrodes 771 C, 772C positioned in the electrolyte A 3 using one or more of the power supplies 775A 3 , 775B 3 .
  • FIG. 7H illustrates a side partial-sectional view of a plating system 795 that contains an electrolyte tank 796 that allows the substrates positioned in a head assembly 776 to be sequentially plated by positioning the head assembly 776 near two or more electrode assemblies 797 positioned in the electrolyte tank 796.
  • the substrates contained in the head assembly 776 are positioned within a single electrolyte "A" that is used in conjunction with a two or more electrode assemblies 797 to sequentially plate the substrates using different plating parameters (e.g., local electrolyte flow rate, current density).
  • the metallized substrates 320 positioned in the head assembly 776 can be plated by positioning them near or slowly transferring them past each of the electrode assemblies 797 that are biased relative to the conductive features on the substrate surface.
  • one or more of the plating parameters are varied as the head assembly 776 are positioned near different electrode assemblies 797.
  • both sides of a substrate are plated by electrically biasing a first electrode 797A positioned on one side of the head assembly 767 and by electrically biasing a second electrode 797B positioned on the other side of the head assembly 767 relative to the conductive features formed on the substrate surface using one or more power supplies (not shown) and the system controller 251.
  • the actuator 787 is a device, such as a conventional robot, gantry crane or similar devices, that can be used to transfer the head assembly 776 "in” and "out” of the electrolyte tank 796 and near the various electrode assemblies 797.
  • a device such as a conventional robot, gantry crane or similar devices, that can be used to transfer the head assembly 776 "in” and "out” of the electrolyte tank 796 and near the various electrode assemblies 797.
  • multiple head assemblies 776 can be inserted into the electrolyte tank 796 at one time to allow for a more seemless "assembly line” type process flow through the various different process steps that may be used to form the conductors 325 on the surface of the substrates contained in each of the head assembly 776.
  • an optional seed layer removal step is performed after completing step 208.
  • the seed layer removal step generally entails performing a conventional wet or dry etching step to remove any unwanted and/or excess metal found on the surface of the substrate, such as unused or un-necessary portions of the seed layer 321.
  • Conventional wet etching steps may involve immersing the substrate in an acidic or basic solution that is adapted to remove the unwanted and/or excess metal on the surface of the substrate.
  • a wet etch chemistry that preferentially etches the seed layer 321 versus the material in the interface layer 323.
  • step 210 one or more post processing steps are performed to reduce the stress or improve the properties of the deposited metal layers ⁇ e.g., metal layers 321 , 322 ,323, 331 , 332, 333).
  • the post processing steps that may be performed during step 210 may be include an anneal step, a clean step, a metrology step or other similar types of processing steps that are commonly performed on after metallizing a surface of the substrate.
  • an annealing step is performed on the solar cell substrate to reduce or even out the intrinsic stress contained in the formed metal layers.
  • the annealing process is performed at a temperature between about 200 and 450 °C in a low partial pressure of nitrogen environment.
  • an anneal process is used to enhance the electrical contact between the formed metal layers and/or the adhesion of the metal layers to the substrate surface, and suicide formation.
  • the electrolyte solution is removed from the plating tank 751 ( Figures 7A and 7B) after processing and then a rinsing process is performed on the metallized substrates contained in each of the batch plating apparatuses 701.
  • the rinsing process may include a Dl water rinse and a spin dry step ⁇ e.g., rotating the head assembly 405) to remove the electrolyte from the surface of the substrate and dry the substrates.
  • FIG. 8 illustrates a series of method steps 800 that are used to form metal contact structures on a solar cell device using the apparatus described herein.
  • the processes described below may be used to form a solar cell having interconnects formed using any conventional device interconnection technique.
  • this interconnect configuration is not intended to be limiting as to the scope of the invention, since other device configurations, such as PUM or multilayer buried contact structures (both contacts on one side), may be formed using the apparatus and methods described herein without varying from the basic scope of the invention.
  • FIGS 9A-9E illustrate the various states of a metallized substrate 320 after each step of method steps 800 has been performed.
  • the method steps 800 start with step 802 in which a substrate 301 ( Figure 9A) is formed using conventional solar cell and/or semiconductor fabrication techniques.
  • the substrate 301 may be formed using the steps described in step 202, discussed above.
  • a blanket seed layer 321 A is deposited over the surface of the substrate 301.
  • a blanket seed layer 321 A may be deposited using a physical vapor deposition (PVD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), or atomic layer deposition (ALD) process.
  • PVD physical vapor deposition
  • CVD chemical vapor deposition
  • MBE molecular beam epitaxy
  • ALD atomic layer deposition
  • step 806 the masking plate 410 ( Figures 4A-4D) is used to mask regions of the blanket seed layer 321 A and preferentially expose regions of the blanket seed layer 321 A where the metal layer 322 of the conductors 325 are to be formed.
  • an aperture i.e., aperture 413 in Figure 4A-4D
  • the masking plate reference numeral 410 in Figures 4A-4D
  • a conductor 325 can be formed thereon using of the apparatuses, chemicals and methods discussed in conjunction with step 206 above.
  • the blanket seed layer 321 A is cathodically biased relative to an electrode (reference numeral 420 in Figures 4A-4D) using a power supply that causes the ions in an electrolyte to form a metal layer 322 on the exposed areas of the blanket seed layer 321 A created within the apertures in the masking plate.
  • an optional contact interface layer 323 is deposited over the surface of the metal layer 322 formed during step 806.
  • the contact interface layer 323 can be formed using an electrochemical deposition process that utilizes a masking plate (reference numeral 410 in Figures 4A-4D) to preferentially form an interface layer 323 over the metal layer 322 formed in step 806.
  • the interface layer 323 formed in step 808 may be formed using the apparatus, chemicals and methods described above in conjunction with step 208.
  • the blanket seed layer 321 A is removed from surface of the substrate.
  • the blanket seed layer removal step generally entails performing a conventional wet or dry etching step to remove any unwanted and/or excess metal found on the surface of the substrate, such as unused portions of the blanket seed layer 321 A.
  • Conventional wet etching steps may involve immersing the substrate in an acidic or basic solution that is adapted to remove the unwanted and/or excess metal on the surface of the substrate.
  • a wet etch chemistry that preferentially etches the seed layer 321A versus the material in the interface layer 323 is used.
  • a backside metallization process is performed on the metallized substrate 320 after step 810 by use of a process similar to the one discussed above in conjunction the Figure 3F, described above.
  • step 810 is performed prior to performing step 808.
  • step 810 is performed prior to performing step 808.
  • the excess blanket seed layer 321 A is removed from the surface of the metallized substrate 321 A, thus leaving the metal layer 322 or a good portion thereof, so that the interface layer 323 can be preferentially formed on the metal layer 322 using an electroless deposition process, a conventional selective CVD deposition process, electrochemical deposition process, or other comparable deposition processes.
  • FIG. 10 illustrates a series of method steps 1000 that can be used to form the conductors 325 on a surface of the solar cell substrate.
  • Figures 11 A-111 illustrate the various states of a metallized substrate 320 after each step of method steps 1000 has been performed. The method steps 1000 start with step 1002 in which a substrate 301 ( Figure 11A) is formed using conventional solar cell and/or semiconductor fabrication techniques.
  • the substrate 301 may be formed using the steps described in step 202, discussed above.
  • step 1004 as shown in Figures 10 and 11 B, blanket seed layer 321 A is deposited over the surface of the substrate 301.
  • a blanket seed layer 321 A may be deposited using a physical vapor deposition (PVD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), or atomic layer deposition (ALD) process.
  • PVD physical vapor deposition
  • CVD chemical vapor deposition
  • MBE molecular beam epitaxy
  • ALD atomic layer deposition
  • a masking layer 821 is deposited over the blanket seed layer 321 A.
  • the masking layer 821 is a non-conductive material that can be deposited on a surface of the substrate.
  • the masking layer is an organic material, such as photoresist, that is deposited on the blanket seed layer 321 A by use of a conventional spin-coating, CVD or other similar process.
  • step 1006 the masking layer 821 is patterned to expose regions of the substrate surface where conductors are to be formed.
  • an aperture 822 is formed in the masking layer 821 to expose the blanket seed layer 321 A by use of conventional photolithography exposure and chemical develop steps, laser ablation, or other methods of preferentially removing regions of a masking layer.
  • steps 1004 and 1006 are combined so that a patterned layer is directly formed on the surface of the blanket seed layer 321 A.
  • the masking layer 821 is directly formed in a patterned configuration (Ae., having apertures 822 form therein), similar to Figure 11 D, by use of a screen-printing, ink-jet printing, rubber stamping, or other similar process that deposits a material that cannot be "plated on" on the substrate surface.
  • the masking layer 821 is a non-conductive material, such an organic material. In this configuration the masking layer 821 that can directly deposits a patterned masking layer material on the surface of the substrate.
  • step 1008 the conductors 325 are formed in the apertures 822 by use of an electrochemical plating process.
  • step 1008 uses the processes and chemistries described above in conjunction with step 206.
  • the blanket seed layer 321 A is cathodically biased relative to an electrode (not shown) using a power supply that causes the ions in an electrolyte to form a metal layer 322 on the exposed areas of the blanket seed layer 321 A created within the apertures 822.
  • the masking plate 410 used in steps 206-208 is not needed, since the masking layer 821 contains a desired pattern that is used to form the deposited conductors 325.
  • the light-receiving side of the solar cell may have a metal pattern similar to the pattern shown in Figure 1 D, which is discussed above.
  • the patterned masking layer 821 is removed from surface of the blanket seed layer 321 A.
  • the masking layer 821 can be removed by use of a liquid solvent, RF plasma oxidation process (e.g., conventional ashing processes), thermal baking processing, or other similar conventional techniques.
  • step 1012 the blanket seed layer 321 A is removed from surface of the substrate.
  • the blanket seed layer removal step generally entails performing a conventional wet or dry etching step to remove any unwanted and/or excess metal on the surface of the substrate, such as unused portions of the blanket seed layer 321 A.
  • Conventional wet etching steps may involve immersing the substrate in an acidic or basic solution that is adapted to remove the unwanted and/or excess metal on the surface of the substrate.
  • an optional contact interface layer 323 is deposited over the surface of the metal layer 322 formed during step 1008.
  • the contact interface layer 323 can be formed using an electrochemical deposition process, an electroless deposition process, a CVD deposition process, or other comparable deposition processes to form a good ohmic contact between the formed conductors 325 and an external interconnection bus (not shown) that is adapted to connect one or more solar cells together.
  • Step 1014 may be used to form the metal layer 323 using of the chemicals and methods described above in conjunction with step 208.
  • the contact interface layer 323 is deposited over the surface of the metal layer 322, using step 1014, prior to removing the patterned masking layer 821 using step 1012.
  • a backside metallization process is performed on the metallized substrate 320 by use of a process similar to the one discussed above in conjunction the Figure 3F, described above.

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Abstract

Des modes de réalisation de l'invention concernent la formation d'une cellule solaire à faible coût en utilisant un nouveau procédé et un nouvel appareil permettant de former une structure de contact métallique comportant des lignes métalliques formées sélectivement en employant un procédé de placage électrochimique. L'appareil et les procédés décrits ici évitent la mise en œuvre d'un ou plusieurs procédés de sérigraphie à haute température visant à former des caractéristiques conductrices sur la surface d'un substrat de cellule solaire. La résistance des interconnexions formées dans un dispositif de cellule solaire affecte considérablement l'efficacité de la cellule solaire. Il est donc souhaitable de former un dispositif de cellule solaire qui a une connexion de faible résistance, qui est fiable et économique. Par conséquent, un ou plusieurs modes de réalisation de l'invention décrits ici sont adaptés à la formation d'une couche d'interconnexion à faible coût et fiable en employant un procédé de placage électrochimique contenant un métal courant, tel que le cuivre.
PCT/US2007/086145 2006-12-01 2007-11-30 Appareil et procédé de dépôt électrochimique sur un substrat de cellule solaire WO2008070568A2 (fr)

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US11/566,201 2006-12-01
US11/566,202 2006-12-01
US11/566,202 US7704352B2 (en) 2006-12-01 2006-12-01 High-aspect ratio anode and apparatus for high-speed electroplating on a solar cell substrate
US11/566,201 US20080128019A1 (en) 2006-12-01 2006-12-01 Method of metallizing a solar cell substrate

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL2009382A (en) * 2012-08-29 2014-03-03 M4Si B V Method for manufacturing a solar cell and solar cell obtained therewith.
DE102019134116A1 (de) * 2019-12-12 2021-06-17 AP&S International GmbH Vorrichtung zum stromlosen Metallisieren einer Zieloberfläche wenigstens eines Werkstücks sowie Verfahren und Diffusorplatte hierzu
CN115498050A (zh) * 2022-09-23 2022-12-20 通威太阳能（成都）有限公司 一种太阳电池及其制备方法
CN116845116A (zh) * 2022-03-24 2023-10-03 环晟光伏(江苏)有限公司 太阳能电池及其制作方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI422054B (zh) * 2010-04-16 2014-01-01 Gintech Energy Corp 光伏面板及其製造方法
CN114959842B (zh) * 2021-02-18 2024-06-07 日月光半导体制造股份有限公司 电镀装置及制造封装结构的方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849880A (en) * 1969-12-12 1974-11-26 Communications Satellite Corp Solar cell array
US20040074762A1 (en) * 2002-10-18 2004-04-22 Applied Materials, Inc. Method and apparatus for sealing electrical contacts during an electrochemical deposition process
US20050199489A1 (en) * 2002-01-28 2005-09-15 Applied Materials, Inc. Electroless deposition apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849880A (en) * 1969-12-12 1974-11-26 Communications Satellite Corp Solar cell array
US20050199489A1 (en) * 2002-01-28 2005-09-15 Applied Materials, Inc. Electroless deposition apparatus
US20040074762A1 (en) * 2002-10-18 2004-04-22 Applied Materials, Inc. Method and apparatus for sealing electrical contacts during an electrochemical deposition process

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL2009382A (en) * 2012-08-29 2014-03-03 M4Si B V Method for manufacturing a solar cell and solar cell obtained therewith.
WO2014035242A1 (fr) * 2012-08-29 2014-03-06 M4Si B.V. Procédé de fabrication d'une cellule solaire et cellule solaire obtenue par ce procédé
CN104737299B (zh) * 2012-08-29 2017-04-05 M4Si公司 太阳能电池的制造方法及其制得的太阳能电池
DE102019134116A1 (de) * 2019-12-12 2021-06-17 AP&S International GmbH Vorrichtung zum stromlosen Metallisieren einer Zieloberfläche wenigstens eines Werkstücks sowie Verfahren und Diffusorplatte hierzu
US12247292B2 (en) 2019-12-12 2025-03-11 Ap & S International Gmbh Apparatus for electroless metallization of a target surface of at least one workpiece, and method and diffuser plate for this purpose
CN116845116A (zh) * 2022-03-24 2023-10-03 环晟光伏(江苏)有限公司 太阳能电池及其制作方法
CN115498050A (zh) * 2022-09-23 2022-12-20 通威太阳能（成都）有限公司 一种太阳电池及其制备方法
CN115498050B (zh) * 2022-09-23 2024-03-29 通威太阳能（成都）有限公司 一种太阳电池及其制备方法

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