Single-chip multispectral image sensor with perovskite

Abstract

An integrated circuit (IC) structure includes a multispectral image sensor structure including a first electrode layer; a second electrode layer; and a plurality of optical sensing elements arranged in a single layer disposed between the first electrode layer and the second electrode layer, wherein each of the plurality of optical sensing elements comprises a perovskite material, and two or more optical sensing elements of the plurality of optical sensing elements comprise different perovskite materials.

Description

Atty. Docket No. 4502-90600 (6000789PCT01)Single-Chip Multispectral Image Sensor with PerovskiteTECHNICAL FIELD

[0001] The present disclosure is generally related to semiconductor structures and electronics and, in particular embodiments, to multispectral image sensors for electronic devices.BACKGROUND

[0002] Multispectral imaging is a technique that captures and analyzes image data across multiple specific wavelength bands within the electromagnetic spectrum, for example, spanning the visible light range into the near-infrared and the short-wave infrared regions. Unlike conventional red-blue-green (RGB) sensors or cameras that only capture three broad color channels (red, blue, and green), multispectral image sensors may acquire image data in four or more narrow spectral bands, enabling the detection of subtle differences in the absorption, reflectiveness, patterns, and / or compositions of materials that are invisible to the human eye. Multispectral imaging has a wide range of applications, including geographic surveying, environmental monitoring, agricultural analysis, water quality analysis, medical imaging, remote sensing, industry quality control, security inspection, and scientific research. Multispectral imaging can enable enhanced data analysis and the extraction of insights beyond conventional imaging methods. Accordingly, improvements to techniques for fabricating a multispectral image sensor may be desirable.SUMMARY

[0003] The disclosed aspects / embodiments of the present disclosure provide systems and / or devices that include multispectral image sensors. More specifically, a multispectral image sensor includes an array of optical sensing elements arranged in a single layer, where two or more of the optical sensing elements in the array are formed from different semiconductor materials to provide optical sensing in different spectral bands (e.g., visible band, infrared (IR) band, ultra-violet (UV) band, X-ray band, etc.). The optical sensing elements can include perovskite materials, quantum dot (QD) materials, organic materials, and / or two-dimensional (2D) semiconductor materials. The array of optical sensing elements is fabricated using lithography and spin-coating processes that are compatible with complementary metal-oxide-semiconductor (CMOS) processes. The multispectral perovskite image sensor further provides per pixel readout by disposing the array ofAtty. Docket No. 4502-90600 (6000789PCT01)optical sensing elements between a common transparent electrode and an array of metal electrode pads, where each optical sensing element is coupled to a pixel readout circuit via a respective metal electrode pad. The transparent electrode, the array of perovskite sensing elements, the metal electrode pads, and the pixel readout circuits are integrated on a single semiconductor wafer. The disclosed multispectral image sensor can provide simultaneous high-resolution, multispectral band imaging.

[0004] A first aspect of the embodiments of the present disclosure relates to an integrated circuit (IC) structure comprising a multispectral image sensor structure. The multispectral image sensor structure comprises a first electrode layer; a second electrode layer; and a plurality of optical sensing elements arranged in a single layer disposed between the first electrode layer and the second electrode layer, wherein each of the plurality of optical sensing elements comprises a perovskite material, and two or more optical sensing elements of the plurality of optical sensing elements comprise different perovskite materials.

[0005] Optionally, in any of the preceding aspects, another implementation of the aspect provides that a first optical sensing element of the plurality of optical sensing elements comprises a first perovskite material that absorbs at least a portion of an optical signal in a first wavelength band, and a second optical sensing element of the plurality of optical sensing elements comprises a second perovskite material that absorbs at least a portion of an optical signal in a second wavelength band different than the first wavelength band.

[0006] Optionally, in any of the preceding aspects, another implementation of the aspect provides that a first optical sensing element of the plurality of optical sensing elements comprises a first perovskite material having a first bandgap voltage, and a second optical sensing element of the plurality of optical sensing elements comprises a second perovskite material having a second bandgap voltage different than the first bandgap voltage.

[0007] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first electrode layer comprises a transparent conductive material.

[0008] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the multispectral image sensor structure further comprises an isolation layer disposed between the first electrode layer and the plurality of optical sensing elements, the isolation layer comprising a non-conductive material.Atty. Docket No. 4502-90600 (6000789PCT01)

[0009] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the second electrode layer comprises a plurality of electrode elements spaced apart from one another, each comprising a conductive metal material.

[0010] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the multispectral image sensor structure further comprises a plurality of readout integrated circuits (ICs), each coupled to a respective one of the plurality of optical sensing elements via a respective one of the plurality of electrode elements.

[0011] Optionally, in any of the preceding aspects, another implementation of the aspect provides that one of the plurality of readout ICs is configured to generate a signal corresponding to an intensity of an incident optical signal within a wavelength band associated with a respective one of the plurality of optical sensing elements, based on a voltage applied to the first electrode layer.

[0012] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the plurality of readout ICs comprises at least one of a voltage-mode readout IC or a current-mode readout IC.

[0013] Optionally, in any of the preceding aspects, another implementation of the aspect provides that a pitch between a pair of adjacent optical sensing elements of the plurality of optical sensing elements is less than 100 nanometers (nm).

[0014] Optionally, in any of the preceding aspects, another implementation of the aspect provides that a thickness of a first optical sensing element of the plurality of optical sensing elements is between 10 nanometers (nm) and 4000 nm.

[0015] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first electrode layer, the plurality of optical sensing elements, and the second electrode layer are disposed on a common semiconductor substrate.

[0016] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the common semiconductor substrate is a complementary metal-oxide-semiconductor (CMOS) substrate.

[0017] A second aspect of the embodiments of the present disclosure relates to a multispectral image sensor device, comprising a semiconductor die; and an array of optical sensing elements arranged in a single layer on the semiconductor die, wherein at least a first optical sensing element of the array of optical sensing elements comprises a first semiconductor material that absorbs atAtty. Docket No. 4502-90600 (6000789PCT01)least a portion of an optical signal within a visible wavelength band, and a second optical sensing element of the array of optical sensing elements comprises a second semiconductor material that absorbs at least a portion of an optical signal within a non-visible wavelength band.

[0018] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the non-visible wavelength band comprises at least one of an X-ray band, an ultraviolet (UV) wavelength band, or an infrared (IR) wavelength band.

[0019] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the non-visible wavelength band comprises at least two of an X-ray band, an ultraviolet (UV) wavelength band, or an infrared (IR) wavelength band.

[0020] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first semiconductor material and the second semiconductor material comprise different perovskite materials.

[0021] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first semiconductor material and the second semiconductor material comprise different quantum dot materials.

[0022] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first semiconductor material and the second semiconductor material comprise different two-dimensional (2D) semiconductor materials.

[0023] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the multispectral image sensor device further comprises a first electrode layer comprising a transparent conductive material; and a second electrode layer comprising a plurality of electrode elements comprising a conductive metal material, wherein the array of optical sensing elements is disposed between the first electrode layer and the second electrode layer.

[0024] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the multispectral image sensor device further comprises a plurality of readout integrated circuits (ICs) formed on the same semiconductor die, wherein each readout IC is electrically coupled to a respective optical sensing element of the array of optical sensing elements via a respective one of the plurality of electrode elements.

[0025] Optionally, in any of the preceding aspects, another implementation of the aspect provides that an individual one of the plurality of readout ICs is configured to generate a signal corresponding to an intensity of a portion of the optical signal within a wavelength band associatedAtty. Docket No. 4502-90600 (6000789PCT01)with a respective optical sensing element of the array of optical sensing elements, based on a voltage applied to the first electrode layer.

[0026] A third aspect of the embodiments of the present disclosure relates to a method of fabricating a multispectral perovskite image sensor. The method includes providing a semiconductor substrate comprising a plurality of electrode elements spaced apart from each other on a surface of the semiconductor substrate; forming a first photoresist pattern over the semiconductor substrate and the plurality of electrode elements, wherein the first photoresist pattern comprises first openings exposing a first set of electrode elements; forming a first semiconductor material over the first photoresist pattern and within the first openings; removing the first photoresist pattern and the first semiconductor material over the first photoresist pattern yet retaining the first semiconductor material from within the respective first openings to provide a first structure; forming a second photoresist pattern over the first structure, wherein the second photoresist pattern comprises second openings exposing a second set of electrode elements; forming a second semiconductor material over the second photoresist pattern and within the second openings; and removing the second photoresist pattern and the second semiconductor material over the second photoresist pattern yet retaining the second semiconductor material from within the respective second openings to provide a second structure.

[0027] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first semiconductor material comprises a perovskite crystal structure that absorbs at least a portion of a first optical signal in a first wavelength band, and the second semiconductor material comprises a perovskite crystal structure that absorbs at least a portion of a second optical signal in a second wavelength band different than the first wavelength band.

[0028] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first and second semiconductor materials comprise different quantum dot (QD) materials.

[0029] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first and second semiconductor materials comprise different organic semiconductor materials.

[0030] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the first and second semiconductor materials comprise different two-dimensional (2D) semiconductor materials.Atty. Docket No. 4502-90600 (6000789PCT01)

[0031] Optionally, in any of the preceding aspects, another implementation of the aspect provides that at least one of the forming the first semiconductor material over the first photoresist pattern and within the first openings or forming the second semiconductor material over the second photoresist pattern and within the second openings comprises a spin-coat process.

[0032] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the plurality of electrode elements comprise conductive metal material.

[0033] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the method further includes adding an isolation layer over the second structure, the isolation layer comprising a non-conductive material.

[0034] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the method further includes adding a transparent electrode layer over the isolation layer, the transparent electrode layer comprising a transparent conductive material.

[0035] For the purpose of clarity, any one of the foregoing embodiments may be combined with any one or more of the other foregoing embodiments to create a new embodiment within the scope of the present disclosure.

[0036] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a more complete understanding of this disclosure, reference is now made to the following brief description, which should be taken in connection with the accompanying drawings and detailed description for a more complete understanding, like reference numerals represent like parts throughout the drawings and specification.

[0038] FIG. 1 illustrates a side cross-sectional view of a multispectral image sensor structure according to an embodiment of the present disclosure.

[0039] FIG. 2 illustrates a perspective view of a multispectral image sensor structure according to an embodiment of the present disclosure.

[0040] FIG. 3 illustrates a side cross-sectional view of a multispectral image sensor structure including pixel readout circuits according to an embodiment of the present disclosure.

[0041] FIG. 4 illustrates an example pixel voltage-mode readout circuit according to an embodiment of the present disclosure.Atty. Docket No. 4502-90600 (6000789PCT01)

[0042] FIG. 5 illustrates an example pixel current-mode readout circuit according to an embodiment of the present disclosure.

[0043] FIGS. 6A and 6B are block diagrams illustrating an example method of fabricating a multispectral image sensor on a single semiconductor wafer according to an embodiment of the present disclosure.

[0044] FIG. 7 is a block diagram of an electronic device including a multispectral image sensor according to an embodiment of the present disclosure.

[0045] FIG. 8 is a flowchart of an example method of providing a multispectral perovskite image sensor structure according to an embodiment of the present disclosure.DETAILED DESCRIPTION

[0046] It should be understood at the outset that although an illustrative implementation of one or more embodiments is provided below, the disclosed systems and / or methods may be implemented using any number of techniques, whether currently known or later developed. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0047] The following terms are defined as follows unless used in a contrary context herein. Specifically, the following definitions are intended to provide additional clarity to the present disclosure. However, terms may be described differently in different contexts. Accordingly, the following definitions should be considered as a supplement and should not be considered to limit any other definitions of descriptions provided for such terms herein.

[0048] The digital image processing technology market is experiencing significant growth, driven by the increasing adoption of computer vision, artificial intelligence (Al), and machine learning across various industries. One type of image sensor that is commonly used in electronic devices is complementary metal-oxide-semiconductor (CMOS) image sensors. In a CMOS image sensor, the light-sensing semiconductor material that converts light (e.g., photons) into electrical charge (e.g., electrons) may be made of silicon. While CMOS technology offers advantages such as low power consumption, high integration capability, and scalability, integrating multispectral functionality directly onto CMOS platforms present various challenges. For instance, silicon is effective for visible light detection (from approximately 400 nanometers (nm) to 700 nm), butAtty. Docket No. 4502-90600 (6000789PCT01)imaging other wavelengths, such as infrared (IR), relies on other sensor materials, such as germanium and / or III-V semiconductor materials. These other materials may involve dedicated fabrication processes. As such, it may be difficult to integrate these other sensor materials together with the silicon sensor material onto the same semiconductor die in an effective way. In one approach, multiple sensor arrays for sensing in different spectral bands are formed on separate semiconductor wafers and stacked to provide a multispectral image sensor. Other approaches may use complex optical filtering (e.g., by adjusting the thickness of the filters to control the filter center wavelengths) in conjunction with silicon-based sensors to enable multispectral imaging, often involving trade-offs among pixel-size, sensitivity, and spectral resolution.

[0049] Recent studies show that perovskite materials have desirable optoelectronic properties, such as a high or large photo response (e.g., providing high photosensitivity) and tunable optical bandgaps over a wide range (e.g., from about 1.2 electron volt (eV) to about 3 eV). Perovskite may refer to calcium titanate mineral (CaTiCh), or generally, to a class of chemical compounds having the same type of crystal structure as CaTiCh. That is, a perovskite material may be composed of a chemical compound described by a general chemical formula: ABX3, where A and B may be cations and X may be anions.

[0050] The bandgap of a semiconductor is the energy difference between its valence band and conduction band. Photons with energy equal to or greater than the bandgap can excite electrons to produce an electrical signal, thereby determining the detectable wavelength range and spectral sensitivity. As such, the wide tunable optical bandgap feature of the perovskite materials has great potential for enabling multispectral imaging. While there are various studies conducted for fabricating image sensors using perovskite materials, these image sensors do not support multispectral imaging and are often provided using a stacked solution (e.g., multiple sensor arrays vertically stacked to form a color image sensor).

[0051] Disclosed herein are techniques for providing high-resolution, multispectral image sensors in a single integrated circuit (IC) chip. More specifically, a multispectral image sensor includes an array of optical sensing elements (e.g., pixel elements) arranged in a single layer, where two or more of the optical sensing elements in the array are formed from different semiconductor materials to provide optical sensing in different spectral bands (e.g., visible band, IR band, UV band, X-ray band, etc.). In an example, the optical sensing elements in the array for sensing different spectral bands may be arranged in a mosaic pattern. The optical sensing elements canAtty. Docket No. 4502-90600 (6000789PCT01)include different perovskite materials, different quantum dot (QD) materials, different organic materials, and / or different two-dimensional (2D) semiconductor materials for sensing in different spectral bands. The multispectral image sensor further provides per pixel readout by disposing the array of optical sensing elements between a common transparent electrode (e.g., a top electrode layer) and an array of metal electrode pads (e.g., a bottom electrode layer). Each optical sensing element is coupled to a pixel readout circuit via a respective metal electrode pad.

[0052] To enable a single IC chip solution, the array of optical sensing elements is fabricated using lithography and spin-coating processes that are CMOS processes. For instance, optical sensing elements of different semiconductor materials in a single-layer array may be formed sequentially using lithography patterning and spin-coating processes. As such, the transparent electrode, the array of optical sensing elements, the metal electrode pads, and the pixel readout circuits can be integrated onto a single semiconductor wafer or die to provide simultaneous high-resolution, imaging in multiple distinct spectral bands (e.g., including visible or non-visible bands). For instance, the disclosed multispectral image sensor structure can be integrated into a single camera chip (e.g., camera-on-a-chip). The disclosed multispectral image sensor is suitable for multispectral analysis across a variety of industries, for example, including, but not limited to, agriculture (e.g., crop health monitoring and fertilizer management), environmental monitoring, geographic or soil analysis, water quality monitoring, disaster impact analysis, skin healthcare and wound analysis, industry quality control, and security inspection.

[0053] The terms “spectral band,” “wavelength band,” and “frequency band” may be used interchangeably herein, such that a description referring to one of the terms shall be treated as though the description also referred to the other term.

[0054] FIG. 1 illustrates a side cross-sectional view of a multispectral image sensor structure 100 according to an embodiment of the present disclosure. The side cross-sectional view is in a y-z plane along line A-A of FIG. 2. In an embodiment, the multispectral image sensor structure 100 (e.g., an IC structure) is part of an electronic device (e.g., as shown in FIG. 7). At a high level, the multispectral image sensor structure 100 captures an optical signal 101 (e.g., reflected off an object or a scene) and converts the captured optical signal 101 into electrical signals for forming images in different spectral bands. For example, one image may be an image of a scene in a visible band and another image may be an image of the same scene in an IR band. As shown in FIG. 1, the multispectral image sensor structure 100 includes a glass layer 102, a filter layer 104, a topAtty. Docket No. 4502-90600 (6000789PCT01)electrode layer 106 (e.g., a first electrode layer), an isolation layer 108, an optical sensing layer 110, and a bottom electrode layer 112 (e.g., a second electrode layer) disposed on a substrate 114.

[0055] The optical sensing layer 110 is disposed between the top electrode layer 106 and the bottom electrode layer 112. The optical sensing layer 110 includes a plurality of optical sensing elements 122 (individually shown as 122a and 122b). The plurality of optical sensing elements 122 are arranged in a single layer with each optical sensing element 122 spaced apart from adjacent optical sensing elements 122. For simplicity, FIG. 1 only illustrates two optical sensing elements 122 along the y-axis. However, the optical sensing layer 110 may include any suitable number of optical sensing elements 122 (e.g., 64, 128, 1024, 4096 or more) along the y-axis. Generally, the plurality of optical sensing elements 122 are arranged in an array of uniformly spaced-apart rows and columns in an x-y plane (e.g., as shown in FIG. 2).

[0056] To provide multispectral imaging, the optical sensing elements 122 are composed of different semiconductor materials having different bandgap voltages. FIG. 1 illustrates the different semiconductor materials in the optical sensing elements 122a and 122b by using different patterned boxes. For instance, the optical sensing element 122a includes a first semiconductor material that absorbs a portion of an optical signal 101 within a first wavelength band, and the optical sensing element 122b includes a second semiconductor material that absorbs a portion of an optical signal 101 within a second wavelength band different than the first wavelength band. That is, each optical sensing element 122 includes a specific semiconductor material for sensing in a specific wavelength band, and a group of the optical sensing elements 122 each include a different semiconductor material for sensing in a respective wavelength band. In an embodiment, the first wavelength band includes a visible wavelength band (e.g., between about 400 nm and 700 nm), and the second wavelength band includes a non-visible wavelength band. In an embodiment, the non-visible wavelength band includes at least one of an X-ray wavelength band (e.g., between about 0.01 nm and 10 nm), an ultraviolet (UV) wavelength band (e.g., between about 10 nm and 100 nm), or an IR wavelength band (e.g., between about 700 nm and 1 millimeters (mm)). In an embodiment, the non-visible wavelength band includes at least two of an X-ray band, an UV wavelength band, or an IR wavelength band.

[0057] Generally, two or more optical sensing elements 122 in the optical sensing layer 110 include different semiconductor materials. In an embodiment, four or more optical sensing elements 122 in the optical sensing layer 110 include different semiconductor materials. ForAtty. Docket No. 4502-90600 (6000789PCT01)instance, a first set of the optical sensing elements 122 includes a first semiconductor material that absorbs a portion of an optical signal 101 within a first wavelength band, a second set of the optical sensing element 122 includes a second semiconductor material that absorbs a portion of an optical signal 101 within a second wavelength band, a third set of the optical sensing element 122 includes a third semiconductor material that absorbs a portion of an optical signal 101 within a third wavelength band, and a fourth set of the optical sensing element 122 includes a fourth semiconductor material that absorbs a portion of an optical signal 101 within a fourth wavelength band, where the first, second, third, and fourth wavelength bands are different wavelength bands.

[0058] In an embodiment, the semiconductor materials of the optical sensing elements 122 include perovskite materials. More specifically, the optical sensing element 122a includes a first perovskite material that absorbs a portion of an optical signal 101 within a first wavelength band, and the optical sensing element 122b includes a second perovskite material that absorbs a portion of an optical signal 101 within a second wavelength band different than the first wavelength band. As discussed above, a perovskite material includes a chemical compound described by a general chemical formula: ABX3. In an example, A in the chemical formula comprises at least one of methylammonium ion (MA+), formamidinium cation (FA+), caesium ion (Cs+), calcium ion (Ca2+), or strontium ion (Sr2), B in the chemical formula comprises at least one of lead (II) ion (Pb2+), tin (II) ion (Sn2+), titanium(IV) cation (Ti4+), niobium(V) ion (Nb5+), or manganese (IV) cation (Mn4+), and X in the chemical formula comprises at least one of oxygen (O2), fluoride ion (F'), chloride ion (C1‘), bromide ion (Br), or iodide ion (I‘). In a certain example, an optical sensing element 122 includes a perovskite compound having a composition CsPbCb (e.g., with a bandgap of about 3 eV) for sensing in an X-ray band. In an example, an optical sensing element 122 includes a perovskite material having a composition CsPbBr2l (e.g., with a bandgap of about 2.5 eV) for sensing in an UV band. In an example, an optical sensing element 122 includes a perovskite compound having a composition MAPbh (e.g., with a bandgap of about 1.6 eV) for sensing in visible and / or UV bands. In an example, an optical sensing element 122 includes a perovskite compound having a composition FA066 A0.34Pb0.5Sn0.5I3 (e.g., with a bandgap of about 1.23 eV) for sensing in a near-infrared (NIR) band. Generally, the optical sensing elements 122 may include any suitable perovskite compounds that can be tuned for optical sensing in specific wavelength bands.

[0059] In other embodiments, the semiconductor materials of the optical sensing elements 122 include QD materials, organic semiconductor materials, and / or 2D semiconductor materials. QDAtty. Docket No. 4502-90600 (6000789PCT01)materials are nanoscale semiconductor crystals with diameters in the range of a few nanometers (e.g., between about 2 nm and 10 nm). Organic semiconductor materials are carbon-based compounds that can conduct electricity under certain conditions. 2D semiconductor materials are extremely thin semiconductor materials made of a single layer (or a few layers) of atoms, allowing them to conduct electricity in a controlled way while being almost flat. QD materials, organic semiconductor materials, and 2D semiconductor materials can be tuned for optical sensing in specific wavelength bands

[0060] In an embodiment, two or more optical sensing elements 122 in the optical sensing layer 110 include different QD materials. In an embodiment, two or more optical sensing elements 122 in the optical sensing layer 110 include different organic semiconductor materials. In an embodiment, two or more optical sensing elements 122 in the optical sensing layer 110 include different 2D semiconductor materials. Generally, the different semiconductor materials in the optical sensing elements 122 can include perovskite materials, QD materials, organic materials, and / or 2D semiconductor materials. As will be discussed more fully below with reference to FIGS.6A-6B and 8, the plurality of optical sensing elements 122 with different semiconductor materials in the optical sensing layer 110 may be fabricated using lithography patterning and spin-coating processes that are compatible with CMOS processes to provide a multispectral image sensor in a single IC chip.

[0061] The top electrode layer 106 may be a common transparent electrode for all the optical sensing elements 122 in the optical sensing layer 110. Generally, the top electrode layer 106 includes a transparent conductive material, for example, including, but not limited to, indium tin oxide (ITO), transparent conductive oxide (TCO), conducting polymers, and carbon-based nanomaterials (e.g., including carbon nanotube and graphene or conducting nanowire networks and / or metal mesh). The bottom electrodelayer 112 includes a plurality of electrode elements 124. The plurality of electrode elements 124 are formed on a surface (e.g., in an x-y plane) of the substrate 114 with each electrode element 124 spaced apart from adjacent electrode elements along the surface. Each electrode element 124 includes a conductive metal material, for example, including, but not limited to, copper (Cu), aluminum (Al), and tungsten (W). The electrode elements 124 may also be referred to as electrode pads or metal pads. Each individual electrode elements 124 may correspond to and be in electrical contact with a respective one of the plurality of optical sensing elements 122.Atty. Docket No. 4502-90600 (6000789PCT01)

[0062] The top electrode layer 106 (the common transparent electrode) allows photons (from incident optical signal 101) to pass through to the optical sensing elements 122, where optical absorption occurs and charge carriers are generated. As will be discussed more fully below with reference to FIG. 3, a bias voltage is applied to the top electrode layer 106 to establish an electric field or potential between the top electrode layer 106 and the bottom electrode layer 112, and each individual electrode element 124 in the bottom electrode layer 112 independently collects charge carriers for a respective optical sensing element 122.

[0063] The isolation layer 108 between the top electrode layer 106 and the optical sensing elements 122 includes a thin non-conductive material or dielectric material (e.g., silicon dioxide (SiCh), silicon nitride (SisN^, aluminum oxide (AI2O3), etc.). The isolation layer 108 acts as a non-conductive barrier that allows photons to pass through while preventing current generated from the applied potential to flow to the optical sensing elements 122. In this way, the electrode elements 124 collect the photocurrent and not the electric current due to the bias voltage (applied to the top electrode layer 106). The photocurrent generated by an optical sensing element 122 may be proportional to the intensity of an incident optical signal 101 within the wavelength band associated with the semiconductor material in that optical sensing element 122.

[0064] The filter layer 104 includes a plurality of filter elements 120 (individually shown as 120a and 120b) spaced apart from one another. Each filter element 120 is associated with (e.g., aligned to) a respective one of the plurality optical sensing elements 122. For instance, the filter 120a is aligned to and corresponds to the optical sensing elements 122a, and the filter 120b is aligned to and corresponds to the optical sensing elements 122b. Each filter element 120 is configured to transmit a portion of an optical signal 101 within a wavelength band corresponding to the respective optical sensing element 122. In some examples, the filter elements 120 can include different color filters. While an optical sensing element 122 may have a substantially narrow wavelength band, the response of the optical sensing element 122 may still be wide (e.g., not a complete cutoff outside the wavelength band). Thus, the inclusion of the filter elements 120 can improve the optical sensing performance of the respective optical sensing elements 122. However, in some examples, the filter layer 104 can be optional.

[0065] The glass layer 102 is disposed on the top layer of the multispectral image sensor structure 100 to protect the multispectral image sensor structure 100. The glass layer 102 may be composed of any suitable transparent non-conductive materials that allow an incident optical signalAtty. Docket No. 4502-90600 (6000789PCT01)101 to pass through with a minimal loss. In some examples, the multi spectral image sensor structure 100 can further include a plurality of micro lens disposed between the glass layer 102 and the filter layer 104. Each micro lens is aligned to a respective one of the optical sensing elements 122 to focus an incident optical signal 101 onto the respective optical sensing element 122.

[0066] As discussed above, perovskite materials can provide high photosensitivity. Similarly, QD material, organic materials, and 2D semiconductor materials may provide high photosensitivity. Thus, the optical sensing elements 122 can be substantially thin. In an embodiment, each optical sensing elements 122 has a thickness 134 (a dimension along the z-axis) between about 10 nm and 4000 nm, depending on specific application and detection light wave frequency. In an embodiment, the top electrode layer 106 (the common transparent electrode) has a thickness 130 (a dimension along the z-axis) between about 5 nm and 200 nm or between about 5 nm and 100 nm. In an embodiment, the isolation layer 108, such as AI2O3 and TiCh, has athickness 132 (a dimension along the z-axis) between about 2 nm and 50 nm.

[0067] FIG. 2 illustrates a perspective view of the multispectral image sensor structure 100 according to an embodiment of the present disclosure. The perspective view is in an x-y-z plane. In FIG. 2, the glass layer 102, the filter layer 104, the top electrode layer 106, the isolation layer 108, the optical sensing layer 110, and the electrode elements 124 (e.g., the bottom electrode layer 112) formed on the substrate 114 in the multispectral image sensor structure 100 are illustrated separately. As shown in FIG. 2, the optical sensing elements 122 (individually shown as 122a, 122b, 122c, and 122d) in the optical sensing layer 110 are arranged in an array of rows and columns, for example, uniformly spaced apart from one another in an x-y plane. The optical sensing elements 122 may be referred to as a sensor array. For simplicity, FIG. 2 only illustrates four optical sensing elements 122 (individually shown as 122a, 122b, 122c, and 122d) in the optical sensing layer 110 with two optical sensing elements 122 along the y-axis and two optical sensing elements 122 along the x-axis. However, the optical sensing layer 110 may include any suitable number of optical sensing elements 122 (e.g., 64, 128, 1024, 4096 or more) along the y-axis and / or along the x-axis.

[0068] Each of the optical sensing elements 122a, 122b, 122c, and 122d may be composed of a different semiconductor material with a different bandgap voltage to provide multispectral imaging in the same sensor array. Similar to FIG. 1, FIG. 2 illustrates the different semiconductor materials in the optical sensing elements 122a and 122b by using different patterned boxes.Atty. Docket No. 4502-90600 (6000789PCT01)Generally, the different optical sensing elements 122a, 122b, 122c, and 122d can have different perovskite materials, different QD materials, different organic semiconductor materials, and / or different 2D semiconductor materials. In an embodiment, the optical sensing element 122a has a first semiconductor material for sensing in an X-ray wavelength band (e.g., between about 0.01 nm and 10 nm), the optical sensing element 122b has a second semiconductor material for sensing in a visible wavelength band (e.g., between about 400 nm and 600 nm), the optical sensing element 122c has a third semiconductor material for sensing in a visible and UV wavelength band (e.g., between about 600 nm and 775 nm), and the optical sensing element 122d has a fourth semiconductor material for sensing in an infrared wavelength band (e.g., between about 775 nm and 1 mm). In an example, the four optical sensing elements 122a, 122b, 122c, and 122d correspond to one pixel of an image output by the multispectral image sensor structure 100. In such an example, the optical sensing elements 122 are arranged in a mosaic pattern, with groups of four optical sensing elements 122a, 122b, 122c, and 122d repeating in the array. Generally, the optical sensing elements 122 include any suitable number of different semiconductor materials for simultaneously sensing multiple wavelength channels or bands (e.g., about 2, 3, 4, 5, 6, 7, 8, 9, or more) of interest in the electromagnetic spectrum. Further, the optical sensing elements 122 of different semiconductor materials are arranged in any suitable way within the array.

[0069] In an embodiment, a pitch 202 between two adjacent optical sensing elements 122 along the y-axis is less than 10 pm. In an embodiment, a pitch 202 between two adjacent optical sensing elements 122 is about 0.1 to 1 pm. In an embodiment, a pitch 202 between two adjacent optical sensing elements 122 is about between about 0.6 pm. In some examples, a pitch 204 between two adjacent optical sensing elements 122 along the x-axis is about the same as the pitch 202. In some examples, the pitch 204 can be different than the pitch 202. In an example, the optical sensing elements 122 have the same size and are uniformly spaced to provide a high-resolution and high-quality image sensing.

[0070] As discussed above, each filter element 120 is aligned to a respective one of the optical sensing elements 122. As shown in FIG. 2, the filter layer 104 includes filter elements 120 (individually shown as 120a, 120b, 120c, and 120d) arranged in an array of rows and columns similar to the optical sensing elements 124. Each filter element 120 is configured to transmit a portion of an optical signal 101 within a wavelength band corresponding to the respective optical sensing element 122.Atty. Docket No. 4502-90600 (6000789PCT01)

[0071] FIG. 3 illustrates a side cross-sectional view of the multispectral image sensor structure 100 including pixel readout circuits 310 according to an embodiment of the present disclosure. The side cross-sectional view is in a y-z plane along line A- A of FIG. 2 and may be substantially similar to FIG. 1. FIG. 3 further illustrates the generation and collection of photo charge carriers in the multispectral image sensor structure 100. As shown in FIG. 3, the multispectral image sensor structure 100 includes a plurality of pixel readout circuits 310 formed in the substrate 114. Each of the pixel readout circuits 310 may be a separate IC. Each pixel readout circuit 310 is coupled to a respective one of the plurality of optical sensing elements 122 via a respective electrode element 124.

[0072] When an optical signal 101 strikes the semiconductor material of an individual optical sensing element 122, photons with sufficient energy excite electrons from the valence band to the conduction band, creating electron-hole pairs. The top electrode layer 106 (the common transparent electrode) and the pixel readout circuit 310 corresponding to the optical sensing element 122 create a path for these charge carriers. For instance, a bias voltage, represented by Vbias, is applied across the top electrode layer 106 (the common transparent electrode) and the electrode element 124 to generate an internal electric field. The electric field drives electrons (e.g., photocurrent) toward the electrode element 122 (in the bottom electrode layer 112). The pixel readout circuit 310 measures a voltage, represented by Vin, that results from the photocurrent to determine an intensity of the optical signal 101 within the wavelength band configured for the optical sensing element 122. Each pixel readout circuit 310 can be a voltage-mode readout circuit (e g., as shown in FIG. 4) or a current-mode readout circuit (e.g., as shown in FIG. 5).

[0073] FIG. 4 illustrates an example pixel voltage-mode readout circuit 400 according to an embodiment of the present disclosure. In an embodiment, an individual pixel readout circuit 310 in the multispectral image sensor structure 100 is implemented as shown in the voltage-mode readout circuit 400. As shown in FIG. 4, the voltage-mode readout circuit 400 includes three transistors 402, 404, and 406. The transistor 402 is connected to an optical sensing element (e.g., the optical sensing elements 122) at node Nl. The input voltage from the optical sensing element are represented by Vin. The transistor 402 (e.g., a reset transistor) acts as a switch to reset the node Nl to a reference voltage, represented by Vrst. The transistor 404 is connected to the transistor 402 in a source-follower configuration, where the source of the transistor 404 forms an outputAtty. Docket No. 4502-90600 (6000789PCT01)node N2. The transistor 404 acts as a buffer to collect charges generated by the optical sensing element. The transistor 406 acts as a switch to connect the output node N2 for pixel read out.

[0074] During operation, when the transistor 402 is turned on (e.g., controlled by a reset signal represented by RST), the node N1 is connected to Vrst. The reset clears all charges integrated at the optical sensing element. After the reset, the transistor 402 is turned off for charge integration. When an incident light hits the optical sensing element, the optical sensing element converts photons into charges, which are buffered or collected by the transistor 404. After a predetermined charge integration time, the transistor 406 is turned on (e.g., controlled by a selection signal represented by SEL) and the voltage signal, represented by Vout, is read out. The output voltage signal may be proportional to the magnitude of the intensity of the optical signal absorbed by the optical sensing element.

[0075] FIG. 5 illustrates an example pixel current-mode readout circuit 500 according to an embodiment of the present disclosure. In an embodiment, an individual pixel readout circuit 310 in the multispectral image sensor structure 100 is implemented as shown in the current-mode readout circuit 500. As shown in FIG. 5, the current-mode readout circuit 500 includes an operational amplifier 506, a feedback capacitor 504, and a reset transistor 502. A first input (e.g., an inverting input) of the operational amplifier 506 is connected to an optical sensing element (e.g., the optical sensing elements 122), and a second input (e.g., a non-inverting input) of the operational amplifier 506 is connected to a reference voltage, represented by Vref. The input voltage from the optical sensing element is represented by Vin. The feedback capacitor 504 is connected across the first input and the output of the operational amplifier 506. The reset transistor 502 is connected in parallel with feedback capacitor 504.

[0076] During operation, the reset transistor 502 is turned on (e.g., controlled by a reset signal represented by RST) to discharge the feedback capacitor 504. After the reset, the transistor 502 is turned off for charge integration. When an incident light hits the optical sensing element, the optical sensing element converts photons into charges. The generated charges flow into the operational amplifier 506 and charge the feedback capacitor 504. The operational amplifier 506 maintains a constant input voltage (Vref), so all the current builds up at the capacitor 504, causing the output voltage, represented by Vout, to change over time. After a predetermined integration time, the output voltage is then be read out. The output voltage signal may be proportional to the magnitude of the intensity of the optical signal absorbed by the optical sensing element.Atty. Docket No. 4502-90600 (6000789PCT01)

[0077] FIGS. 6A and 6B are block diagrams illustrating an example method 600 of fabricating a multispectral image sensor (e.g., the multispectral image sensor structure 100) on a single semiconductor wafer according to an embodiment of the present disclosure. The method 600 is illustrated using cross-sectional side views of IC structures at various steps in a y-z plane. For simplicity, FIGS. 6A and 6B use the same reference numerals to refer to the same layers and / or elements as in FIGS. 1 and 3. Further, FIGS. 6A and 6B only illustrate the fabrication of four optical sensing elements (e.g., optical sensing elements 122) with different semiconductor materials on a single semiconductor wafer to provide sensing in four distinct wavelength bands. However, the method 600 may be extended to fabricate a multispectral image sensor array with any suitable number of optical sensing elements (e.g., 1024-by-1024, 4096-by-4096, etc.) of any suitable number of semiconductor materials (e.g., 2, 3, 4, 5, 6, 7, 8 or more). At a high level, the method 600 forms optical sensing elements of different semiconductor materials sequentially over a semiconductor wafer using lithography patterning and spin-coating processes.

[0078] Turning now to FIG. 6A, a semiconductor substrate 114 including a plurality of openings 670 is provided. Each opening 670 exposes a respective one of a plurality of electrode elements 124. At operation 602, a first photoresist layer 650 is formed over the semiconductor substrate 114 and the plurality of electrode elements 124 (e.g., using a spin-coating process). The first photoresist layer 650 may include a light-sensitive polymer (e.g., parylene) suitable for photolithography processes. At operation 604, the first photoresist layer 650 is patterned to define at least a first opening 672 exposing at least a portion of a first electrode element 124 (shown by 124a) of the plurality of electrode elements 124. A lithography process may be used to pattern the first photoresist layer 650. At operation 606, a first semiconductor material 658 is formed over the first photoresist layer 650 and within the first opening 672 (e.g., using a spin-coating process). The first semiconductor material 658 absorbs an optical signal in a first wavelength band. At operation 608, the first semiconductor material 658 formed over the patterned first photoresist layer 650 and the patterned first photoresist layer 650 is removed (e.g., using a wet or dry etching process) while retaining the first semiconductor material 658 from within the first opening 672 to form a first structure 680. The first structure 680 includes an optical sensing element 122a formed from the first semiconductor material 658 and in contact with the first electrode element 124a.

[0079] Next, at operation 610, a second photoresist layer 652 is formed over the first structure 680 (e.g., using a spin-coating process). The second photoresist layer 652 may include a similarAtty. Docket No. 4502-90600 (6000789PCT01)material as the first photoresist layer 650. At operation 612, the second photoresist layer 652 is patterned (e.g., using a lithography process) to define at least a second opening 674 exposing at least a portion of a second electrode element 124 (shown by 124b) of the plurality of electrode elements 124. At operation 614, a second semiconductor material 660 is formed over the second photoresist layer 652 and within the second opening 674 (e.g., using a spin-coating process). The second semiconductor material 660 may be different than the first semiconductor material 658. The second semiconductor material 660 absorbs an optical signal in a second wavelength band different than the first wavelength band. At operation 616, the second semiconductor material 660 formed over the second patterned photoresist layer 652 and the second patterned photoresist layer 652 is removed while retaining the second semiconductor material 660 from within the first opening 672 to form a second structure 682. The second structure 682 includes the optical sensing element 122a formed from the first semiconductor material 658 and an optical sensing element 122b formed from the second semiconductor material 660. The optical sensing elements 122a and 122b are respectively in contact with the electrode elements 124a and 124b.

[0080] Next, at operation 618, a third photoresist layer 654 is formed over the second structure 682 (e.g., using a spin-coating process). The third photoresist layer 654 may include a similar material as the first photoresist layer 650 and the second photoresist layer 652. At operation 620, the third photoresist layer 654 is patterned (e.g., using a lithography process) to define at least a third opening 676 exposing at least a portion of a third electrode element 124 (shown by 124c) of the plurality of electrode elements 124. At operation 622, a third semiconductor material 662 is formed over the third photoresist layer 654 and within the third opening 676 (e.g., using a spincoating process). The third semiconductor material 662 may be different than the first semiconductor material 658 and the second semiconductor material 660. The third semiconductor material 662 absorbs an optical signal in a third wavelength band different than the first and second wavelength bands. At operation 624, the third semiconductor material 662 formed over the third patterned photoresist layer 654 and the third patterned photoresist layer 654 is removed while retaining the third semiconductor material 662 from within the third opening 676 to form a third structure 684. The third structure 684 includes the optical sensing element 122a formed from the first semiconductor material 658, the optical sensing element 122b formed from the second semiconductor material 660, and an optical sensing element 122c formed from the thirdAtty. Docket No. 4502-90600 (6000789PCT01)semiconductor material 662. The optical sensing elements 122a, 122b, and 122c are respectively in contact with the electrode elements 124a, 124b, and 124c.

[0081] Turning now to FIG. 6B, at operation 626, after forming the third semiconductor structure 684 including the optical sensing elements 122a, 122b, and 122c, a fourth photoresist layer 656 is formed over the third structure 684 (e.g., using a spin-coating process). The fourth photoresist layer 656 may include a similar material as the first photoresist layer 650, the second photoresist layer 652, and the third photoresist layer 654. At operation 628, the fourth photoresist layer 656 is patterned (e.g., using a lithography process) to define at least a fourth opening 678 exposing at least a portion of a fourth electrode element 124 (shown by 124d) of the plurality of electrode elements 124. At operation 630, a fourth semiconductor material 664 is formed over the fourth photoresist layer 656 and within the fourth opening 678 (e.g., using a spin-coating process). The fourth semiconductor material 664 may be different than the first semiconductor material 658, the second semiconductor material 660, and the third semiconductor material 662. The fourth semiconductor material 664 absorbs an optical signal in a fourth wavelength band different than the first, second, and third wavelength bands. At operation 632, the fourth semiconductor material 664 formed over the patterned fourth photoresist layer 656 and the patterned fourth photoresist layer 656 are removed while retaining the fourth semiconductor material 664 from within the fourth opening 678 to form a fourth structure 686. The fourth structure 686 may include the optical sensing element 122a formed from the first semiconductor material 658, the optical sensing element 122b formed from the second semiconductor material 660, the optical sensing element 122c formed from the third semiconductor material 662, and an optical sensing element 122d formed from the fourth semiconductor material 664.

[0082] Next, at operation 636, an isolation layer 108 is formed over the fourth structure 664. The isolation layer 108 may include a non-conductive material or dielectric material (e.g., SiCh, SisN , AI2O3, etc.). The non-conductive material or dielectric material may also fill the gaps between adjacent optical sensing elements 122. The isolation layer 108 is formed using semiconductor processes, such as chemical vapor deposition (CVD), spin-coating, and / or planarization. At operation 638, a top electrode layer 106 is formed over the isolation layer 108. The top electrode layer 106 includes a transparent conductive material (e.g., ITO, TCO, conducting polymers, carbon-based nanomaterials, etc.). The top electrode layer 106 is formed using semiconductor processes, such as sputtering, lithography, and / or etching.Atty. Docket No. 4502-90600 (6000789PCT01)

[0083] Subsequently, filter elements (e.g., the filter elements 120) are formed over the top electrode layer 106 and a glass layer (e.g., the glass layer 102) are formed over the filter elements. Each filter element is aligned to a respective one of the optical sensing elements 122 and configured to pass an optical signal within the wavelength band absorbed by the respective optical sensing element 122. In some examples, micro lens are formed over the transparent electrode layer 106 before forming the glass layer. Each micro lens is aligned to a respective one of the optical sensing elements 122 to focus incoming light to the respective optical sensing element 122. The filter elements and the glass layer may be formed using industry standard processes for color filters and micro lens, respectively.

[0084] FIG. 7 is a block diagram of an electronic device 700 including a multispectral image sensor 704 according to an embodiment of the present disclosure. In an embodiment, the multispectral image sensor 704 corresponds to the multispectral image sensor structure 100 formed on a single IC chip as discussed above with reference to FIGS. 1 and 3. In an embodiment, the electronic device 700 is a single camera chip. As shown in FIG. 7, the electronic device 700 includes a lens module 702, the multispectral image sensor 704, and an electrical signal processing module 706. The lens module 702 is configured to converge or focus optical signals reflected by an external object towards the multispectral image sensor 704. The multispectral image sensor 704 is configured to convert optical signals in multiple wavelength bands (e.g., X-ray, visible, UV, and / or IR bands) into analog electrical signals as discussed above with reference to FIGS. 3-5. The electrical signal processing module 706 is configured to construct images in multiple wavelength bands based on the electrical signals received from the multispectral image sensor 704. In some embodiments, the electrical signal processing module 706 includes analog-to-digital (A / D) converter(s) to convert the analog electrical signals into digital electrical signal. The electrical signal processing module 706 may further include a digital signal processor (DSP) to apply a series of mathematical algorithm operations to generate output images.

[0085] FIG. 8 is a flowchart of an example method 800 of providing a multispectral image sensor structure according to an embodiment of the present disclosure. The method 800 may use substantially similar mechanisms as discussed above with reference to FIGS. 6A and 6B. As illustrated, FIG. 8 includes a number of enumerated operations, but embodiments of the operations in FIG. 8 may include additional operations before, after, and in between the enumeratedAtty. Docket No. 4502-90600 (6000789PCT01)operations. Tn some embodiments, one or more of the enumerated operations may be omitted or performed in a different order.

[0086] At operation 802, a semiconductor substrate (e.g., the semiconductor substrate 114) including a plurality of electrode elements (e.g., the electrode elements 124) spaced apart from each other on a surface of the semiconductor substrate is provided. In an embodiment, the plurality of electrode elements include a conductive metal material. In an embodiment, the semiconductor substrate further includes a plurality of readout ICs (e.g., the pixel readout ICs 310), where each readout IC is coupled to a respective one of the plurality of electrode elements.

[0087] At operation 804, a first photoresist pattern is formed over the semiconductor substrate and the plurality of electrode elements (e.g., using a lithography patterning process as discussed above with reference to operations 602 and 604). The first photoresist pattern includes first openings (e.g., the first opening 672) exposing a first set of electrode elements. At operation 806, a first semiconductor material (e.g., the first semiconductor material 658) is formed over the first photoresist pattern and within the first openings (e.g., using a spin-coating process). At operation 808, the first photoresist pattern and the first semiconductor material over the first photoresist pattern are removed yet retaining the first semiconductor material from within the respective first openings to provide a first structure (e.g., the first structure 680). The first structure includes a first set of optical sensing elements formed from the first semiconductor material retained from within the first openings. Each of the first set of optical sensing elements is in contact with a respective electrode element in the first set of electrode elements.

[0088] At operation 810, a second photoresist pattern is formed over the first structure (e.g., using a lithography patterning process as discussed above with reference to operations 610 and 612). The second photoresist pattern includes second openings (e.g., the first opening 674) exposing a second set of electrode elements. The second set of electrode elements is different than the first set of electrode elements. At operation 812, a second semiconductor material (e.g., the first semiconductor material 660) is formed over the second photoresist pattern and within the second openings (e.g., using a spin-coating process). In an embodiment, the first semiconductor material includes a perovskite crystal structure that absorbs at least a portion of a first optical signal in a first wavelength band, and the second semiconductor material includes a perovskite crystal structure that absorbs at least a portion of a second optical signal in a second wavelength band different than the first wavelength band. In another embodiment, the first semiconductor materialAtty. Docket No. 4502-90600 (6000789PCT01)and the second semiconductor material are different QD materials. Tn yet another embodiment, the first semiconductor material and the second semiconductor material are different organic semiconductor materials. In a further embodiment, the first semiconductor material and the second semiconductor material are different 2D semiconductor materials. At operation 814, the second photoresist pattern and the second semiconductor material over the second photoresist pattern are removed yet retaining the second semiconductor material from within the respective second openings to provide a second structure (e.g., the first structure 682). The second structure includes a second set of optical sensing elements formed from the second semiconductor material retained from within the second openings. Each of the second set of optical sensing elements is in contact with a respective electrode element in the second set of electrode elements.

[0089] In an embodiment, an isolation layer (e.g., the isolation layer 108) is further added over the second structure. The isolation layer includes non-conductive material (e.g., SiCh, Si3N4, AI2O3, etc.). In an embodiment, a transparent electrode layer is further added over the isolation layer. The transparent electrode layer includes transparent conductive material (e.g., ITO, TCO, conducting polymers, carbon-based nanomaterials, etc.). Generally, any suitable number of different semiconductor materials may be further formed over the second structure to form additional sets of optical sensing elements using similar mechanisms as in operations 810, 812, and 814 before the isolation layer and the transparent electrode layer are added.

[0090] It should also be understood that the steps of the exemplary methods set forth herein are not necessarily required to be performed in the order described, and the order of the steps of such methods should be understood to be merely exemplary. Likewise, additional steps may be included in such methods, and certain steps may be omitted or combined, in methods consistent with various embodiments of the present disclosure.

[0091] While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.

[0092] In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems,Atty. Docket No. 4502-90600 (6000789PCT01)modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

Atty. Docket No. 4502-90600 (6000789PCT01)CLAIMSWhat is claimed is:

1. An integrated circuit (IC) structure, comprising:a multi spectral image sensor structure comprising:a first electrode layer;a second electrode layer; anda plurality of optical sensing elements arranged in a single layer disposed between the first electrode layer and the second electrode layer,wherein:each of the plurality of optical sensing elements comprises a perovskite material, andtwo or more optical sensing elements of the plurality of optical sensing elements comprise different perovskite materials.

2. The IC structure of claim 1, wherein:a first optical sensing element of the plurality of optical sensing elements comprises a first perovskite material that absorbs at least a portion of an optical signal in a first wavelength band, anda second optical sensing element of the plurality of optical sensing elements comprises a second perovskite material that absorbs at least a portion of an optical signal in a second wavelength band different than the first wavelength band.

3. The IC structure of any of claims 1-2, wherein:a first optical sensing element of the plurality of optical sensing elements comprises a first perovskite material having a first bandgap voltage, anda second optical sensing element of the plurality of optical sensing elements comprises a second perovskite material having a second bandgap voltage different than the first bandgap voltage.Atty. Docket No. 4502-90600 (6000789PCT01)4. The IC structure of any of claims 1-2, wherein the first electrode layer comprises a transparent conductive material.

5. The IC structure of claim 4, wherein the multispectral image sensor structure further comprises:an isolation layer disposed between the first electrode layer and the plurality of optical sensing elements, the isolation layer comprising a non-conductive material.

6. The IC structure of any of claims 1-5, wherein the second electrode layer comprises a plurality of electrode elements spaced apart from one another, each comprising a conductive metal material.

7. The IC structure of claim 6, wherein the multispectral image sensor structure further comprises:a plurality of readout integrated circuits (ICs), each coupled to a respective one of the plurality of optical sensing elements via a respective one of the plurality of electrode elements.

8. The IC structure of claim 7, wherein an individual one of the plurality of readout ICs is configured to generate a signal corresponding to an intensity of an incident optical signal within a wavelength band associated with a respective one of the plurality of optical sensing elements, based on a voltage applied to the first electrode layer.

9. The IC structure of any of claims 7-8, wherein the plurality of readout ICs comprises at least one of a voltage-mode readout IC or a current-mode readout IC.

10. The IC structure of any of claims 1-9, wherein a pitch between a pair of adjacent optical sensing elements of the plurality of optical sensing elements is less than 100 nanometers (nm).

11. The IC structure of any of claims 1-10, wherein a thickness of a first optical sensing element of the plurality of optical sensing elements is between 10 nanometers (nm) and 4000 nm.Atty. Docket No. 4502-90600 (6000789PCT01)12. The IC structure of any of claims 1-11, wherein the first electrode layer, the plurality of optical sensing elements, and the second electrode layer are disposed on a common semiconductor substrate.

13. The IC structure of claim 12, wherein the common semiconductor substrate is a complementary metal-oxide-semiconductor (CMOS) substrate.

14. A multi spectral image sensor, comprising:a semiconductor die; andan array of optical sensing elements arranged in a single layer on the semiconductor die, wherein at least:a first optical sensing element of the array of optical sensing elements comprises a first semiconductor material that absorbs at least a portion of an optical signal within a visible wavelength band, anda second optical sensing element of the array of optical sensing elements comprises a second semiconductor material that absorbs at least a portion of an optical signal within a non-visible wavelength band.

15. The multispectral image sensor of claim 14, wherein the non-visible wavelength band comprises at least one of an X-ray band, an ultraviolet (UV) wavelength band, or an infrared (IR) wavelength band.

16. The multispectral image sensor of any of claims 14-15, wherein the non-visible wavelength band comprises at least two of an X-ray band, an ultraviolet (UV) wavelength band, or an infrared (IR) wavelength band.

17. The multispectral image sensor of any of claims 14-16, wherein the first semiconductor material and the second semiconductor material comprise different perovskite materials.

18. The multispectral image sensor of any of claims 14-16, wherein the first semiconductor material and the second semiconductor material comprise different quantum dot materials.Atty. Docket No. 4502-90600 (6000789PCT01)19. The multispectral image sensor of any of claims 14-16, wherein the first semiconductor material and the second semiconductor material comprise different two-dimensional (2D) semiconductor materials.

20. The multispectral image sensor of any of claims 14-19, further comprising:a first electrode layer comprising a transparent conductive material; anda second electrode layer comprising a plurality of electrode elements comprising a conductive metal material,wherein the array of optical sensing elements is disposed between the first electrode layer and the second electrode layer.

21. The multispectral image sensor of claim 20, further comprising:a plurality of readout integrated circuits (ICs) formed on the same semiconductor die, wherein each readout IC is electrically coupled to a respective optical sensing element of the array of optical sensing elements via a respective one of the plurality of electrode elements.

22. The multispectral image sensor of claim 21, wherein one of the plurality of readout ICs is configured to generate a signal corresponding to an intensity of a portion of the optical signal within a wavelength band associated with a respective optical sensing element of the array of optical sensing elements, based on a voltage applied to the first electrode layer.

23. A method of fabricating a multispectral perovskite image sensor, the method comprising:providing a semiconductor substrate comprising a plurality of electrode elements spaced apart from each other on a surface of the semiconductor substrate;forming a first photoresist pattern over the semiconductor substrate and the plurality of electrode elements, wherein the first photoresist pattern comprises first openings exposing a first set of electrode elements;forming a first semiconductor material over the first photoresist pattern and within the first openings;Atty. Docket No. 4502-90600 (6000789PCT01)removing the first photoresist pattern and the first semiconductor material over the first photoresist pattern yet retaining the first semiconductor material from within the respective first openings to provide a first structure;forming a second photoresist pattern over the first structure, wherein the second photoresist pattern comprises second openings exposing a second set of electrode elements;forming a second semiconductor material over the second photoresist pattern and within the second openings; andremoving the second photoresist pattern and the second semiconductor material over the second photoresist pattern yet retaining the second semiconductor material from within the respective second openings to provide a second structure.

24. The method of claim 23, wherein:the first semiconductor material comprises a perovskite crystal structure that absorbs at least a portion of a first optical signal in a first wavelength band, andthe second semiconductor material comprises a perovskite crystal structure that absorbs at least a portion of a second optical signal in a second wavelength band different than the first wavelength band.

25. The method of claim 23, wherein the first and second semiconductor materials comprise different quantum dot (QD) materials.

26. The method of claim 23, wherein the first and second semiconductor materials comprise different organic semiconductor materials.

27. The method of claim 23, wherein the first and second semiconductor materials comprise different two-dimensional (2D) semiconductor materials.

28. The method of any of claims 23-27, wherein at least one of the forming the first semiconductor material over the first photoresist pattern and within the first openings or forming the second semiconductor material over the second photoresist pattern and within the second openings comprises a spin-coat process.Atty. Docket No. 4502-90600 (6000789PCT01)29. The method of any of claims 23-28, wherein the plurality of electrode elements comprise conductive metal material.

30. The method of any of claims 23-29, further comprising:adding an isolation layer over the second structure, the isolation layer comprising a non-conductive material.

31. The method of claim 30, further comprising:adding a transparent electrode layer over the isolation layer, the transparent electrode layer comprising a transparent conductive material.

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