WO2012036794A2

WO2012036794A2 - Photodetectors with light incident surface and contact surface and applications thereof

Info

Publication number: WO2012036794A2
Application number: PCT/US2011/046146
Authority: WO
Inventors: Alexander O. Goushcha; Frederick Flitsch; Daniel Codi; George Papadopoulos; Sandeep Dave
Original assignee: Array Optronix, Inc.
Priority date: 2010-08-01
Filing date: 2011-08-01
Publication date: 2012-03-22
Also published as: WO2012036794A3

Abstract

The disclosed invention relates to structures and fabrication methods of photodetectors based on photodiodes for various applications using 3D integration approach. The structure of the photodetector comprises at least two layers (202, 203) bonded to each other, wherein a first layer (202) is made of a semiconductor material having a first conductivity type and a first concentration. A second layer (203) is made of a semiconductor material which is either in direct contact with the first layer (202) or bonded to the first layer by a bonding layer (216) made of a thin dielectric material. At least one region (206) of second conductivity type, at least a p/n junction and at least one region (207) of the first conductivity type with a second concentration heavier than the first concentration is formed within the first layer (202). A through silicon via (211, 214) is formed in the second layer (203). The at least one region (206) of the second conductivity type detects light photons scattered from along a reference path that traverses a reference region (220, 221) which defines a reference point within the first layer (202) of the structure for aligning the impinging light and comprises a part of the photodetector for a particle sizing application.

Description

PHOTODETECTORS WITH LIGHT INCIDENT SURFACE AND CONTACT

SURFACE AND APPLICATIONS THEREOF

FIELD OF THE INVENTION

The present invention relates to semiconductor photo detectors and their applications, and in particular, to the structures . of high performance, back-illuminated or front illuminated photodiodes with or without through vias for contacting purpose and the methods of fabricating such structures.

BACKGROUND OF THE INVENTION

Photodetectors based on various structures that include photodiode(s) are widely used in different applications ranging from nano- and micro- structures analysis through detection of distant extra terrestrial objects and events, etc. Among the known photodiode structures for a variety of analytical applications are those having typically two surfaces, one of which serves as the light entering (incident) surface. The active element(s) of the photodetector based on semiconductor photodiode structures may be arranged either close to the light entering surface, or close to the opposite surface of the structure, or in-between the surfaces. Accordingly, the contacts to the downstream electronics may be provided through either of the two surfaces of a structure.

Photodiode structures used traditionally for various photodetector applications were based on developed semiconductor technologies. They used mainly backlit or front-illuminated structures built on a single semiconductor layer (substrate). Such structures had specific regions enabling specific analytical applications. For example, the structures developed for particle sizing applications might have, as an example, active elements shaped in the form of concentric rings arranged around the feature that allowed easy alignment of a laser beam.

Recently emerged technologies allowed building improved photodetector structures for a variety applications. For example, wafer bounding and through-semiconductor via technologies allowed building 3-D structures that may greatly enhance detection capabilities and application of different devices. The current invention describes the structures and fabrication methods of photodetectors based on photodiodes for various applications using 3-D integration approach.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, that are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and, together with the description, serve to explain the principles of the preferred embodiments of the invention:

Figure 1 (prior art) is the cross sectional view of a typical front-illuminated photodiode structure with wire bonding capabilities for multiple analytical applications.

Figure 2 (prior art) is the cross sectional view of a typical back-illuminated structure with flip- chip die attach capability for multiple analytical applications.

Figure 3 is the cross sectional view of a sample photodiode structure built on bonded layers with contact vias having also reference regions useful for multiple analytical applications.

Figure 4a is the cross sectional view of a sample photodiode structure in accord with present embodiments, built on bonded layers with contact vias and having also reference region spanning across the structure and allowing variety of applications. The figure demonstrates one of the possible applications of the structure - particle sizing detector, in which impinging light propagates along the axis of a reference region while particles scatter photons from their original path.

Figure 4b is an example of the top view of the sample photodiode structure (ring detector) of Figure 4a. Rings outlined with dashed lines show buried photosensitive regions. Dashed-and- dotted line indicates the region cross-sectioned in Figure 4a.

Figure 4c is an example of the bottom view of a sample photodiode structure (ring detector) of Figure 4a. Rings outlined with dashed lines show buried photosensitive regions. Small circles are the pads on the bottom of the structure. Figure 5a is the cross sectional view of another sample photodiode structure in accord with present embodiments, built on bonded layers with contact vias. The structure has active regions arranged symmetrically with respect to a reference region. The figure demonstrates multiple applications, including remote sensing, remote object targeting, positioning, etc., in which impinging light may create different response in neighboring active regions, producing a difference signal. Figure 5b is an example of the top view of a sample photodiode structure cross-sectioned in Figure 5a. Four active regions arranged in quadrant architecture exemplify detector for targeting applications. They also may be a part of a detector with larger number of elements, in which case the detector may be useful for positioning applications. As an example, the circle with dashed- and-dotted line outlines the area where the photons may impinge the surface. Dashed-and -dotted straight line exemplifies the place where cross-section of Figure 5a was made.

Figure 5c is an example of the bottom view of a sample photodiode structure (position or targeting detector) of Figure 5a. Dashed lines show buried regions. The circles indicate pads on the bottom of the structure. Dashed-and -dotted straight line exemplifies the place where a cross- section of Figure 5a was made. Figure 6a is the cross sectional view of another sample photodiode structure in accord with present embodiments, built on bonded layers with contact vias. The structure has a single active region arranged symmetrically with respect to a reference region. The figure demonstrates position sensitive application using resistive charge division sensor, in which impinging light may create different photocurrent in different charge collecting electrodes of a single active regions.

Figure 6b is an example of the top view of a sample photodiode structure cross-sectioned in Figure 6a. A single active region arranged around the center. As an example, the circle with dashed-and-dotted line outlines the area where the photons may impinge the surface. Photogenerated charges ql, q2, q3, and q4 create photocurrents II, 12, 13, and 14, respectively. Dashed-and -dotted straight line exemplifies the place where cross-section of Figure 6a was made.

Figure 6c is an example of the bottom view of a sample photodiode structure for position sensitive application of Figure 6a. Dashed lines outline buried regions. The circles indicate pads on the bottom of the structure. Dashed-and -dotted straight line exemplifies the place where a cross-section of Figure 6a was made. Photogenerated charges ql, q2, q3, and q4 create photocurrents II, 12, 13, and 14, respectively. The value of each photocurrent depends on the resistance to the respective collecting electrode.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Accordingly, the first set of embodiments of the present invention provides backside illuminated photosensitive devices for multiple analytical applications that may employ standard semiconductor processing equipment. The devices of these embodiments are the structures comprising either a single photosensitive element or one-dimensional or two-dimensional arrays of photodiodes, built on the first semiconductor layer having the first and second surfaces and having also the second layer bonded or deposited on the second surface of the first semiconductor layer. Therefore, the second layer has the first surface in contact with either the first semiconductor layer directly or with the bonding layer on the second surface of the first semiconductor layer and the second surface. In some embodiments, the second layer may be a semiconductor layer. In other embodiments, the bonding layer may comprise a thin layer of dielectric material.

The anode/cathode of each photodiode is formed by the first doping regions proximate to the second surface of the first semiconductor layer. This doping region does not reach the first surface of the first semiconductor layer. The isolating regions penetrate all the way through the first layer and may reach the first surface of the first semiconductor layer. In some embodiments, the isolating regions may enclose the anode/cathode region of a single photodiode of the array. The isolation regions may be created by trenches or through vias, backfilled with standard filler. Alternatively, these isolation regions may be formed by the second doping regions, or a combination of trenches with the second doping regions. In the former case (doping regions only), the second doping regions extend from the first surface of the first semiconductor layer reaching the second surface of the first semiconductor layer. In the latter case (combination of doping regions and trenches), the second doping regions may extend from the first surface of the first semiconductor layer and stop inside the bulk of the first semiconductor layer, not reaching the second surface of the first semiconductor layer; The isolation is completed in this case by trenches extending from the second surface of the first semiconductor layer inside its bulk and possibly touching the second doping regions. In other embodiments, the second doping regions and trenches may be swapped in location.

The sidewalls of the trenches may be doped to comprise the portions of the second doping regions. In all cases, the second doping regions concentration may not necessarily be uniform along the path connecting the surfaces of the two semiconductor layers. Moreover, they may have gaps along this path, located inside the first semiconductor layer, with a very low or nonexistent second doping concentration. The third doping region is located proximate to the first surface of the first semiconductor layer and forms a common cathode/anode of the photodiodes. The first surface of the first semiconductor layer has a passivation layer.

All elements of the structured described above are arranged in a specific way that they have a reference region either at least on one of the surfaces of the first semiconductor layer, or in the bulk of that layer. Alternatively, the reference region may be located in the second layer or on the surface(s) of that layer. The reference region is designed to serve as a starting (or reference) point for quantification of various parameters that depend on the impinging light intensity and other parameters of the incoming light (for example, a spectral composition of light). As an example, such parameter may be the light intensity impinging different photodiodes of the array and the reference region may be a spot or other feature on the first surface of the first semiconductor layer that serves as a target for impinging light alignment. In the other example, such parameter may be a difference in light fluxes impinging neighboring active regions of the photodetector and the reference region may be a gap between those active regions. There may be multiple embodiments showing other possible applications and related reference regions in the photodetectors of the current invention.

In some cases, the first semiconductor layer may consist of more than one sub-layers and additional doping regions or other structural elements may be located in those sub-layers. The second surface of the first semiconductor layer is attached to the second layer using one or more bonding adhesion, etch-stopping, and/or isolation layers.

The through vias are made in these second layer and bonding layers to open the first and second doping regions on the surface or in the bulk of the first semiconductor layer. There could be at least one through via per photosensitive element of a structure reaching the first doping region of each photodiode. There could be at least one through via per structure reaching the second doping region. Inside openings, the regions of the first semiconductor layer proximate to its second surface are covered or enriched with silicide or other known in the industry material to provide good Ohmic contact to the semiconductor regions. The vias are used to create conductive paths with metal or other highly conductive material from the surface of the support substrate to the first and second doping areas. The vias may be backfilled with oxide, polysilicon, or other standard filler and the contact pads may be deposited on the top completing the structure of the backlit photodiode array. Alternatively, the metal that contacts the semiconductor doping regions may be patterned to form the contact pads. The second set of embodiments of the present invention comprises the methods to manufacture backlit photodiode structures for multiple analytical applications bonded to the support substrate in accord with the first set of embodiments described in the above paragraphs.

The third set of embodiments of the present invention provides front illuminated photosensitive device and array structures for multiple analytical applications that may employ standard semiconductor processing equipment. The devices of these embodiments are the structures comprising either a single photosensitive element or one dimensional or two dimensional arrays of photodiodes, each having the first semiconductor layer and the second layer and many structural features similar or identical to the previous set of embodiments. Also, these devices have reference regions similar to the ones described in the preceding paragraphs. However, the main feature of this set of embodiments that distinguishes it from the previous set is that the anode/cathode is formed proximate to the first (light impinging) surface of the first semiconductor layer, which results in the anode/cathode region formed proximate to the very top of the finished device structure. Accordingly, the through vias may be required in the top semiconductor layers to contact these anode/cathode regions and to bring signals to the bottom of the structure. Also, no vias through the top semiconductor layers may be required to contact the isolation regions.

The forth set of embodiments of the present invention comprises methods to manufacture the front-illuminated photodiode photosensitive devices for multiple analytical applications bonded to the second layer in accord with the third set of embodiments described in the above paragraphs.

The present invention relates to photosensitive structures and methods of manufacturing the same. The active portion of the devices may be created in the first semiconductor layer of the first conductivity type. As an example, this semiconductor layer may be comprised of silicon. It may be obvious to one skilled in the arts that other embodiments may derive from the use of other semiconductor materials than silicon.

The semiconductor layer has first and second surfaces. As an example, silicon layer may be used. In some embodiments of this invention, the basic cell architecture of the photodiode includes regions of the second conductivity type created proximate to the second surface of the first semiconductor layer and separated by intrinsic regions from the regions of the first conductivity type on the first surface of the device thickness layer. A region or a plurality of regions of the first conductivity type with concentration heavier than the background of the unprocessed first semiconductor layer may be made between the regions of the second conductivity, type on the second surface of the first semiconductor layer. Additionally, a region or a plurality of regions of the first conductivity type with concentration heavier than the background concentration may be made on the first surface of the first semiconductor layer and may be aligned with the region of the plurality of regions of the first conductivity type on the second surface. The two aligned regions of the first conductivity type created on opposite surfaces of the first semiconductor layer may be in contact, in some embodiments, through doped regions that pervade from both surfaces of the first semiconductor layer used to define the active portion of the device. In some embodiments of this invention, thin processing of the active portion of the semiconductor device is accomplished by bonding of the semiconductor material onto another semiconductor substrate where some level of device processing has occurred. Still further embodiments may derive when non semiconductor material substrates are bonded to the active portion of the device.

Some features distinguishing the current invention from the previous art are depicted in Figure 1 and Figure 2.

Figure 1, item 001, shows a typical example of photosensitive device for analytical application (prior art) having the anode 015 and cathode 013 contacts on the opposite sides of the device structure. Moreover, the wire bonding 034 is usually applied to bring signals to the downstream electronics. The device is front-illuminated and the anode/cathode diffusion region 006 with p/n junction 008 is located on the first (top) surface 004 of the semiconductor layer 002. The cathode/anode diffusion region 009 is of the opposite polarity and locates on the opposite (bottom) surface 005 of the semiconductor layer 002. The isolation region 007 is on the first surface of the semiconductor layer 002. The passivation layer 010 is also shown. The second (bottom) surface 005 of the structure is attached to the bonding pad 032 that resides on top of the support substrate 031, which is usually the part of the device packaging. The wire bonding is made to the pad 033 on the surface of the support substrate 031. The routing of the signals is made usually on the same surface of this support substrate 031. The features 020 and 021 may be required as the reference structures for different applications of the photosensitive device. For example, in applications involving light scattering by small size particles 040, these features 020 and 021 may perform the role of a target structure for incident light.

Figure 2, item 100, is another typical example of a prior art photodetector (photosensitive device) for analytical application. This is a backlit device having the anode/cathode diffusion 108 and p/n junction proximate to the second (bottom) surface 105. The cathode/anode diffusion 109 is of the opposite polarity and locates on the first (top) surface 104 of the semiconductor layer 002. The isolation regions 007 and 107 may also apply. The features 120 and 121 are the reference structures that may be required for various applications; these features are similar to the features 20 and 21 of Figure 1. The items 110 and 111 are passivation layers and 113 and 115 are the metal pads, the device in such applications is flip-chip attached to the support substrate 031 using stud bumps or solder bumps 134. The bonding pads 132 and 133 connect device to a downstream electronics.

The embodiments of current invention rely on photodetector designs for various analytical applications having specific reference structures and having the second layer bonded to the first semiconductor layer with through vias in the said second layer to bring signals to the downstream electronics.

It may be possible to envision the steps of one embodiment by referring to Figure 3, item 200. A first semiconductor layer 202 of a first conductivity type has a first surface 204 and a second surface 244. A lithography step may next be performed on the layer surface 244 to define features 207 - the regions of the first conductivity type with concentration heavier than that of the background concentration of the first semiconductor layer 202. In some embodiments, these regions may form a matrix on the surface 244. In some embodiments, region 207 may be defined with a N type dopant. In most steps of doping of this invention it may be apparent to one skilled in the art that thermal diffusion processes or ion implantation may comprise acceptable means for locally doping a region.

After regions 207 are doped a diffusion step may occur to drive the dopant into the bulk. There may be numerous means to effect the diffusion of the dopants herein. For example, a thermal furnace may be operated at a high temperature, for example 1100 degrees centigrade. A next lithography step may define the plurality of regions 206 of the second conductivity type on the semiconductor surface 244. It may be apparent that in defining these regions the lithography step may either just define imaged regions of photoresist that may block implantation in selected regions or alternatively, films upon the surface of the substrate may be selectively removed in the lithography defined regions therefore allowing diffusion processes to occur into the semiconductor. It may be apparent to one skilled in the arts that numerous means of defining the location of doped regions in these embodiments may comprise elements of the art herein. Item 130 may be defined with a P type dopant. Again in some embodiments a thermal diffusion process may drive the dopant into the bulk of layer 202. In some embodiments, after the definition of regions 207 and 206, an epitaxial growth step may occur. It may be apparent to one skilled in the art that numerous embodiments of different resistivity and epitaxial layer thickness may comprise consistent definitions of the epitaxial layer consistent with this art. And, further embodiments may come from a variation of certain layer characteristics including, for example the resistivity, while the layer is being grown. Still further embodiments may be derived from performing the epitaxial layer definition in numerous steps.

In further embodiments, the surface 204 of the first semiconductor layer 202 will be processed with lithography steps to define regions 217. Into these regions in many embodiments with methods similar to those used to form regions 207, the first conductivity type dopant regions may be defined. Further thermal processing may be used to drive the regions 207 and 217 toward each other within the first semiconductor layer 210. For the skilled in the art it may be apparent that the regions 217 may be defined on top of the epitaxially grown layer, although the latter is not shown in the figure.

In some embodiments, the dopant regions of 207 and 217 may touch or overlap. Other embodiments may include these layers being close to each other but not necessarily overlapping. It may be apparent to one skilled in the arts, that a significant diversity of processing embodiments may comprise results consistent with the formation of elements of a photo detector array.

The regions 207/217 may perform a role of electrical and optical isolation from the neighbor elements of the photodetector structure; as described above in some embodiments, these regions may be formed by the dopant of the first conductivity type. In other embodiments, they may be created by trenches or through vias; in still other embodiments the trenches may be backfilled with a standard filler. Alternatively, these isolation regions may be formed by a combination of trenches with the doping regions of the first conductivity type. In the case of the regions 207/217 being doping regions only, these regions extend from the first surface 204 of the first semiconductor layer 202 reaching the second surface 244 of the first semiconductor layer. In the case of combination of doping regions and trenches, the regions 207/217 may extend from the first surface 204 of the first semiconductor layer and stop inside the bulk of the first semiconductor layer, not reaching the second surface 244 of the first semiconductor layer; The isolation is completed in this case by trenches extending from the second surface 244 of the first semiconductor layer inside its bulk and possibly touching the doping regions 207/217. In other embodiments, the second doping regions and trenches may be swapped in surface location.

In some embodiments, the regions 207 and 217 may abut the regions 206 of the second conductivity type. In some embodiments, such abutting may provide a rectangular shaped structure or other type of matrix.

In some embodiments additional processing may occur to define a region 209 of the same conductivity type as regions 217 across the device surface. In some cases, this region may be defined as a narrow feature at the very surface of the first semiconductor layer. In some embodiments, the region 209 may be defined on the surfaceof the epitaxial layer(s) if they were grown during the previous steps as described above. In these embodiments it may be preferential to limit thermal exposure of the device in subsequent steps so as not to significantly thermally diffuse the defined layer 209. Further embodiments may be defined by using a dopant species for layer 209 that while the same conductivity type as 217 may include a species that diffuses less rapidly for any thermal exposure that may be necessary for subsequent processing. It may be apparent to a skilled artisan that the numerous options for doping a semiconductor layer to form one type of doped region comprise consistent scope for embodiments in this art. Some embodiments will further process the device by forming a film 210 of insulating material. As a non limiting example, the film 210 may include silicon dioxide that has been either thermally grown onto the surface 204 or deposited by various means onto that surface. In some embodiments, this film will comprise an optically relevant portion of the path photons may take in impinging the photodiodes of this invention. It may be important that the characteristics of this film therefore are tuned to optimize the photodiode photoresponse.

Additional embodiments may derive from the reference regions 220 and 221 created on the surfaces of the first semiconductor layer 202. These regions may serve as reference points to align the impinging light. In some embodiments, these features may propagate inside the bulk of the layer 202. In the other embodiments, they can even touch in the bulk. These regions may include, in a non-limiting sense, diffusion regions of either the first or the second conductivity type and may be located at a certain distance from the region 206 to define a reference point. In other embodiments, at least the portion of these regions may contain at least a single via or trench. In still other embodiments, the vias or trenches may propagate all the way through the thickness of the first semiconductor layer 202. Furthermore, the regions 220 and 221 may comprise at least partially different materials than materials of the layers 202 and 203.

Item 216 shows a bondable film. In some embodiments this film may be a bondable oxide 216 and it may be deposited or grown into a surface 244. The second layer 203 having the first surface 245 and the second surface 205 is bonded to the first semiconductor layer 202 through the bonding film 216. It may be obvious to one skilled in the art that the various types of materials for the layer 203 ranging from semiconductors to non semiconductor substrates are consistent with the invention herein described.

In some embodiments, the layer 203 may be thinned from the surface 205 after bonding to the first semiconductor la er 202.

Next, electrical connections may be made to the regions 206 and 207. Contact openings 211 and 214 may be defined into the second layer 203 and bonding layer 216. In some embodiments enhancement diffusions or implantations with dopants of the corresponding types may be made into the surface 244 where contact will be made in either or both of the diffusion types as shown by items 218 and 219. In other embodiments, these items 218 and 219 may be silicides. For example, some embodiments may use a titanium deposition process. Thermal reaction of the titanium with exposed silicon, if the semiconductor is silicon, will form a good contact definition and in the insulator regions will not form a silicide.

As a non-limiting example, each photosensitive element has at least one item 214, Also, only one or a few items 211 may be made across the whole structure.

In some embodiments, a layer 212 may be deposited into the formed vias. This layer may, by means of non limiting example, be a doped poly silicon film, and may be deposited using CVD. In other embodiments, the layer 212 may comprise an evaporated or sputtered metal film. Still other embodiments may be defined by combinations of a CVD layer and a metal layer. From a general perspective, it may be obvious that any means to form an electrical contact in a via formed in the substrate material may comprise art consistent with this invention. In the case when the second layer 203 was a semiconductor, the additional layer deposited on the sidewalls of vias 211 and 214 may comprise the sandwich of the isolating 222 and conductive 212 films, wherein the isolating film was deposited first followed by deposition of the conductive film.

A lithographic process may be employed to regionally etch away materials between contact regions to define isolated contact regions. In some embodiments, the regional definition may be used to also define the contact pads for external connection. In many embodiments a voided region will exist in the vias regions 211 and 214. In some embodiments, a filling layer may be introduced into the voids followed by the surface planarization. The insulator material layer 223 may be added to the surface 205 between vias.

In alternative embodiments a second level of metal may be added after the vias 211/214 are filled in and etched back to expose the regions 212. In a non limiting example an Aluminum layer could be deposited to define the contact pads items 213 and 215. In some embodiments additional materials may be added to this feature to allow for appropriate layers to place solder bumps or other interconnection solutions.

Another set of embodiments may describe structures similar to those shown in Figure 3 but comprising front-illuminated photodetector devices. As the main features of the embodiments describing such devices, the region of the second conductivity type with the dopant concentration heavier than the background concentration may be applied at the very end of the thermal processing flow to allow this region to remain shallow, in a close proximity to the surface 204 (top surface of the device structure) of Figure 3. No blanket doping 209 of the first conductivity type will be required proximate to the surface 204. Instead, a heavily doped layer of the first conductivity type may be applied proximate to the surface 244 of the first semiconductor layer of the structure. For those skilled in the art it may be obvious that to complete the front-illuminated structure of this type, one may provide a through via contacting the regions of the second conductivity type on the top surface of the device structure and bringing the signals to the bottom surface of the device structure. In some embodiments, the sidewalls of those vias may be coated with insulator (dielectric). In yet other embodiments, the conductive later may be aligned inside vias to connect features on the device surfaces.

Yet another set of embodiments refers to the structure similar to the one shown in Figure 3, but with the region 206 of the second conductivity type sitting above the surface 244. In this case, the region of the first conductivity type may separate the region 206 and the surface 244. The via 214 may penetrate inside the bulk of the first semiconductor layer 202 at least partially to reach the region 206.

Proceeding to Figure 4a, item 300, an example of application of the structure shown in Figure 3 is depicted. In this particular case of particle sizing application, the impinging light may propagate along the axis 321 of the reference structure 210. In some embodiments, the reference structure 320 may be a drilled hole or through via with sidewalls 317 either doped with the dopant or lined with the dielectric or other material liner. In some embodiments, the doping material/region 317 may be of the first conductivity type; in the other embodiments this material/region may be of the second conductivity type. In still other embodiments, the region 317 may be intermittent. In the application of Figure 4a, the particles of different sizes 326 scatter impinging light 325 differently, which results in optical quanta propagating towards different spots of the photodetector surface 204. In some embodiments, there may be several photosensitive regions located at different distances from the reference region 320, in which case different photosensitive regions will detect light scattered by the particles of different size. Figure 4b, item 300a, depicts the front (light impinging side) view of one of the possible realizations of the structure shown in Figure 4a. In this case, the dashed-dotted line 301 shows the cross-sectional plane viewed in Figure 4a. The embodiments of Figure 4b depict a version of a particle sizing detector with photosensitive regions 206/306 arranged in concentric rings (outlined with the dashed line since they are buried under the surface). In some embodiments, the photosensitive regions 206/306 may be separated from each other with the isolating regions 217/307, wherein each of the regions 307 is similar structurally to the region 207. There may be multiple rings in a single photodetector. Figure 4c, item 300b, comprises further an example of a bottom view of the structure depicted in Figure 4a and Figure 4b. In some embodiments, the metal pads 215/315 contact different regions 206/306 of the second conductivity type, whereas the metal pads 213/313 contact the regions 207/307 of the first conductivity type. In some embodiments, rings comprising photosensitive regions may be the portions of arc areas. In other embodiments, the isolation regions may form a matrix also comprising the arc areas. It is obvious for a skilled artisan that the the photosensitive regions may comprise a matrix of elements of various shapes, designed appropriately for ease and convenience of a specific application. Proceeding to Figure 5a, item 400, another application example of the structure shown in Figure 3 is depicted. In this particular case of the detector for targeting application, the impinging light 425 may propagate along the axis 421 of the reference structures 420/427. In some embodiments, the reference structures 420/427 may be doped regions with the dopant of either the first or the second conductivity type. In other embodiments, the doped regions 427 may have a layer of different material 420 on the top. As a non-limiting example, this layer may be a metal layer 420. In some embodiments, the regions 206 and 406 comprise two neighbor photosensitive elements of the photodetector for targeting applications. These items 206 and 406 are located at a specific distance from the reference structure 420/427. The isolation structures 407/417 may be similar to isolation structures 207/217. Similarly, some embodiments may provide vias 414 that contact regions of the second conductivity type 406. In other embodiments the additional contact pads 415 and 413 are provided to bring signals from the items 406 and 407, respectively, up to the downstream electronics.

Figure 5b, item 400a, depicts the front (light impinging side) view of one of the possible realizations of the structure shown in Figure 5a. In this case, the dashed-dotted line 434 shows the cross-sectional plane viewed in Figure 5a. The embodiments of Figure 5b depict a version of a quadrant detector for targeting application with photosensitive regions 206/406/416 arranged in quadrants (outlined with the dashed line since they are buried under the surface). In some embodiments, the photosensitive regions 206/406/416 may be sorrounded with the isolating regions 217/417, wherein each of the regions 417 is similar structurally to the region 217. In some embodiments, the reference structure 420/427 may consist of diffusion 427 of the first conductivity type and deposited material item 420. In other embodiments, the structure 420/427 may be a combination of diffusions of different conductivity type, revealing for example the p-n- p or n-p-n transistor structures. Figure 5c, item 400b, comprises further an example of a bottom view of the structure depicted in Figure 5a and Figure 5b. In some embodiments, the metal pads 215/415 contact different regions 206/406/416 of the second conductivity type, whereas the metal pads 213/413 contact the regions 207/407 of the first conductivity type.

Proceeding further to Figure 6a, item 500, another application example of the structure shown in Figure 3 is depicted. In this particular case of the detector for position sensitive application (a resistive charge division sensor), the impinging light 525 may propagate along the axis 521 of the reference structures 520. In some embodiments described by Figure 6a, the reference structure 520 may be just a virtual center of the diffusion region 506 of the second conductivity type (having the p/n junction along the item 508), which equidistant from the contact vias 514 and 518. The metal pads 515 and 517 provide electrical contacts to the areas of the region 506 located directly above the vias 514 and 518; those areas are equidistant from the reference virtual structure 520. The metal pads 513 and 516 provide electrical contacts to the isolation areas 207 and 407.

Figure 6b, item 500a, depicts the front (light impinging side) view of one of the possible realizations of the structure shown in Figure 6a. In this case, the dashed-dotted line 534 shows the cross-sectional plane viewed in Figure 6a. The embodiments of Figure 6b depict a version of a resistive charge division sensor application with photosensitive region 506 of a second conductivity type with a specially designed resistivity. In some embodiments, the photosensitive region 506 may be surrounded with the isolating regions 217/417, wherein each of the regions 417 is similar structurally to the region 217. The circle 535 outlined with the dashed line shows schematically the surface area impeded by light. The photogenerated charges ql, q2, q3, and q4 are devided into photocurrents II, 12, 13, and 14 in accord with the respective resistance to the contact electrodes 515, 517, and 545 (see Figure 6c). Figure 6c, item 500b, comprises further an example of a bottom view of the structure depicted in Figure 6a and Figure 6b. In some embodiments, the metal pads 515/517/545 contact different areas of the same region 506 of the second conductivity type, whereas the metal pads 513/516/546 contact the regions 207/407 of the first conductivity type. It may be apparent to one skilled in the art that while certain embodiments have been described with specific dopant types identified that devices may be performed where different polarity of dopant type species and substrate characteristics may be used within the scope of this invention.

It may be apparent to one skilled in the art that specific embodiments have been described to define how a through silicon via may electrically contact a specific region of a photodetector structure. However, any method, including through vias that connect to metal pads that are electrically connected with other vias to a specific region of a photo detector, that allows a through silicon or through insulator via to make an electrical contact to a region beyond it may comprise art within the scope of this invention.

While the invention has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this description is intended to embrace all such alternatives, modifications and variations as fall within its spirit and scope.

Claims

1. A photodetector comprising:

a structure having at least two layers bonded to each other; wherein at least the first layer is a semiconductor layer of a first conductivity type with a first concentration; the said structure also having a first and a second surfaces wherein the first surface being the light entering surface; at least one region of the second conductivity type within the first layer of the first conductivity type;

at least one p/n junction within the first layer of the first conductivity type;

at least one region of the first conductivity type with a second concentration heavier than the first concentration and arranged within the first layer of the first conductivity type;

at least one through silicon via electrically contacting the at least one region of the second conductivity type from the second surface of the structure; and,

wherein the at least one region of the second conductivity type detects light photons scattered from along the reference path that traverses a reference region within the first layer of the structure and comprises a part of the photodetector for particle sizing application.

2. A photodetector of the claim 1 wherein:

at least one region of the second conductivity type within the first layer of the first conductivity type having a ring shape and comprises a part of a ring-shaped detector.

3. A photodetector comprising:

at least one region of the first conductivity type with a second concentration heavier than the first concentration and arranged within the first layer of the first conductivity type; at least one through silicon via reaching the at least one region of the second conductivity type from the second surface of the structure;

and, wherein the at least one region of the second conductivity type being placed close to a reference region of a second conductivity type within the first layer comprising a part of the photodetector for remote targeting application.

4. A photodetector comprising:

at least one through silicon via reaching the at least one region of the second

conductivity type from the second surface of the structure;

and, wherein the at least one region of the second conductivity type is placed relative to the reference region comprising a part of the photodetector for identifying the physical location on the first surface where the light photons impinge that surface.

5. A photodetector of claim 4 for position sensitive application wherein:

the at least one region of the second conductivity type shifted laterally in x- and y- direction with respect to the reference regions comprises a part of the photodetector for identifying x-y coordinates on the first surface where the light photons impinge the first surface. .

6. A photodetector of claim 4 for position sensitive application wherein:

the at least one region of the second conductivity type shifted laterally in radial and azimuth direction with respect to the reference regions comprises a part of the photodetector for identifying polar coordinates on the surface where the light photons impinge the first surface.

7. A photodetector of the claim 4 for position sensitive applications using linear arrays, in which:

at least one region of the second conductivity type within the first layer of the first conductivity type is repeated laterally in one direction producing a one dimensional array.

8. A photodetector of the claim 4 for position sensitive applications using two-dimensional arrays, in which:

at least one region of the second conductivity type within the first layer of the first conductivity type is repeated laterally in two directions producing a two dimensional array.

9. A photodetector of the claim 4 for position sensitive applications wherein:

at least one region of the second conductivity type within the first layer of a first conductivity type having more than one electrical contact through more than one through via and having a resistivity designed to be used in a resistive charge division sensor.

10. A photodetector of the claim 4 for position sensitive applications wherein:

at least one region of the second conductivity type within the first layer of the first conductivity type having a shape of a strip placed next to the reference region(s) , and designed to be used as a strip detector.

11. A photodetector comprising:

and,

wherein at least one region of the second conductivity type within the first layer of the first conductivity type has at least two different light sensitive area within it, being designed for a laser gyros application.

12. A photodetector comprising:

at least one through silicon via electrically contacting the at least one region of the second conductivity type from the second surface of the structure; the electrical contacts being provided to the at least one region of the second conductivity type through the said at least one through silicon via; and,

wherein at least one region of the second conductivity type within the first layer of the first conductivity type being placed next to the reference region as designed for a phase shift detection;

13. A photodetector comprising:

a structure having at least two layers bonded to each other; wherein at least the first layer is a semiconductor layer of a first conductivity type with a first concentration; the said structure also having a first and a second surfaces wherein the first surface being the light entering surface; at least one region of the second conductivity type within the first layer of the first conductivity type; at least one p/n junction within the first layer of the first conductivity type; at least one region of the first conductivity type with a second concentration heavier than the first concentration and arranged within the first layer of the first conductivity type;

wherein the first layer of the first conductivity type is a thin layer and at least one region of the second conductivity type within the first layer of the first conductivity type is a thin region with the thickness smaller than that of the first layer, being designed specifically for fast response/switching applications.

14. A photodetector comprising :

wherein at least one region of the second conductivity type within the first layer of the first conductivity type is distant from the first surface and buried in it to be a part of a color sensor.

A photodetector comprising: a structure having at least two layers bonded to each other; wherein at least the first layer is a semiconductor layer of a first conductivity type with a first concentration; the said structure also having a first and a second surfaces wherein the first surface being the light entering surface; at least one region of the second conductivity type within the first layer of the first conductivity type;

at least one through silicon via electrically contacting the at least one region of the second conductivity type from the second surface of the structure; the electrical contacts being provided to the at least one region of the second conductivity type through the said at least one through silicon via; and, wherein at least one region of the second conductivity type within the first layer of the first conductivity type having a color filter on top of the first surface being a part of a color sensor.

16. A method of using a photodetector for particle sizing applications comprising:

providing a photodetector structure having at least two layers bonded to each other;

wherein the structure having a first layer comprised of a semiconductor of a first conductivity type with a first concentration; and wherein the structure having at least one region of the second conductivity type and one region of the first conductivity type with the second concentration within the first layer of a first conductivity type; said regions of first and second conductivity types located to spatially distinguish exposure to incident radiation; wherein the structure having at least one via reaching through at least a second layer within the structure; and,

irradiating a medium with photons; where the photons scatter upon interaction with components of the medium and then impinge on at least one of the spatially distinguished regions of the second conductivity type.

17. The method of claim 16 wherein:

the provided photodetector structure additionally comprising an electronic circuit in contact with at least one of the vias through at least the second layer

18. The method of claim 16 wherein:

the at least one region of the second conductivity type represent as least a portion of a ring.

19. The method of claim 16 wherein:

the said via traverses a layer of at least 100 microns of thickness.

20. A method of using a photodetector for position sensitive applications comprising:

providing a photodetector structure having at least two layers bonded to each other; wherein the structure having a first layer comprised of a semiconductor of a first conductivity type with a first concentration; and wherein the structure having at least one region of the second conductivity type and one region of the first conductivity type with the second concentration within the first layer of a first conductivity type; said regions of the first and second conductivity types located to spatially distinguish exposure to incident radiation; wherein the structure having at least one via reaching through at least the second layer within the structure; and,

irradiating a medium with photons; where the photons impinge on at least one of the spatially distinguished regions of the second conductivity type providing the means of identifying a photon-impinged region.

21. The method of claim 20 wherein:

the photodetector structure provided additionally comprising an electronic circuit in contact with at least one of the vias through at least the second layer.

22. The method of claim 20 wherein:

the said via traverses a layer of at least 100 microns of thickness

23. The method of claim 20 wherein: the at least one region of the second conductivity type has a resistivity designed to be used in a resistive charge division sensor.

24. The method of claim 23 wherein:

25. A method of using a photodetector for remote targeting applications comprising:

providing a photodetector structure having at least two layers bonded to each other; wherein the structure having a first layer comprised of a semiconductor of a first conductivity type with a first concentration; and wherein the structure having at least one region of the second conductivity type and one region of the first conductivity type with the second concentration within the first layer of a first conductivity type; said regions of first and second conductivity types located to spatially distinguish exposure to incident radiation; wherein the structure having at least one via reaching through at least a second layer within the structure; and,

irradiating a medium with photons; where the photons propagate from a remote object and then impinge on at least one of the spatially distinguished regions of the second conductivity type creating specific photo response that provides means of detecting the coordinates of a remote radiation source.

26. The method of claim 25 wherein:

the photodetector structure provided additionally comprises an electronic circuit in contact with at least one of the vias through at least the second layer.

27. The method of claim 25 wherein:

The said via traverses a layer of at least 100 microns of thickness.

28. A method of using a photodetector for identifying position (location) applications comprising:

providing a photodetector structure having at least two layers bonded to each other; wherein the structure having a first layer comprised of a semiconductor of a first conductivity type with a first concentration; and wherein the structure having at least one region of the second conductivity type and one region of the first conductivity type with the second concentration within the first layer of a first conductivity type; said regions of first and second conductivity types being located to spatially distinguish exposure to incident radiation; wherein the structure having at least one via reaching through at least a second layer within the structure;

irradiating said photodetector structure with photons from a source physically unconnected to said photodetector structure; where the photons impinge on at least one of the spatially distinguished regions of the second conductivity type;

comparing the photodetector signals from at least two regions within the photodetector structure; and,

adjusting the physical location of at least one of the photodetector structure or the irradiation source based on said comparison of photodetector signals.

29. The method of claim 28 wherein:

the at least one region of the second conductivity type has a resistivity designed to be used in a resistive charge division sensor.

30. The method of claim 28 wherein:

31. A method of using an amplified photodetector comprising:

providing a photodetector structure having at least two layers bonded to each other; wherein the structure having a first layer comprised of a semiconductor of the first conductivity type with the first concentration; and wherein the structure having at least one region of the second conductivity type and one region of the first conductivity type with the second concentration within the first layer of the first conductivity type; wherein the structure has at least one via reaching through at least the second layer within the structure where the thickness of said second layer is at least 100 microns; the photodetector structure additionally comprising an electronic amplifying circuit in contact with at least one of the vias; and, irradiating said photodetector structure with photons where the photons impinge on at least one region of a first conductivity type.

32. The method of claim 31 wherein:

the amplified photodetector structure has the at least one via reaching through the thickness of the second layer of at least 100 microns.