Image sensor structure

Abstract

The invention relates to an image sensor structure. An example image sensor structure includes an image layer. The image layer includes an array of light detectors disposed therein. The device stack is disposed on the image layer. The light guide array is disposed in the device stack-up. Each light guide is associated with at least one light detector of the array of light detectors. The passivation stack is disposed on the device stack. The passivation stack includes a bottom surface 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 a 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.

Description

[0001] This application is a divisional application of the application with the filing date of December 13, 2018, application number 201811524210.5, and invention title "Image Sensor Structure".

[0002] Cross - reference to related applications

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 610,354, filed on December 26, 2017, and Dutch Application No. 2020615, filed on March 19, 2018. The entire contents of the above applications are incorporated herein by reference. Technical Field

[0004] This application relates to, but is not limited to, image sensor structures. Background Art

[0005] An 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 (referred to herein as "passivation stack") in the top layer of the passivation stack layer of the image sensor structure to perform a controlled reaction scheme on an analyte disposed within the nanowells.

[0006] In an example of such a reaction scheme, an analyte (such as a DNA fragment cluster, a nucleic acid molecular strand, etc.) disposed in the nanowell array of the image sensor structure can be labeled with an identifiable marker (such as a fluorescently labeled molecule), and the marker is delivered to the analyte via fluid flowing through the flow cell. Then, one or more excitation lights can be directed onto the labeled analyte within the nanowell. The analyte can then emit photons of emitted light, which can be transmitted through the passivation stack and into the light guide of the image sensor structure, which is associated with each nanowell (e.g., located directly below).

[0007] The top surface of each light guide is in direct contact with the bottom surface of the passivation stack, where the top surface of each light guide receives a large portion of the emitted light photons transmitted from its associated nanowell. The light guide directs the emitted light photons to a light detector disposed within the image sensor structure and associated with the light guide (e.g., located directly below). The light detector detects the emitted light photons. Then, device circuitry within the image sensor structure processes and transmits data signals using those detected photons. The data signals can then be analyzed to reveal the nature of the analyte. Examples of such reaction schemes include high - throughput DNA sequencing for the health and medicine industries, etc.

[0008] Due to the growing demand for increasing the throughput of reaction schemes, there is also a growing demand for continuously reducing the size of the nanowells in the nanowell array in an image sensor structure and thus increasing the number of nanowells in the nanowell array. As the spacing between the rows of nanowells in the array (i.e., the distance between repeating structures in the semiconductor structure) becomes smaller and smaller, crosstalk becomes an increasingly important factor.

[0009] Crosstalk includes emitted light that is transmitted from a nanowell through a passivation stack and into an adjacent non-associated photoconductor and detected by a non-associated photodetector. Crosstalk results in a noise level in the data signal processed by the photodetector and its associated device circuitry. In some cases, for some spacing ranges of the rows of nanowells (e.g., ranges of about 1.5 microns or less, or ranges of about 1.0 micron or less), crosstalk can become a major factor in noise contribution. Additionally, the nanowell size (diameter) is typically reduced to accommodate the closer spacing. As a result, the total amount of analyte in each nanowell (and thus the total available emission signal from each well) is reduced, further exacerbating the impact of noise such as crosstalk.

[0010] Accordingly, there is a need to reduce crosstalk transmitted within an image sensor structure. More specifically, there is a need to reduce crosstalk in an image sensor structure that is transmitted from a nanowell through the passivation stack of the image sensor structure and into the top surface of a photoconductor that is not associated with that nanowell. Additionally, there is a need to reduce such crosstalk that is transmitted through the passivation stack before the crosstalk enters the photoconductor. Further, there is a need to reduce crosstalk in an image sensor structure where the spacing between the rows of nanowells is about 1.5 microns or less. SUMMARY OF THE INVENTION

[0011] 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 can include columns 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 photoconductor of the image sensor structure.

[0012] 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 photoconductors is disposed in the device stack. Each photoconductor is associated with at least one photodetector in the array of photodetectors. A passivation stack is disposed on the device stack. The passivation stack includes a bottom surface that is in direct contact with the top surface of the photoconductor. An array of nanowells is disposed in the top layer of the passivation stack. Each nanowell is associated with a photoconductor of the array of photoconductors. A crosstalk-blocking metal structure is disposed in the passivation stack. The crosstalk-blocking metal structure reduces crosstalk within the passivation stack.

[0013] 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 light guides is disposed in the device stack. Each light guide is associated with at least one photodetector 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 the top surface of the light guide. The passivation stack further includes a first chemical protection layer disposed on the first passivation layer. The passivation stack further includes a second passivation layer disposed on the first chemical protection layer and a second chemical protection layer disposed on the second passivation layer. An array of nanotraps is disposed in the top layer of the passivation stack. Each nanotrap is associated with a light guide of the array of light guides.

[0014] 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 light guide holes is etched into the device stack. An array of light guides is formed in the light guide holes. Each light guide is associated with at least one photodetector in the array of photodetectors. A first passivation layer is disposed on the array of light guides such that the bottom surface of the first passivation layer is in direct contact with the top surface of the light guide. 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 nanotraps is formed in the top layer of the passivation stack. Each nanotrap is associated with a light guide of the array of light guides. 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

[0015] The present disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0016] Figure 1 is a simplified cross-sectional side view of a sensor system having an image sensor structure disposed therein;

[0017] Figure 2 is a simplified cross-sectional side view of an image sensor structure according to one example described herein, the image sensor structure having a crosstalk blocking metal structure in the form of pillars in the passivation stack;

[0018] Figure 3 is a simplified cross-sectional side view of an image sensor structure according to one example described herein, the image sensor structure having a crosstalk blocking metal structure in the form of pillars;

[0019] Figure 4 is a simplified cross-sectional side view of an image sensor structure according to one example described herein, the image sensor structure having a crosstalk blocking metal structure in the form of pillars;

[0020] Figure 5 is a simplified cross-sectional side view of an image sensor structure according to an example described herein, the image sensor structure having a crosstalk-blocking metal structure in the form of parallel metal layers;

[0021] Figure 6 is a simplified cross-sectional side view of an image sensor structure at an intermediate stage of manufacture according to an example described herein, the image sensor structure having a light guide hole disposed in a device stack;

[0022] Figure 7 is according to an example described herein Figure 6 of a simplified cross-sectional side view of an image sensor structure having a light guide layer disposed thereon;

[0023] Figure 8 is according to an example described herein Figure 7 of a simplified cross-sectional side view of an image sensor structure having a light guide layer planarized downward to form a light guide;

[0024] Figure 9 is according to an example described herein Figure 8 of a simplified cross-sectional side view of an image sensor structure having a light guide recessed below the top of a light guide hole;

[0025] Figure 10 is according to an example described herein Figure 9 of a simplified cross-sectional side view of an image sensor structure having a crosstalk-blocking metal structure in the form of pillars in a passivation stack, the passivation stack disposed on a top surface of a light guide to form a complete image sensor structure;

[0026] Figure 11 is a simplified cross-sectional side view of an image sensor structure at an intermediate stage of manufacture according to an example described herein, the image sensor structure having a crosstalk-blocking metal structure in the form of pillars in a partially formed passivation stack;

[0027] Figure 12 is according to an example described herein Figure 11 of a simplified cross-sectional side view of an image sensor structure having a fully formed passivation stack to form a complete image sensor structure;

[0028] Figure 13 is a simplified cross-sectional side view of an image sensor structure at an intermediate stage of manufacture according to an example described herein, the image sensor structure having a crosstalk-blocking metal structure in the form of pillars in a partially formed passivation stack;

[0029] Figure 14 Based on an example described in this article Figure 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;

[0030] Figure 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

[0031] Figure 16 Based on an example described in this article Figure 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

[0032] 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.

[0033] 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%.

[0034] 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.

[0035] Figure 1 A sensor system is shown having one type of image sensor structure disposed therein. Figures 2 - 5Shows various examples of an image sensor structure in accordance with the present disclosure. Figures 6 - 16 Shows various examples of a method of manufacturing an image sensor structure in accordance with the present disclosure.

[0036] Referring Figure 1 , 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 lid 16 secured to the flow cell sidewalls 18. The flow cell sidewalls 18 are coupled to the top layer 22 of a passivation stack 24 of the image sensor structure 14 to form a flow channel 20 therebetween.

[0037] The top layer 22 of the passivation stack 24 includes a large array of nano-wells 26 disposed thereon. Analytes 28 (such as, DNA fragments, oligonucleotides, other nucleic acid strands, etc.) may be disposed within the nano-wells 26. The flow cell lid includes an inlet 30 and an outlet 32, the sizes of the inlet 30 and the outlet 32 being set to permit 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 schemes on the analytes 28 disposed within the nano-wells 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.

[0038] 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. As used herein, the photodetectors 42 can be, for example, semiconductors, such as photodiodes, complementary metal oxide semiconductor (CMOS) materials, or both. The photodetectors 42 detect photons of emitted light 44 emitted from fluorescent markers 36 attached to analytes 28 within the nano-wells 26. The bottom substrate 38 can be glass, silicon, or other similar material.

[0039] A device stack 46 is disposed on the image layer 40. The device stack 46 can include a plurality of dielectric layers (not shown) that include various device circuits 48 that interface with the photodetectors 42 and process data signals using the detected photons.

[0040] An array of optical waveguides 50 is also disposed in the device stack 46. Each optical waveguide 50 is associated with at least one photodetector 42 in the array of photodetectors. For example, the optical waveguide 50 can be located directly above its associated photodetector. The optical waveguides 50 direct photons of the emitted light 44 from the fluorescent markers 36 on the analytes 28 disposed within the nano-wells 26 to their associated photodetectors 42.

[0041] Also disposed within the device stack 46 are a light-blocking layer 52, an anti-reflection layer 54, and a protective liner layer 56. The protective liner layer 56 can be composed of silicon nitride (SiN) and is arranged along the inner wall of the optical waveguide 50. The light-blocking layer 52 can be composed of tungsten (W) and attenuates the emitted light 44 and the excitation light 58 transmitted into the device stack 46. The anti-reflection layer 54 can be composed of silicon oxynitride (SiON) and is used for lithographic patterning of the underlying metal layer.

[0042] A 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 optical waveguide 50. The passivation stack 24 can include a passivation layer 64 and a chemical protection layer 66 (which is the top layer 22 of the passivation stack 24 in this case). The passivation layer 64 can be composed of SiN and includes the bottom surface 60 of the passivation stack 24. The chemical protection layer 66 can be composed of tantalum pentoxide (Ta 2 O 5 ) and can be the top layer 22 of the passivation stack 24.

[0043] An array of nanowells 26 is also disposed in the top layer 22 of the passivation stack 24, where each nanowell 26 is associated with an optical waveguide 50 of the optical waveguide array. For example, each nanowell 26 can be located directly above the associated optical waveguide 50 such that most of the photons of the emitted light 44 entering the top surface 62 of each optical waveguide 50 are generated within the associated nanowell 26 of that optical waveguide.

[0044] During operation, various types of excitation light 58 are radiated onto the analyte 28 in the nanowells 26, causing the labeled molecules 36 to emit fluorescent emitted light 44. Most of the photons of the emitted light 44 can be transmitted through the passivation stack 24 and enter the top surface 62 of its associated optical waveguide 50. The optical waveguide 50 can filter out most of the excitation light 58 and direct the emitted light 44 to the associated photodetector 42 located directly below the optical waveguide 50.

[0045] The photodetector 42 detects the emitted light photons. The device circuitry 48 within the device stack 46 then processes and transmits data signals using those detected photons. The data signals can then be analyzed to reveal the properties of the analyte.

[0046] However, some photons of the emitted light from one nanowell may inadvertently be transmitted through the passivation stack 24 to an adjacent non-associated optical waveguide 50, thereby being detected as unwanted crosstalk (or crosstalk emitted light) in the non-associated photodetector 42. This crosstalk results in noise in the data signals.

[0047] For an image sensor structure 14 having small pitch between rows of nano-wells (e.g., nano-wells with a pitch of about 1.5 microns or less, or nano-wells with a pitch of about 1.25 microns or less, or even nano-wells with a pitch of about 1 micron or less), this crosstalk can significantly increase the noise level associated with the data signal. Additionally, the nano-well size (diameter) typically decreases to accommodate the closer pitch. As a result, the total number of analytes in each nano-well (and thus the total available emission signal from each well) decreases, further exacerbating the impact of noise such as crosstalk. Therefore, the more the image sensor structure is scaled down, the more it is desired to reduce the crosstalk transmitted within the passivation stack 24.

[0048] The example sensor systems described herein differ from some pre-existing sensor systems in several aspects. For example, in one comparative example, a crosstalk shield (not shown) is provided 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 leaking out from its light guide 50 and transmitted through its device stack 46 to another light guide 50. These crosstalk shields do not reduce the crosstalk transmitted through its passivation stack 24 and into the top surface 62 of its light guide 50. The crosstalk shields of this comparative example are different from those provided herein.

[0049] Referring to Figure 2 , a cross-sectional side view of an example of an image sensor structure 100 having a crosstalk blocking metal structure 102 in its passivation stack 104 is shown. 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. As used herein, the term "pillar" includes a structure extending from the bottom surface to the top surface of a layer in the passivation stack. For example, Figure 2 the metal pillars 106 in extend from the bottom surface 140 of the first passivation layer 142 to the top surface of the first passivation layer 142 within the passivation stack 104.

[0050] The image sensor structure 100 can be incorporated into a flow cell to form a sensor system similar to Figure 1 the sensor system 10 in . The sensor system can be, for example, a biosensor system.

[0051] The image sensor structure 100 includes an image layer 108 disposed on a bottom substrate 110. The bottom substrate 110 can include glass or silicon. The image layer 108 can include a dielectric layer, such as SiN.

[0052] An array of photodetectors 112 is disposed within the image layer 108. The photodetectors 112 as used herein can be, for example, semiconductors such as photodiodes, complementary metal oxide semiconductor (CMOS) materials, or both. The photodetectors 112 detect photons of the emitted light 114 emitted from the fluorescent label 116 of the analyte 118 attached to the nanowells 120 disposed in the top layer 122 of the passivation stack 104. During various controlled reaction schemes, the fluorescent label 116 fluoresces by the excitation light 124.

[0053] The device stack 126 is disposed on the image layer. The device stack 126 can include a plurality of dielectric layers (not shown) that include various device circuits 128 that interface with the photodetectors 112 and process data signals using the detected photons of the emitted light 114.

[0054] An array of optical waveguides 130 is also disposed in the device stack 126. Each optical waveguide 130 is associated with at least one of the photodetectors 112 in the array of photodetectors. For example, the optical waveguide 130 can be located directly above its associated photodetector 112. The optical waveguide 130 guides photons of the emitted light 114 from the fluorescent label 116 on the analyte 118 disposed in the nanowells 120 to their associated photodetectors 112.

[0055] In this example, also disposed within the device stack 126 are a light-shielding layer 134, an anti-reflection layer 136, and a protective liner layer 138. The protective liner layer 138 can be composed of a dielectric material such as silicon nitride (SiN) or other similar materials and is arranged along the inner wall of the optical waveguide 130. The light-shielding layer 134 can be composed of a transition material such as tungsten (W) or other similar materials and attenuates the emitted light 114 and the excitation light 124 transmitted into the device stack 126. The anti-reflection layer 136 can be composed of an anti-reflection compound (such as silicon oxynitride (SiON)) or other similar materials and is used for lithographically patterning the underlying metal layer.

[0056] 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 optical waveguide 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 (Ta 2 O 5 )) or other similar materials and can be the top layer 122 of the passivation stack 104.

[0057] An array of nano-traps 120 is also provided in the top layer 122 of the passivation stack 104, where each nano-trap 120 is associated with a light guide 130 of the light guide array. For example, each nano-trap 120 can be located directly above the associated light guide 130 such that most of the photons of the emitted light 114 entering the top surface 132 of each light guide 130 are generated within the associated nano-trap 120 of that light guide.

[0058] The crosstalk-blocking metal structure 102 is provided in the passivation stack 104, where the crosstalk-blocking metal structure 102 can reduce crosstalk within the passivation stack 104. The crosstalk-blocking metal structure 102 can be of any suitable shape, but in this example, they are in the form of metal posts 106. The crosstalk-blocking metal structure 102 can be provided at any appropriate location within the passivation stack 104, but in this example, they are provided only in the first passivation layer 142 and between the nano-traps 120. The crosstalk-blocking metal structure 102 can be composed of a metal such as, for example, tantalum (Ta), tungsten (W), aluminum (Al), or copper (Cu).

[0059] 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 the emitted light of a given emission light frequency or blocks the 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 such that the crosstalk-blocking metal structure 102 can direct the emitted light 114 away from the top surface 132 of the light guide 130.

[0060] During operation, each nano-trap 120 receives an analyte 118 labeled with a fluorescent molecular label 116 that generates emitted light 114 in response to the excitation light 124. Photons of the emitted light 114 are transmitted from the nano-trap 120, through the passivation stack, and into the top surface 132 of the associated light guide 130, which can be located directly below the nano-trap 120. The photons of the emitted light 114 are then guided by the associated light guide 130 to the associated light detector 112, which can be located directly below the light guide 130. The associated light detector 112 detects the photons of the emitted light 114. Additionally, the device circuitry 128 is integrated with the light detector 112 to process the detected emitted light photons and provide a data signal using the detected emitted light photons.

[0061] While processing such data signals, the crosstalk-blocking metal structure 102 can significantly reduce the number of photons of the emitted light 114 that can 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 can otherwise be transmitted from the nanowell 120 to an unassociated adjacent optical waveguide 130 and detected as crosstalk by an unassociated photodetector 112. Since such crosstalk can cause a noise level in the data signal, the noise level of the data signal is significantly reduced.

[0062] Referring Figure 3 , a cross-sectional side view of another example of an image sensor structure 200 with a crosstalk-blocking metal structure 102 in the form of a pillar 202 is shown. The image sensor structure 200 is similar to the image sensor structure 100, where the same features are labeled with the same reference numerals.

[0063] The passivation stack 104 of the image sensor structure 200 includes four layers. These four layers include:

[0064] · A first passivation layer 142, which is disposed on the optical waveguide 130.

[0065] · A first chemical protection layer 144, which is disposed on the first passivation layer 142.

[0066] · A second passivation layer 204, which is disposed on the first chemical protection layer 144.

[0067] · A second chemical protection layer 206, which is disposed on the second passivation layer 204.

[0068] The passivation stack 104 (i.e., the four-layer passivation stack) of four layers 142, 144, 204, 206 of the image sensor structure 200 and subsequent image sensor structures 300 and 400 can provide certain advantages over the passivation stack 104 (i.e., the two-layer passivation stack) of two layers 142, 144 of the image sensor 100. These advantages can include but are not limited to:

[0069] · The four-layer passivation stack enables the deposition of larger and more geometrically complex crosstalk-blocking metal structures, which can reduce crosstalk more effectively than crosstalk-blocking metal structures that can be disposed in a two-layer passivation stack.

[0070] · The four-layer passivation stack enables more flexibility in nanowell design because, due to the additional layer, the geometry of the nanowell will be less restricted by the underlying optical waveguide structure.

[0071] · Due to the increased thickness of the passivation stack and the additional layers, the four-layer passivation stack provides stronger robustness against any chemical or mechanical damage.

[0072] In this example, the bottom surface 140 of the first passivation layer 142 remains 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 protection layer 206. Additionally, the nano-traps 120 are disposed in the second chemical protection layer 206.

[0073] The compositions of the second passivation layer 204 and the second chemical protection layer 206 can be the same as or similar to those of the first passivation layer 142 and the first chemical protection layer 144, respectively. For example, the second passivation layer 204 can be composed of SiN, and the second chemical protection layer 206 can be composed of tantalum pentoxide (Ta 2 O 5 ).

[0074] The crosstalk-blocking metal structure 102 of the image sensor structure 200 includes metal pillars 202. The metal pillars 202 are disposed in the first passivation layer 142 and are located between the nano-traps 120.

[0075] Referring Figure 4 , 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 is shown. The image sensor structure 300 is similar to the image sensor structures 100 and 200, where the same features are labeled with the same reference numerals.

[0076] The passivation stack 104 of the image sensor structure 300 is the same as or similar to the passivation stack of the image sensor structure 200 and also includes four layers. These four layers include:

[0077] · A first passivation layer 142, which is disposed on the light guide 130.

[0078] · A first chemical protection layer 144, which is disposed on the first passivation layer 142.

[0079] · A second passivation layer 204, which is disposed on the first chemical protection layer 144.

[0080] · A second chemical protection layer 206, which is disposed on the second passivation layer 204.

[0081] In this example, the bottom surface 140 of the first passivation layer 142 remains 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 protection layer 206. Furthermore, the nano-traps 120 are disposed in the second chemical protection layer 206.

[0082] However, the crosstalk-blocking metal structure 102 of the image sensor structure 300 includes metal posts 302. The metal posts 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 posts are also disposed between the nano-wells 120.

[0083] Referring to 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, more than two such parallel metal layers 402 may be used in the image sensor structure 400 depending on design requirements and objectives. The image sensor structure 400 is similar to the image sensor structures 100, 200, and 300, where the same features are labeled with the same reference numerals.

[0084] The passivation stack 104 of the image sensor structure 400 is the same as or similar to the passivation stacks of the image sensor structures 200 and 300 and also includes four layers. These four layers include:

[0085] · A first passivation layer 142, which is disposed on the light guide 130.

[0086] · A first chemical protection layer 144, which is disposed on the first passivation layer 142.

[0087] · A second passivation layer 204, which is disposed on the first chemical protection layer 144.

[0088] · A second chemical protection layer 206, which is disposed on the second passivation layer 204.

[0089] In this example, the bottom surface 140 of the first passivation layer 142 remains 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 protection layer 206. Further, the nano-wells 120 are disposed in the second chemical protection layer 206.

[0090] 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 nano-wells 120. However, the parallel metal layers 402 may be disposed in the first passivation layer 142 and also between the nano-wells 120.

[0091] The geometry and placement of the parallel metal layer 402 are such that these specific crosstalk-blocking metal structures 102 can direct crosstalk-emitted light (or crosstalk) in a direction relatively parallel to the metal layer 402 and away from non-associated photodetectors 112. Additionally, the composition of the parallel metal layer 402 is such that these specific crosstalk-blocking metal structures 102 can absorb this crosstalk-emitted light.

[0092] In addition, there are several other mechanisms that can support crosstalk reduction in the parallel metal layer 402. For example, since the spacing distance 404 between the parallel metal layers 402A, 402B is less than the wavelength of the crosstalk-emitted light that is targeted to be blocked or reduced, the parallel metal layers 402A and 402B can absorb the crosstalk-emitted light. An example of a specific range for the spacing distance 404 between the parallel metal layers 402A and 402B for reducing crosstalk-emitted light can be a spacing distance 404 that is 1 / 2 or less of the wavelength of the crosstalk-emitted light.

[0093] Another example of a mechanism that can support crosstalk reduction in the parallel metal layer 402 can be the width 406 of the metal layer. For example, since the width 406 of the parallel metal layers 402A, 402B is 1 / 2 or greater than the wavelength of the crosstalk-emitted light, the parallel metal layers 402A and 402B can absorb the crosstalk-emitted light.

[0094] Various factors can affect the ranges used for the spacing distance 404 and width 406 of the parallel metal layer 402 to reduce crosstalk-emitted light. These factors can include the refractive index of the parallel metal layer 402 and the composition of the material (in this case layer 204) that separates the parallel metal layers 402.

[0095] Reference Figures 6 - 15 , the following figures illustrate various methods of manufacturing the image sensor structures 100, 200, 300, and 400.

[0096] Referring Figure 6 , a cross-sectional side view of an example of the image sensor structure 100 at an intermediate stage of manufacturing is shown. At this stage of the process flow, the image layer 108 is disposed on the bottom substrate 110. The image layer includes an array of photodetectors 112 disposed therein. The image layer 108 can be disposed on the bottom substrate 110 using deposition techniques such as chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0097] Multiple dielectric layers (not shown) of the device stack 126 and their associated device circuits can also be disposed on the image layer 108 using deposition techniques. The light-shielding layer 134 and the anti-reflection layer 136 can then be disposed on the device stack 126 using any suitable deposition technique such as CVD, PVD, atomic layer deposition (ALD), or electroplating.

[0098] Thereafter, in the process flow, an array of optical vias 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.

[0099] Then, a protective liner 138 can be disposed over the entire image sensor structure 100, including the sidewalls 152 and the bottom 154 of the vias 150. This can be done using any suitable deposition technique (such as CVD, PVD, or ALD).

[0100] Referring Figure 7 , thereafter in the process flow, an optical guiding layer 156 is disposed over the entire structure 100 to fill the vias 150. The optical guiding layer can be composed of an organic filtering material that can filter out excitation light 124 of a known wavelength and allow emission light 114 of a known wavelength to pass through. The optical guiding layer 156 can be composed of custom-formulated dye molecules disposed in a high refractive index polymer matrix.

[0101] Referring Figure 8 , the optical guiding layer 156 is then planarized downward to form an optical guide 130, wherein the top surface 132 of the optical guide 130 is substantially flush with the top surface of the protective liner 138. This can be done using any suitable polishing technique, such as a chemical mechanical polishing (CMP) process. Once polished downward, the entire top surface of the image sensor structure 100 is substantially flat.

[0102] Referring Figure 9 , the optical guide 130 is then recessed downward into the optical vias 150, wherein each optical guide 130 is associated with at least one photodetector 112 of an array of photodetectors. This can be done by a timed etching process that recesses the optical guiding layer 156 downward at a given rate over a known amount of time.

[0103] When the etching process is complete, the optical guide 130 has been recessed into the optical vias 150 such that the upper portion 158 of the inner sidewall 152 of the optical vias 150 is exposed. Additionally, the top surface 132 of the optical guide 130 is recessed to a predetermined depth below the top opening 160 of the optical vias 150.

[0104] Referring Figure 10 , thereafter, a first passivation layer 142 is disposed over the array of optical 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 optical guides 130. A first chemical protection layer 144 can then be disposed over the first passivation layer 142. Both of these processes can be done by CVD or PVD. The first chemical protection layer 144 and the first passivation layer 142 form at least a part of the passivation stack 104.

[0105] An array of nano-traps 120 can be formed in the top layer 122 of the passivation stack 104 at an appropriate moment in the process flow. Each nano-trap 120 is associated with a light guide 130 of the light guide array.

[0106] For Figure 10 For the specific example of the image sensor structure 100 shown in, the nano-traps 120 can be formed by setting the first passivation layer 142 such that it conforms to the upper part 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 nano-traps 120 in the first passivation layer, such that each nano-trap is associated with a single light guide 130 and is self-aligned.

[0107] Additionally, the crosstalk blocking metal structures 102 can be disposed within the passivation stack 104 at an appropriate moment in the process flow. Each crosstalk blocking metal structure 102 can reduce crosstalk within the passivation stack 104.

[0108] For Figure 10 For the specific example of the image sensor structure 100 shown in, the crosstalk blocking structure can be formed as the metal pillars 106 by lithographically etching the column cavities 162 into the first passivation layer 142 such that the column cavities 162 are disposed between the nano-traps 120. This can be accomplished via an RIE process.

[0109] The metal pillars 106 can then be disposed within the column cavities 162. This can be done by a metal electroplating process. Subsequently, any overflow caused by the electroplating process can be removed by a chemical mechanical polishing (CMP) process.

[0110] After the deposition of the first passivation layer 142 and the formation of the metal pillars 106, a first chemical protection layer 144 can be disposed on the first passivation layer 142 to complete the formation of the image sensor structure 100. The first chemical protection layer 144 can be disposed using CVD, PVD or ALD.

[0111] Referring to Figure 11 , a cross-sectional side view of an example of the image sensor structure 200 at an intermediate stage of manufacturing is shown. This example of the process flow of the image sensor structure 200 is the same as or similar to the example of the process flow of the image sensor 100, corresponding to and including the process flow disclosed with respect to 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.

[0112] Thereafter, a first passivation layer 142 is disposed on the structure 200 such that a bottom surface 140 of the first passivation layer 142 is in direct contact with a top surface 132 of the optical waveguide 130. This first passivation layer 142 of the structure 200 provides a substantially horizontal upper surface 208 of the first passivation layer 142. This can be accomplished by CVD or PVD.

[0113] Then, a metal pillar 202 (a crosstalk blocking metal structure 102 in this example) can be disposed into the first passivation layer 142. This can be accomplished by first etching a pillar cavity 210 into the first passivation layer 142. This can be done using an RIE process. Then the metal pillar 202 can be disposed within the pillar cavity 210 using CVD, PVD, or electroplating. Any overfill caused by the deposition of the metal pillar 202 into the pillar cavity 210 can subsequently be removed by a chemical mechanical polishing (CMP) process.

[0114] Thereafter, a first chemical protection layer 144 can be disposed on the relatively flat upper surface 208 of the first passivation layer 142. This can be accomplished by CVD, PVD, or ALD.

[0115] Reference Figure 12 Thereafter, in the process flow, a second passivation layer 204 is disposed on the first chemical protection layer 144. This can be done using any suitable deposition technique such as CVD, PVD, or ALD.

[0116] The nano-traps 120 can then be formed in the second passivation layer 204. This can be accomplished by lithographically patterning the nano-traps 120 and etching the nano-traps 120 into the second passivation layer 204.

[0117] 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 can be accomplished by using any suitable deposition technique such as CVD, PVD, or ALD. The deposition process conforms the second chemical protection layer 206 to the profile of the nano-traps 120 in the second passivation layer 204, thus forming the nano-traps 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.

[0118] Referring to Figure 13 shows a cross-sectional side view of an example of an image sensor structure 300 at an intermediate stage of manufacture. This example of the process flow of the image sensor structure 300 is the same as or similar to the example of the process flow of the image sensor 100 and is equivalent to and includes with respect to Figure 8The disclosed process flow. Thus, at this stage of the process flow, the top surface 132 of the optical waveguide 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.

[0119] 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 optical waveguide 130. This first passivation layer 142 of the structure 300 provides a substantially horizontal upper surface 208 of the first passivation layer 142. This can be accomplished by any suitable deposition technique (such as CVD or PVD).

[0120] Thereafter, a first chemical protection layer 144 can be disposed on the relatively flat upper surface 208 of the first passivation layer 142. Then, a second passivation layer 204 can be disposed on the first chemical protection layer 144. These two layers 144, 204 can be accomplished using any suitable deposition technique (such as CVD, PVD or ALD).

[0121] 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 accomplished 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. Then the metal pillar 302 can 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 subsequently be removed by any suitable polishing technique, such as a chemical mechanical polishing (CMP) process.

[0122] Reference Figure 14 , thereafter the nano-traps 120 can then be formed in the second passivation layer 204. This can be accomplished by lithographically patterning the nano-traps and etching the nano-traps 120 into the second passivation layer 204.

[0123] 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 can be accomplished by CVD, PVD or ALD. The deposition process conforms the second chemical protection layer 206 to the profile of the nano-traps 120 in the second passivation layer 204, thus forming the nano-traps 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.

[0124] Refer to Figure 15, a cross-sectional side view showing an example of an image sensor structure 400 at an intermediate stage of manufacturing. This example of the process flow of the image sensor structure 400 is the same as or similar to the example of the process flow of the image sensor 100, equivalent to and including the process flow Figure 8 disclosed. 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 layer 138. Thus, the entire top surface of the image sensor structure 400 is substantially flat.

[0125] 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 can be accomplished by using any suitable deposition technique (such as CVD or PVD).

[0126] Thereafter, a first chemical protection layer 144 can be disposed on the relatively flat upper surface 208 of the first passivation layer 142. This can be accomplished by using any suitable deposition technique (such as CVD, PVD or ALD).

[0127] Referring to Figure 16 , thereafter, a first parallel metal layer 402A (which is one of the crosstalk blocking metal structures 102 of the image sensor structure 400) can be disposed on the first chemical protection layer 144. The metal layer 402A can be disposed by using any suitable deposition technique (such as CVD, PVD, ALD or electroplating).

[0128] Then, a second passivation layer 204 can be disposed on the first metal layer 402A. This can be accomplished by using any suitable deposition technique (such as CVC or PVD).

[0129] Then a second parallel metal layer 402B can be disposed on the second passivation layer 204 such that it is parallel to the first parallel metal layer 402A. This can be accomplished by using any suitable deposition technique (such as CVD, PVD, ALD or electroplating).

[0130] Thereafter, the nano-wells 120 can then be formed in the second passivation layer 204 and in the parallel metal layers 402A, 402B. This can be accomplished by lithographically patterning the nano-wells 120 and etching the nano-wells 120 into the second passivation layer 204 and the parallel metal layers 402A, 402B.

[0131] Thereafter, a second chemical passivation layer 206 is disposed on the second passivation layer 204 to complete the formation of the image sensor structure 400. This can be accomplished by using any suitable deposition technique, such as CVD, PVD, or ALD. The deposition process conforms the second chemical passivation layer 206 to the profile of the nano-traps 120 in the second passivation layer 204, and thus nano-traps 120 are formed in the second chemical passivation layer 206. The second chemical passivation layer 206, the second passivation layer 204, the first chemical passivation layer 144, and the first passivation layer 142 are all included in the passivation stack 104 of the image sensor structure 400.

[0132] Thereafter, the image sensor structures 100, 200, 300, 400 can be disposed on a printed circuit board (not shown). For example, any one of the image sensor structures 100, 200, 300, 400 can be coupled to a flow cell (such as flow cell 12) by using any suitable coupling technique to form a sensor system (e.g., such as biosensor system 10). Thereafter, the sensor system can be coupled to the printed circuit board by using any suitable coupling technique. This can be achieved, for example, by adhesive bonding.

[0133] It should be recognized that all combinations of the foregoing concepts (assuming these concepts are not mutually inconsistent) 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.

[0134] Although the foregoing examples are described by reference to specific examples, it should be understood that many changes can be made within the spirit and scope of the described inventive concepts. Accordingly, it is intended that the examples are not limited to the examples described, but rather that they have the full scope defined by the language of the claims.

[0135] Aspects of the present disclosure can be implemented in one or more of the embodiments described below:

[0136] 1) An image sensor structure, comprising:

[0137] an image layer including an array of photodetectors disposed in the image layer;

[0138] a device stack disposed on the image layer;

[0139] an array of light guides disposed in the device stack, each light guide being associated with at least one photodetector in the array of photodetectors;

[0140] a passivation stack disposed on the device stack, the passivation stack including a bottom surface that is in direct contact with a top surface of the light guide;

[0141] An array of nano-traps, which is disposed in the top layer of the passivation stack, and each nano-trap is associated with a light guide in the array of light guides; and

[0142] A crosstalk blocking metal structure, which is disposed in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

[0143] 2) The image sensor structure according to 1), comprising:

[0144] The passivation stack including multiple layers, the multiple layers including a first (No. 1) passivation layer disposed on the light guide and a first chemical protection layer disposed on the first passivation layer.

[0145] 3) The image sensor structure according to 2), wherein the crosstalk blocking metal structure includes metal pillars disposed in the first passivation layer.

[0146] 4) The image sensor structure according to 2), wherein the crosstalk blocking metal structure includes parallel metal layers disposed in the first passivation layer.

[0147] 5) The image sensor structure according to 2), wherein the multiple layers include:

[0148] A second (No. 2) passivation layer, which is disposed on the first chemical protection layer; and

[0149] A second chemical protection layer, which is disposed on the second passivation layer;

[0150] wherein the nano-trap is disposed in the top layer of the second chemical protection layer.

[0151] 6) The image sensor structure according to 5), wherein the crosstalk blocking metal structure includes parallel metal layers disposed in the second passivation layer.

[0152] 7) The image sensor structure according to 5), wherein the crosstalk blocking metal structure includes metal pillars disposed in the first passivation layer.

[0153] 8) The image sensor structure according to 5), wherein the crosstalk blocking metal structure includes metal pillars extending from the bottom surface of the first passivation layer to the top surface of the second passivation layer, and the metal pillars are disposed between the nano-traps.

[0154] 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).

[0155] 10) The image sensor structure according to 2), wherein the first passivation layer is made of silicon nitride (SiN), and the first chemical protection layer is made of tantalum pentoxide (Ta 2 O 5 ).

[0156] 11) The image sensor structure according to 1), including a light-shielding layer disposed between the device stack and the passivation stack.

[0157] 12) The image sensor structure according to 5), wherein the second passivation layer is made of silicon nitride (SiN), and the second chemical protection layer is made of tantalum pentoxide (Ta 2 O 5 ).

[0158] 13) The image sensor structure according to 4), wherein the parallel metal layer includes at least one of the following:

[0159] having a spacing distance between the parallel metal layers that is half or less of the wavelength of the crosstalk; and

[0160] having a width of the parallel metal layer that is half or more of the wavelength of the crosstalk.

[0161] 14) The image sensor structure according to 6), wherein the parallel metal layer includes at least one of the following:

[0162] having a spacing distance between the parallel metal layers that is half or less of the wavelength of the crosstalk; and

[0163] having a width of the parallel metal layer that is half or more of the wavelength of the crosstalk.

[0164] 15) An image sensor structure, comprising:

[0165] an image layer including an array of photodetectors disposed therein;

[0166] a device stack disposed on the image layer;

[0167] an array of light guides disposed in the device stack, each light guide being associated with at least one photodetector in the array of photodetectors;

[0168] a passivation stack disposed on the device stack, the passivation stack including:

[0169] a first passivation layer having a bottom surface in direct contact with the top surface of the light guide,

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

[0171] A second passivation layer disposed on the first chemical protection layer, and

[0172] A second chemical protection layer disposed on the second passivation layer; and

[0173] An array of nano-traps disposed in the top layer of the passivation stack, each nano-trap being associated with a light guide in the array of light guides.

[0174] 16) The image sensor structure according to 15), comprising a crosstalk blocking metal structure disposed in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk in the passivation stack.

[0175] 17) The image sensor structure according to 16), wherein the crosstalk blocking metal structure comprises at least one of metal pillars disposed between the nano-traps and parallel metal layers.

[0176] 18) A method comprising:

[0177] Etching an array of light guide holes into a device stack disposed on an image layer, the image layer comprising an array of light detectors disposed therein;

[0178] Forming an array of light guides in the light guide holes, each light guide being associated with at least one light detector in the array of light detectors;

[0179] 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;

[0180] 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 part of a passivation stack;

[0181] Forming an array of nano-traps in a top layer of the passivation stack, each nano-trap being associated with a light guide in the array of light guides; and

[0182] Disposing a crosstalk blocking metal structure in the passivation stack, wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

[0183] 19) The method according to 18), comprising:

[0184] Recessing the light guides into the light guide holes such that an upper portion of an inner sidewall of the light guide holes is exposed and a top surface of the light guides is recessed to a predetermined depth below a top opening of the light guide holes; and

[0185] Wherein, setting the first passivation layer further includes conforming the first passivation layer to an upper portion of an inner wall of the optical via to form an array of the nano-traps in a top layer of the first passivation layer, each nano-trap being associated with a single optical guide.

[0186] 20) The method according to 19), wherein setting the crosstalk blocking metal structure further includes disposing metal pillars within the first passivation layer between the nano-traps.

[0187] 21) The method according to 18), comprising:

[0188] Disposing a second passivation layer on the first chemical protection layer; and

[0189] Disposing a second chemical protection layer on the second passivation layer, the second chemical protection layer and the second passivation layer further including the passivation stack.

[0190] 22) The method according to 18), wherein setting the crosstalk blocking metal structure further includes disposing one of metal pillars and a parallel metal layer within the passivation stack between the nano-traps.

Claims

1. An image sensor structure, comprising: an image layer including an array of photodetectors disposed in the image 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 photodetector in the array of photodetectors; a passivation stack disposed on the device stack; a crosstalk blocking metal structure disposed in the passivation stack, wherein the crosstalk blocking metal structure extends from the top surface of at least one layer of the passivation stack and through at least a portion of the layer, and wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

2. The image sensor structure according to claim 1, wherein, the passivation stack includes a bottom surface in direct contact with the top surface of the light guide.

3. The image sensor structure according to claim 1, further comprising an array of nano-traps disposed in the top layer of the passivation stack, each nano-trap being associated with a light guide in the array of light guides.

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

5. The image sensor structure according to claim 1, wherein, the passivation stack includes a plurality of layers, the 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.

6. The image sensor structure according to claim 5, wherein, the plurality of layers further includes: a second passivation layer disposed on the first chemical protection layer; and a second chemical protection layer disposed on the second passivation layer; wherein nano-traps are disposed in the top layer of the second chemical protection layer.

7. The image sensor structure according to claim 5, wherein, The first passivation layer is composed of silicon nitride (SiN), and the first chemical protection layer is composed of tantalum pentoxide (Ta 2 O 5 ).

8. The image sensor structure according to claim 6, wherein, The second passivation layer is composed of silicon nitride (SiN), and the second chemical protection layer is composed of tantalum pentoxide (Ta 2 O 5 ).

9. An image sensor structure, comprising: an image layer including an array of photodetectors disposed in the image 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 photodetector in the array of photodetectors; a passivation stack disposed on the device stack; a crosstalk blocking metal structure disposed in the passivation stack, wherein the crosstalk blocking metal structure includes parallel metal layers, and wherein the crosstalk blocking metal structure reduces crosstalk within the passivation stack.

10. The image sensor structure according to claim 9, wherein, the parallel metal layers have a spacing distance between the parallel metal layers that is half or less of the wavelength of the crosstalk.

11. The image sensor structure according to claim 9, wherein, the parallel metal layers have a width of the parallel metal layers that is half or greater of the wavelength of the crosstalk.

12. The image sensor structure according to claim 9, wherein, the passivation stack includes a bottom surface in direct contact with the top surface of the light guide.

13. The image sensor structure according to claim 9 further includes an array of nano-traps, which is disposed in the top layer of the passivation stack, and each nano-trap is associated with a light guide in the array of light guides.

14. The image sensor structure according to claim 9, wherein, the passivation stack includes multiple layers, and the multiple layers include a passivation layer disposed on the light guide and a chemical protection layer disposed on the passivation layer.

15. The image sensor structure according to claim 9, wherein, the passivation stack includes multiple layers, and the multiple layers include a first passivation layer disposed on the light guide and a first chemical protection layer disposed on the first passivation layer.

16. The image sensor structure according to claim 15, wherein, the multiple layers further include: a second passivation layer, which is disposed on the first chemical protection layer; and a second chemical protection layer, which is disposed on the second passivation layer; wherein, the nano-trap is disposed in the top layer of the second chemical protection layer.

17. The image sensor structure according to claim 15, wherein, The first passivation layer is composed of silicon nitride (SiN), and the first chemical protection layer is composed of tantalum pentoxide (Ta 2 O 5 ).

18. The image sensor structure according to claim 16, wherein, The second passivation layer is composed of silicon nitride (SiN), and the second chemical protection layer is composed of tantalum pentoxide (Ta 2 O 5 ).

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