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WO1996030163A1 - A wafer retainer for retaining a wafer to be polished and a method for attaching/detaching the wafer retainer to/from a base plate of a polishing machine - Google Patents

A wafer retainer for retaining a wafer to be polished and a method for attaching/detaching the wafer retainer to/from a base plate of a polishing machine Download PDF

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Publication number
WO1996030163A1
WO1996030163A1 PCT/JP1996/000806 JP9600806W WO9630163A1 WO 1996030163 A1 WO1996030163 A1 WO 1996030163A1 JP 9600806 W JP9600806 W JP 9600806W WO 9630163 A1 WO9630163 A1 WO 9630163A1
Authority
WO
WIPO (PCT)
Prior art keywords
base plate
wafer
wafer retainer
temperature
retainer
Prior art date
Application number
PCT/JP1996/000806
Other languages
French (fr)
Inventor
Hideyuki Ishii
Yoshitane Shigeta
Original Assignee
Nitta Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nitta Corporation filed Critical Nitta Corporation
Publication of WO1996030163A1 publication Critical patent/WO1996030163A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/687—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches
    • H01L21/68714—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support
    • H01L21/68757—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support characterised by a coating or a hardness or a material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B5/00—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor
    • B24B5/18—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor involving centreless means for supporting, guiding, floating or rotating work
    • B24B5/307—Means for supporting work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/27—Work carriers
    • B24B37/30—Work carriers for single side lapping of plane surfaces
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/26—Porous or cellular plastics
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/68—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for positioning, orientation or alignment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L21/6836—Wafer tapes, e.g. grinding or dicing support tapes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/687—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches
    • H01L21/68714—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support
    • H01L21/68785—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support characterised by the mechanical construction of the susceptor, stage or support
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
    • H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L2221/68327—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support used during dicing or grinding

Definitions

  • the present invention relates to a retainer used for retaining a workplace to be polished, such as a semiconductor wafer, when the workpiece is placed on a base plate of a polishing machine for polishing, and a method for attaching/detaching the retainer to/from the base plate of the polishing machine.
  • the total thickness variation for a wafer after final mirrorfinishing and polishing needs to be 1 micron or less, while the local thickness variation (LTV) over a 20 mm square, which is to be one IC chip, needs to be 0.2 micron or less.
  • the wafer In order to satisfy these precision requirements during the wafer polishing process, the wafer must be mounted on a base plate of a polishing machine precisely in parallel with the plane of the base plate. In general, the following two methods are conventionally employed for mounting the wafer on the base plate of the polishing machine.
  • One of the methods includes applying molten wax to a heated base plate.
  • the wafer is secured to the base plate via the wax.
  • the wafer secured to the base plate is polished.
  • the base plate is heated again to melt the wax, detaching the wafer from the base plate.
  • the wafer is then cleaned with an organic solvent to remove wax attachments from the wafer.
  • This method is advantageous in that variations in the thickness of the polished wafer are small.
  • the steps of heating and cooling the base plate are required before and after each polishing. This undesirably necessitates a heating step of heating and melting wax and the use of a harmful organic solvent for cleaning the wafer to remove wax attachments.
  • the other method uses a wafer retainer which is to be described in the present invention.
  • a retainer is adhered to a base plate in advance, and a wafer is adsorbed to the surface of the retainer via liquid such as water. According to this method, the wafer can be easily mounted on and detached from the base plate during the polishing process, thereby improving the efficiency and facilitating automatization.
  • the wafer retainer is generally secured to the base plate with a pressure-sensitive adhesive (PSA) with high tack strength.
  • PSA pressure-sensitive adhesive
  • This method is disadvantageous in that the adhesive layer formed on the back surface of the wafer retainer is so firmly adhered to the base plate that a tack strength as large as about 2 to 3 kg/inch width is exhibited when the wafer retainer is intended to be detached from the base plate in a general manner. Specifically, a force of 57 kg at maximum is required to detach the wafer retainer from a polishing machine base plate with a diameter of 485 mm. Thus, it takes an extraordinarily large amount of labor to exchange the used wafer retainer with a new one.
  • the objectives of the present invention are (1) to provide a wafer retainer for retaining a wafer to be polished which adheres to a base plate of a polishing machine firmly and stably when the wafer is polished and is easily peeled off the base plate when Intended to be detached, (2) to provide a method for attaching/detaching the wafer retainer to/from the base plate of the polishing machine, (3) to provide a wafer retainer for retaining a wafer to be polished which, when being exchanged or replaced, can be easily peeled off a base plate of a polishing machine by simply cooling the base plate and an adhesive layer of the wafer retainer, and (4) to provide a method for attaching/detaching the wafer retainer to/from the base plate of the polishing machine.
  • a wafer retainer for retaining a wafer to be polished includes: a foam layer capable of adsorbing a wafer on a surface of the foam layer in a detachable manner; a pressure-sensitive adhesive layer for attaching the foam layer to a base plate of a polishing machine; and a release sheet attached to the pressure-sensitive adhesive layer in a releasable manner, wherein the pressure-sensitive adhesive layer includes an adhesive composition containing a polymer, the polymer having a first-order melt transition occurring in a temperature range narrower than 15oC.
  • the adhesive composition includes a side-chain crystallizable polymer as the polymer in an amount such that the pressure-sensitive adhesive layer becomes substantially untacky to the base plate of the polishing machine at 20oC or less and substantially tacky to the base plate of the polishing machine at a temperature higher than 20oC.
  • the side-chain crystallizable polymer includes as a main component thereof an acrylic acid ester and/or methacryl acid ester which has a straight-chain alykyl group including 10 or more carbons as a side chain.
  • the side-chain crystallizable polymer is a copolymer of (meth)acrylate having 10 to 14 carbons and at least one monomer selected from the group consisting of acrylic acid and (meth)acrylate having 1 to 4 carbons.
  • the copolymer includes the following components: 40% to 95% by weight of (meth)acrylate having 10 to 14 carbons; 1% to 10% by weight of acrylic acid; and/or 5% to 40% by weight of (meth)acrylate having 1 to 4 carbons.
  • a method for attaching/detaching the wafer retainer according to the present invention to/from a base plate of a polishing machine includes the steps of: attaching the wafer retainer to the base plate of the polishing machine by removing the release sheet of the wafer retainer from the pressure-sensitive adhesive layer, and thereafter allowing the pressure-sensitive adhesive layer of the wafer retainer to adhere to the base plate of the polishing machine while keeping the base plate at a temperature T1; and after use of the wafer retainer, detaching the wafer retainer from the base plate of the polishing machine while cooling the base plate from the temperature T1 to a temperature T2, the temperature T2 being lower than the temperature T1.
  • the temperature T1 is 20oC or above, and the temperature T2 is below 20°C.
  • the temperature T1 is 25oC or above, and the temperature T2 is below 20°C.
  • Figure 1 is a sectional view of a wafer retainer according to the present invention.
  • Figure 22 is a sectional view showing the status where a foam layer is formed on a substrate, forming a backing film.
  • Figure 2B is a sectional view showing an adhesive film.
  • Figure 3 is a sectional view showing the status where the surface area of the foam layer of the backing film shown in Figure 2A has been buffed.
  • Figure 4 is a sectional view showing the status where a template is placed on the top surface of the backing film shown in Figure 3.
  • Figure 5 is a sectional view showing the status where the wafer retainer of the present invention has been adhered to a base plate.
  • the wafer retainer for retaining wafers to be polished according to the present invention includes at least: a foam layer capable of adsorbing a wafer on a surface of the foam layer in a detachable manner; a pressure-sensitive adhesive layer for attaching the foam layer to a base plate of a polishing machine; and a release sheet attached to the pressure-sensitive adhesive layer in a releasable manner.
  • the wafer retainer may be composed of three layers as described above, or may include an additional layer.
  • a sheet substrate may be additionally formed between the foam layer and the adhesive layer to obtain a 4-layered wafer retainer.
  • a sheet made of a synthetic resin such as polyethylene terephthalate, polyetherimide, and polyurethane may be used.
  • a polyester film (Lumirror, manufactured by Toray Industries, Inc.) may be used.
  • the foam layer is formed, for example, by applying to the sheet substrate a foam composition including urethane polymer, vinyl polymer such as vinyl chloride polymer, vinyl chloride-vinyl acetate copolymer, and vinyl chloride-vinyl acetate-vinyl alcohol ternary polymer, and a suitable foam solvent such as dimethylformaldehyde and solidifying the foam composition by a wet solidification method.
  • a foam composition including urethane polymer, vinyl polymer such as vinyl chloride polymer, vinyl chloride-vinyl acetate copolymer, and vinyl chloride-vinyl acetate-vinyl alcohol ternary polymer, and a suitable foam solvent such as dimethylformaldehyde and solidifying the foam composition by a wet solidification method.
  • the surface area of the foam layer especially a skin layer formed on the surface, is preferably buffed to allow a wafer to be adsorbed thereon easily.
  • the adhesive layer is formed on the back surface of the foam layer
  • the adhesive layer is made of an adhesive composition which contains a polymer having a first-order melt transition occurring in a range narrower than about 15oC.
  • the adhesive composition is a polymer composition having a first melt transition somewhere between about 5oC and 50°C. This transition occurs preferably in a range narrower than about 15oC, more preferably in a range narrower than about 10oC.
  • the first-order melt transition of the polymer can be measured by a viscoelasticity meter.
  • the adhesive composition contains a sufficient amount of a side-chain crystallizable polymer so that the resultant adhesive layer can be substantially non-tacky to the base plate of the polishing machine at a temperature of about 20oC or less and substantially tacky to the base plate at a temperature more than about 20oC.
  • the temperature T1 of the wafer retainer during the polishing of the wafer is preferably 20oC or more, more preferably in the range of about 25 to about 35oC, most preferably in the range of about 25 to about 30oC.
  • the temperature T2 of the wafer retainer at the detachment of the wafer retainer from the base plate is preferably less than 20°C, more preferably in the range of about 10 to about 20oC.
  • side-chain crystallizable polymer side-chain crystallizable and/or main-chain crystallizable polymers are preferred. These polymers include polymers which exhibit the temperature-dependent adhesion properties. Crystallizable polymers which may be used in the adhesive composition may include both side-chain crystallizable and main-chain crystallizable polymers. The side-chain crystallizable polymers contain crystallizable side-chain moieties, while the main-chain crystallizable polymers are rendered crystallizable by their backbone structure. Examples of such polymers include those selected from the group consisting of single stereoregular polyolefin alkylacrylate, and alkylmethacrylate.
  • the side-chain crystallizable polymer used in the present invention can be formulated so as to contain a mixture of two or more different polymers.
  • these polymers contain monomer units X of the formula:
  • M is a bivalent group capable of forming a main chain of a polymer (or a backbone atom)
  • S is a spacer unit
  • C is a crystallizable group.
  • These polymers generally have a heat of fusion ( ⁇ Hf) of at least about 20 Joules/g, preferably at least about 40 Joules/g.
  • the polymers contain about 50 to about 100 vt.% monomer units represented by "X".
  • the polymer contains less than 100% X, it additionally contains monomer units which may be represented by "Y” or “Z", or both, wherein Y is any polar or nonpolar monomer or mixture of polar or nonpolar monomers capable of polymerizing with X or Z, and Z is a mixture of polar or nonpolar monomers.
  • Y is any polar or nonpolar monomer or mixture of polar or nonpolar monomers capable of polymerizing with X or Z
  • Z is a mixture of polar or nonpolar monomers.
  • the polar monomers include polyoxyalkylenes, acrylates including hydroxyethylacrylate, acrylamides, and methacrylamide. These monomers increase adhesion to most substrates.
  • the backbone of the polymer may be any organic structure (aliphatic or aromatic hydrocarbon, ester, ether, amide, etc.) or an inorganic structure (sulfide, phosphazine, silicone, etc.), and may include spacer linkages which can be any suitable organic or inorganic unit, for example, ester, amide, hydrocarbon, phenyl, ether, or ionic salt (e.g., a carboxyl-alkyl ammonium or sulphonium or phosphonium ion pair or other known ionic salt pair).
  • ionic salt e.g., a carboxyl-alkyl ammonium or sulphonium or phosphonium ion pair or other known ionic salt pair.
  • the side-chain may be aliphatic or aromatic or a combination of aliphatic and aromatic, but must be capable of entering into a crystalline state.
  • Common examples are: linear aliphatic side-chains of at least 10 carbon atoms, e.g., C 14 -C 22 acrylates or methacrylates, acrylamides or methacrylamides, vinyl ethers or esters, siloxanes or alpha olefins; fluorinated aliphatic side-chains of at least 6 carbon atoms; and p-alkyl styrene side-chains wherein the alkyl group contains 8 to 24 carbon atoms.
  • the length of the side-chain moiety is usually greater than 5 times the distance between side-chains in the case of acrylates, methacrylates, vinyl esters, acrylamides, methacrylamides, vinyl ethers, and ⁇ -olefins.
  • the side-chain units should make up greater than 50% of the volume of the polymer, preferably greater than 65% of the volume.
  • the adhesive composition may contain conventional additives such as a tackifier (e.g., rosin, polyester), an antioxidant, a fibrous or non-fibrous filler, and a colorant.
  • a tackifier e.g., rosin, polyester
  • An additional adhesive may also be contained in the adhesive composition unless it significantly affects the overall temperature-sensitive property of the adhesion composition.
  • the amount of the crystallizable polymer contained in the adhesive composition is preferably in the range of about 40% by weight to about 100% by weight.
  • suitable examples of the polymer contained in the adhesive composition are as follows:
  • the temperature at which the adhesiveness greatly lowers is about 15oC or less.
  • the temperature at which the adhesiveness greatly lowers is about 5oC or less when about 10oC is used and about 15°C or less when about 20oC is used.
  • the temperature at which the adhesiveness greatly lowers is about -5oC or less when about 0oC is used and about 10°C or less when about 15oC is used.
  • the temperature at which the adhesiveness greatly lowers is about 10oC or less when about 15°C is used and about 30oC or less when about 35oC is used.
  • a copolymer of (meth)acrylate having 10-14 carbons, acrylic acid, and/or (meth)acrylate having 1-4 carbons of which temperature sensitivity and tackiness are well balanced.
  • Such a copolymer contains 40% by weight or more, preferably 45 to 95% by weight of (meth)acrylate having 10-14 carbons, 1 to 10% by weight, preferably 2 to 5% by weight of acrylic acid, and/or 5 to 40% by weight, preferably 10 to 35% by weight of (meth)acrylate.
  • the adhesive composition containing the polymer exhibiting the above-described temperature-dependent adhesion properties may be directly applied to the foam layer or the sheet substrate to form the adhesive layer with a uniform thickness.
  • the adhesive composition may be thinly and uniformly applied to a thin sheet substrate, and then the resultant substrate with the adhesive layer may be laminated with the foam layer or the sheet substrate with the foam layer formed thereon.
  • the adhesive composition may be applied as it is or as an emulsion or a latex with an appropriate solvent.
  • Appropriate monomers which can form a polymer and additives may be directly applied to the foam layer or the sheet substrate and cured by heating, radiation, or any other appropriate method known to those skilled in the art.
  • a release sheet (or a release film) is attached to the exposed surface of the adhesive layer, so that the adhesive layer is protected by the release sheet until the wafer retainer is actually used.
  • the release sheet is composed of a soft thin film, for example, a paper sheet, a plastic film such as a polypropylene film, and a metal foil, which is surface-treated with a release agent, if necessary, to facilitate the releasing.
  • a silicone-treated polyester film is preferred in the aspect of dusting characteristics and smoothness.
  • the base plate is removed from the polishing machine, cleaned, and secured horizontally so that the surface thereof to which the wafer retainer is to be attached is exposed at room temperature (generally, about 25°C).
  • the wafer retainer is taken out from a package and, after removing the release sheet from the tacky surface of the wafer retainer, placed on the base plate so that the tacky surface comes into contact with the exposed surface of the base plate.
  • the wafer retainer is desirably curved lightly before being attached to the base plate, so that the center portion of the retainer can attach to the base plate first, followed by gradual attachment toward the periphery of the retainer. Pressure is then applied to the entire top surface of the wafer retainer from above uniformly by any appropriate method.
  • the pressure is preferably 1 kg/cm 2 or less.
  • the wafer retainer may be pressed with a flat plane via a sufficiently thick elastic member.
  • the retainer may be covered with a plastic sheet. Air under the plastic sheet is absorbed to obtain negative pressure and thus pressurize the wafer retainer.
  • the adhesive layer on the back surface of the substrate of the wafer retainer closely adheres to the base plate.
  • the tack strength of the wafer retainer attached to the base plate at this time is as strong as about 2 to 3 kg/inch width, which is exhibited when the former is intended to be detached from the latter in a general manner.
  • the wafer retainer is detached from the base plate in the following manner.
  • the tackiness of the temperature-activated pressure-sensitive adhesive formed on the back surface of the wafer retainer rapidly decreases by cooling the base plate by about 5oC below room temperature, i.e., to about 20oC.
  • the tack strength lowers to about 0.2 to 0.5 kg/inch width, allowing the wafer retainer from detaching from the base plate easily.
  • the base plate may be cooled by immersing it in water or cold water, showering it with water or cold water, or exposing it to cold air blow.
  • the adhesive composition constituting the adhesive layer includes a polymer' having a first-order melt transition occurring in a range narrower than 15°C. With such an adhesive composition including a temperature-activated pressure-sensitive adhesive, the tackiness of the adhesive layer to the base plate can be greatly lowered by cooling the base plate and the wafer retainer. Thus, the wafer retainer can be easily detached from the base plate at the time of the exchange of the used wafer retainer with a new one.
  • the first-order melt transition refers to a phenomenon occurring at a temperature in about the middle between the glass transition point and the melting point, observed when the viscoelasticity of a polymer is measured by gradually increasing the temperature.
  • an arbitrarily set temperature for example, 2 to 5oC
  • the polymer becomes crystalline or non-crystalline reversibly, resulting in an aggressive change in the tackiness of the polymer to the base plate as described above.
  • Composition I (having the composition shown in Table 1) was coated at a thickness of 700 microns on a polyester film 1 (Lumirror, manufactured by Toray Industries, Inc.; thickness: 188 microns). Composition I was then allowed to wet-coagulate so as to form a foam layer 2. This composite was subjected to a washing process and a drying process, whereby a backing film was obtained. The outermost 100 microns (indicated as 2a in Figure 2A) of the resultant backing film was eliminated by buffing, whereby a backing film shown in Figure 3 was obtained.
  • a temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) was coated at a thickness of 20 microns on one face of a polyester film 3c (Lumirror, manufactured by Toray Industries, Inc.; thickness: 25 microns), thereby forming an adhesive layer 3a.
  • a conventional adhesive composition (AR-798: an acrylic adhesive manufactured by Sankyo Chemical Co., Ltd.) was coated so as to have a thickness of 20 microns, thereby forming an adhesive layer 3b. Then, each adhesive layer was covered with a release sheet 4.
  • a double coated adhesive film A with release sheets 4 was obtained as shown in Figure 2B.
  • the backing film 5 was cut into a circle having a diameter of 485 mm.
  • a template 6 (composed of glass epoxy resin) with recesses for positioning and retaining wafers was attached to the backing film 5 by means of a press.
  • a template with a backing film was obtained ( Figure 4).
  • the template 6 having the doubled coated adhesive tape thereon had an outer diameter of 485 mm and seven 6-inch pockets (recesses).
  • the template 6 includes an adhesive layer provided on one face thereof, with a release sheet being attached to the adhesive layer. The release sheet was peeled off the adhesive layer, and the template 6 was attached onto the backing film 5. Thus, a wafer retainer was completed.
  • the release sheet 4 of the wafer retainer was peeled off the wafer retainer, and the wafer retainer was lightly attached to a ceramic upper base plate 7 of a polishing machine. Thereafter, a flat composed of quartz (weight: 10 kg; outer diameter: 485 mm) was uniformly placed on the template 6 and was left for 30 minutes so as to allow the adhesive to gain intimacy with the upper base plate 7.
  • the adhesion temperature was at 25oC.
  • the above-described wafer retainer was evaluated by using a single-side polishing machine (SPM-19, manufactured by Fujikoshi Kikai). Wafers of silicon monocrystal P (100) (diameter: 6 inches) were subjected to a polishing under the conditions described in Table 2. Fifty polishes, each requiring 30 minutes, were continuously performed. After the wafer retainer was thus used, the ceramic upper base plate with the non-usable wafer retainer was immersed in pure water at 20oC. The wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off the upper base plate at a peeling force of at most 7 kg.
  • a temperature-activated pressure-sensitive adhesive was directly coated at a thickness of 20 microns, thereby forming an adhesive layer 3, on a back face (i.e., on a polyester film 1 side) of a backing film which was fabricated by the same manner described in Example 1.
  • a release sheet 4 was attached to this adhesive layer 3 so as to fabricate a backing film 5 having the structure shown in Figure 1.
  • a template (composed of a glass epoxy resin sheet) having a diameter of 485 mm and seven 6-inch pockets (recesses) was attached to a ceramic upper base plate by using the same double coated adhesive film A employed in Example 1. Specifically, the adhesive layer 3a of the double coated adhesive film A was attached to the ceramic upper base plate. The adhesion was conducted at 25oC for 2 minutes, with a load of 1.5 kg /cm 2 applied to the template. Furthermore, the above-mentioned backing film was cut into circles having a diameter of 6 inches. After the release sheet 4 was peeled, each circular-shaped backing film was Inserted into a pocket (recess) of the template. Thus, the backing films were secured to the ceramic upper base plate, whereby a wafer retainer was obtained.
  • the above-described wafer retainer was evaluated by using a single-side polishing machine (SPM-19, manufactured by Fujikoshi Kikai). Wafers of silicon monocrystal P (100) (diameter: 6 inches) were subjected to a polishing under the conditions described in Table 2. Fifty polishes, each requiring 30 minutes, were continuously performed. After the wafer retainer was thus used, the ceramic upper base plate with the non-usable wafer retainer was immersed in pure water at 20oC. Each backing film having the temperature-activated pressure-sensitive adhesive easily peeled off the upper base plate at a peeling force of at most 2.4 kg. The template also easily peeled off the upper base plate at a peeling force of at most 2.8 kg.
  • Composition I was coated at a thickness of 700 microns on a polyester film 1 (Lumirror, manufactured by Toray Industries, Inc.; thickness: 188 microns). Composition I was then allowed to wet-coagulate. This composite was subjected to a washing process and a drying process, whereby a backing film having the structure shown in Figure 2 was obtained. The outermost 100 microns of (indicated as 2a in Figure 2) of the backing film was eliminated by buffing, whereby a backing film shown in Figure 3 was obtained.
  • a commercially available double coated adhesive tape (ST-442, manufactured by Sumitomo 3M Corporation) was attached to the polyester film 1 of the above-mentioned backing film, thereby producing a backing film with a conventional pressure-sensitive adhesive.
  • This backing film was cut into a circle having a diameter of 485 mm.
  • a template 6 (composed of glass epoxy resin) with recesses for positioning and retaining wafers was attached to the backing film 5 by means of a press.
  • a template with a backing film was obtained ( Figure 4).
  • the template 6 having the doubled coated adhesive tape had an outer diameter of 485 mm and seven 6-inch pockets (recesses).
  • the template 6 includes an adhesive layer provided on one face thereof, a release sheet being attached to the adhesive layer. Thus, a wafer retainer was completed.
  • the release sheet of the wafer retainer was peeled off, and the wafer retainer was lightly attached to a ceramic upper base plate of a polishing machine. Thereafter, a flat composed of quartz (weight: 10 kg; outer diameter: 485 mm) was uniformly placed on the template 6 and was left for 30 minutes so as to allow the adhesive to gain intimacy with the upper base plate 7. The adhesion temperature was at 25°C.
  • the above-described wafer retainer was evaluated by using a single-side polishing machine (SPM-19, manufactured by Fujikoshi Kikai). Wafers of silicon monocrystal P (100) (diameter: 6 inches) were subjected to a polishing under the conditions described in Table 2.
  • tetradecylacrylate Forty-five parts of tetradecylacrylate, 50 parts of dodecylacrylate, 5 parts of acrylic acid, and 0.3 parts of azobis isobutyronitrile (AIBN) were mixed in 200 parts of toluene, and stirred at 60oC for 20 hours to allow these monomers to polymerize.
  • the resultant polymer had a molecular weight of 500,000 and a melting point of 10oC.
  • a temperature-activated pressure-sensitive adhesive was obtained by adding 0.1 parts of a cross-linking agent (Kemitaito PZ-33) to 100 parts of this polymer solution.
  • a double coated adhesive film B with release sheets provided thereon was obtained in the same manner the double coated adhesive film A in Example 1 was produced except that the above-mentioned temperature-activated pressure-sensitive adhesive was used in the place of the temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) of the double coated adhesive film A.
  • a wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the double coated adhesive film B having release sheets.
  • the resultant wafer retainer was evaluated in the same manner as in Example 1 except that the ceramic upper base plate with the wafer retainer was immersed in pure water at about 0oC.
  • the wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 6 kg.
  • a polymer solution was prepared by using a solvent (heptane:ethyl acetate - 90 parts: 10 parts) so that the solid portion in the polymer solution accounted for 30% by weight.
  • a temperature-activated pressure-sensitive adhesive was obtained by adding 0.1 parts of a cross-linking agent (Kemitaito PZ-33) to 100 parts of this polymer solution.
  • a wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the above-mentioned double coated adhesive film C having release sheets.
  • the resultant wafer retainer was evaluated in the same manner as in Example 1 except that the ceramic upper base plate with the wafer retainer was immersed in pure water at about 10oC.
  • the wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 5 kg.
  • a temperature-activated pressure-sensitive adhesive was obtained by adding 0.1 parts of a cross-linking agent (Kemitaito PZ-33) to 100 parts of this polymer solution.
  • a wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the above-mentioned double coated adhesive film D having release sheets.
  • the resultant wafer retainer was evaluated in the same manner as in Example 1 except that the ceramic upper base plate with the wafer retainer was immersed in pure water at about 10oC.
  • the wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 4 kg.
  • a polymer solution was prepared by using a solvent (heptane:ethyl acetate - 90 parts: 10 parts) so that the solid portion in the polymer solution accounted for 30% by weight.
  • a temperature-activated pressure-sensitive adhesive was obtained by adding 0.1 parts of a cross-linking agent (Kemitaito PZ-33) to 100 parts of this polymer solution.
  • a double coated adhesive film E with release sheets provided thereon was obtained in the same manner the double coated adhesive film A in Example 1 was produced except that the above-mentioned temperature-activated pressure-sensitive adhesive was used in the place of the temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) of the double coated adhesive film A.
  • a wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the above-mentioned double coated adhesive film E having release sheets.
  • the resultant wafer retainer was evaluated in the same manner as in Example 1 except that the ceramic upper base plate with the wafer retainer was immersed in pure water at about 10oC.
  • the wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 7 kg.
  • Example 2 An adhesive composed of 100 parts of butylacrylate, 5 parts of acrylonitrile, and 5 parts of acrylic acid was prepared.
  • a double coated adhesive film with release sheets provided thereon was obtained in the same manner the double coated adhesive film A in Example 1 was produced except that the above-mentioned temperature-activated pressure-sensitive adhesive was used in the place of the temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) of the double coated adhesive film A.
  • a wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the above-mentioned double coated adhesive film having release sheets. The resultant wafer retainer was evaluated in the same manner as in Example 1.
  • the wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 28 kg.
  • the exchanging or replacement of a wafer retainer for retaining wafers to be polished according to the present invention, conducted after each polishing process, is substantially facilitated because the wafer retainer can be peeled off a base plate by simply cooling the base plate and an adhesive layer of the wafer retainer.

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Abstract

A wafer retainer for retaining a wafer to be polished according to the present invention includes: a foam layer (2) capable of adsorbing a wafer on a surface of the foam layer (2) in a detachable manner; a pressure-sensitive adhesive layer (3) for attaching the foam layer (2) to a base plate (7) of a polishing machine; and a release sheet (4) attached to the pressure-sensitive adhesive layer (3) in a releasable manner, wherein the pressure-sensitive adhesive layer (3) includes an adhesive composition containing a polymer, the polymer having a first-order melt transition in a temperature range narrower than 15 °C. Thus, the present invention provides a wafer retainer and a method for attaching/detaching the wafer retainer to/from a base plate of a polishing machine such that the wafer retainer can be peeled off the base plate by simply cooling the base plate (7) and the adhesive layer (3) of the wafer retainer, thereby facilitating the exchanging or replacement of the wafer retainer occurring after each polishing process.

Description

DESCRIPTION
A WAFER RETAINER FOR RETAINING A WAFER TO BE POLISHED
AND A METHOD FOR ATTACHING/DETACHING THE WAFER RETAINER TO/FROM A BASE PLATE OF A POLISHING MACHINE
TECHNICAL FIELD The present invention relates to a retainer used for retaining a workplace to be polished, such as a semiconductor wafer, when the workpiece is placed on a base plate of a polishing machine for polishing, and a method for attaching/detaching the retainer to/from the base plate of the polishing machine.
BACKGROUND ART
In recent years in the semiconductor industry, the integration level of ICs has rapidly increased. It has increased from 4M to 16M and is now proceeding to the 64M level.
In light of the above circumstances, demand for a. wafer having a higher-quality surface from which ICs are formed has increased. In order to increase the integration level of ICs, aside from improvement on the chemical and electrical properties of the wafer, reduction of the minimum width allocated for devices to be formed on the wafer is increasingly demanded. Now, 0.35 microns is requested, as compared to 0.5 microns in the past. In order to achieve such high-precision processing, the flatness of the surface of the wafer, i.e., the uniformity and precision of the thickness of the wafer is requested to be more strict. Specifically, the total thickness variation for a wafer after final mirrorfinishing and polishing needs to be 1 micron or less, while the local thickness variation (LTV) over a 20 mm square, which is to be one IC chip, needs to be 0.2 micron or less.
In order to satisfy these precision requirements during the wafer polishing process, the wafer must be mounted on a base plate of a polishing machine precisely in parallel with the plane of the base plate. In general, the following two methods are conventionally employed for mounting the wafer on the base plate of the polishing machine.
One of the methods includes applying molten wax to a heated base plate. The wafer is secured to the base plate via the wax.
According to this method, the wafer secured to the base plate is polished. After polishing, the base plate is heated again to melt the wax, detaching the wafer from the base plate. The wafer is then cleaned with an organic solvent to remove wax attachments from the wafer. This method is advantageous in that variations in the thickness of the polished wafer are small. However, the steps of heating and cooling the base plate are required before and after each polishing. This undesirably necessitates a heating step of heating and melting wax and the use of a harmful organic solvent for cleaning the wafer to remove wax attachments. The other method uses a wafer retainer which is to be described in the present invention. A retainer is adhered to a base plate in advance, and a wafer is adsorbed to the surface of the retainer via liquid such as water. According to this method, the wafer can be easily mounted on and detached from the base plate during the polishing process, thereby improving the efficiency and facilitating automatization. The wafer retainer is generally secured to the base plate with a pressure-sensitive adhesive (PSA) with high tack strength.
This method, however, is disadvantageous in that the adhesive layer formed on the back surface of the wafer retainer is so firmly adhered to the base plate that a tack strength as large as about 2 to 3 kg/inch width is exhibited when the wafer retainer is intended to be detached from the base plate in a general manner. Specifically, a force of 57 kg at maximum is required to detach the wafer retainer from a polishing machine base plate with a diameter of 485 mm. Thus, it takes an extraordinarily large amount of labor to exchange the used wafer retainer with a new one.
Thus, the objectives of the present invention are (1) to provide a wafer retainer for retaining a wafer to be polished which adheres to a base plate of a polishing machine firmly and stably when the wafer is polished and is easily peeled off the base plate when Intended to be detached, (2) to provide a method for attaching/detaching the wafer retainer to/from the base plate of the polishing machine, (3) to provide a wafer retainer for retaining a wafer to be polished which, when being exchanged or replaced, can be easily peeled off a base plate of a polishing machine by simply cooling the base plate and an adhesive layer of the wafer retainer, and (4) to provide a method for attaching/detaching the wafer retainer to/from the base plate of the polishing machine. DISCLOSURE OF THE INVENTION
A wafer retainer for retaining a wafer to be polished according to the present invention includes: a foam layer capable of adsorbing a wafer on a surface of the foam layer in a detachable manner; a pressure-sensitive adhesive layer for attaching the foam layer to a base plate of a polishing machine; and a release sheet attached to the pressure-sensitive adhesive layer in a releasable manner, wherein the pressure-sensitive adhesive layer includes an adhesive composition containing a polymer, the polymer having a first-order melt transition occurring in a temperature range narrower than 15ºC.
In one embodiment of the invention, the adhesive composition includes a side-chain crystallizable polymer as the polymer in an amount such that the pressure-sensitive adhesive layer becomes substantially untacky to the base plate of the polishing machine at 20ºC or less and substantially tacky to the base plate of the polishing machine at a temperature higher than 20ºC.
In another embodiment of the invention, the side-chain crystallizable polymer includes as a main component thereof an acrylic acid ester and/or methacryl acid ester which has a straight-chain alykyl group including 10 or more carbons as a side chain. In still another embodiment of the invention, the side-chain crystallizable polymer is a copolymer of (meth)acrylate having 10 to 14 carbons and at least one monomer selected from the group consisting of acrylic acid and (meth)acrylate having 1 to 4 carbons.
In still another embodiment of the invention, the copolymer includes the following components: 40% to 95% by weight of (meth)acrylate having 10 to 14 carbons; 1% to 10% by weight of acrylic acid; and/or 5% to 40% by weight of (meth)acrylate having 1 to 4 carbons.
A method for attaching/detaching the wafer retainer according to the present invention to/from a base plate of a polishing machine includes the steps of: attaching the wafer retainer to the base plate of the polishing machine by removing the release sheet of the wafer retainer from the pressure-sensitive adhesive layer, and thereafter allowing the pressure-sensitive adhesive layer of the wafer retainer to adhere to the base plate of the polishing machine while keeping the base plate at a temperature T1; and after use of the wafer retainer, detaching the wafer retainer from the base plate of the polishing machine while cooling the base plate from the temperature T1 to a temperature T2, the temperature T2 being lower than the temperature T1.
In one embodiment of the invention, the temperature T1 is 20ºC or above, and the temperature T2 is below 20°C.
In another embodiment of the invention, the temperature T1 is 25ºC or above, and the temperature T2 is below 20°C.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectional view of a wafer retainer according to the present invention.
Figure 22. is a sectional view showing the status where a foam layer is formed on a substrate, forming a backing film. Figure 2B is a sectional view showing an adhesive film.
Figure 3 is a sectional view showing the status where the surface area of the foam layer of the backing film shown in Figure 2A has been buffed.
Figure 4 is a sectional view showing the status where a template is placed on the top surface of the backing film shown in Figure 3. Figure 5 is a sectional view showing the status where the wafer retainer of the present invention has been adhered to a base plate.
BEST MODE FOR CARRYING OUT THE INVENTION
The wafer retainer for retaining wafers to be polished according to the present invention includes at least: a foam layer capable of adsorbing a wafer on a surface of the foam layer in a detachable manner; a pressure-sensitive adhesive layer for attaching the foam layer to a base plate of a polishing machine; and a release sheet attached to the pressure-sensitive adhesive layer in a releasable manner. The wafer retainer may be composed of three layers as described above, or may include an additional layer. For example, a sheet substrate may be additionally formed between the foam layer and the adhesive layer to obtain a 4-layered wafer retainer.
As the sheet substrate, a sheet made of a synthetic resin such as polyethylene terephthalate, polyetherimide, and polyurethane may be used. For example, a polyester film (Lumirror, manufactured by Toray Industries, Inc.) may be used.
The foam layer is formed, for example, by applying to the sheet substrate a foam composition including urethane polymer, vinyl polymer such as vinyl chloride polymer, vinyl chloride-vinyl acetate copolymer, and vinyl chloride-vinyl acetate-vinyl alcohol ternary polymer, and a suitable foam solvent such as dimethylformaldehyde and solidifying the foam composition by a wet solidification method. The surface area of the foam layer, especially a skin layer formed on the surface, is preferably buffed to allow a wafer to be adsorbed thereon easily. The adhesive layer is formed on the back surface of the foam layer or on the back surface (the surface facing the base plate of the polishing machine) of the substrate when the wafer retainer includes the substrate. The adhesive layer is made of an adhesive composition which contains a polymer having a first-order melt transition occurring in a range narrower than about 15ºC. The adhesive composition is a polymer composition having a first melt transition somewhere between about 5ºC and 50°C. This transition occurs preferably in a range narrower than about 15ºC, more preferably in a range narrower than about 10ºC. The first-order melt transition of the polymer can be measured by a viscoelasticity meter.
As disclosed in Japanese National Patent Publication No. 4-507425, the adhesive composition contains a sufficient amount of a side-chain crystallizable polymer so that the resultant adhesive layer can be substantially non-tacky to the base plate of the polishing machine at a temperature of about 20ºC or less and substantially tacky to the base plate at a temperature more than about 20ºC.
The temperature T1 of the wafer retainer during the polishing of the wafer is preferably 20ºC or more, more preferably in the range of about 25 to about 35ºC, most preferably in the range of about 25 to about 30ºC. The temperature T2 of the wafer retainer at the detachment of the wafer retainer from the base plate is preferably less than 20°C, more preferably in the range of about 10 to about 20ºC.
As the side-chain crystallizable polymer, side-chain crystallizable and/or main-chain crystallizable polymers are preferred. These polymers include polymers which exhibit the temperature-dependent adhesion properties. Crystallizable polymers which may be used in the adhesive composition may include both side-chain crystallizable and main-chain crystallizable polymers. The side-chain crystallizable polymers contain crystallizable side-chain moieties, while the main-chain crystallizable polymers are rendered crystallizable by their backbone structure. Examples of such polymers include those selected from the group consisting of single stereoregular polyolefin alkylacrylate, and alkylmethacrylate.
The side-chain crystallizable polymer used in the present invention can be formulated so as to contain a mixture of two or more different polymers.
In general, these polymers contain monomer units X of the formula:
Figure imgf000011_0001
wherein M is a bivalent group capable of forming a main chain of a polymer (or a backbone atom), S is a spacer unit, and C is a crystallizable group. These polymers generally have a heat of fusion (ΔHf) of at least about 20 Joules/g, preferably at least about 40 Joules/g. The polymers contain about 50 to about 100 vt.% monomer units represented by "X". If the polymer contains less than 100% X, it additionally contains monomer units which may be represented by "Y" or "Z", or both, wherein Y is any polar or nonpolar monomer or mixture of polar or nonpolar monomers capable of polymerizing with X or Z, and Z is a mixture of polar or nonpolar monomers. Examples of the polar monomers include polyoxyalkylenes, acrylates including hydroxyethylacrylate, acrylamides, and methacrylamide. These monomers increase adhesion to most substrates. The backbone of the polymer (defined by "M" ) may be any organic structure (aliphatic or aromatic hydrocarbon, ester, ether, amide, etc.) or an inorganic structure (sulfide, phosphazine, silicone, etc.), and may include spacer linkages which can be any suitable organic or inorganic unit, for example, ester, amide, hydrocarbon, phenyl, ether, or ionic salt (e.g., a carboxyl-alkyl ammonium or sulphonium or phosphonium ion pair or other known ionic salt pair). The side-chain (defined by "S" and "C") may be aliphatic or aromatic or a combination of aliphatic and aromatic, but must be capable of entering into a crystalline state. Common examples are: linear aliphatic side-chains of at least 10 carbon atoms, e.g., C14-C22 acrylates or methacrylates, acrylamides or methacrylamides, vinyl ethers or esters, siloxanes or alpha olefins; fluorinated aliphatic side-chains of at least 6 carbon atoms; and p-alkyl styrene side-chains wherein the alkyl group contains 8 to 24 carbon atoms.
The length of the side-chain moiety is usually greater than 5 times the distance between side-chains in the case of acrylates, methacrylates, vinyl esters, acrylamides, methacrylamides, vinyl ethers, and α-olefins.
The side-chain units should make up greater than 50% of the volume of the polymer, preferably greater than 65% of the volume.
In addition to one or more type of the above-described polymers, the adhesive composition may contain conventional additives such as a tackifier (e.g., rosin, polyester), an antioxidant, a fibrous or non-fibrous filler, and a colorant. An additional adhesive may also be contained in the adhesive composition unless it significantly affects the overall temperature-sensitive property of the adhesion composition. The amount of the crystallizable polymer contained in the adhesive composition is preferably in the range of about 40% by weight to about 100% by weight. Especially suitable examples of the polymer contained in the adhesive composition are as follows:
(1) the copolymer of 90-97 parts by weight of tetradecyl acrylate and 3-10 parts by weight of acrylic acid
(2) the copolymer of 10-60 parts by weight of lauryl acrylate, 40-90 parts by weight of tetradecyl acrylate, and 3-10 parts by weight of acrylic acid
(3) the copolymer of 70-90 parts by weight of tetradecyl acrylate, 5-20 parts by weight of butyl acrylate, and 3-10 parts by weight of acrylic acid (4) the copolymer of 70-90 parts by weight of hexadecyl acrylate, 5-20 parts by weight of butyl acrylate, and 3-10 parts by weight of acrylic acid The suitable temperatures at use of the adhesive compositions including the above copolymers (1) to (4) are as follows:
(1) about 20ºC. The temperature at which the adhesiveness greatly lowers is about 15ºC or less.
(2) about 10 to about 20ºC. The temperature at which the adhesiveness greatly lowers is about 5ºC or less when about 10ºC is used and about 15°C or less when about 20ºC is used.
(3) about 0 to about 15ºC. The temperature at which the adhesiveness greatly lowers is about -5ºC or less when about 0ºC is used and about 10°C or less when about 15ºC is used.
(4) about 15 to about 35ºC. The temperature at which the adhesiveness greatly lowers is about 10ºC or less when about 15°C is used and about 30ºC or less when about 35ºC is used.
Especially suitable is a copolymer of (meth)acrylate having 10-14 carbons, acrylic acid, and/or (meth)acrylate having 1-4 carbons, of which temperature sensitivity and tackiness are well balanced. Such a copolymer contains 40% by weight or more, preferably 45 to 95% by weight of (meth)acrylate having 10-14 carbons, 1 to 10% by weight, preferably 2 to 5% by weight of acrylic acid, and/or 5 to 40% by weight, preferably 10 to 35% by weight of (meth)acrylate.
The adhesive composition containing the polymer exhibiting the above-described temperature-dependent adhesion properties may be directly applied to the foam layer or the sheet substrate to form the adhesive layer with a uniform thickness. Alternatively, the adhesive composition may be thinly and uniformly applied to a thin sheet substrate, and then the resultant substrate with the adhesive layer may be laminated with the foam layer or the sheet substrate with the foam layer formed thereon. The adhesive composition may be applied as it is or as an emulsion or a latex with an appropriate solvent. Appropriate monomers which can form a polymer and additives may be directly applied to the foam layer or the sheet substrate and cured by heating, radiation, or any other appropriate method known to those skilled in the art.
A release sheet (or a release film) is attached to the exposed surface of the adhesive layer, so that the adhesive layer is protected by the release sheet until the wafer retainer is actually used. The release sheet is composed of a soft thin film, for example, a paper sheet, a plastic film such as a polypropylene film, and a metal foil, which is surface-treated with a release agent, if necessary, to facilitate the releasing. In particular, a silicone-treated polyester film is preferred in the aspect of dusting characteristics and smoothness. The wafer retainer with the above structure is attached to the base plate of the polishing machine typically in the following manner. First, the base plate is removed from the polishing machine, cleaned, and secured horizontally so that the surface thereof to which the wafer retainer is to be attached is exposed at room temperature (generally, about 25°C). The wafer retainer is taken out from a package and, after removing the release sheet from the tacky surface of the wafer retainer, placed on the base plate so that the tacky surface comes into contact with the exposed surface of the base plate. At this time, the wafer retainer is desirably curved lightly before being attached to the base plate, so that the center portion of the retainer can attach to the base plate first, followed by gradual attachment toward the periphery of the retainer. Pressure is then applied to the entire top surface of the wafer retainer from above uniformly by any appropriate method. The pressure is preferably 1 kg/cm2 or less. As an example of pressure application, the wafer retainer may be pressed with a flat plane via a sufficiently thick elastic member. Most preferably, the retainer may be covered with a plastic sheet. Air under the plastic sheet is absorbed to obtain negative pressure and thus pressurize the wafer retainer.
Through the above process, the adhesive layer on the back surface of the substrate of the wafer retainer closely adheres to the base plate. The tack strength of the wafer retainer attached to the base plate at this time is as strong as about 2 to 3 kg/inch width, which is exhibited when the former is intended to be detached from the latter in a general manner. After the attachment of the wafer retainer to the polishing machine in the above manner and subsequent processing of the wafer, the wafer retainer is detached from the base plate in the following manner. The tackiness of the temperature-activated pressure-sensitive adhesive formed on the back surface of the wafer retainer rapidly decreases by cooling the base plate by about 5ºC below room temperature, i.e., to about 20ºC. The tack strength lowers to about 0.2 to 0.5 kg/inch width, allowing the wafer retainer from detaching from the base plate easily. The base plate may be cooled by immersing it in water or cold water, showering it with water or cold water, or exposing it to cold air blow. Thus, in the wafer retainer according to the present invention, the adhesive composition constituting the adhesive layer includes a polymer' having a first-order melt transition occurring in a range narrower than 15°C. With such an adhesive composition including a temperature-activated pressure-sensitive adhesive, the tackiness of the adhesive layer to the base plate can be greatly lowered by cooling the base plate and the wafer retainer. Thus, the wafer retainer can be easily detached from the base plate at the time of the exchange of the used wafer retainer with a new one.
The first-order melt transition refers to a phenomenon occurring at a temperature in about the middle between the glass transition point and the melting point, observed when the viscoelasticity of a polymer is measured by gradually increasing the temperature. By slightly varying the temperature from an arbitrarily set temperature (for example, 2 to 5ºC), the polymer becomes crystalline or non-crystalline reversibly, resulting in an aggressive change in the tackiness of the polymer to the base plate as described above. Hereinafter, the present invention will be specifically described by way of examples. However, the invention is not limited to the examples.
(Example 1)
As shown in Figure 2A, Composition I (having the composition shown in Table 1) was coated at a thickness of 700 microns on a polyester film 1 (Lumirror, manufactured by Toray Industries, Inc.; thickness: 188 microns). Composition I was then allowed to wet-coagulate so as to form a foam layer 2. This composite was subjected to a washing process and a drying process, whereby a backing film was obtained. The outermost 100 microns (indicated as 2a in Figure 2A) of the resultant backing film was eliminated by buffing, whereby a backing film shown in Figure 3 was obtained.
A temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) was coated at a thickness of 20 microns on one face of a polyester film 3c (Lumirror, manufactured by Toray Industries, Inc.; thickness: 25 microns), thereby forming an adhesive layer 3a. On the other face of this polyester film, a conventional adhesive composition (AR-798: an acrylic adhesive manufactured by Sankyo Chemical Co., Ltd.) was coated so as to have a thickness of 20 microns, thereby forming an adhesive layer 3b. Then, each adhesive layer was covered with a release sheet 4. Thus, a double coated adhesive film A with release sheets 4 was obtained as shown in Figure 2B.
The release sheet 4 on the adhesive layer 3b of the above adhesive film A was peeled, and thus the adhesive layer 3b of the above adhesive film A was attached to the polyester film 1 of the backing film, thereby producing a backing film 5 (shown in Figure 1) with a temperature-activated pressure-sensitive adhesive provided thereon. In Figure 1, reference numeral 3 (including 3a, 3b, and 3c) denotes an adhesive layer, and 4 denotes a release sheet.
The backing film 5 was cut into a circle having a diameter of 485 mm. A template 6 (composed of glass epoxy resin) with recesses for positioning and retaining wafers was attached to the backing film 5 by means of a press. Thus, a template with a backing film was obtained (Figure 4). The template 6 having the doubled coated adhesive tape thereon had an outer diameter of 485 mm and seven 6-inch pockets (recesses). The template 6 includes an adhesive layer provided on one face thereof, with a release sheet being attached to the adhesive layer. The release sheet was peeled off the adhesive layer, and the template 6 was attached onto the backing film 5. Thus, a wafer retainer was completed.
Next, as shown in Figure 5, the release sheet 4 of the wafer retainer was peeled off the wafer retainer, and the wafer retainer was lightly attached to a ceramic upper base plate 7 of a polishing machine. Thereafter, a flat composed of quartz (weight: 10 kg; outer diameter: 485 mm) was uniformly placed on the template 6 and was left for 30 minutes so as to allow the adhesive to gain intimacy with the upper base plate 7. The adhesion temperature was at 25ºC.
The above-described wafer retainer was evaluated by using a single-side polishing machine (SPM-19, manufactured by Fujikoshi Kikai). Wafers of silicon monocrystal P (100) (diameter: 6 inches) were subjected to a polishing under the conditions described in Table 2. Fifty polishes, each requiring 30 minutes, were continuously performed. After the wafer retainer was thus used, the ceramic upper base plate with the non-usable wafer retainer was immersed in pure water at 20ºC. The wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off the upper base plate at a peeling force of at most 7 kg.
(Example 2)
A temperature-activated pressure-sensitive adhesive was directly coated at a thickness of 20 microns, thereby forming an adhesive layer 3, on a back face (i.e., on a polyester film 1 side) of a backing film which was fabricated by the same manner described in Example 1. A release sheet 4 was attached to this adhesive layer 3 so as to fabricate a backing film 5 having the structure shown in Figure 1.
A template (composed of a glass epoxy resin sheet) having a diameter of 485 mm and seven 6-inch pockets (recesses) was attached to a ceramic upper base plate by using the same double coated adhesive film A employed in Example 1. Specifically, the adhesive layer 3a of the double coated adhesive film A was attached to the ceramic upper base plate. The adhesion was conducted at 25ºC for 2 minutes, with a load of 1.5 kg /cm2 applied to the template. Furthermore, the above-mentioned backing film was cut into circles having a diameter of 6 inches. After the release sheet 4 was peeled, each circular-shaped backing film was Inserted into a pocket (recess) of the template. Thus, the backing films were secured to the ceramic upper base plate, whereby a wafer retainer was obtained.
The above-described wafer retainer was evaluated by using a single-side polishing machine (SPM-19, manufactured by Fujikoshi Kikai). Wafers of silicon monocrystal P (100) (diameter: 6 inches) were subjected to a polishing under the conditions described in Table 2. Fifty polishes, each requiring 30 minutes, were continuously performed. After the wafer retainer was thus used, the ceramic upper base plate with the non-usable wafer retainer was immersed in pure water at 20ºC. Each backing film having the temperature-activated pressure-sensitive adhesive easily peeled off the upper base plate at a peeling force of at most 2.4 kg. The template also easily peeled off the upper base plate at a peeling force of at most 2.8 kg.
(Comparative Example 1)
Composition I was coated at a thickness of 700 microns on a polyester film 1 (Lumirror, manufactured by Toray Industries, Inc.; thickness: 188 microns). Composition I was then allowed to wet-coagulate. This composite was subjected to a washing process and a drying process, whereby a backing film having the structure shown in Figure 2 was obtained. The outermost 100 microns of (indicated as 2a in Figure 2) of the backing film was eliminated by buffing, whereby a backing film shown in Figure 3 was obtained.
A commercially available double coated adhesive tape (ST-442, manufactured by Sumitomo 3M Corporation) was attached to the polyester film 1 of the above-mentioned backing film, thereby producing a backing film with a conventional pressure-sensitive adhesive.
This backing film was cut into a circle having a diameter of 485 mm. As in Example 1, a template 6 (composed of glass epoxy resin) with recesses for positioning and retaining wafers was attached to the backing film 5 by means of a press. Thus, a template with a backing film was obtained (Figure 4).
The template 6 having the doubled coated adhesive tape had an outer diameter of 485 mm and seven 6-inch pockets (recesses). As described above, the template 6 includes an adhesive layer provided on one face thereof, a release sheet being attached to the adhesive layer. Thus, a wafer retainer was completed.
Next, as shown in Figure 5, the release sheet of the wafer retainer was peeled off, and the wafer retainer was lightly attached to a ceramic upper base plate of a polishing machine. Thereafter, a flat composed of quartz (weight: 10 kg; outer diameter: 485 mm) was uniformly placed on the template 6 and was left for 30 minutes so as to allow the adhesive to gain intimacy with the upper base plate 7. The adhesion temperature was at 25°C. The above-described wafer retainer was evaluated by using a single-side polishing machine (SPM-19, manufactured by Fujikoshi Kikai). Wafers of silicon monocrystal P (100) (diameter: 6 inches) were subjected to a polishing under the conditions described in Table 2. Fifty polishes, each requiring 30 minutes, were continuously performed. After the wafer retainer was thus used, the non-usable wafer retainer was peeled off the ceramic upper base plate, requiring a peeling force of at most 34 kg. As will be appreciated, the template of the wafer retainer of Comparative Example 1 could not be peeled off as easily as the templates of the wafer retainers of Examples 1 and 2.
Figure imgf000023_0001
Figure imgf000024_0001
(Example 3)
(Hereinafter, "parts" represent "parts by weight".) A. Preparation of a polymer
Forty-five parts of tetradecylacrylate, 50 parts of dodecylacrylate, 5 parts of acrylic acid, and 0.3 parts of azobis isobutyronitrile (AIBN) were mixed in 200 parts of toluene, and stirred at 60ºC for 20 hours to allow these monomers to polymerize. The resultant polymer had a molecular weight of 500,000 and a melting point of 10ºC. A polymer solution was prepared by using a solvent (heptane:ethyl acetate = 90 parts: 10 parts) so that the solid portion in the polymer solution accounted for 30% by weight. A temperature-activated pressure-sensitive adhesive was obtained by adding 0.1 parts of a cross-linking agent (Kemitaito PZ-33) to 100 parts of this polymer solution.
B. Fabrication of a wafer retainer and an evaluation thereof
A double coated adhesive film B with release sheets provided thereon was obtained in the same manner the double coated adhesive film A in Example 1 was produced except that the above-mentioned temperature-activated pressure-sensitive adhesive was used in the place of the temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) of the double coated adhesive film A.
A wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the double coated adhesive film B having release sheets. The resultant wafer retainer was evaluated in the same manner as in Example 1 except that the ceramic upper base plate with the wafer retainer was immersed in pure water at about 0ºC.
The wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 6 kg.
(Example 4) A. Preparation of a polymer
Ninety-five parts of tetradecylacrylate, 5 parts of acrylic acid, and 0.3 parts of azobis isobutyronitrile (AIBN) were mixed in 200 parts of toluene, and stirred at 60ºC for 20 hours to allow these monomers to polymerize. The resultant polymer had a molecular weight of 500,000 and a melting point of 21ºC.
A polymer solution was prepared by using a solvent (heptane:ethyl acetate - 90 parts: 10 parts) so that the solid portion in the polymer solution accounted for 30% by weight. A temperature-activated pressure-sensitive adhesive was obtained by adding 0.1 parts of a cross-linking agent (Kemitaito PZ-33) to 100 parts of this polymer solution.
B. Fabrication of a wafer retainer and an evaluation thereof A double coated adhesive film C with release sheets provided thereon was obtained in the same manner the double coated adhesive film A in Example 1 was produced except that the above-mentioned temperature-activated pressure-sensitive adhesive was used in the place of the temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) of the double coated adhesive film A.
A wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the above-mentioned double coated adhesive film C having release sheets. The resultant wafer retainer was evaluated in the same manner as in Example 1 except that the ceramic upper base plate with the wafer retainer was immersed in pure water at about 10ºC.
The wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 5 kg.
(Example 5) A. Preparation of a polymer
Fifty parts of hexadecylacrylate, 45 parts of dodecylacrylate, 5 parts of acrylic acid, and 0.3 parts of azobis isobutyronitrile (AIBN) were mixed in 200 parts of toluene, and stirred at 60ºC for 20 hours to allow these monomers to polymerize. The resultant polymer had a molecular weight of 500,000 and a melting point of 20ºC.
A polymer solution was prepared by using a solvent (heptane: ethyl acetate = 90 parts: 10 parts) so that the solid portion in the polymer solution accounted for 30% by weight. A temperature-activated pressure-sensitive adhesive was obtained by adding 0.1 parts of a cross-linking agent (Kemitaito PZ-33) to 100 parts of this polymer solution.
B. Fabrication of a wafer retainer and an evaluation thereof A double coated adhesive film D with release sheets provided thereon was obtained in the same manner the double coated adhesive film A in Example 1 was produced except that the above-mentioned temperature- activated pressure-sensitive adhesive was used in the place of the temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) of the double coated adhesive film A.
A wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the above-mentioned double coated adhesive film D having release sheets. The resultant wafer retainer was evaluated in the same manner as in Example 1 except that the ceramic upper base plate with the wafer retainer was immersed in pure water at about 10ºC.
The wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 4 kg.
(Example 6) A. Preparation of a polymer
Seventy-five parts of hexadecylacrylate, 20 parts of butylacrylate, 5 parts of acrylic acid, and 0.3 parts of azobis isobutyronitrile (AIBN) were mixed in 200 parts of toluene, and stirred at 60ºC for 20 hours to allow these monomers to polymerize. The resultant polymer had a molecular weight of 400,000 and a melting point of 20ºC.
A polymer solution was prepared by using a solvent (heptane:ethyl acetate - 90 parts: 10 parts) so that the solid portion in the polymer solution accounted for 30% by weight. A temperature-activated pressure-sensitive adhesive was obtained by adding 0.1 parts of a cross-linking agent (Kemitaito PZ-33) to 100 parts of this polymer solution.
B. Fabrication of a wafer retainer and an evaluation thereof
A double coated adhesive film E with release sheets provided thereon was obtained in the same manner the double coated adhesive film A in Example 1 was produced except that the above-mentioned temperature-activated pressure-sensitive adhesive was used in the place of the temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) of the double coated adhesive film A.
A wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the above-mentioned double coated adhesive film E having release sheets. The resultant wafer retainer was evaluated in the same manner as in Example 1 except that the ceramic upper base plate with the wafer retainer was immersed in pure water at about 10ºC.
The wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 7 kg.
(Comparative Example 2) An adhesive composed of 100 parts of butylacrylate, 5 parts of acrylonitrile, and 5 parts of acrylic acid was prepared. A double coated adhesive film with release sheets provided thereon was obtained in the same manner the double coated adhesive film A in Example 1 was produced except that the above-mentioned temperature-activated pressure-sensitive adhesive was used in the place of the temperature-activated pressure-sensitive adhesive (manufactured by Landeck Corporation) of the double coated adhesive film A. A wafer retainer was obtained in the same manner the wafer retainer of Example 1 was obtained except for using the above-mentioned double coated adhesive film having release sheets. The resultant wafer retainer was evaluated in the same manner as in Example 1.
The wafer retainer having the temperature-activated pressure-sensitive adhesive easily peeled off an upper base plate at a peeling force of at most 28 kg. The exchanging or replacement of a wafer retainer for retaining wafers to be polished according to the present invention, conducted after each polishing process, is substantially facilitated because the wafer retainer can be peeled off a base plate by simply cooling the base plate and an adhesive layer of the wafer retainer.

Claims

1. A wafer retainer for retaining a wafer to be polished, the wafer retainer comprising:
a foam layer capable of adsorbing a wafer on a surface of the foam layer in a detachable manner;
a pressure-sensitive adhesive layer for attaching the foam layer to a base plate of a polishing machine; and a release sheet attached to the pressure-sensitive adhesive layer in a releasable manner,
wherein the pressure-sensitive adhesive layer comprises an adhesive composition containing a polymer, the polymer having a first-order melt transition occurring in a temperature range narrower than 15ºC.
2. A wafer retainer according to claim 1, wherein the adhesive composition comprises a side-chain crystallizable polymer as the polymer in an amount such that the pressure-sensitive adhesive layer becomes substantially untacky to the base plate of the polishing machine at 20ºC or less and substantially tacky to the base plate of the polishing machine at a temperature higher than 20ºC.
3. A wafer retainer according to claim 2, wherein the side-chain crystallizable polymer comprises as a main component thereof an acrylic acid ester and/or methacryl acid ester which has a straight-chain alykyl group including 10 or more carbons as a side chain.
4. A wafer retainer according to claim 2, wherein the side-chain crystallizable polymer is a copolymer of (meth)acrylate having 10 to 14 carbons and at least one monomer selected from the group consisting of acrylic acid and (meth)acrylate having 1 to 4 carbons.
5. A wafer retainer according to claim 4, wherein the copolymer comprises the following components:
40% to 95% by weight of (meth)acrylate having 10 to 14 carbons;
1% to 10% by weight of acrylic acid; and/or
5% to 40% by weight of (meth)acrylate having 1 to 4 carbons.
6. A method for attaching/detaching the wafer retainer according to claim 1 to/from a base plate of a polishing machine, the method comprising the steps of:
attaching the wafer retainer to the base plate of the polishing machine by removing the release sheet of the wafer retainer from the pressure-sensitive adhesive layer, and thereafter allowing the pressure-sensitive adhesive layer of the wafer retainer to adhere to the base plate of the polishing machine while keeping the base plate at a temperature T1; and
after use of the wafer retainer, detaching the wafer retainer from the base plate of the polishing machine while cooling the base plate from the temperature T1 to a. temperature T2, the temperature T2 being lower than the temperature T1.
7. A method according to claim 6, wherein the temperature T1 is 20ºC or above, and the temperature T2 is below 20ºC.
8. A method according to claim 6, wherein the temperature T1 is 25°C or above, and the temperature T2 is below 20ºC.
PCT/JP1996/000806 1995-03-29 1996-03-27 A wafer retainer for retaining a wafer to be polished and a method for attaching/detaching the wafer retainer to/from a base plate of a polishing machine WO1996030163A1 (en)

Applications Claiming Priority (2)

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JP7/72105 1995-03-29
JP7210595A JPH08267668A (en) 1995-03-29 1995-03-29 Polishing wafer holding component and method for attaching and detaching wafer holding component to and from polishing machine surface plate

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WO2000012643A1 (en) * 1998-08-28 2000-03-09 Nitta Corporation Wafer retainer and method for attaching/detaching the wafer retainer to/from polishing machine base plate
WO2000017284A1 (en) * 1998-09-17 2000-03-30 Nitta Corporation Workpiece retainer and method for attaching/detaching workpiece by using the same
US7913595B2 (en) 2007-02-23 2011-03-29 Esa Eppinger Gmbh Clutch device for tool holders or for workpiece chucking device

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JP4364535B2 (en) 2003-03-27 2009-11-18 シャープ株式会社 Manufacturing method of semiconductor device
KR100689096B1 (en) * 2005-06-16 2007-03-08 윤재남 Micro Device Polishing Device and Polishing Method
US8950459B2 (en) * 2009-04-16 2015-02-10 Suss Microtec Lithography Gmbh Debonding temporarily bonded semiconductor wafers
JP6162976B2 (en) * 2013-02-26 2017-07-12 東京応化工業株式会社 Substrate processing method

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Publication number Priority date Publication date Assignee Title
WO2000012643A1 (en) * 1998-08-28 2000-03-09 Nitta Corporation Wafer retainer and method for attaching/detaching the wafer retainer to/from polishing machine base plate
US6666752B1 (en) 1998-08-28 2003-12-23 Nitta Corporation Wafer retainer and method for attaching/detaching the wafer retainer to/from polishing machine base plate
WO2000017284A1 (en) * 1998-09-17 2000-03-30 Nitta Corporation Workpiece retainer and method for attaching/detaching workpiece by using the same
US7913595B2 (en) 2007-02-23 2011-03-29 Esa Eppinger Gmbh Clutch device for tool holders or for workpiece chucking device

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MY113901A (en) 2002-06-29
TW289144B (en) 1996-10-21
JPH08267668A (en) 1996-10-15
KR19980703331A (en) 1998-10-15

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