Image sensor structure

Abstract

The present invention discloses an image sensor structure, which includes an image stack disposed above a device stack. The image stack includes a plurality of photodetectors. A first filter stack is disposed above the image stack. The first filter stack includes a light guide layer. A light guide cavity is disposed in the light guide layer. Each light guide cavity is associated with a photodetector. Each light guide cavity has an aspect ratio greater than about 2.5: about 1. A nanopore layer is disposed above the first filter stack. Nanopores are disposed in the nanopore layer. Each nanopore is associated with a photodetector.

Description

[0001] Cross-references to related patent applications

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 62 / 912,908, filed on October 9, 2019, and entitled “Image Sensor Structure.” The entire contents of the aforementioned application are hereby incorporated herein by reference. Background Art

[0003] Image sensor structures (such as CMOS image sensors) typically utilize a plurality of high-density nanowells disposed in a nanowell layer to perform reactions on analytes disposed within the nanowells. The nanowell layer is disposed on the front or back side of the image sensor structure, which collects and analyzes data from the reactions. For example, analytes (such as clusters of DNA fragments, etc.) may be labeled with fluorescent markers, and excitation light may be directed to the labeled analytes to cause them to emit fluorescent emission light.

[0004] The analyte may then emit photons of fluorescent emission light, which may be transmitted from the nanopore to a plurality of photodetectors (e.g., photodiodes) associated with the nanopore. The photodetectors detect the emission light photons. Device circuitry may be connected to the photodetectors from within the device stack. The device circuitry may then process and transmit data signals based on these detected photons. The data signals may then be analyzed to reveal characteristics of the analyte.

[0005] In a front-illuminated (FSI) image sensor structure, a nanopore layer is disposed on the front side of the image sensor structure, which is illuminated by excitation light. In an FSI image sensor structure, a device stack is positioned between the nanopore layer and a plurality of photodetectors. However, in such an image sensor structure, a portion of the active (e.g., light sensing) area of ​​the photodetector may be blocked by device circuitry in the device stack. As photodetector size and spacing become smaller, the portion of the active area blocked by the device stack may increase, thereby reducing the sensitivity of the photodetector.

[0006] In a back-illuminated (BSI) image sensor structure, the nanopore layer is disposed on the back side of the image sensor structure, which is illuminated by excitation light. In a BSI image sensor structure, the device stack is not positioned between the nanopore layer and the plurality of photodetectors. Therefore, the device stack may not block the active area of ​​the photodetectors.

[0007] However, device circuits of a device stack are typically used to help reduce crosstalk in FSI image sensor structures. Such device circuits may not be available to help reduce crosstalk in BSI image sensor structures. Crosstalk includes emission light transmitted from a nanopore that is accidentally detected by a photodetector not associated with the nanopore.

[0008] Additionally, unlike the FSI image sensor structure, the device stack may not be available in the BSI image sensor structure to help adequately block the excitation light from reaching the photodetector. Additionally, the device stack may not be available in the BSI image sensor structure to help effectively collect and focus the emission light emitted from the nanohole onto the photodetector.

[0009] Brief Description

[0010] Examples provided herein can overcome the above challenges. For example, one example provides a BSI image sensor structure that reduces crosstalk between a nanopore and an unassociated photodetector without resorting to a device stack. In addition, another example provides a BSI image sensor structure that can substantially block excitation light from reaching the photodetector and can effectively collect and focus emission light onto the photodetector without resorting to a device stack.

[0011] The present disclosure provides advantages and alternatives over the prior art by providing an image sensor structure that, when illuminated with excitation light directed from its back side toward the nanopore, can reduce crosstalk between a nanopore and an unassociated light detector disposed in the image sensor structure without resorting to a device stack. Additionally, a light pipe cavity disposed in the image sensor structure has an aspect ratio and sidewall angle that are sized to adequately block the excitation light and effectively collect the emitted light without resorting to a device stack. Furthermore, the aspect ratio is not too large, and the sidewall angle is not too small, so as not to render the image sensor structure unreliable to manufacture.

[0012] An image sensor structure according to one or more aspects of the present disclosure includes an image stack disposed above a device stack. The image stack includes a plurality of photodetectors. A first filter stack is disposed above the image stack. The first filter stack includes a light guide layer and a plurality of light pipe cavities disposed in the light guide layer. Each light pipe cavity in the plurality of light pipe cavities is associated with a light detector in the plurality of photodetectors. Each light pipe cavity has an aspect ratio greater than about 2.5:1. A nanopore layer is disposed above the first filter stack. A plurality of nanopores are disposed in the nanopore layer. Each nanopore is associated with a light detector in the plurality of photodetectors.

[0013] In some examples, the light pipe cavity of the image sensor structure has a sidewall angle in a range from about 11 degrees to about 1.2 degrees.

[0014] In some examples, the image sensor structure includes a filter material disposed in a light pipe cavity. The filter material is in direct contact with the light guide layer at a sidewall of the light pipe cavity.

[0015] In some examples, the image sensor structure includes a second filter stack disposed above the first filter stack. The first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

[0016] In some examples, the photoconductive layer of the image sensor structure includes one of a polymer material, a semiconductor material, and a dielectric material.

[0017] In some examples, the first optical stack of the image sensor structure includes an intermediate layer disposed above the image stack and a light guide layer disposed above the intermediate layer. The light guide layer is a metal layer disposed on the sidewalls of the light pipe cavity and not disposed on the bottom surface of the light pipe cavity. The light guide layer has a thickness of about 100 nanometers or less.

[0018] In some examples, an image stack of an image sensor structure includes a base layer, a plurality of isolation grooves, and a dielectric material. The base layer is disposed above the plurality of photodetectors. The base layer is used to transmit emission light and excitation light. A plurality of isolation grooves are disposed in the base layer. Each isolation groove is disposed adjacent to a photodetector in the plurality of photodetectors. A dielectric material is disposed in each isolation groove. The dielectric material is used to electrically isolate each photodetector in the plurality of photodetectors.

[0019] In some examples of image sensor structures, an intermediate layer disposed in the first filter stack and a base layer of the image stack are composed of the same material.

[0020] In some examples of image sensor structures, the intermediate layer and the base layer are composed of silicon.

[0021] In some examples, the image sensor structure includes a light guide layer composed of an optically absorbing material. An optically transparent material is disposed in the light guide cavity. The optically transparent material has a refractive index greater than a refractive index of the optically absorbing material.

[0022] In some examples, the image sensor structure includes a crosstalk layer, a crosstalk curtain, a diffuser layer, and a light pipe extension. The crosstalk layer is disposed above the top surface of the filter stack and between one or more light pipe cavities in the light pipe cavity. The crosstalk curtain extends downward from the top surface of the filter stack between one or more light pipe cavities in the light pipe cavity. The diffuser layer is disposed between the filter stack and the image stack. The light pipe extension is disposed at the bottom of one or more light pipe cavities in the light pipe cavity. The light pipe extension extends through the diffuser layer.

[0023] Another image sensor structure according to one or more aspects of the present disclosure includes an image stack disposed above a device stack. The image stack includes a plurality of photodetectors. A first filter stack is disposed above the image stack. The first filter stack includes a light guide layer, a plurality of light pipe cavities disposed in the light guide layer, and a filter material disposed in the light pipe cavity. Each light pipe cavity is associated with a light detector in the plurality of photodetectors. The filter material is in direct contact with the light guide layer at a sidewall of the light pipe cavity. A nanopore layer is disposed above the first filter stack. A plurality of nanopores are disposed in the nanopore layer. Each nanopore is associated with a light detector in the plurality of photodetectors.

[0024] In some examples of image sensor structures, the light pipe cavity has an aspect ratio greater than about 2.5:about 1.

[0025] In some examples of image sensor structures, the light pipe cavity has a sidewall angle in a range of about 11 degrees to about 1.2 degrees.

[0026] In some examples of image sensor structures, the photoconductive layer includes one of a polymer material, a semiconductor material, and a dielectric material.

[0027] In some examples of image sensor structures, the first filter stack includes an intermediate layer disposed above the image stack. The light guide layer is disposed above the intermediate layer. The light guide layer is a metal layer disposed on a sidewall of the light guide cavity and not disposed on a bottom surface of the light guide cavity. The light guide layer has a thickness of about 100 nanometers or less.

[0028] In some examples of image sensor structures, an image stack includes a base layer, a plurality of isolation grooves, and a dielectric material. The base layer is disposed above a plurality of photodetectors. The base layer is used to transmit emission light and excitation light. A plurality of isolation grooves are disposed in the base layer. Each isolation groove is disposed adjacent to a photodetector in the plurality of photodetectors. A dielectric material is disposed in each isolation groove. The dielectric material is used to electrically isolate each photodetector in the plurality of photodetectors.

[0029] In some examples of image sensor structures, an intermediate layer disposed in the first filter stack and a base layer disposed in the image stack are formed of the same material.

[0030] In some examples, the image sensor structure includes a second filter stack disposed above the first filter stack. The first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

[0031] In some examples, the image sensor structure includes a crosstalk layer, a crosstalk curtain, a diffuser layer, and a light pipe extension. The crosstalk layer is disposed above the top surface of the filter stack and between one or more light pipe cavities in the light pipe cavity. The crosstalk curtain extends downward from the top surface of the filter stack between one or more light pipe cavities in the light pipe cavity. The diffuser layer is disposed between the filter stack and the image stack. The light pipe extension is disposed at the bottom of one or more light pipe cavities in the light pipe cavity. The light pipe extension extends through the diffuser layer.

[0032] Another image sensor structure according to one or more aspects of the present disclosure includes an image stack disposed above a device stack. The image stack includes a plurality of photodetectors. A first filter stack is disposed above the image stack. The first filter stack includes a light guide layer composed of an optically absorbing material, a plurality of light pipe cavities disposed in the light guide layer, and an optically transparent material disposed in the light pipe cavity. Each light pipe cavity is associated with a light detector in the plurality of photodetectors. The optically transparent material has a refractive index greater than a refractive index of the optically absorbing material. A nanopore layer is disposed above the first filter stack. A plurality of nanopores are disposed in the nanopore layer. Each nanopore is associated with a light detector in the plurality of photodetectors.

[0033] In some examples of image sensor structures, the light pipe cavity has a sidewall angle in a range of about 11 degrees to about 1.2 degrees and an aspect ratio greater than about 2.5:about 1.

[0034] In some examples of image sensor structures, the optically absorptive material is in direct contact with the optically transparent material at the sidewalls of the light pipe cavity.

[0035] In some examples, the image sensor structure includes a crosstalk layer, a crosstalk curtain, a diffuser layer, and a light pipe extension. The crosstalk layer is disposed above the top surface of the filter stack and between one or more light pipe cavities in the light pipe cavity. The crosstalk curtain extends downward from the top surface of the filter stack between one or more light pipe cavities in the light pipe cavity. The diffuser layer is disposed between the filter stack and the image stack. The light pipe extension is disposed at the bottom of one or more light pipe cavities in the light pipe cavity. The light pipe extension extends through the diffuser layer.

[0036] A method of forming an image sensor structure according to one or more aspects of the present disclosure includes disposing an image stack above a device stack. The image stack includes a plurality of photodetectors. A light guide layer is disposed above the image stack. A plurality of light pipe cavities are etched in the light guide layer. Each light pipe cavity is associated with a light detector in the plurality of photodetectors. Each light pipe cavity has an aspect ratio greater than about 2.5:1. A nanopore layer is disposed above the light guide layer. A plurality of nanopores are disposed in the nanopore layer. Each nanopore is associated with a light detector in the plurality of photodetectors. The light guide layer, the plurality of light pipe cavities, and the filter material include a first filter stack disposed above the image stack.

[0037] In some examples, the method includes disposing an intermediate layer above the image stack. A light guide layer is disposed above the intermediate layer. The light guide layer is a metal layer disposed on a sidewall of the light pipe cavity and not disposed on a bottom surface of the light pipe cavity. The light guide layer has a thickness of about 100 nanometers or less.

[0038] In some examples, the method includes disposing a filter material in the light pipe cavity. The filter material is in direct contact with the light guide layer at a sidewall of the light pipe cavity.

[0039] In some examples, the method includes disposing a second filter stack above the first filter stack.The first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

[0040] In some examples, the method includes a light guide layer composed of an optically absorbing material. An optically transparent material is disposed in the light guide cavity. The optically transparent material has a refractive index greater than a refractive index of the optically absorbing material.

[0041] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein and can be used to achieve the benefits and advantages described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present disclosure will be more fully understood through the following detailed description taken in conjunction with the accompanying drawings, in which:

[0043] Figure 1 A cross-sectional view of an example of an image sensor structure at an intermediate stage of fabrication is depicted according to aspects described herein, wherein an image stack including a plurality of photodetectors is disposed above a device stack;

[0044] Figure 2 According to various aspects described herein, a method for manufacturing an intermediate stage of Figure 1A cross-sectional view of an example of an image sensor structure, wherein a photoconductive layer is disposed above an image stack;

[0045] Figure 3 According to various aspects described herein, a method for manufacturing an intermediate stage of Figure 2 A cross-sectional view of an example of an image sensor structure in which a plurality of light pipe cavities are etched into a light guide layer such that each light pipe cavity is associated with a photodetector of a plurality of photodetectors;

[0046] Figure 4 According to various aspects described herein, Figure 3 A cross-sectional view of an example of an enlarged view of the circular area 4-4 of FIG. 4, showing the aspect ratio and sidewall angle of the light pipe cavity;

[0047] Figure 5 According to various aspects described herein, a method for manufacturing an intermediate stage of Figure 3 a cross-sectional view of an example of an image sensor structure wherein a filter material is disposed in a light pipe cavity and wherein the light guide layer, the plurality of light pipe cavities, and the filter material form a first filter stack;

[0048] Figure 6 According to various aspects described herein, a method for manufacturing an intermediate stage of Figure 5 A cross-sectional view of an example of an image sensor structure in which the second filter stack is arranged Figure 5 above the first filter stack;

[0049] Figure 7 According to various aspects described herein, a method of manufacturing a finished product is depicted. Figure 5 A cross-sectional view of an example of an image sensor structure, wherein a nanopore layer having a plurality of nanopores is disposed above a first filter stack;

[0050] Figure 8 Depicted is a cross-sectional view of an example of an image sensor structure at an intermediate stage of fabrication, wherein a plurality of light pipe cavities are etched into an intermediate layer and a metal light guide layer is disposed on sidewalls of the light pipe cavities, according to aspects described herein;

[0051] Fig. 9 According to various aspects described herein, a method for manufacturing an intermediate stage of Figure 8 a cross-sectional view of an example of an image sensor structure wherein a filter material is disposed in a light pipe cavity and wherein the intermediate layer, the light guide layer, the plurality of light pipe cavities, and the filter material form a first filter stack;

[0052] Fig.10 According to various aspects described herein, a method of manufacturing a finished product is depicted. Fig. 9A cross-sectional view of an example of an image sensor structure, wherein a nanopore layer having a plurality of nanopores is disposed above a first filter stack;

[0053] Fig.11 Depicted is a cross-sectional view of an example of an image sensor structure at an intermediate stage of fabrication, wherein an intermediate layer is disposed above a base layer of an image stack, wherein the intermediate layer and the base layer are comprised of the same material, and wherein a plurality of light pipe cavities are etched into the intermediate layer, according to aspects described herein;

[0054] Fig.12 According to various aspects described herein, a method for manufacturing an intermediate stage of Fig.11 A cross-sectional view of an example of an image sensor structure, wherein a metal light guide layer is disposed on a side wall of a light pipe cavity;

[0055] Fig.13 According to various aspects described herein, a method for manufacturing an intermediate stage of Fig.12 a cross-sectional view of an example of an image sensor structure wherein a filter material is disposed in a light pipe cavity and wherein the intermediate layer, the light guide layer, the plurality of light pipe cavities, and the filter material form a first filter stack;

[0056] Fig.14 According to various aspects described herein, a method of manufacturing a finished product is depicted. Fig.13 A cross-sectional view of an example of an image sensor structure, wherein a nanopore layer having a plurality of nanopores is disposed above a first filter stack;

[0057] Fig.15 depicts a cross-sectional view of an example of another image sensor structure 400 at a completed stage of fabrication, wherein a diffuse layer is disposed between an image stack and a filter stack, according to aspects described herein; and

[0058] Fig.16 A cross-sectional view of another example of an image sensor structure 500 at a completed stage of fabrication is depicted, wherein the light guide layer is composed of a filter material and the light pipe cavity is filled with an optically transparent material, according to various aspects described herein. DETAILED DESCRIPTION

[0059] 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.

[0060] The terms "substantially," "approximately," "about," "relatively," or other such 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 process variations from a reference or parameter). Such small fluctuations also include zero fluctuations from a reference or parameter. 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%.

[0061] See also Figures 1 to 16 , like reference numerals are used throughout the several views to indicate like or similar parts. Figures 1 to 6 , Figures 8 to 9 and Figures 11 to 13 Examples of image sensor structures 100 , 200 , and 300 , respectively, are shown at various intermediate stages of fabrication in accordance with various aspects described herein. Figure 7 , Fig.10 , Fig.14 , Fig.15 and Fig.16 Examples of image sensor structures 100 , 200 , 300 , 400 , and 500 are shown at respective stages of completed manufacturing.

[0062] See also Figure 1 , depicts a cross-sectional view of an example of an image sensor structure 100 at an intermediate stage of fabrication in accordance with various aspects described herein. At this stage of fabrication, the image sensor structure 100 includes an image stack 102 disposed above a device stack 104. As will be discussed in greater detail herein, the image sensor structure 100 is a backside illuminated (BSI) image sensor structure.

[0063] To provide mechanical support for the image sensor structure 100, a carrier substrate 106 is bonded to the device stack 104. The carrier substrate 106 may include or be silicon or another semiconductor material. The thickness of the carrier substrate 106 may be in the range of 400 microns to 800 microns.

[0064] Electrical input / output connections may be established from device stack 104 to conductive pads 108 bonded to the front side of carrier substrate 106 using through silicon vias (TSVs) 110. TSVs may have metal linings 109 or be filled with a metal such as tungsten (W), aluminum (Al), or copper (Cu).

[0065] The device stack 104 may include a plurality of dielectric layers 111. The dielectric layers 111 may include or be SiO2, SiN, SiON, or other dielectric materials.

[0066] The dielectric layer 111 may include various device circuits 112, such as, for example, resistors, capacitors, diodes, and / or transistors and their interconnects. The device circuits 112 of the device stack 104 interface with a plurality of light detectors 114A, 114B, 114C, 114D, 114E (collectively 114) disposed in the image stack 102. The device circuits 112 may be operable to use the emitted light 158 ​​( Figure 7 The data signal from the photodetector 114 is processed based on the detected visible light photons (best seen in FIG. 1 ).

[0067] As used herein, the photodetector 114 may be, for example, a semiconductor. The semiconductor may include a photodiode, a complementary metal oxide semiconductor (CMOS) material, or both. The photodetector 114 may also be a photodiode junction region or an implant in a semiconductor material. For example, the photodiode 114 may be an n-doped region in a p-substrate, an n-doped region on a p-well on an n-doped substrate, or any other diode combination.

[0068] The image stack 102 includes the plurality of photodetectors 114 disposed above the device stack 104. A substrate layer 116 is disposed above the plurality of photodetectors 114. The substrate layer 116 may include or be silicon, silicon germanium, gallium arsenide, or other semiconductor materials. As will be explained in more detail herein, the substrate layer 116 is used to transmit light from a nanohole 148 ( Figure 7 150 and the excitation light 156. The emission light 158 ​​may, for example, be in the wavelength range of about 500 nanometers (nm) to about 650 nm. The excitation light 156 may, for example, be in the wavelength range of about 400 nm to about 570 nm. The emission light 158 ​​may have a wavelength greater than the excitation light 156. More specifically, the emission light 158 ​​may have a wavelength in the range of about 40 nm to 140 nm greater than the wavelength of the excitation light 156.

[0069] The image stack 102 also includes a plurality of isolation trenches 118A, 118B, 118C, 118D, and 118E (collectively 118) disposed in the base layer 116. Each isolation trench 118 is disposed adjacent to a photodetector 114 of the plurality of photodetectors 114. The isolation trenches 118 may be deep trenches and may have a large aspect ratio AR of about 5:1 to about 25:1. As used herein, the aspect ratio AR is the ratio of the height of a feature (in this case, the isolation trenches 118) to the maximum width of the feature.

[0070] Due to manufacturing tolerances, isolation trenches 118 may not all have the same height. For example, isolation trenches 118A- 118D are shown as not extending across the full thickness of base layer 116 , and isolation trenches 118E- 118F are shown as extending across the entire thickness of base layer 116 .

[0071] The image stack 102 also includes a dielectric material 120 disposed in each isolation trench 118. The dielectric material 118 is used to electrically isolate each of the plurality of photodetectors 114. The dielectric material 118 is also used to significantly reduce crosstalk between the photodetectors by blocking or significantly reducing light transmission or photogenerated electrons between the photodetectors 114. The dielectric material may include or be SiO2, SiN, SiON, or other dielectric materials.

[0072] exist Figure 1 The example of a method of preparing the image sensor structure 100 at the intermediate stage of manufacturing shown may include first providing a base layer 116. Various doping techniques may then be utilized to form n-doped and p-doped photodiode junction regions in the base layer 116 to form the photodetectors 114. Isolation trenches 118 may then be anisotropically etched between the photodetectors 114 (e.g., using a reactive ion etching (RIE) process). The isolation trenches 118 may then be filled with a dielectric material 120 to provide electrical deep trench isolation (DTI) and significantly reduce crosstalk between the photodetectors 114. Any excess dielectric material 120 may be planarized all the way to the level of the photodetectors 114, for example, by a chemical mechanical planarization (CMP) process. The device stack 104 may then be disposed directly above the photodetectors 114 to complete the formation of the image stack 102 and device stack 104 of the image sensor structure 100. The carrier substrate 106 may then be bonded to the device stack 104 to provide mechanical support to the image sensor structure 100.

[0073] See also Figure 2 , depicting a process for manufacturing an intermediate stage according to various aspects described herein Figure 1 100, wherein a photoconductive layer 122 is disposed above the image stack 102. The photoconductive layer 122 may include or be, for example, a polymer material, a semiconductor material, or a dielectric material. If the photoconductive layer is a polymer, it may include or be a SU-8 photoresist material, benzocyclobutene (BCB), polyamide, polymethyl methacrylate (PMMA), or other dye-colored film. If the photoconductive layer is a dielectric, it may include or be SiO2, SiN, SiC, silicon oxynitride, or other dielectrics. If it is a semiconductor material, it may include or be silicon or other semiconductor materials.

[0074] See also Figure 3, depicting a process for manufacturing an intermediate stage according to various aspects described herein Figure 2 1 is a cross-sectional view of an example of an image sensor structure 100, wherein a plurality of light pipe cavities 124A, 124B, 124C, 124D, 124E (collectively referred to as 124) are formed into a light guide layer 122. Each light pipe cavity 124 is associated with a light detector 114 of the plurality of light detectors 114. More specifically, each light pipe cavity 124A, 124B, 124C, 124D, 124E is aligned with an associated light detector 114A, 114B, 114C, 114D, 114E, respectively. Thus, light passing through a light pipe cavity 124 can be directed to its associated light detector 114, and not to any non-associated light detector.

[0075] The light pipe cavity 124 may be anisotropically etched and / or photolithographically patterned into the light guide layer 122. Due to manufacturing tolerances, the light pipe cavity 124 may not always penetrate the entire thickness of the light guide layer 122. For example, the light pipe cavity 124D is shown as having a smaller thickness of the light guide layer 122 material disposed at the bottom of the light pipe cavity. However, the thickness of the light guide layer 122 at the bottom of the light pipe cavity 124D is small enough that it does not significantly block light directed toward the light sensor 114. In order not to significantly block light, the thickness of the light guide layer 122 at the bottom of the light pipe cavity 124 may be about 50 nanometers thick or less, or may be about 20 nanometers thick or less.

[0076] The light guiding layer 122 significantly reduces or blocks the transmission of light from one light pipe cavity 124 to another light pipe cavity to help reduce crosstalk between the light detectors 114. The term "substantially" may refer to greater than or equal to about 50% herein. For example, the light guiding layer 122 may reduce the transmission of light from one light pipe cavity 124 to another light pipe cavity by 50%, 60%, 75%, or more. The light guiding layer 122 also helps guide a substantial portion of the emitted light 156 through the light pipe cavity 124 and onto its associated light detector 114. For example, the light guiding layer may help guide 50%, 60%, 75%, or more of the emitted light 156 to its associated light detector 114.

[0077] See also Figure 4 , according to the various aspects described herein, depicts Figure 3 4 is an enlarged cross-sectional view of an example of a circular area 4-4 of the image sensor structure 100, showing the aspect ratio AR and the sidewall angle θ of the light pipe cavity 124. As will be explained in more detail herein, the aspect ratio AR of the light pipe cavity 124 can be in the range of about 2.5:1 to about 25:1, depending on the need to block excitation light and collect emission light emitted from the nanohole 148 directly above the light pipe cavity 124 disposed in the image sensor structure 100. More specifically, Figure 3 and Figure 4 The aspect ratio AR of the light pipe cavity 124 is the ratio of the actual height H of the light pipe cavity 124 to the maximum width W, which happens to be the top width W at the top of the light pipe cavity 124 .

[0078] It may not be practical or cost-effective to reliably manufacture such high aspect ratio light pipe cavities 124 where the bottom width W′ at the bottom of the cavity 124 is equal to the top width W at the top of the cavity 124. In other words, a reliable and cost-effective manufacturing process for these high aspect ratio light pipe cavities 124 may more likely include sidewalls 130 having a non-zero sidewall angle θ relative to a vertical reference line 126 (i.e., a line 126 that is substantially perpendicular to the top surface 128 of the light guide layer 122).

[0079] The sidewall angles θ on either side of the light pipe cavity 124 are more likely to be substantially equal. Therefore, the horizontal distance d of the bottom width W' from a vertical reference line 126 extending downward from the top edge 129 of the cavity 124 may also be substantially equal (on either side of the light pipe cavity 124).

[0080] Such a non-zero sidewall angle θ will limit the maximum attainable height Hmax and, therefore, the maximum attainable aspect ratio ARmax that the light pipe cavity 124 can achieve for any given sidewall angle θ. That is, the maximum attainable height Hmax is limited to the height at which the bottom width W' at the bottom of the light pipe cavity 124 can become zero. In other words, the maximum attainable height Hmax is limited to the height at which the sidewalls 130 can intersect at point 132 for any given sidewall angle θ. Since the sidewall angles θ on either side of the light pipe cavity 124 are substantially equal, point 132 is horizontally positioned in the middle of the width W at the top of the cavity 124. Therefore, the horizontal distance of the bottom point 132 from the vertical reference line 126 may also be substantially equal to W / 2.

[0081] The relationship between the actual aspect ratio AR, the maximum achievable aspect ratio ARmax, the actual height H, the maximum achievable height Hmax, the side wall angle θ, the top width W, the bottom width W' and the distance d can be expressed as follows:

[0082] AR = H / W;

[0083] tanθ=d / H=0.5W / Hmax;and

[0084] ARmax=Hmax / W=H / (2d)=H / (W-W′)=0.5 / (tanθ).

[0085] Therefore, since ARmax=0.5 / (tanθ), the smaller the sidewall angle θ is, the larger the maximum achievable aspect ratio ARmax that can be obtained is.

[0086] See also Figure 5 , depicting a process for manufacturing an intermediate stage according to various aspects described herein Figure 3 1 is a cross-sectional view of an example of an image sensor structure 100 with filter material 134 disposed in light pipe cavities 124. At this stage of manufacturing, light guide layer 122, multiple light pipe cavities 124, and filter material 134 form a completed first filter stack 136 disposed above image stack 102.

[0087] The filter material 134 may block a substantial portion of the excitation light. For example, the filter material may transmit a substantial portion of the emission light wavelengths in the range of about 500 nm to 650 nm, and may block a substantial portion of the excitation light in the range of about 400 nm to 570 nm.

[0088] The filter material 134 is disposed in the light pipe cavity 124 such that it is in direct contact with the light guide layer 122 at the sidewalls 130 of the light pipe cavity 124. Having the filter material 134 in direct contact with the light guide layer 122 at the sidewalls 130 of the light pipe cavity 124 ensures that a significant amount of the excitation light 156 is not accidentally transmitted between the filter material 134 and the light guide layer 122 to reach the photodetector 114 below.

[0089] The filter material 134 may include or be a dye-polymer blend, wherein the dye may have low fluorescence. For example, the dye may include or be a member of the class of metallized azo dye complexes, such as an ornitro orange dye, an ornitro yellow dye, a solvent yellow dye, a solvent orange dye, or a solvent red dye. The polymer may include or be, for example, cellulose acetate butyrate.

[0090] The material 134 may be spin coated or spray coated into the light guide cavity 124, dried and / or baked. Any excess filter material 134 may be planarized down to the level of the top surface 128 of the light guide layer 122.

[0091] The light pipe cavity 124 and the filter material 130 effectively act as a light guide that blocks most of the excitation light 156 and transmits a substantial portion of the emission light 158 ​​to the plurality of light detectors 114. To effectively function as a light guide, the light pipe cavity 124 in some implementations has a height H that is high enough to enable the selected light guide material 134 to block a substantial portion of the excitation light 156 from being transmitted to the light detectors 114 below.

[0092] Additionally, to effectively function as a light guide, the top width W of the cavity 124 is large enough in some implementations to effectively collect a substantial amount of emitted light 158 ​​even when the spacing between the light detectors 114 is small (e.g., less than about 0.5 microns). When the spacing between the light detectors 114 is small compared to the top width W, the bottom width W' of the light pipe cavity 124 may also be small compared to the top width W.

[0093] One way to achieve a large height H and a large difference between the top width W and the bottom width W' of the light pipe cavity is to have a high aspect ratio. For example, the aspect ratio H / W can be greater than about 2.5:1, greater than about 5:1, greater than about 10:1, and greater than about 20:1.

[0094] The higher the actual aspect ratio H / W, the higher the maximum achievable aspect ratio Hmax / W can be and the smaller the sidewall angle θ can be. For example:

[0095] For an actual aspect ratio of about 2.5:1, the maximum achievable aspect ratio may be about 2.5:1 or greater, and the sidewall angle θ may be about 11 degrees or less;

[0096] For an actual aspect ratio of about 5:1, the maximum achievable aspect ratio may be about 5:1 or greater, and the sidewall angle θ may be about 6 degrees or less;

[0097] For an actual aspect ratio of about 10:1, the maximum achievable aspect ratio may be about 10:1 or greater, and the sidewall angle θ may be about 3 degrees or less; and

[0098] • For an actual aspect ratio of about 20:1, the maximum achievable aspect ratio may be about 20:1 or greater, and the sidewall angle θ may be about 1.5 degrees or less.

[0099] However, higher maximum achievable aspect ratios and corresponding smaller sidewall angles θ may be impractical, unreliable, and expensive to manufacture. For example, a maximum achievable aspect ratio greater than about 25:1 and a corresponding sidewall angle θ less than about 1.2 degrees may be difficult to manufacture reliably in significant quantities.

[0100] Therefore, in order to achieve reliable manufacturing of a light guide (i.e., a light pipe cavity 124 filled with filter material 134) that effectively blocks excitation light 156 and collects emission light 158, the aspect ratio H / W and the sidewall angle θ of the light pipe cavity can be made within certain predetermined ranges. For example, the light pipe cavity can have:

[0101] An aspect ratio of about 2.5:1 or greater and a sidewall angle in a range of about 11 degrees to about 1.2 degrees;

[0102] An aspect ratio of about 5:1 or greater and a sidewall angle in a range of about 6 degrees to about 1.2 degrees;

[0103] An aspect ratio of about 5:1 or greater and a sidewall angle in the range of about 6 degrees to about 1.5 degrees;

[0104] An aspect ratio of about 10:1 or greater and a sidewall angle in the range of about 3 degrees to about 1.2 degrees; and

[0105] • An aspect ratio of about 10:1 or greater and a sidewall angle in a range of about 3 degrees to about 1.5 degrees.

[0106] See also Figure 6 , depicting a process for manufacturing an intermediate stage according to various aspects described herein Figure 5 A cross-sectional view of an example of an image sensor structure in which the second filter stack 138 is disposed Figure 5 The combined first filter stack 136 and second filter stack 138 have an overall aspect ratio that is greater than either of the first filter stack and the second filter stack.

[0107] High aspect ratios may generally be difficult to manufacture reliably, but may be desirable to achieve parameters such as substantially blocking excitation light 156 or efficiently collecting emission light 158. For example, overall aspect ratios greater than about 10, greater than about 15, greater than about 20, and greater than about 25 may be desirable. To achieve such high aspect ratios, but still have a sidewall angle θ within reasonable manufacturing limits, a second filter stack 138 may be disposed above the first filter stack 136. Such reasonable manufacturing limits for the sidewall angle θ may be, for example, 1.2 degrees or more, 1.5 degrees or more, and 3 degrees or more.

[0108] The second filter stack 138 may include a second light guide layer 140 disposed above the first filter stack 136. A second plurality of light pipe cavities 142 may be formed into the second light guide layer 140. Each second light pipe cavity is associated with a light detector 114 of the plurality of light detectors. A second filter material 144 may be disposed within each second light pipe cavity 142. The second light pipe cavities may have a second light pipe cavity height H2 and a second light pipe cavity top width W2.

[0109] The overall aspect ratio may be approximately equal to the total height H of the combined first light pipe cavity 124 and second light pipe cavity 140. TOT divided by the maximum width of the combined first light pipe cavity 124 and second light pipe cavity 140. If the second filter stack 138 is substantially geometrically identical to the first filter stack 136, the overall aspect ratio may effectively be about twice the aspect ratio of the first light pipe cavity 124 and the sidewall angle θ may remain about the same.

[0110] That is, the overall aspect ratio may be approximately equal to the total height H of the combined heights H and H2 of the first light pipe cavity 124 and the second light pipe cavity 140. TOT Divided by the maximum width of the combined first light pipe cavity 124 and the second light pipe cavity 140. The maximum width can be the wider of the two top widths W, W2. TOT The sidewall angle θ may be approximately twice the height H of the first light pipe cavity 124, and the maximum width may be approximately equal to the width W of the first light pipe cavity, so the overall aspect ratio may be approximately twice that of the first light pipe cavity 124. However, the sidewall angle θ may remain approximately the same throughout the first light pipe cavity 124 and the second light pipe cavity 142.

[0111] Although the second filter stack 138 is Figure 6 1 is shown as being substantially the same as the first filter stack 136, but other configurations of the second filter stack 138 may also be utilized. For example, the second filter stack 138 may differ from the first filter stack 136 in the material and dimensions of the second light guide layer 140, the material and dimensions of the second light guide cavity 142, and the material and dimensions of the second filter material.

[0112] See also Figure 7 , depicting a manufacturing completion stage according to various aspects described herein Figure 5 1 is a cross-sectional view of an example of an image sensor structure 100, wherein a nanohole layer 146 having a plurality of nanoholes 148A, 148B, 148C, 148D, 148E (collectively referred to as 148) is disposed above a first filter stack 136. Each nanohole 148 is associated with a photodetector 114 of the plurality of photodetectors. More specifically, each nanohole 148A, 148B, 148C, 148D, 148E may be aligned with an associated light pipe cavity 124A, 124B, 124C, 124D, 124E and an associated photodetector 114A, 114B, 114C, 114D, 114E, respectively. Thus, some light emitted from a nanohole 148 may pass through its associated light pipe cavity 124 and may be directed to its associated photodetector 114, but not to any non-associated photodetector.

[0113] Nanopore layer 146 may be one or more layers of a dielectric material such as silicon nitride SiN or a type of tantalum oxide such as tantalum pentoxide Ta 2 O 5 . Nanopores 148 may be photolithographically patterned and etched into nanopore layer 146 .

[0114] A passivation stack 150 may optionally be disposed directly above the first filter stack 136, wherein the nanopore layer 146 may be disposed above the passivation stack. The passivation stack may be one or more layers of a dielectric material, such as SiO2 or SiN. The passivation stack may also be one or more layers of a polymer, such as BCB or SU8. The passivation stack may be used to reduce the chemical reactivity of the first filter stack 136, wherein the chemical reaction is performed in the nanopore 148.

[0115] During operation, certain analytes 152 (such as clusters of DNA fragments, etc.) may be labeled with fluorescently labeled molecules 154 and these analytes may be disposed in the nanopore 148. Various types of excitation light 156 may then be radiated onto the analytes 152 in the nanopore 148, causing the labeled molecules 154 to emit fluorescent emission light 158. Most photons of the emission light 158 ​​may pass through the passivation stack 150 and enter its associated light pipe cavity 124. The light pipe cavity 124, together with its filter material 134, acts as a light guide that may filter out most of the excitation light 156 and direct a substantial portion of the emission light 158 ​​to an associated light detector 114 located directly below the light guide.

[0116] The light detector 114 detects the emitted light photons 158. The device circuitry 112 within the device stack 104 then processes and transmits a data signal based on those detected photons of the emitted light 158. The data signal may then be analyzed to reveal characteristics of the analyte 152.

[0117] The image sensor structure 100 is a backside illuminated (BSI) image sensor structure because the nanohole 148 is disposed on the back side of the image sensor structure 100 and because the device stack 104 is not disposed between the nanohole layer 146 and the plurality of photodetectors 114. In other words, the device stack 104 and the nanohole layer 146 are disposed on opposite sides of the plurality of photodetectors 114. Therefore, the nanohole 148 is illuminated by the excitation light 156 from the back side of the image sensor structure 100.

[0118] However, due to the location of the device stack 104, the device circuitry 112 may not be available to help reduce crosstalk of emission light photons 158 emitted from the nanopore 148 and reaching the unassociated light detector 114. To compensate for the inadequacy of the device stack 104, the light guide layer 122 is utilized to block most of the emission light 158 ​​and excitation light 156 from being transmitted from one light pipe cavity 124 to another light pipe cavity. In other words, the light guide layer 122 is used to prevent or at least substantially prevent the emission light 158 ​​emitted from the fluorescently labeled molecules 154 in the nanopore 148 and the excitation light 156 from back-illuminating the nanopore 148 of the image sensor structure 100 from passing therethrough.

[0119] Additionally, the light guide layer 122 is in direct contact with the filter material 134 at the sidewalls 130 of the light pipe cavity 124. Thus, little to no excitation light 156 can pass through the light pipe cavity 124 without passing through the filter material 134. The filter material 134 serves to block the excitation light 156 and pass the emission light 158 ​​through to the light detector 114.

[0120] The high aspect ratio H / W of the light pipe cavity 124 geometrically shapes the filter material 134 filling the cavity 124. Thus, the high aspect ratio of the light pipe cavity 124 helps provide the filter material 134 with a sufficient height H, which enables the filter material 134 to block a substantial portion of the excitation light 156 from passing through.

[0121] The high aspect ratio H / W of the light pipe cavity 124 also provides a significantly wider top width W relative to the bottom width W' of the light pipe cavity 124. Therefore, the light pipe cavity 124 can effectively collect the emission light 158 ​​even when the spacing between the light detectors 114 is as small as, for example, about 0.6 microns to 0.5 microns or less.

[0122] The high aspect ratio H / W of the light pipe cavity 124 can be as high as about 2.5:1, about 5:1, about 10:1, about 20:1, or more. In addition, the sidewall angle θ is small enough to allow for a high aspect ratio in the light pipe cavity 124, but not so large that the light pipe cavity is unreliable and / or too expensive to manufacture. The sidewall angle θ of the light pipe cavity 124 can be in the range of about 11 degrees to about 1.2 degrees, in the range of about 10 degrees to about 1.5 degrees, in the range of about 6 degrees to about 1.2 degrees, in the range of about 3 degrees to about 1.2 degrees, and in the range of about 3 degrees to about 1.5 degrees.

[0123] See also Figure 8 , depicts a cross-sectional view of an example of another image sensor structure 200 at an intermediate stage of fabrication, wherein a plurality of light pipe cavities 124 are etched into an intermediate layer 160 and a metal light guide layer 162 is disposed on the sidewalls 130 of the light pipe cavities 124, according to aspects described herein. The light guide layer 162 may include or be a metal, such as aluminum, gold, or copper. However, if the thickness of the metal light guide layer 162 between the light pipe cavities 124 is too great, the metal may absorb too much of the emitted light 158 ​​before the emitted light 158 ​​reaches the light detector 114. In order not to absorb too much of the emitted light 158, the thickness of the metal light guide layer 162 between the light pipe cavities 124 may be, for example, about 100 nanometers or less, about 50 nanometers or less, or about 40 nanometers or less.

[0124] An intermediate layer 160 is disposed over the image stack 102 and provides mechanical support for a relatively thin metal light guide layer 162. The light guide layer 162 is disposed over the intermediate layer 160 and on the sidewalls 130 of the light pipe cavity 124. In one implementation, the metal layer is disposed directly on the sidewalls.

[0125] The metal light guide layer 162 may not be disposed on the bottom surface 164 of the light pipe cavity 124. This is because the metal light guide layer 162, even if as thin as 100 nanometers or less, may prevent a substantial portion of the emitted light 158 ​​from being transmitted into the image stack 102 if the image stack is disposed on the bottom surface 164 of the light pipe cavity 124.

[0126] The intermediate layer 160 may include or be, for example, a polymer material, a semiconductor material, or a dielectric material. If the intermediate layer includes a polymer, the polymer may include or be a SU-8 photoresist material, benzocyclobutene (BCB), polyamide, polymethyl methacrylate (PMMA), or other dye-colored films. If the light-guiding layer includes a dielectric, the dielectric may include or be SiO2, SiN, SiC, or other dielectrics. If it is a semiconductor material, it may include or be silicon or other semiconductor materials. The light pipe cavity 124 may be anisotropically etched and / or photolithographically patterned into the intermediate layer 160.

[0127] The intermediate layer 160 may be composed of a material that is too transparent to act as a light guiding layer, but can be easily and reliably etched to the high aspect ratios discussed previously herein. In such cases, it may be advantageous to use the intermediate layer 160 to enable the fabrication of such a high aspect ratio light pipe cavity 124, and then coat the cavity sidewalls 130 with a thin metallic light guiding layer 162.

[0128] The metal light guide layer 162 may be coated on the sidewalls 130 of the light pipe cavity 124 using, for example, a blank deposition process, atomic layer deposition, chemical plating, or electroplating. Any metal light guide layer 162 accidentally disposed on the bottom surface 164 of the light pipe cavity 124 may be removed by, for example, an anisotropic etching process such as a reactive ion etching process. The anisotropic etching process leaves the metal light guide layer 162 on the sidewalls 130 of the light pipe cavity 124.

[0129] See also Fig. 9 , depicting a process for manufacturing an intermediate stage according to various aspects described herein Figure 8 2 is a cross-sectional view of an example of an image sensor structure 200 in which the filter material 134 is disposed in the light pipe cavity 124 and in which the intermediate layer 160, the light guide layer 162, the plurality of light pipe cavities 124 and the filter material 134 form a first filter stack 136.

[0130] The filter material 134 is disposed in the light pipe cavity 124 such that it is in direct contact with the light guide layer 162 at the sidewalls 130 of the light pipe cavity 124. Having the filter material 134 in direct contact with the light guide layer 162 at the sidewalls 130 of the light pipe cavity 124 ensures that a significant amount of the excitation light 156 is not accidentally transmitted between the filter material 134 and the light guide layer 162 to reach the photodetector 114 below.

[0131] The filter material 134 may be a dye-based polymer. The material 134 may be spin-coated or spray-coated into the light pipe cavity 124, dried and / or baked. Any excess filter material 134 may be planarized down to the level of the top surface 128 of the intermediate layer 160.

[0132] See also Fig.10 , depicting a manufacturing completion stage according to various aspects described herein Fig. 9 1 is a cross-sectional view of an example of an image sensor structure 200 in which a nanohole layer 146 having a plurality of nanoholes 148 is disposed above a first filter stack 136. All aspects of the image sensor structure 200 are substantially the same or similar to the aspects of the image sensor structure 100 discussed previously, except that a metal light guide layer 162 is disposed on the sidewalls 130 of the light pipe guide 124 and the intermediate layer 160 mechanically supports the light guide layer 162.

[0133] During operation, certain analytes 152 (such as clusters of DNA fragments, etc.) may be labeled with fluorescently labeled molecules 154 and these analytes may be disposed in the nanopore 148. Various types of excitation light 156 may then be radiated onto the analytes 152 in the nanopore 148, causing the labeled molecules 154 to emit fluorescent emission light 158. Most photons of the emission light 158 ​​may pass through the passivation stack 150 and enter its associated light pipe cavity 124. The light pipe cavity 124, together with its filter material 134, acts as a light guide that may filter out most of the excitation light 156 and direct a substantial portion of the emission light 158 ​​to an associated light detector 114 located directly below the light guide.

[0134] The light detector 114 detects the emitted light photons 158. The device circuitry 112 within the device stack 104 then processes and transmits a data signal based on those detected photons of the emitted light 158. The data signal may then be analyzed to reveal characteristics of the analyte 152.

[0135] The image sensor structure 200 is a backside illuminated (BSI) image sensor structure because the nanohole 148 is disposed on the back side of the image sensor structure 200 and because the device stack 104 is not disposed between the nanohole layer 146 and the plurality of photodetectors 114. Therefore, the nanohole 148 is illuminated by the excitation light 156 from the back side of the image sensor structure 200.

[0136] However, due to the location of the device stack 104, the device circuitry 112 may not be available to help reduce crosstalk of emission light photons 158 that are emitted from the nanopores 148 and arrive at unassociated light detectors 114. To compensate for the deficiency of the device stack 104, a light guiding layer 162 is disposed above the intermediate layer 160 and is utilized to block most of the emission light 158 ​​and excitation light 156 from being transmitted from one light pipe cavity 124 to another light pipe cavity.

[0137] Additionally, the light guide layer 162 is in direct contact with the filter material 134 at the sidewalls 130 of the light pipe cavity 124. Thus, little to no excitation light 156 can pass through the light pipe cavity 124 without passing through the filter material 134. The filter material 134 serves to block the excitation light 156 and pass the emission light 158 ​​through to the light detector 114.

[0138] The high aspect ratio H / W of the light pipe cavity 124 geometrically shapes the filter material 134 filling the cavity 124. Thus, the high aspect ratio of the light pipe cavity 124 helps provide the filter material 134 with a sufficient height H, which enables the filter material 134 to block a substantial portion of the excitation light 156 from passing through.

[0139] The high aspect ratio H / W of the light pipe cavity 124 also provides a significantly wider top width W relative to the bottom width W' of the light pipe cavity 124. Therefore, the light pipe cavity 124 can effectively collect the emission light 158 ​​even when the spacing between the light detectors 114 is as small as, for example, about 0.6 microns to 0.5 microns or less.

[0140] The high aspect ratio H / W of the light pipe cavity 124 can be as high as about 2.5:1, about 5:1, about 10:1, about 20:1, or more. In addition, the sidewall angle θ is small enough to allow for a high aspect ratio in the light pipe cavity 124, but not so large that the light pipe cavity is unreliable and / or too expensive to manufacture. The sidewall angle θ of the light pipe cavity 124 can be in the range of about 11 degrees to about 1.2 degrees, in the range of about 10 degrees to about 1.5 degrees, in the range of about 6 degrees to about 1.2 degrees, in the range of about 3 degrees to about 1.2 degrees, and in the range of about 3 degrees to about 1.5 degrees.

[0141] See also Fig.11, depicts a cross-sectional view of an example of an image sensor structure 300 at an intermediate stage of fabrication according to various aspects described herein. In structure 300, intermediate layer 166 is disposed above base layer 116 of image stack 102. Intermediate layer 166 and base layer 116 are composed of the same material. Intermediate layer 166 and base layer 116 may include or be silicon, silicon germanium, gallium arsenide, or other semiconductor materials.

[0142] During an early stage of manufacturing, combined layer 168 may be disposed above device stack 104 at a height that is at least as high as the height of combined image stack 102 and first filter stack 136. Combined layer 168 may then be planarized down to a predetermined height 170 that is substantially equal to the combined height of image stack 102 and first filter stack 136. At this stage of manufacturing, intermediate layer 166 constitutes an upper portion of combined layer 168 and base layer 116 constitutes a lower portion of combined layer 168.

[0143] A plurality of light pipe cavities 124 may be anisotropically etched into the intermediate layer 166. This may be done, for example, by a reactive ion etching process. Since the intermediate layer 166 is a semiconductor material, it is easier to etch to a high aspect ratio. However, the intermediate layer 166 is too transparent to act as a light guiding layer.

[0144] See also Fig.12 , i.e., at an intermediate stage of manufacturing according to the various aspects described herein Fig.11 3 is a cross-sectional view of an example of an image sensor structure 300 in which a metal light guide layer 172 is disposed on the sidewalls 130 of the light pipe cavity 124. Much like image sensor structure 200, metal light guide layer 172 is disposed on the sidewalls 130 of the light pipe cavity 124 because intermediate layer 166 is too transparent to act as a light guide layer.

[0145] The light guide layer 172 may include or be a metal, such as aluminum, gold, or copper. However, if the thickness of the metal light guide layer 172 between the light pipe cavities 124 is too large, the metal may absorb too much of the emitted light 158 ​​before it reaches the light detector 114. In order not to absorb too much of the emitted light 158, the thickness of the metal light guide layer 172 between the light pipe cavities 124 may be, for example, about 100 nanometers or less, about 50 nanometers or less, or about 40 nanometers or less.

[0146] The intermediate layer 166 is disposed over the image stack 102 and provides mechanical support for the relatively thin metal light guide layer 172. The light guide layer 172 is disposed over the intermediate layer 166 and on the sidewalls 130 of the light pipe cavity 124.

[0147] The metal light guide layer 172 may not be disposed on the bottom surface 174 of the light pipe cavity 124. This is because the metal light guide layer 162, even as thin as 100 nanometers or less, may reduce, and in some cases even prevent, a substantial portion of the emitted light 158 ​​from being transmitted into the image stack 102 if the image stack is disposed on the bottom surface 174 of the light pipe cavity 124.

[0148] The metal light guide layer 172 may be coated on the sidewalls 130 of the light pipe cavity 124 using, for example, a blank deposition process, atomic layer deposition, chemical plating, or electroplating. Any metal light guide layer 172 accidentally disposed on the bottom surface 174 of the light pipe cavity 124 may be removed by, for example, an anisotropic etching process such as a reactive ion etching process. The anisotropic etching process leaves the metal light guide layer 172 on the sidewalls 130 of the light pipe cavity 124.

[0149] See also Fig.13 , depicting a process for manufacturing an intermediate stage according to various aspects described herein Fig.12 1 is a cross-sectional view of an example of an image sensor structure 300 in which the filter material 134 is disposed in the light pipe cavity 124 and in which the intermediate layer 166, the light guide layer 172, the plurality of light pipe cavities 124, and the filter material 134 form a first filter stack 136.

[0150] The filter material 134 is disposed in the light pipe cavity 124 such that it is in direct contact with the light guide layer 172 at the sidewalls 130 of the light pipe cavity 124. Having the filter material 134 in direct contact with the light guide layer 172 at the sidewalls 130 of the light pipe cavity 124 ensures that a significant amount of the excitation light 156 is not accidentally transmitted between the filter material 134 and the light guide layer 172 to reach the photodetector 114 below.

[0151] The filter material 134 may be a dye-based polymer. The material 134 may be spin-coated or spray-coated into the light pipe cavity 124, dried and / or baked. Any excess filter material 134 may be planarized down to the level of the top surface 128 of the intermediate layer 166.

[0152] See also Fig.14 , depicting a manufacturing completion stage according to various aspects described herein Fig.13 1 is a cross-sectional view of an example of an image sensor structure 300 in which a nanopore layer 146 having a plurality of nanopores 148 is disposed above a first filter stack 136. All aspects of the image sensor structure 300 are substantially the same or similar to aspects of the image sensor structure 200 discussed previously, except that the intermediate layer 166 and the base layer 116 are the same material.

[0153] During operation, certain analytes 152 (such as clusters of DNA fragments, etc.) may be labeled with fluorescently labeled molecules 154 and these analytes may be disposed in the nanopore 148. Various types of excitation light 156 may then be radiated onto the analytes 152 in the nanopore 148, causing the labeled molecules 154 to emit fluorescent emission light 158. Most photons of the emission light 158 ​​may pass through the passivation stack 150 and enter its associated light pipe cavity 124. The light pipe cavity 124, together with its filter material 134, acts as a light guide that may filter out most of the excitation light 156 and direct a substantial portion of the emission light 158 ​​to an associated light detector 114 located directly below the light guide.

[0154] The light detector 114 detects the emitted light photons 158. The device circuitry 112 within the device stack 104 then processes and transmits a data signal based on those detected photons of the emitted light 158. The data signal may then be analyzed to reveal characteristics of the analyte 152.

[0155] Image sensor structure 300 is a backside illuminated (BSI) image sensor structure because nanohole 148 is disposed on the back side of image sensor structure 300 and because device stack 104 is not disposed between nanohole layer 146 and plurality of photodetectors 114. Thus, nanohole 148 is illuminated by excitation light 156 from the back side of image sensor structure 300.

[0156] However, due to the location of the device stack 104, the device circuitry 112 may not be available to help reduce crosstalk of emission light photons 158 that are emitted from the nanopores 148 and arrive at unassociated light detectors 114. To compensate for the deficiency of the device stack 104, a light guiding layer 172 is disposed above the intermediate layer 166 and is utilized to block most of the emission light 158 ​​and excitation light 156 from being transmitted from one light pipe cavity 124 to another light pipe cavity.

[0157] Additionally, the light guide layer 172 is in direct contact with the filter material 134 at the sidewalls 130 of the light pipe cavity 124. Thus, little to no excitation light 156 can pass through the light pipe cavity 124 without passing through the filter material 134. The filter material 134 serves to block the excitation light 156 and pass the emission light 158 ​​through to the light detector 114.

[0158] The high aspect ratio H / W of the light pipe cavity 124 geometrically shapes the filter material 134 filling the cavity 124. Thus, the high aspect ratio of the light pipe cavity 124 helps provide the filter material 134 with a sufficient height H, which enables the filter material 134 to block a substantial portion of the excitation light 156 from passing through.

[0159] The high aspect ratio H / W of the light pipe cavity 124 also provides a significantly wider top width W relative to the bottom width W' of the light pipe cavity 124. Therefore, the light pipe cavity 124 can effectively collect the emission light 158 ​​even when the spacing between the light detectors 114 is as small as, for example, about 0.6 microns to 0.5 microns or less.

[0160] The high aspect ratio H / W of the light pipe cavity 124 can be as high as about 2.5:1, about 5:1, about 10:1, about 20:1, or more. In addition, the sidewall angle θ is small enough to allow for a high aspect ratio in the light pipe cavity 124, but not so large that the light pipe cavity is unreliable and / or too expensive to manufacture. The sidewall angle θ of the light pipe cavity 124 can be in the range of about 11 degrees to about 1.2 degrees, in the range of about 10 degrees to about 1.5 degrees, in the range of about 6 degrees to about 1.2 degrees, in the range of about 3 degrees to about 1.2 degrees, and in the range of about 3 degrees to about 1.5 degrees.

[0161] See also Fig.15 , depicts a cross-sectional view of another example of an image sensor structure 400 at a completed stage of fabrication in accordance with aspects described herein. Image sensor structure 400 is similar to image sensor structure 200, except that crosstalk blocking layer 180 and diffusion layer 182 are added.

[0162] A crosstalk layer 180 can be disposed over the top surface of the filter stack 136 and between one or more light pipe cavities 124. The crosstalk layer 180 helps reduce crosstalk between the light pipe cavities 124.

[0163] The crosstalk layer 180 may be made of a metal material. The crosstalk layer 180 may be made of W, Al, AlSi, Cu or Ta. The crosstalk layer material may include a metal material capable of forming a CMOS material. The thickness of the layer 180 may be in the range of about 20 nm to 150 nm.

[0164] Although the crosstalk layer 180 is shown in this example of the image sensor structure 400, the crosstalk layer 180 may also be used in other image sensor structures. For example, the crosstalk layer 180 may be used in the image sensor structures 100, 200, 300, or 500 (see Fig.16 ) in any example.

[0165] A diffuser layer 182 may be disposed between the filter stack 136 and the image stack 102. The diffuser layer 182 may serve as a diffusion barrier. The diffuser layer 182 may be used to reduce free ion flow from the filter material 134 or from other impurities such as packaging or moisture. The diffuser layer 182 may also serve as a planarization layer to planarize the surface of the base layer 116.

[0166] The diffusion layer 182 may be made of a dielectric metal oxide material or a nitride material. The diffusion layer 182 may be made of, for example, SiO2, TaO x The diffusion layer 182 may have a thickness in the range of about 50 nm to about 350 nm.

[0167] Although the diffuser layer 182 is shown in this example of the image sensor structure 400, the diffuser layer 182 may also be used in other image sensor structures. For example, the diffuser layer 182 may be used in the image sensor structures 100, 200, 300, or 500 (see Fig.16 ) in any example.

[0168] See also Fig.16 , depicts a cross-sectional view of another example of an image sensor structure 500 at a completed stage of fabrication in accordance with various aspects described herein. Image sensor structure 500 differs from prior image sensor structures 100 - 400 primarily in its filter stack 136 .

[0169] In the filter stack 136 of the image sensor structure 500, the light guide layer 184 is composed of an optically absorbing material. The optically absorbing material can be, for example, the same material as the filter material 134 used to fill the light pipe cavity 124 in the image sensor structures 100-400. The optically absorbing material can have a refractive index in a range of, for example, between about 1.5 and 1.8.

[0170] The filter material 184 may include or be, for example, a dye-polymer blend, wherein the dye may have low fluorescence. For example, the dye may include or be a member of the class of metallized azo dye complexes, such as an ornitro orange dye, an ornitro yellow dye, a solvent yellow dye, a solvent orange dye, or a solvent red dye. The polymer may include or be, for example, cellulose acetate butyrate.

[0171] Furthermore, unlike the previous image sensor structures 100-400 having the filter material 134 disposed in the light pipe cavity 124 thereof, an optically transparent material 186 is disposed in the light pipe cavity 124 of the image sensor structure 500. The transparent material 186 may be composed of, for example, tantalum pentoxide (Ta2O5), titanium dioxide (TiO2), or silicon nitride (SiN).

[0172] The optically transparent material 186 has a refractive index greater than the refractive index of the optically absorptive material 184. The refractive index of the transparent material 186 may have a refractive index in a range between approximately 1.8 to 2.7.

[0173] The difference in refractive index between the optically absorbing material constituting the light guide layer 184 and the optically transparent material 186 disposed in the light pipe cavity 124 significantly reduces crosstalk between the light pipe cavities 124 and helps guide the emission light 158 ​​through the light pipe cavity and onto the light detector 114 in the image stack 102. At the same time, the optically absorbing material absorbs a major portion of the excitation light 156 and serves to significantly reduce or prevent the excitation light 156 from reaching the light detector 114.

[0174] The greater the ratio of the height H of the light pipe cavity 124 to the maximum width W of the light pipe cavity (i.e., the actual aspect ratio AR of the light pipe cavity), the greater the amount of excitation light 156 that can be absorbed by the optically absorbing material in the light guide layer 184. Therefore, the aspect ratio can be higher. For example, the aspect ratio of the light pipe cavity can be about 2.5:1 or greater, 5:1 or greater, 10:1 or greater, 15:1 or greater, or 20:1 or greater in order to optimize the absorption of the excitation light 156.

[0175] However, as previously discussed herein, the sidewall angle θ can be within a range that enables reasonable manufacture of the light pipe cavity. For example, the sidewall angle can be within a range of about 1.2 degrees to about 11 degrees, about 1.2 degrees to about 6 degrees, about 1.2 degrees to about 3 degrees, about 1.5 degrees to about 11 degrees, about 1.5 degrees to about 6 degrees, or about 1.5 degrees to about 3 degrees.

[0176] Furthermore, it is important that the optically absorptive material comprising the light guide layer 184 is in direct contact with the optically transparent material 186 disposed in the light guide cavity 124 at the sidewalls 130 of the light guide cavity. Due to the direct contact, the difference in refractive index between the adjacent optically absorptive material and the optically transparent material 186 helps to direct the emitted light 158 ​​downward to the light detector 114. Additionally, because the optically absorptive material and the optically transparent material are in direct contact, less of the excitation light 156 can radiate between the two materials and accidentally reach the light detector 114.

[0177] The filter stack 136 also includes a metal crosstalk curtain 188 disposed in the light guide layer 184 between the light pipe cavities 124. The crosstalk curtain 188 extends downwardly from the top surface of the filter stack 136 into the light guide layer 184. The crosstalk curtain 188 serves to further reduce crosstalk between the light pipe cavities 124. The crosstalk curtain 188 may cooperate with the crosstalk layer 180 to help reduce any crosstalk between the light pipe cavities 124 to an insignificant level.

[0178] Additionally, like the crosstalk layer 180, the crosstalk curtain 188 may also be used on any image sensor structure. For example, the crosstalk curtain may be used on the image sensor structures 100-400.

[0179] The crosstalk curtain 188 may be made of a metal material. For example, the crosstalk curtain 188 may be made of W, Al, AlSi, Cu, Ta, or other CMOS compatible metals.

[0180] Although crosstalk curtain 188 is shown in this example of image sensor structure 500 , crosstalk curtain 188 may also be used in other image sensor structures. For example, crosstalk curtain 188 may be used in any of the examples of image sensor structures 100 , 200 , 300 , or 400 .

[0181] The filter stack 136 of the image sensor structure 500 may also include a light pipe extension 190, which may be disposed at the bottom of the light pipe cavity 124 and may penetrate the diffuser layer 182. The light pipe extension 190 may be composed of a nitride such as silicon nitride (SiN) having a refractive index between approximately 1.7 and 2.1.

[0182] The light pipe extension 190 has a refractive index greater than that of the diffuser layer 182. For example, the diffuser layer 182 may be composed of SiO2 having a refractive index between about 1.4 and 1.55. If so, a light pipe extension 190 comprising silicon nitride (SiN) may be appropriate because SiN has a refractive index between about 1.7 and 2.1. The greater refractive index of the light pipe extension 190 than that of the diffuser layer 182 helps to better focus the emitted light 158 ​​onto the light detector 114 than if the emitted light passed through the diffuser layer 182 instead of the light pipe extension 190.

[0183] Although light pipe extension 190 is shown in this example of image sensor structure 500 , light pipe extension 190 may also be used in other image sensor structures. For example, light pipe extension 190 may be used in any of the examples of image sensor structures 100 , 200 , 300 , or 400 .

[0184] It should be understood that all combinations of the foregoing concepts and additional concepts discussed in greater detail herein (assuming such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein and are intended to achieve the benefits and advantages as described herein. In particular, all combinations of the claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein.

[0185] Although the present invention has been described by reference to particular examples, it should be understood that many changes may be made within the spirit and scope of the inventive concepts described. It is therefore intended that the present disclosure not be limited to the examples described, but rather that it has the full scope defined by the language of the following claims.

Claims

1. An image sensor structure, comprising: an image stack disposed above the device stack, the image stack comprising a plurality of light detectors; A first filter stack disposed above the image stack, the first filter stack comprising: Photoconductive layer; light pipe cavities disposed in the light guiding layer, each light pipe cavity being associated with a light detector of the plurality of light detectors and each light pipe cavity having an aspect ratio greater than 2.5:1; and a nanoporous layer disposed above the first filter stack; an intermediate layer disposed above the image stack; and The light guide layer is disposed above the intermediate layer; and A plurality of nanoholes are disposed in the nanohole layer, each nanohole being associated with a photodetector in the plurality of photodetectors, wherein the light guide layer is a metal layer disposed on the sidewalls of the light pipe cavity and not disposed on the bottom surface of the light pipe cavity. 2 . The image sensor structure of claim 1 , wherein the light pipe cavity has a side wall angle in the range of 11 degrees to 1.2 degrees. 3 . The image sensor structure of claim 1 , comprising a filter material disposed in the light pipe cavity, the filter material being in direct contact with the light guide layer at a sidewall of the light pipe cavity.

4. The image sensor structure according to claim 1, comprising: a second filter stack disposed above the first filter stack; Wherein the first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack. 5 . The image sensor structure of claim 1 , wherein the photoconductive layer is composed of one of a polymer material, a semiconductor material, and a dielectric material.

6. The image sensor structure of claim 1, wherein the photoconductive layer of the first filter stack has a thickness of 100 nanometers or less.

7. The image sensor structure of claim 6, wherein the image stack comprises: A substrate layer disposed above the plurality of light detectors, the substrate layer being used to transmit the emission light and the excitation light; a plurality of isolation trenches disposed in the base layer, each isolation trench disposed adjacent to a photodetector of the plurality of photodetectors; as well as A dielectric material is disposed in each isolation trench, the dielectric material being used to electrically isolate each of the plurality of photodetectors.

8. The image sensor structure of claim 7, wherein the intermediate layer disposed in the first filter stack and the base layer of the image stack are made of the same material.

9. The image sensor structure of claim 8, wherein the intermediate layer and the base layer are made of silicon.

10. The image sensor structure according to claim 1, comprising: said light-guiding layer being composed of an optically absorbing material; as well as An optically transparent material is disposed in the light pipe cavity, the optically transparent material having a refractive index greater than a refractive index of the optically absorptive material.

11. The image sensor structure according to claim 1, comprising: a crosstalk layer disposed over a top surface of the filter stack and between one or more of the light pipe cavities; a crosstalk curtain extending downwardly from the top surface of the filter stack between one or more of the light pipe cavities; a diffuser layer disposed between the filter stack and the image stack; as well as A light pipe extension is disposed at a bottom of one or more of the light pipe cavities, the light pipe extension extending through the diffusion layer.

12. The image sensor structure of any one of claims 3 to 11, wherein the light pipe cavity has a side wall angle in the range of 11 degrees to 1.2 degrees.

13. The image sensor structure according to any one of claims 4 to 11, comprising a filter material disposed in the light pipe cavity, the filter material being in direct contact with the light guide layer at a side wall of the light pipe cavity.

14. The image sensor structure according to any one of claims 5 to 11, comprising: a second filter stack disposed above the first filter stack; Wherein the first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

15. The image sensor structure according to any one of claims 6 to 11, wherein the photoconductive layer is composed of one of a polymer material, a semiconductor material and a dielectric material.

16. The image sensor structure of claim 7, wherein the intermediate layer and the base layer are composed of silicon.

17. The image sensor structure according to claim 11, comprising: said light-guiding layer being composed of an optically absorbing material; as well as An optically transparent material is disposed in the light pipe cavity, the optically transparent material having a refractive index greater than a refractive index of the optically absorptive material.

18. The image sensor structure according to any one of claims 6 to 9, comprising: a crosstalk layer disposed over a top surface of the filter stack and between one or more of the light pipe cavities; a crosstalk curtain extending downwardly from the top surface of the filter stack between one or more of the light pipe cavities; a diffuser layer disposed between the filter stack and the image stack; as well as A light pipe extension is disposed at a bottom of one or more of the light pipe cavities, the light pipe extension extending through the diffusion layer.

19. An image sensor structure, comprising: an image stack disposed above the device stack, the image stack comprising a plurality of light detectors; A first filter stack disposed above the image stack, the first filter stack comprising: Light guide layer, a light pipe cavity disposed in the light guiding layer, each light pipe cavity being associated with a light detector of the plurality of light detectors, and a filter material disposed in the light pipe cavity, the filter material being in direct contact with the light guide layer at a side wall of the light pipe cavity; a nanoporous layer disposed above the first filter stack; an intermediate layer disposed above the image stack; and The light guide layer is disposed above the intermediate layer; and A plurality of nanoholes are disposed in the nanohole layer, each nanohole being associated with a photodetector in the plurality of photodetectors, wherein the light guide layer is a metal layer disposed on the sidewalls of the light pipe cavity and not disposed on a bottom surface of the light pipe cavity.

20. The image sensor structure of claim 19, wherein the light pipe cavity has an aspect ratio greater than 2.5:

1.

21. The image sensor structure of claim 20, wherein the light pipe cavity has a side wall angle in the range of 11 degrees to 1.2 degrees.

22. The image sensor structure of claim 19, wherein the photoconductive layer comprises one of a polymer material, a semiconductor material, and a dielectric material.

23. The image sensor structure according to claim 19, Wherein the light guiding layer of the first filter stack has a thickness of 100 nanometers or less.

24. The image sensor structure of claim 23, wherein the image stack comprises: A substrate layer disposed above the plurality of light detectors, the substrate layer being used to transmit the emission light and the excitation light; a plurality of isolation trenches disposed in the base layer, each isolation trench disposed adjacent to a photodetector of the plurality of photodetectors; as well as A dielectric material is disposed in each isolation trench, the dielectric material being used to electrically isolate each of the plurality of photodetectors.

25. The image sensor structure of claim 24, wherein the intermediate layer disposed in the first filter stack and the base layer disposed in the image stack are composed of the same material.

26. The image sensor structure according to claim 19, comprising: a second filter stack disposed above the first filter stack; Wherein the first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

27. The image sensor structure according to claim 19, comprising: a crosstalk layer disposed over a top surface of the filter stack and between one or more of the light pipe cavities; a crosstalk curtain extending downwardly from the top surface of the filter stack between one or more of the light pipe cavities; a diffuser layer disposed between the filter stack and the image stack; as well as A light pipe extension is disposed at a bottom of one or more of the light pipe cavities, the light pipe extension extending through the diffusion layer.

28. The image sensor structure of any one of claims 21 to 27, wherein the light pipe cavity has an aspect ratio greater than 2.5:

1.

29. The image sensor structure of any one of claims 22 to 27, wherein the light pipe cavity has a side wall angle in the range of 11 degrees to 1.2 degrees.

30. The image sensor structure of any one of claims 26 or 27, wherein the photoconductive layer comprises one of a polymer material, a semiconductor material, and a dielectric material.

31. The image sensor structure of any one of claims 26 or 27, wherein the first filter stack comprises: an intermediate layer disposed above the image stack; as well as the light-guiding layer disposed above the intermediate layer; wherein the light guide layer is a metal layer disposed on the side wall of the light pipe cavity and not disposed on the bottom surface of the light pipe cavity; and Wherein the photoconductive layer has a thickness of 100 nanometers or less.

32. The image sensor structure of any one of claims 22 to 23, 26 or 27, wherein the image stack comprises: A substrate layer disposed above the plurality of light detectors, the substrate layer being used to transmit the emission light and the excitation light; a plurality of isolation trenches disposed in the base layer, each isolation trench disposed adjacent to a photodetector of the plurality of photodetectors; as well as A dielectric material is disposed in each isolation trench, the dielectric material being used to electrically isolate each of the plurality of photodetectors.

33. The image sensor structure according to any one of claims 25 or 27, comprising: a second filter stack disposed above the first filter stack; Wherein the first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

34. The image sensor structure according to claim 25, comprising: a crosstalk layer disposed over a top surface of the filter stack and between one or more of the light pipe cavities; a crosstalk curtain extending downwardly from the top surface of the filter stack between one or more of the light pipe cavities; a diffuser layer disposed between the filter stack and the image stack; as well as A light pipe extension is disposed at a bottom of one or more of the light pipe cavities, the light pipe extension extending through the diffusion layer.

35. An image sensor structure, the image sensor structure comprising: an image stack disposed above the device stack, the image stack comprising a plurality of light detectors; A first filter stack disposed above the image stack, the first filter stack comprising: a light-guiding layer composed of an optically absorbing material, a light pipe cavity disposed in the light guiding layer, each light pipe cavity being associated with a light detector of the plurality of light detectors, and an optically transparent material disposed in the light pipe cavity, the optically transparent material having a refractive index greater than a refractive index of the optically absorbing material; a nanoporous layer disposed above the first filter stack; and A plurality of nanopores is disposed in the nanopore layer, each nanopore being associated with a photodetector of the plurality of photodetectors.

36. The image sensor structure of claim 35, wherein the light pipe cavity has a sidewall angle in the range of 11 degrees to 1.2 degrees and an aspect ratio greater than 2.5:

1.

37. The image sensor structure of claim 35, wherein the optically absorptive material is in direct contact with the optically transparent material at the sidewalls of the light pipe cavity.

38. The image sensor structure according to claim 35, comprising: a crosstalk layer disposed over a top surface of the filter stack and between one or more of the light pipe cavities; a crosstalk curtain extending downwardly from the top surface of the filter stack between one or more of the light pipe cavities; a diffuser layer disposed between the filter stack and the image stack; as well as A light pipe extension is disposed at a bottom of one or more of the light pipe cavities, the light pipe extension extending through the diffusion layer.

39. The image sensor structure of any one of claims 37 or 38, wherein the light pipe cavity has a side wall angle in the range of 11 degrees to 1.2 degrees and an aspect ratio greater than 2.5:

1.

40. The image sensor structure of any one of claims 36 or 38, wherein the optically absorptive material is in direct contact with the optically transparent material at the sidewalls of the light pipe cavity.

41. The image sensor structure according to any one of claims 36 or 37, comprising: a crosstalk layer disposed over a top surface of the filter stack and between one or more of the light pipe cavities; a crosstalk curtain extending downwardly from the top surface of the filter stack between one or more of the light pipe cavities; a diffuser layer disposed between the filter stack and the image stack; as well as A light pipe extension is disposed at a bottom of one or more of the light pipe cavities, the light pipe extension extending through the diffusion layer.

42. The image sensor structure of claim 35, wherein the optically transparent material disposed in the light pipe cavity is in direct contact with the light guide layer at a sidewall of the light pipe cavity.

43. The image sensor structure according to claim 35, comprising: a second filter stack disposed above the first filter stack; Wherein the first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

44. A method of forming an image sensor structure, the method comprising: disposing an image stack above the device stack, the image stack comprising a plurality of light detectors; disposing a light-guiding layer over the image stack; etching a plurality of light pipe cavities in the light guide layer, each light pipe cavity being associated with a light detector of the plurality of light detectors, the light pipe cavities having an aspect ratio greater than 2.5:1 and a sidewall angle in a range of 11 degrees to 1.2 degrees; disposing a nanoporous layer above the light-guiding layer; as well as disposing a plurality of nanopores in the nanopore layer, each nanopore being associated with a photodetector of the plurality of photodetectors; wherein the light guide layer and the plurality of light guide cavities include a first filter stack disposed above the image stack; disposing an intermediate layer above the image stack; as well as Disposing the light-guiding layer above the intermediate layer; The light guide layer is a metal layer disposed on the side wall of the light pipe cavity and not disposed on the bottom surface of the light pipe cavity.

45. The method according to claim 44, Wherein the photoconductive layer has a thickness of 100 nanometers or less.

46. ​​The method of claim 44, comprising: A filter material is disposed in the light pipe cavity, the filter material being in direct contact with the light guide layer at a side wall of the light pipe cavity.

47. The method of claim 44, comprising: placing a second filter stack above the first filter stack; Wherein the first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

48. The method of claim 44, comprising: wherein the light-guiding layer is composed of an optically absorbing material; as well as An optically transparent material is disposed in the light pipe cavity, the optically transparent material having a refractive index greater than a refractive index of the optically absorptive material.

49. A method according to any one of claims 46 to 48, comprising: disposing an intermediate layer above the image stack; as well as Disposing the light-guiding layer above the intermediate layer; wherein the light guide layer is a metal layer disposed on the side wall of the light pipe cavity and not disposed on the bottom surface of the light pipe cavity; and Wherein the photoconductive layer has a thickness of 100 nanometers or less.

50. The method of any one of claims 45, 47 or 48, comprising: A filter material is disposed in the light pipe cavity, the filter material being in direct contact with the light guide layer at a side wall of the light pipe cavity.

51. The method of any one of claims 45, 46 or 48, comprising: placing a second filter stack above the first filter stack; Wherein the first filter stack and the second filter stack have an overall aspect ratio greater than either of the first filter stack and the second filter stack.

52. A method according to any one of claims 45 to 47, comprising: wherein the light-guiding layer is composed of an optically absorbing material; as well as An optically transparent material is disposed in the light pipe cavity, the optically transparent material having a refractive index greater than a refractive index of the optically absorptive material.

Images