Image sensor structure

Abstract

An example image sensor structure includes an image layer. The image layer includes an array of photodetectors disposed therein. A device stack is disposed on the image layer. An array of lightguides is disposed in the device stack. Each lightguide is associated with at least one light detector in the array of photodetectors. A passivation stack is disposed on the device stack. The passivation stack includes a bottom surface in direct contact with a top surface of the lightguide. An array of nanowells is disposed in a top layer of the passivation stack. Each nanowell is associated with a lightguide of the array of lightguides. A crosstalk blocking metal structure is disposed in the passivation stack. The crosstalk blocking metal structure reduces crosstalk within the passivation stack.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 610,354, filed on December 26, 2017, and Netherlands Application No. 2020615, filed on March 19, 2018, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to, but is not limited to, image sensor structures. Background Art

[0004] The image sensor structure can be coupled with a microfluidic device such as a flow cell to form a sensor system. The sensor system may be, for example, a biosensor system. Such a sensor system typically utilizes an array of high-density nanowells disposed in the top layer of a passivation stack (referred to herein as a "passivation stack") of the image sensor structure to perform a controlled reaction protocol on an analyte disposed within the nanowell.

[0005] In an example of such a reaction scheme, analytes (such as clusters of DNA fragments, nucleic acid molecule chains, etc.) disposed in a nanotrap array of an image sensor structure can be labeled with an identifiable marker (such as a fluorescently labeled molecule) that is delivered to the analyte via a fluid flow through a flow cell. One or more excitation lights can then be directed to the labeled analyte within the nanotrap. The analyte can then emit a photon of emission light that can be transmitted through a passivation stack and into a light guide of the image sensor structure that is associated with (e.g., located directly below) each nanotrap.

[0006] The top surface of each light guide is in direct contact with the bottom surface of the passivation stack, wherein the top surface of each light guide receives a significant portion of the emitted light photons transmitted from its associated nanotrap. The light guide guides the emitted light photons to a photodetector disposed within the image sensor structure and associated with (e.g., located directly below) the light guide. The photodetector detects the emitted light photons. Device circuitry within the image sensor structure then uses those detected photons to process and transmit data signals. The data signal can then be analyzed to reveal the properties of the analyte. Examples of such reaction schemes include high-throughput DNA sequencing for the health and pharmaceutical industries, among others.

[0007] As the need to increase the throughput of reaction protocols continues to grow, there is a growing need to continuously reduce the size of nanowells in nanowell arrays in image sensor structures, and thus increase the number of nanowells in nanowell arrays. As the spacing between rows of nanowells in an array (i.e., the distance between repeating structures in a semiconductor structure) becomes smaller and smaller, crosstalk becomes an increasingly important factor.

[0008] Crosstalk includes emitted light that is transmitted from a nanotrap through a passivation stack and into an adjacent, non-associated light guide and detected by a non-associated light detector. Crosstalk contributes to the noise level of the data signal processed from the light detector and its associated device circuitry. In some cases, for some ranges of spacing of rows of nanowells (e.g., a range of about 1.5 microns or less, or a range of about 1.0 microns or less), crosstalk may become a dominant factor in noise contribution. In addition, nanowell size (diameter) is typically reduced to accommodate tighter spacing. As a result, the total number of analytes in each nanowell (and therefore the total available emission signal from each well) is reduced, further exacerbating the effects of noise such as crosstalk.

[0009] Therefore, there is a need to reduce crosstalk that is transmitted within an image sensor structure. More specifically, there is a need to reduce crosstalk of an image sensor structure that is transmitted from a nanowell through a passivation stack of the image sensor structure and into a top surface of a light guide that is not associated with the nanowell. Additionally, there is a need to reduce such crosstalk that is transmitted through the passivation stack before the crosstalk enters the light guide. Furthermore, there is a need to reduce crosstalk of an image sensor structure wherein the spacing between rows of nanowells is about 1.5 microns or less. Summary of the invention

[0010] The present disclosure provides advantages and alternatives over the prior art by providing an image sensor structure having a crosstalk blocking metal structure disposed in a passivation stack. The crosstalk blocking metal structure may include pillars or parallel metal plates. By being disposed within the passivation structure, the crosstalk blocking metal structure significantly reduces crosstalk transmitted within the passivation layer and before entering the top surface of the light guide of the image sensor structure.

[0011] An image sensor structure according to one or more aspects of the present disclosure includes an image layer. The image layer includes an array of photodetectors disposed therein. A device stack is disposed on the image layer. An array of light guides is disposed in the device stack. Each light guide is associated with at least one light detector in the array of light detectors. A passivation stack is disposed on the device stack. The passivation stack includes a bottom surface that is in direct contact with a top surface of the light guide. An array of nanowells is disposed in a top layer of the passivation stack. Each nanowell is associated with a light guide of the light guide array. A crosstalk blocking metal structure is disposed in the passivation stack. The crosstalk blocking metal structure reduces crosstalk within the passivation stack.

[0012] Another image sensor structure according to one or more aspects of the present disclosure includes an image layer. The image layer includes an array of photodetectors disposed therein. A device stack is disposed on the image layer. An array of lightguides is disposed in the device stack. Each lightguide is associated with at least one light detector in the array of photodetectors. A passivation stack is disposed on the device stack. The passivation stack includes a first passivation layer having a bottom surface in direct contact with a top surface of the lightguide. The passivation stack also includes a first chemical protective layer disposed on the first passivation layer. The passivation stack also includes a second passivation layer disposed on the first chemical protective layer and a second chemical protective layer disposed on the second passivation layer. An array of nanowells is disposed in a top layer of the passivation stack. Each nanowell is associated with a lightguide of the array of lightguides.

[0013] A method of forming an image sensor structure according to one or more aspects of the present disclosure includes disposing a device stack on an image layer. The image layer includes an array of photodetectors disposed therein. An array of lightguide holes is etched into the device stack. An array of lightguides is formed in the lightguide holes. Each lightguide is associated with at least one light detector in the array of lightdetectors. A first passivation layer is disposed on the array of lightguides such that a bottom surface of the first passivation layer is in direct contact with a top surface of the lightguide. A first chemical protection layer is disposed on the first passivation layer. The first chemical protection layer and the first passivation layer are included in a passivation stack. An array of nanowells is formed in a top layer of the passivation stack. Each nanowell is associated with a lightguide of the lightguide array. A crosstalk blocking metal structure is disposed within the passivation stack. The crosstalk blocking metal structure reduces crosstalk within the passivation stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0015] Figure 1 is a simplified cross-sectional side view of a sensor system having an image sensor structure disposed therein;

[0016] Figure 2 is a simplified cross-sectional side view of an image sensor structure having a crosstalk blocking metal structure in the form of a pillar in a passivation stack according to one example described herein;

[0017] Figure 3 is a simplified cross-sectional side view of an image sensor structure having a crosstalk blocking metal structure in the form of a pillar according to one example described herein;

[0018] Figure 4 is a simplified cross-sectional side view of an image sensor structure having a crosstalk blocking metal structure in the form of a pillar according to one example described herein;

[0019] Figure 5 is a simplified cross-sectional side view of an image sensor structure having a crosstalk-blocking metal structure in the form of parallel metal layers according to one example described herein;

[0020] Figure 6 is a simplified cross-sectional side view of an image sensor structure at an intermediate stage of fabrication according to one example described herein, the image sensor structure having a light guide aperture disposed in a device stack;

[0021] Figure 7 Based on an example described in this article Figure 6 A simplified cross-sectional side view of an image sensor structure having a light guide layer disposed thereon;

[0022] Figure 8 Based on an example described in this article Figure 7 a simplified cross-sectional side view of an image sensor structure having a light guide layer planarized downward to form a light guide;

[0023] Fig. 9 Based on an example described in this article Figure 8 a simplified cross-sectional side view of an image sensor structure having a light guide recessed below a top of a light guide aperture;

[0024] Fig.10 Based on an example described in this article Fig. 9 a simplified cross-sectional side view of an image sensor structure having a crosstalk blocking metal structure in the form of a pillar in a passivation stack disposed on a top surface of a light guide to form a complete image sensor structure;

[0025] Fig.11 is a simplified cross-sectional side view of an image sensor structure at an intermediate stage of fabrication according to one example described herein, the image sensor structure having a crosstalk blocking metal structure in the form of a pillar in a partially formed passivation stack;

[0026] Fig.12 Based on an example described in this article Fig.11 A simplified cross-sectional side view of an image sensor structure having a fully formed passivation stack to form a complete image sensor structure;

[0027] Fig.13 is a simplified cross-sectional side view of an image sensor structure at an intermediate stage of fabrication according to one example described herein, the image sensor structure having a crosstalk blocking metal structure in the form of a pillar in a partially formed passivation stack;

[0028] Fig.14 Based on an example described in this article Fig.13 A simplified cross-sectional side view of an image sensor structure having a fully formed passivation stack to form a complete image sensor structure;

[0029] Fig.15 is a simplified cross-sectional side view of an image sensor structure having a partially formed passivation stack at an intermediate stage of fabrication according to one example described herein; and

[0030] Fig.16 Based on an example described in this article Fig.15 0026] A simplified cross-sectional side view of an image sensor structure having a crosstalk blocking metal structure in the form of parallel metal layers in a fully formed passivation stack to form a complete image sensor structure. DETAILED DESCRIPTION

[0031] Certain examples will now be described to provide a comprehensive understanding of the principles of structure, function, manufacture and use of the methods, systems and devices disclosed herein. One or more examples are shown in the accompanying drawings. It will be understood by those skilled in the art that the methods, systems and devices specifically described herein and shown in the accompanying drawings are non-limiting examples, and the scope of the present disclosure is limited only by the claims. Features shown or described in conjunction with one example may be combined with features of other examples. Such modifications and variations are intended to be included within the scope of the present disclosure.

[0032] The terms "substantially," "approximately," "about," "relatively," or other similar terms that may be used throughout this disclosure, including the claims, are used to describe and take into account small fluctuations, such as due to variations in processing. For example, they may refer to less than or equal to ±10%, such as less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%.

[0033] Examples provided herein relate to image sensor structures and methods of manufacturing the same. More specifically, examples provided herein relate to image sensor structures having a crosstalk blocking metal structure disposed within a passivation stack of the image sensor structure.

[0034] Figure 1 A sensor system is shown having one type of image sensor structure disposed therein. Figure 2-5 Various examples of image sensor structures according to the present disclosure are shown. Figure 6-16 Various examples of methods of manufacturing image sensor structures according to the present disclosure are shown.

[0035] Reference Figure 1 , an example sensor system 10, in this example a biosensor system 10, includes a flow cell 12 coupled to an image sensor structure 14. The flow cell 12 of the biosensor system 10 includes a flow cell cover 16 secured to a flow cell sidewall 18. The flow cell sidewall 18 is coupled to a top layer 22 of a passivation stack 24 of the image sensor structure 14 to form a flow channel 20 therebetween.

[0036] The top layer 22 of the passivation stack 24 includes a large array of nanotraps 26 disposed thereon. Analytes 28 (such as DNA fragments, oligonucleotides, other nucleic acid chains, etc.) can be disposed within the nanotraps 26. The flow cell cover includes an inlet 30 and an outlet 32 ​​that are sized to allow a fluid stream 34 to flow into, through, and out of the flow channel 20. The fluid stream 34 can be used to perform a large variety of controlled reaction protocols on the analytes 28 disposed within the nanotraps 26. The fluid stream 34 can also deliver an identifiable marker 36 (such as a fluorescently labeled nucleotide molecule, etc.) that can be used to label the analytes 28.

[0037] The image sensor structure 14 of the biosensor 10 includes an image layer 40 disposed on a bottom substrate 38. The image layer 40 can be a dielectric layer, such as SiN, and can include an array of photodetectors 42 disposed therein. The photodetectors 42, as used herein, can be, for example, semiconductors, such as photodiodes, complementary metal oxide semiconductor (CMOS) materials, or both. The photodetectors 42 detect photons of emission light 44 emitted from the fluorescent markers 36 attached to the analyte 28 in the nanotrap 26. The bottom substrate 38 can be glass, silicon, or other similar materials.

[0038] A device stack 46 is disposed on the imaging layer 40. The device stack 46 may include a plurality of dielectric layers (not shown) that contain various device circuits 48 that interface with the photodetector 42 and process data signals using the detected photons.

[0039] An array of light guides 50 is also disposed in the device stack 46. Each light guide 50 is associated with at least one light detector 42 in the array of light detectors. For example, a light guide 50 can be located directly above its associated light detector. The light guides 50 guide photons of emitted light 44 from the fluorescent markers 36 disposed on the analytes 28 disposed in the nanowells 26 to their associated light detectors 42.

[0040] Also disposed within the device stack 46 are a light shielding layer 52, an anti-reflection layer 54, and a protective liner 56. The protective liner 56 may be composed of silicon nitride (SiN) and is arranged along the inner wall of the light guide 50. The light shielding layer 52 may be composed of tungsten (W) and attenuates the emission light 44 and the excitation light 58 transmitted into the device stack 46. The anti-reflection layer 54 may be composed of silicon oxynitride (SiON) and is used to photolithographically pattern the underlying metal layer.

[0041] The passivation stack 24 is disposed on the device stack 46. The passivation stack 24 includes a bottom surface 60 that is in direct contact with the top surface 62 of the light guide 50. The passivation stack 24 may include the passivation layer 64 and a chemical protection layer 66 (in this case, the top layer 22 of the passivation stack 24). The passivation layer 64 may be composed of SiN and includes the bottom surface 60 of the passivation stack 24. The chemical protection layer 66 may be composed of tantalum pentoxide (Ta2O5) and may be the top layer 22 of the passivation stack 24.

[0042] An array of nanowells 26 is also disposed in the top layer 22 of the passivation stack 24, wherein each nanowell 26 is associated with a lightguide 50 of the lightguide array. For example, each nanowell 26 may be located directly above an associated lightguide 50 such that a majority of photons of the emitted light 44 that enter the top surface 62 of each lightguide 50 are generated from within the associated nanowell 26 of that lightguide.

[0043] During operation, various types of excitation light 58 are radiated onto the analytes 28 in the nanowells 26, causing the labeled molecules 36 to emit fluorescent emission light 44. Most of the photons of the emission light 44 may be transmitted through the passivation stack 24 and into the top surface 62 of its associated light guide 50. The light guide 50 may filter out most of the excitation light 58 and direct the emission light 44 to an associated light detector 42 located directly below the light guide 50.

[0044] The photodetector 42 detects the emitted light photons. The device circuitry 48 within the device stack 46 then uses those detected photons to process and transmit a data signal. The data signal can then be analyzed to reveal the nature of the analyte.

[0045] However, some photons of emitted light from one nanotrap may inadvertently be transmitted through the passivation stack 24 to an adjacent, unassociated lightguide 50, thereby being detected as unwanted crosstalk (or crosstalk emission light) in the unassociated photodetector 42. This crosstalk results in noise in the data signal.

[0046] For image sensor structures 14 having small spacing between rows of nanowells (e.g., nanowells with a spacing of about 1.5 microns or less, or nanowells with a spacing of about 1.25 microns or less, or even nanowells with a spacing of about 1 micron or less), such crosstalk can significantly increase the noise level associated with the data signal. In addition, nanowell size (diameter) is generally reduced to accommodate the tighter spacing. As a result, the total number of analytes in each nanowell (and therefore the total available emission signal from each well) is reduced, further exacerbating the effects of noise such as crosstalk. Therefore, the smaller the image sensor structure, the more desirable it is to reduce the crosstalk transmitted within the passivation stack 24.

[0047] The example sensor systems described herein differ from some pre-existing sensor systems in several respects. For example, in one comparative example, a crosstalk shield (not shown) is disposed in its device stack 46, which is located below its passivation stack 24. In this comparative example, the crosstalk shield is used to reduce crosstalk that leaks out of its light guide 50 and is transmitted through its device stack 46 to another light guide 50. These crosstalk shields do not reduce crosstalk that is transmitted through its passivation stack 24 and into the top surface 62 of its light guide 50. The crosstalk shield of this comparative example is different from the examples provided herein.

[0048] Reference Figure 2 , shows a cross-sectional side view of an example of an image sensor structure 100 having a crosstalk blocking metal structure 102 in a passivation stack 104 of the image sensor structure 100. The crosstalk blocking metal structures 102 can be any suitable shape, but in this example, they are in the form of metal pillars 106. The term "pillar" as used herein includes a structure that extends from the bottom surface to the top surface of a layer in the passivation stack. For example, Figure 2 The metal pillar 106 in FIG. 1 extends within the passivation stack 104 from a bottom surface 140 of the first passivation layer 142 to a top surface of the first passivation layer 142 .

[0049] The image sensor structure 100 can be incorporated into a flow cell to form a similar Figure 1 The sensor system 10 is a sensor system of the present invention. The sensor system may be, for example, a biosensor system.

[0050] The image sensor structure 100 includes an image layer 108 disposed on a base substrate 110. The base substrate 110 may include glass or silicon. The image layer 108 may include a dielectric layer, such as SiN.

[0051] An array of photodetectors 112 is disposed within the imaging layer 108. As used herein, the photodetectors 112 can be, for example, semiconductors such as photodiodes, complementary metal oxide semiconductor (CMOS) materials, or both. The photodetectors 112 detect photons of emission light 114 emitted from fluorescent markers 116 attached to analytes 118 in nanowells 120 disposed in a top layer 122 of the passivation stack 104. During various controlled reaction schemes, the fluorescent markers 116 fluoresce via excitation light 124.

[0052] Disposed on the image layer is a device stack 126. The device stack 126 may include a plurality of dielectric layers (not shown) that include various device circuits 128 that interface with the light detector 112 and use the detected photons of the emitted light 114 to process data signals.

[0053] An array of light guides 130 is also disposed in the device stack 126. Each light guide 130 is associated with at least one photodetector 112 in the array of photodetectors. For example, a light guide 130 can be located directly above its associated photodetector 112. The light guides 130 guide photons of emitted light 114 from fluorescent markers 116 on analytes 118 disposed in the nanowell 120 to their associated photodetectors 112.

[0054] Also disposed within the device stack 126 in this example are a light shielding layer 134, an anti-reflective layer 136, and a protective liner 138. The protective liner 138 may be composed of a dielectric material such as silicon nitride (SiN) or other similar material, and is arranged along the inner wall of the light guide 130. The light shielding layer 134 may be composed of a transition material such as tungsten (W) or other similar material, and attenuates the emission light 114 and the excitation light 124 transmitted into the device stack 126. The anti-reflective layer 136 may be composed of an anti-reflective compound such as silicon oxynitride (SiON) or other similar material, and is used to photolithographically pattern the underlying metal layer.

[0055] The passivation stack 104 is disposed on the device stack 126. The passivation stack 104 includes a bottom surface 140 that is in direct contact with the top surface 132 of the light guide 130. The passivation stack 104 can include any number of material layers suitable for transmitting the emitted light 114. However, in this example, the passivation stack 104 includes a first (1st) passivation layer 142 and a first chemical protection layer 144. The first passivation layer 142 can be composed of SiN and includes the bottom surface 140 of the passivation stack 104. The first chemical protection layer 144 can be composed of a transition metal oxide such as tantalum pentoxide (Ta2O5) or other similar material and can be the top layer 122 of the passivation stack 104.

[0056] An array of nanowells 120 is also disposed in the top layer 122 of the passivation stack 104, wherein each nanowell 120 is associated with a lightguide 130 of the lightguide array. For example, each nanowell 120 can be located directly above an associated lightguide 130 such that a majority of photons of the emitted light 114 that enter the top surface 132 of each lightguide 130 are generated from within the associated nanowell 120 of that lightguide.

[0057] The crosstalk blocking metal structures 102 are disposed in the passivation stack 104, wherein the crosstalk blocking metal structures 102 can reduce crosstalk within the passivation stack 104. The crosstalk blocking metal structures 102 can be of any suitable shape, but in this example, they are in the form of metal pillars 106. The crosstalk blocking metal structures 102 can be disposed in any suitable location within the passivation stack 104, but in this example, they are only disposed in the first passivation layer 142 and between the nanowells 120. The crosstalk blocking metal structures 102 can be made of metals such as tantalum (Ta), tungsten (W), aluminum (Al), or copper (Cu).

[0058] The crosstalk blocking metal structure 102 can reduce the crosstalk transmitted through the passivation stack 104 by any suitable process. For example, the crosstalk blocking metal structure 102 can be composed of a material that absorbs emitted light of a given emission light frequency or blocks emitted light of a given emission light frequency. Optionally, the crosstalk blocking metal structure 102 can have a certain geometry and placement within the passivation stack 104, which enables the crosstalk blocking metal structure 102 to guide the emitted light 114 away from the top surface 132 of the light guide 130.

[0059] During operation, each nanowell 120 receives an analyte 118 labeled with a fluorescent molecular marker 116 that generates emission light 114 in response to excitation light 124. Photons of emission light 114 are transmitted from the nanowell 120, through the passivation stack, and into a top surface 132 of an associated light guide 130, which may be located directly below the nanowell 120. The photons of emission light 114 are then guided by the associated light guide 130 to an associated photodetector 112, which may be located directly below the light guide 130. The associated photodetector 112 detects the photons of emission light 114. In addition, device circuitry 128 is integrated with the photodetector 112 to process the detected emission light photons and provide data signals using the detected emission light photons.

[0060] While processing such data signals, the crosstalk blocking metal structure 102 can significantly reduce the number of photons of emitted light 114 that may become crosstalk. The reduction can be at least about 5% (e.g., at least about 20%, 30%, 40%, 50%, 60% or more). In more examples, the reduction is between about 5% and about 50%, such as between 10% and 30%. Other values ​​are also possible. In one example, the crosstalk blocking metal structure 102 reduces the number of emitted light photons that may otherwise be transmitted from the nanowell 120 to the non-associated adjacent light guide 130 and detected as crosstalk by the non-associated light detector 112. Since such crosstalk can cause a noise level in the data signal, the noise level of the data signal is significantly reduced.

[0061] Reference Figure 3 , shows a cross-sectional side view of another example of an image sensor structure 200 having a crosstalk blocking metal structure 102 in the form of pillars 202. The image sensor structure 200 is similar to the image sensor structure 100, with like features being labeled with like reference numerals.

[0062] The passivation stack 104 of the image sensor structure 200 includes four layers. The four layers include:

[0063] A first passivation layer 142 disposed on the light guide 130 .

[0064] A first chemical protection layer 144 , which is disposed on the first passivation layer 142 .

[0065] A second passivation layer 204 disposed on the first chemical protection layer 144 .

[0066] A second chemical protection layer 206 , which is disposed on the second passivation layer 204 .

[0067] The four layers 142, 144, 204, 206 of the passivation stack 104 (i.e., a four-layer passivation stack) of the image sensor structure 200 and subsequent image sensor structures 300 and 400 may provide certain advantages over the two layers 142, 144 of the passivation stack 104 (i.e., a two-layer passivation stack) of the image sensor 100. These advantages may include, but are not limited to:

[0068] • A four-layer passivation stack enables the deposition of larger and more geometrically complex crosstalk blocking metal structures, which can reduce crosstalk more effectively than a crosstalk blocking metal structure that can be provided in a two-layer passivation stack.

[0069] • The four-layer passivation stack allows for more flexibility in nanowell design, since the geometry of the nanowell will be less restricted by the underlying light-guiding structure due to the added layers.

[0070] The quad passivation stack provides greater robustness against any chemical or mechanical damage due to the increased thickness of the passivation stack and the added layers.

[0071] In this example, the bottom surface 140 of the first passivation layer 142 is still the bottom surface of the passivation stack 104 and is in direct contact with the top surface 132 of the light guide 130. However, the top layer 122 of the passivation stack 104 is now the second chemical protective layer 206. In addition, the nanowell 120 is disposed in the second chemical protective layer 206.

[0072] The second passivation layer 204 and the second chemical protection layer 206 may have the same or similar compositions as the first passivation layer 142 and the first chemical protection layer 144. For example, the second passivation layer 204 may be made of SiN, and the second chemical protection layer 206 may be made of tantalum pentoxide (Ta2O5).

[0073] The crosstalk blocking metal structure 102 of the image sensor structure 200 includes a metal pillar 202. The metal pillar 202 is disposed in the first passivation layer 142 and is located between the nanowells 120.

[0074] Reference Figure 4 , shows a cross-sectional side view of another example of an image sensor structure 300 having a crosstalk blocking metal structure 102 in the form of pillars 302. The image sensor structure 300 is similar to the image sensor structures 100 and 200, with like features being labeled with like reference numerals.

[0075] The passivation stack 104 of the image sensor structure 300 is the same or similar to the passivation stack of the image sensor structure 200 and also includes four layers. The four layers include:

[0076] A first passivation layer 142 disposed on the light guide 130 .

[0077] A first chemical protection layer 144 , which is disposed on the first passivation layer 142 .

[0078] A second passivation layer 204 disposed on the first chemical protection layer 144 .

[0079] A second chemical protection layer 206 , which is disposed on the second passivation layer 204 .

[0080] In this example, the bottom surface 140 of the first passivation layer 142 is still the bottom surface of the passivation stack 104 and is in direct contact with the top surface 132 of the light guide 130. Additionally, the top layer 122 of the passivation stack 104 is the second chemical protective layer 206. Additionally, the nanowell 120 is disposed in the second chemical protective layer 206.

[0081] However, the crosstalk blocking metal structure 102 of the image sensor structure 300 includes metal pillars 302. The metal pillars 302 extend from the bottom surface 140 of the first passivation layer 142 to the top surface 304 of the second passivation layer 204. The metal pillars are also disposed between the nanowells 120.

[0082] Reference Figure 5 , a cross-sectional side view of another example of an image sensor structure 400 having a crosstalk blocking metal structure 102 in the form of parallel metal layers 402 is shown. In this example, two parallel metal layers 402A and 402B are shown. However, depending on design requirements and objectives, more than two such parallel metal layers 402 may be used in the image sensor structure 400. The image sensor structure 400 is similar to the image sensor structures 100, 200, and 300, with like features being labeled with like reference numerals.

[0083] The passivation stack 104 of the image sensor structure 400 is the same or similar to the passivation stacks of the image sensor structures 200 and 300 and also includes four layers. The four layers include:

[0084] A first passivation layer 142 disposed on the light guide 130 .

[0085] A first chemical protection layer 144 , which is disposed on the first passivation layer 142 .

[0086] A second passivation layer 204 disposed on the first chemical protection layer 144 .

[0087] A second chemical protection layer 206 , which is disposed on the second passivation layer 204 .

[0088] In this example, the bottom surface 140 of the first passivation layer 142 is still the bottom surface of the passivation stack 104 and is in direct contact with the top surface 132 of the light guide 130. Additionally, the top layer 122 of the passivation stack 104 is the second chemical protective layer 206. Additionally, the nanowell 120 is disposed in the second chemical protective layer 206.

[0089] However, the crosstalk blocking metal structure 102 of the image sensor structure 400 includes parallel metal layers 402. In this example, the parallel metal layers 402 are disposed in the second passivation layer 204 and between the nanowells 120. However, the parallel metal layers 402 may be disposed in the first passivation layer 142 and also between the nanowells 120.

[0090] The geometry and placement of the parallel metal layers 402 enable these specific crosstalk blocking metal structures 102 to direct crosstalk emission light (or crosstalk) in a direction relatively parallel to the metal layers 402 and away from the non-associated photodetectors 112. Additionally, the composition of the parallel metal layers 402 enables these specific crosstalk blocking metal structures 102 to absorb such crosstalk emission light.

[0091] In addition, there are several other mechanisms that can support crosstalk reduction in parallel metal layers 402. For example, since the spacing distance 404 between parallel metal layers 402A, 402B is smaller than the wavelength of the crosstalk emission light that is the target of being blocked or reduced, parallel metal layers 402A and 402B can absorb the crosstalk emission light. An example of a specific range of the spacing distance 404 between parallel metal layers 402A and 402B for reducing crosstalk emission light may be a spacing distance 404 that is 1 / 2 or less of the wavelength of the crosstalk emission light.

[0092] Another example of a mechanism that can support crosstalk reduction in parallel metal layers 402 may be metal layer width 406. For example, since parallel metal layers 402A, 402B have a width 406 that is 1 / 2 or greater than the wavelength of crosstalk emission light, parallel metal layers 402A and 402B may absorb crosstalk emission light.

[0093] Various factors may affect the range of crosstalk emission light used to reduce the separation distance 404 and width 406 of parallel metal layers 402. These factors may include the refractive index of parallel metal layers 402 and the composition of the material separating parallel metal layers 402 (in this case layer 204).

[0094] refer to Figure 6-15 , the following figures illustrate various methods of manufacturing image sensor structures 100 , 200 , 300 , and 400 .

[0095] Reference Figure 6 , shows a cross-sectional side view of an example of an image sensor structure 100 at an intermediate stage of fabrication. At this stage of the process flow, an image layer 108 is disposed on a base substrate 110. The image layer includes an array of photodetectors 112 disposed therein. The image layer 108 may be disposed on the base substrate 110 using a deposition technique, such as chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0096] The plurality of dielectric layers (not shown) of the device stack 126 and its associated device circuitry may also be disposed using deposition techniques on the image layer 108. The light shielding layer 134 and the anti-reflective layer 136 may then be disposed on the device stack 126 using any suitable deposition technique, such as CVD, PVD, atomic layer deposition (ALD), or electroplating.

[0097] Thereafter, in the process flow, an array of light guide holes 150 is etched into the device stack. This can be done using any suitable etching process, such as an anisotropic etching process, such as reactive ion etching (RIE). The etching process in the present disclosure may include patterning, such as photolithographic patterning.

[0098] A protective liner 138 may then be disposed over the entire image sensor structure 100, including the sidewalls 152 and bottom 154 of the hole 150. This may be accomplished using any suitable deposition technique, such as CVD, PVD, or ALD.

[0099] Reference Figure 7 , later in the process flow, a light-guiding layer 156 is disposed over the entire structure 100 to fill the holes 150. The light-guiding layer may be composed of an organic filter material that is capable of filtering out the known wavelength of the excitation light 124 and transmitting the known wavelength of the emission light 114. The light-guiding layer 156 may be composed of custom formulated dye molecules arranged in a high refractive index polymer matrix.

[0100] Reference Figure 8 , light guide layer 156 is then planarized downward to form light guide 130, wherein top surface 132 of light guide 130 is substantially flush with the top surface of protective liner 138. This can be accomplished using any suitable polishing technique, such as a chemical mechanical polishing (CMP) process. Once polished downward, the entire top surface of image sensor structure 100 is substantially flat.

[0101] Reference Fig. 9 , the light guides 130 are then recessed downwardly into the light guide holes 150, wherein each light guide 130 is associated with at least one light detector 112 of the array of light detectors. This can be accomplished by a timed etching process that recesses the light guide layer 156 downwardly at a given rate within a known amount of time.

[0102] When the etching process is finished, the light guide 130 has been recessed into the light guide hole 150, exposing the upper portion 158 of the inner sidewall 152 of the light guide hole 150. In addition, the top surface 132 of the light guide 130 is recessed to a predetermined depth below the top opening 160 of the light guide hole 150.

[0103] Reference Fig.10 , thereafter, a first passivation layer 142 is disposed on the array of light guides 130 such that the bottom surface 140 of the first passivation layer 142 is in direct contact with the top surface 132 of the light guide 130. A first chemical protective layer 144 can then be disposed on the first passivation layer 142. Both processes can be accomplished by CVD or PVD. The first chemical protective layer 144 and the first passivation layer 142 form at least a portion of the passivation stack 104.

[0104] An array of nanowells 120 may be formed in the top layer 122 of the passivation stack 104 at an appropriate point in the process flow. Each nanowell 120 is associated with a lightguide 130 of the lightguide array.

[0105] for Fig.10 In the specific example of the image sensor structure 100 shown in FIG, the nanowell 120 can be formed by arranging the first passivation layer 142 so that it conforms to the upper portion 158 of the inner sidewall 152 of the light guide hole 150. This can be done by CVD, PVD or ALD. Thus, the profile of the first passivation layer 142 forms an array of nanowells 120 in the first passivation layer, so that each nanowell is associated with a single light guide 130 and is self-aligned.

[0106] Additionally, the crosstalk blocking metal structures 102 may be disposed within the passivation stack 104 at an appropriate point in the process flow. Each crosstalk blocking metal structure 102 may reduce crosstalk within the passivation stack 104.

[0107] for Fig.10 In the specific example of image sensor structure 100 shown in FIG, the crosstalk blocking structure may be formed as metal pillars 106 by photolithographically etching pillar cavities 162 into first passivation layer 142 such that pillar cavities 162 are disposed between nanowells 120. This may be accomplished via a RIE process.

[0108] The metal pillar 106 may then be disposed within the pillar cavity 162. This may be accomplished by a metal electroplating process. Subsequently, any overburden caused by the electroplating process may be removed by a chemical mechanical polishing (CMP) process.

[0109] After deposition of first passivation layer 142 and formation of metal pillars 106, first chemical protection layer 144 may be disposed on first passivation layer 142 to complete formation of image sensor structure 100. First chemical protection layer 144 may be disposed using CVD, PVD, or ALD.

[0110] Reference Fig.11 , shows a cross-sectional side view of an example of an image sensor structure 200 at an intermediate stage of fabrication. This example of a process flow for the image sensor structure 200 is the same or similar to the example of a process flow for the image sensor 100, and includes information about Figure 8 Thus, at this stage of the process flow, the top surface 132 of the light guide 130 is substantially flush with the top surface of the protective liner 138. Thus, the entire top surface of the image sensor structure 200 is substantially flat.

[0111] Thereafter, a first passivation layer 142 is disposed on the structure 200 such that the bottom surface 140 of the first passivation layer 142 is in direct contact with the top surface 132 of the light guide 130. This first passivation layer 142 of the structure 200 provides a substantially horizontal upper surface 208 of the first passivation layer 142. This may be done by CVD or PVD.

[0112] Then, the metal pillar 202 (in this example, the crosstalk blocking metal structure 102) can be set into the first passivation layer 142. This can be done by first etching the pillar cavity 210 into the first passivation layer 142. This can be done using an RIE process. The metal pillar 202 can then be set within the pillar cavity 210 using CVD, PVD, or electroplating. Any overflow caused by the deposition of the metal pillar 202 into the pillar cavity 210 can then be removed by a chemical mechanical polishing (CMP) process.

[0113] Thereafter, a first chemical protection layer 144 may be disposed on the relatively planar upper surface 208 of the first passivation layer 142. This may be done by CVD, PVD, or ALD.

[0114] refer to Fig.12 Later in the process flow, a second passivation layer 204 is disposed on the first chemical protection layer 144. This may be accomplished using any suitable deposition technique such as CVD, PVD or ALD.

[0115] The nanowell 120 may then be formed in the second passivation layer 204. This may be done by photolithographically patterning the nanowell 120 and etching the nanowell 120 into the second passivation layer 204.

[0116] Thereafter, a second chemical protection layer 206 is disposed on the second passivation layer 204 to complete the formation of the image sensor structure 200. This may be accomplished using any suitable deposition technique, such as CVD, PVD, or ALD. The deposition process causes the second chemical protection layer 206 to conform to the contours of the nanowells 120 in the second passivation layer 204, thereby forming the nanowells 120 in the second chemical protection layer 206. The second chemical protection layer 206, the second passivation layer 204, the first chemical protection layer 144, and the first passivation layer 142 are all included in the passivation stack 104 of the image sensor structure 200.

[0117] Reference Fig.13 , shows a cross-sectional side view of an example of an image sensor structure 300 at an intermediate stage of fabrication. This example of a process flow for image sensor structure 300 is the same or similar to the example of a process flow for image sensor 100, and is equivalent to and includes information about Figure 8Thus, at this stage of the process flow, the top surface 132 of the light guide 130 is at least substantially flush with the top surface of the protective liner 138. Thus, the entire top surface of the image sensor structure 300 is substantially flat.

[0118] Thereafter, a first passivation layer 142 is disposed on the structure 300 such that the bottom surface 140 of the first passivation layer 142 is in direct contact with the top surface 132 of the light guide 130. This first passivation layer 142 of the structure 300 provides a substantially horizontal upper surface 208 of the first passivation layer 142. This may be accomplished by any suitable deposition technique, such as CVD or PVD.

[0119] Thereafter, a first chemical protection layer 144 may be disposed on the relatively flat upper surface 208 of the first passivation layer 142. Then, a second passivation layer 204 may be disposed on the first chemical protection layer 144. These two layers 144, 204 may be accomplished using any suitable deposition technique, such as CVD, PVD, or ALD.

[0120] Then, the metal pillar 302 (which is the crosstalk blocking metal structure 102 of the image sensor structure 300) can be disposed in the second passivation layer 204, the first chemical protection layer 144, and the first passivation layer 142. This can be done by first etching the pillar cavity 306 into the first passivation layer 142 and the second passivation layer 204 and into the first chemical protection layer 144. This can be done using an RIE process. The metal pillar 302 can then be disposed within the pillar cavity 306 using any suitable deposition technique, such as CVD, PVD, or electroplating. Any overflow caused by the deposition of the metal pillar 302 into the pillar cavity 306 can then be removed by any suitable polishing technique, such as a chemical mechanical polishing (CMP) process.

[0121] refer to Fig.14 , after which the nanowell 120 may be subsequently formed in the second passivation layer 204. This may be accomplished by photolithographically patterning the nanowell and etching the nanowell 120 into the second passivation layer 204.

[0122] Thereafter, a second chemical protection layer 206 is disposed on the second passivation layer 204 to complete the formation of the image sensor structure 300. This may be accomplished by CVD, PVD, or ALD. The deposition process causes the second chemical protection layer 206 to conform to the contours of the nanowells 120 in the second passivation layer 204, thereby forming the nanowells 120 in the second chemical protection layer 206. The second chemical protection layer 206, the second passivation layer 204, the first chemical protection layer 144, and the first passivation layer 142 are all included in the passivation stack 104 of the image sensor structure 300.

[0123] Reference Fig.15, shows a cross-sectional side view of an example of an image sensor structure 400 at an intermediate stage of fabrication. This example of a process flow for the image sensor structure 400 is the same or similar to the example of a process flow for the image sensor 100, and includes information about Figure 8 Thus, at this stage of the process flow, the top surface 132 of the light guide 130 is substantially flush with the top surface of the protective liner 138. Thus, the entire top surface of the image sensor structure 400 is substantially flat.

[0124] Thereafter, a first passivation layer 142 is disposed on the structure 400 such that the bottom surface 140 of the first passivation layer 142 is in direct contact with the top surface 132 of the light guide 130. This first passivation layer 142 of the structure 400 provides a substantially horizontal upper surface 208 of the first passivation layer 142. This may be accomplished using any suitable deposition technique, such as CVD or PVD.

[0125] Thereafter, a first chemical protection layer 144 may be disposed on the relatively planar upper surface 208 of the first passivation layer 142. This may be accomplished using any suitable deposition technique, such as CVD, PVD, or ALD.

[0126] Reference Fig.16 Thereafter, a first parallel metal layer 402A, which is one of the crosstalk blocking metal structures 102 of the image sensor structure 400, may be disposed on the first chemical protection layer 144. The metal layer 402A may be disposed using any suitable deposition technique, such as CVD, PVD, ALD, or electroplating.

[0127] Then, the second passivation layer 204 may be disposed on the first metal layer 402A. This may be done using any suitable deposition technique, such as CVC or PVD.

[0128] The second parallel metal layer 402B may then be disposed on the second passivation layer 204 such that it is parallel to the first parallel metal layer 402 A. This may be accomplished using any suitable deposition technique such as CVD, PVD, ALD or electroplating.

[0129] Thereafter, nanowells 120 may then be formed in the second passivation layer 204 and in the parallel metal layers 402A, 402B. This may be accomplished by photolithographically patterning the nanowells 120 and etching the nanowells 120 into the second passivation layer 204 and the parallel metal layers 402A, 402B.

[0130] Thereafter, a second chemical protection layer 206 is disposed on the second passivation layer 204 to complete the formation of the image sensor structure 400. This may be accomplished using any suitable deposition technique, such as CVD, PVD, or ALD. The deposition process causes the second chemical protection layer 206 to conform to the contours of the nanowells 120 in the second passivation layer 204, thereby forming the nanowells 120 in the second chemical protection layer 206. The second chemical protection layer 206, the second passivation layer 204, the first chemical protection layer 144, and the first passivation layer 142 are all included in the passivation stack 104 of the image sensor structure 400.

[0131] Thereafter, the image sensor structures 100, 200, 300, 400 may be disposed on a printed circuit board (not shown). For example, any one of the image sensor structures 100, 200, 300, 400 may be bonded to a flow cell (such as flow cell 12) using any suitable bonding technique to form a sensor system (such as biosensor system 10). Thereafter, the sensor system may be bonded to a printed circuit board using any suitable bonding technique. This may be achieved, for example, by adhesive bonding.

[0132] It should be appreciated that all combinations of the aforementioned concepts (assuming these concepts are not mutually contradictory) are considered to be part of the inventive subject matter disclosed herein. In particular, all combinations of the claimed subject matter appearing at the end of this disclosure are considered to be part of the inventive subject matter disclosed herein.

[0133] Although the foregoing examples are described with reference to specific examples, it should be understood that many changes can be made within the spirit and scope of the inventive concepts described. Therefore, it is intended that the examples are not limited to the examples described, but rather have the full scope defined by the language of the claims.

[0134] Aspects of the present disclosure may be implemented in one or more of the following embodiments:

[0135] 1) An image sensor structure, comprising:

[0136] an imaging layer comprising an array of photodetectors disposed in said imaging layer;

[0137] a device stack disposed on the image layer;

[0138] an array of light guides disposed in the device stack, each light guide being associated with at least one light detector in the array of light detectors;

[0139] a passivation stack disposed on the device stack, the passivation stack comprising a bottom surface in direct contact with a top surface of the light guide;

[0140] an array of nanowells disposed in a top layer of the passivation stack, each nanowell being associated with a lightguide in the array of lightguides; and

[0141] A crosstalk blocking metal structure is disposed in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

[0142] 2) The image sensor structure according to 1), comprising:

[0143] The passivation stack includes a plurality of layers including a first (1st) passivation layer disposed on the light guide and a first chemical protection layer disposed on the first passivation layer.

[0144] 3) The image sensor structure according to 2), wherein the crosstalk blocking metal structure comprises a metal pillar disposed in the first passivation layer.

[0145] 4) The image sensor structure according to 2), wherein the crosstalk blocking metal structure comprises parallel metal layers arranged in the first passivation layer.

[0146] 5) The image sensor structure according to 2), wherein the plurality of layers comprises:

[0147] A second (2nd) passivation layer disposed on the first chemical protection layer; and

[0148] a second chemical protection layer disposed on the second passivation layer;

[0149] Wherein, the nanotrap is arranged in the top layer of the second chemical protection layer.

[0150] 6) The image sensor structure according to 5), wherein the crosstalk blocking metal structure includes parallel metal layers arranged in the second passivation layer.

[0151] 7) The image sensor structure according to 5), wherein the crosstalk blocking metal structure comprises a metal pillar disposed in the first passivation layer.

[0152] 8) The image sensor structure according to 5), wherein the crosstalk blocking metal structure includes a metal pillar extending from a bottom surface of the first passivation layer to a top surface of the second passivation layer, and the metal pillar is disposed between the nanowells.

[0153] 9) The image sensor structure according to 1), wherein the crosstalk blocking metal structure is composed of one of tantalum (Ta), tungsten (W), aluminum (Al) and copper (Cu).

[0154] 10) The image sensor structure according to 2), wherein the first passivation layer is composed of silicon nitride (SiN), and the first chemical protection layer is composed of tantalum pentoxide (Ta2O5).

[0155] 11) The image sensor structure according to 1), comprising a light shielding layer arranged between the device stack and the passivation stack.

[0156] 12) The image sensor structure according to 5), wherein the second passivation layer is composed of silicon nitride (SiN), and the second chemical protection layer is composed of tantalum pentoxide (Ta2O5).

[0157] 13) The image sensor structure according to 4), wherein the parallel metal layers include at least one of the following:

[0158] having a separation distance between the parallel metal layers that is half the wavelength of the crosstalk or less; and

[0159] The parallel metal layers have a width that is half or more of a wavelength of the crosstalk.

[0160] 14) The image sensor structure according to 6), wherein the parallel metal layers include at least one of the following:

[0161] having a separation distance between the parallel metal layers that is half the wavelength of the crosstalk or less; and

[0162] The parallel metal layers have a width that is half or more of a wavelength of the crosstalk.

[0163] 15) An image sensor structure, comprising:

[0164] an imaging layer including an array of photodetectors disposed therein;

[0165] a device stack disposed on the image layer;

[0166] an array of light guides disposed in the device stack, each light guide being associated with at least one light detector in the array of light detectors;

[0167] A passivation stack disposed on the device stack, the passivation stack comprising:

[0168] a first passivation layer comprising a bottom surface in direct contact with the top surface of the light guide,

[0169] a first chemical protection layer, which is disposed on the first passivation layer,

[0170] a second passivation layer disposed on the first chemical protection layer, and

[0171] a second chemical protection layer disposed on the second passivation layer; and

[0172] An array of nanowells is disposed in a top layer of the passivation stack, each nanowell being associated with a lightguide in the array of lightguides.

[0173] 16) The image sensor structure according to 15), comprising a crosstalk blocking metal structure arranged in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk in the passivation stack.

[0174] 17) The image sensor structure according to 16), wherein the crosstalk blocking metal structure includes at least one of a metal pillar and a parallel metal layer arranged between the nanowells.

[0175] 18) A method comprising:

[0176] etching an array of light-conducting holes into a device stack disposed on an image layer, the image layer including an array of light detectors disposed therein;

[0177] forming an array of light guides in the light guide aperture, each light guide being associated with at least one light detector in the array of light detectors;

[0178] disposing a first passivation layer on the array of light guides such that a bottom surface of the first passivation layer is in direct contact with a top surface of the light guides;

[0179] disposing a first chemical protection layer on the first passivation layer, the first chemical protection layer and the first passivation layer comprising at least a portion of a passivation stack;

[0180] forming an array of nanowells in a top layer of the passivation stack, each nanowell being associated with a lightguide in the array of lightguides; and

[0181] A crosstalk blocking metal structure is disposed in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

[0182] 19) The method according to 18), comprising:

[0183] recessing the light guide into the light guide hole so that an upper portion of an inner sidewall of the light guide hole is exposed and a top surface of the light guide is recessed to a predetermined depth below a top opening of the light guide hole; and

[0184] Wherein, providing the first passivation layer further comprises conforming the first passivation layer to an upper portion of an inner wall of the light guide hole to form an array of the nanowells in a top layer of the first passivation layer, each nanowell being associated with a single light guide.

[0185] 20) The method according to 19), wherein providing a crosstalk blocking metal structure further comprises providing a metal pillar in the first passivation layer between the nanowells.

[0186] 21) The method according to 18), comprising:

[0187] disposing a second passivation layer on the first chemical protection layer; and

[0188] A second chemical protection layer is disposed on the second passivation layer, the second chemical protection layer and the second passivation layer further comprising the passivation layer stack.

[0189] 22) The method according to 18), wherein providing a crosstalk blocking metal structure further comprises providing one of a metal pillar and a parallel metal layer within the passivation stack between the nanowells.

Claims

1. An image sensor structure, comprising: an imaging layer comprising an array of photodetectors disposed in said imaging layer; a device stack disposed on the image layer; an array of light guides disposed in the device stack, each light guide being associated with at least one light detector in the array of light detectors; a passivation stack disposed on the device stack, the passivation stack comprising a bottom surface in direct contact with a top surface of the light guide; an array of nanowells disposed in a top layer of the passivation stack, each nanowell being associated with a lightguide in the array of lightguides; as well as A crosstalk blocking metal structure is disposed in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

2. The image sensor structure according to claim 1, comprising: The passivation stack includes a plurality of layers including a first passivation layer disposed on the light guide and a first chemical protection layer disposed on the first passivation layer.

3. The image sensor structure according to claim 2, wherein: The crosstalk blocking metal structure includes a metal pillar disposed in the first passivation layer.

4. The image sensor structure according to claim 2, wherein: The crosstalk blocking metal structure includes parallel metal layers disposed in the first passivation layer.

5. The image sensor structure according to claim 2, wherein: The multiple layers include: A second passivation layer disposed on the first chemical protection layer; and a second chemical protection layer disposed on the second passivation layer; Wherein, the nanotrap is arranged in the top layer of the second chemical protection layer.

6. The image sensor structure according to claim 5, wherein: The crosstalk blocking metal structure includes parallel metal layers disposed in the second passivation layer.

7. The image sensor structure according to claim 5, wherein: The crosstalk blocking metal structure includes a metal pillar disposed in the first passivation layer.

8. The image sensor structure according to claim 5, wherein: The crosstalk-blocking metal structure includes a metal pillar extending from a bottom surface of the first passivation layer to a top surface of the second passivation layer, the metal pillar being disposed between the nanowells.

9. The image sensor structure according to claim 1, wherein: The crosstalk blocking metal structure is composed of one of tantalum (Ta), tungsten (W), aluminum (Al) and copper (Cu).

10. The image sensor structure according to claim 2, wherein: The first passivation layer is composed of silicon nitride (SiN), and the first chemical protection layer is composed of tantalum pentoxide (Ta2O5).

11. The image sensor structure of claim 1, comprising a light shielding layer disposed between the device stack and the passivation stack.

12. The image sensor structure according to claim 5, wherein: The second passivation layer is composed of silicon nitride (SiN), and the second chemical protection layer is composed of tantalum pentoxide (Ta2O5).

13. The image sensor structure according to claim 4, wherein: The parallel metal layers include at least one of the following: having a separation distance between the parallel metal layers that is half the wavelength of the crosstalk or less; and The parallel metal layers have a width that is half or more of a wavelength of the crosstalk.

14. The image sensor structure according to claim 6, wherein: The parallel metal layers include at least one of the following: having a separation distance between the parallel metal layers that is half the wavelength of the crosstalk or less; and The parallel metal layers have a width that is half or more of a wavelength of the crosstalk.

15. An image sensor structure, comprising: an imaging layer including an array of photodetectors disposed therein; a device stack disposed on the image layer; an array of light guides disposed in the device stack, each light guide being associated with at least one light detector in the array of light detectors; A passivation stack disposed on the device stack, the passivation stack comprising: a first passivation layer comprising a bottom surface in direct contact with the top surface of the light guide, a first chemical protection layer, which is disposed on the first passivation layer, a second passivation layer disposed on the first chemical protection layer, and a second chemical protection layer disposed on the second passivation layer; and an array of nanowells disposed in a top layer of the passivation stack, each nanowell being associated with a lightguide in the array of lightguides; and A crosstalk blocking metal structure is disposed in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

16. The image sensor structure according to claim 15, wherein: The crosstalk blocking metal structure includes a metal pillar disposed in the first passivation layer.

17. The image sensor structure according to claim 15, wherein: The crosstalk blocking metal structure includes at least one of a metal pillar and a parallel metal layer disposed between the nanowells.

18. A method of forming an image sensor structure, comprising: etching an array of light-conducting holes into a device stack disposed on an image layer, the image layer including an array of light detectors disposed therein; forming an array of light guides in the light guide aperture, each light guide being associated with at least one light detector in the array of light detectors; disposing a first passivation layer on the array of light guides such that a bottom surface of the first passivation layer is in direct contact with a top surface of the light guides; disposing a first chemical protection layer on the first passivation layer, the first chemical protection layer and the first passivation layer comprising at least a portion of a passivation stack; forming an array of nanowells in a top layer of the passivation stack, each nanowell being associated with a lightguide in the array of lightguides; as well as A crosstalk blocking metal structure is disposed in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

19. The method according to claim 18, comprising: recessing the light guide into the light guide hole so that an upper portion of an inner sidewall of the light guide hole is exposed and a top surface of the light guide is recessed to a predetermined depth below a top opening of the light guide hole; as well as Wherein, providing the first passivation layer further comprises conforming the first passivation layer to an upper portion of an inner wall of the light guide hole to form an array of the nanowells in a top layer of the first passivation layer, each nanowell being associated with a single light guide.

20. The method according to claim 19, wherein: Providing a crosstalk blocking metal structure further includes disposing metal pillars in the first passivation layer between the nanowells.

21. The method according to claim 18, comprising: Disposing a second passivation layer on the first chemical protection layer; as well as A second chemical protection layer is disposed on the second passivation layer, the second chemical protection layer and the second passivation layer further comprising the passivation layer stack.

22. The method according to claim 18, wherein: Providing a crosstalk blocking metal structure further includes disposing one of a metal pillar and a parallel metal layer within the passivation stack between the nanowells.

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