Sensor stack

Abstract

A sensor stack is described. The sensor stack includes a first electromagnetic radiation sensor and a second electromagnetic radiation sensor. The first electromagnetic radiation sensor has a high quantum efficiency for converting a first electromagnetic radiation wavelength range into a first set of electrical signals. The second electromagnetic radiation sensor is located in a field of view of the first electromagnetic radiation sensor and has a high quantum efficiency for converting a second electromagnetic radiation wavelength range into a second set of electrical signals and a low quantum efficiency for converting the first electromagnetic radiation wavelength range into the second set of electrical signals. The first wavelength range does not overlap the second wavelength range, and the second electromagnetic radiation sensor at least partially transmits the first electromagnetic radiation wavelength range.

Description

[0001] Cross-reference to related applications

[0002] This Patent Cooperation Treaty patent application claims priority to U.S. Provisional Patent Application No. 62 / 868,746, filed June 28, 2019, the contents of which are incorporated herein by reference as if fully disclosed herein. Technical Field

[0003] The described embodiments generally relate to a device having a first electromagnetic radiation sensor (e.g., a visible light sensor) stacked on a second electromagnetic radiation sensor (e.g., an infrared (IR) sensor, such as an IR depth sensor or an IR image sensor). The described embodiments also generally relate to an electromagnetic radiation sensor having a photosensitive material separate from a semiconductor substrate, the semiconductor substrate including pixel circuitry for a pixel array defined by the semiconductor substrate and, in some respects, by the photosensitive material. Background Technology

[0004] Devices such as cameras (e.g., digital cameras) may sometimes include more than one image sensor (or more generally, more than one electromagnetic radiation sensor). For example, a device may include a visible light sensor and an IR sensor. In some examples, the IR sensor may be used to acquire IR images, and the IR images may be used, for example, to adjust the color or chromaticity of a visible light image acquired by the visible light sensor (e.g., for color processing). IR images may also be used as input to adjust the focus of a visible light image; to improve low-light sensitivity; to identify heat sources that may affect a visible light image; to provide night vision; or for other purposes.

[0005] In some cases, visible light and IR sensors are integrated on a single silicon substrate. For example, red-green-blue (RGB) light sensors and IR sensors are integrated on a single silicon substrate, where RGB pixels and IR pixels share the same silicon-based photosensitive layer. Separation between RGB pixels and IR pixels has been provided in a two-dimensional (2D) spatial domain, where IR pixels replace selected RGB pixels (e.g., where IR pixels replace certain green pixels), and where the IR pixels typically employ a black filter that transmits IR radiation and blocks visible light. Summary of the Invention

[0006] Embodiments of the systems, devices, methods, and apparatuses described in this disclosure relate to stacked electromagnetic radiation sensors. Systems, devices, methods, and apparatuses relating to electromagnetic radiation sensors having a photosensitive material separate from a semiconductor substrate, the semiconductor substrate including pixel circuitry for a pixel array defined by the semiconductor substrate and, in some respects, by the photosensitive material are also described.

[0007] In a first aspect, this disclosure describes a sensor stack. The sensor stack may include a first electromagnetic radiation sensor and a second electromagnetic radiation sensor. The first electromagnetic radiation sensor may have a high quantum efficiency (QE) for converting a first electromagnetic radiation wavelength range into a first set of electrical signals. The second electromagnetic radiation sensor may be located within the field of view (FoV) of the first electromagnetic radiation sensor. The second electromagnetic radiation sensor may have a high quantum efficiency for converting a second electromagnetic radiation wavelength range into a second set of electrical signals, and may have a low quantum efficiency for converting the first electromagnetic radiation wavelength range into the second set of electrical signals: the first electromagnetic radiation wavelength range does not overlap with the second electromagnetic radiation wavelength range, and the second electromagnetic radiation sensor at least partially transmits the first electromagnetic radiation wavelength range.

[0008] In another aspect, this disclosure describes an electromagnetic radiation sensor. The electromagnetic radiation sensor may include a semiconductor substrate and a photosensitive material deposited on the semiconductor substrate. The semiconductor substrate may include pixel circuitry for a pixel array. An electrical connection array may connect the pixel circuitry for the pixel array and the photosensitive material. Electrical connections in the electrical connection array may include heterojunction photodiodes formed between the semiconductor substrate and the photosensitive material.

[0009] In addition to the exemplary aspects and embodiments described herein, further aspects and embodiments will become apparent from the accompanying drawings and by studying the following description. Attached Figure Description

[0010] This disclosure will be readily understood from the following detailed embodiments, taken in conjunction with the accompanying drawings, wherein similar reference numerals denote similar structural elements, and wherein:

[0011] Figure 1 An example of a camera is shown that includes a stacked electromagnetic radiation sensor (or a stacked electromagnetic radiation imager or sensor stack), wherein a first electromagnetic radiation sensor is stacked on the electromagnetic radiation receiving surface of a second electromagnetic radiation sensor (e.g., directly on, above, or over it).

[0012] Figure 2 An exemplary exploded view of a stacked electromagnetic radiation sensor is shown;

[0013] Figure 3A Another exemplary exploded view of a stacked electromagnetic radiation sensor is shown;

[0014] Figure 3B References are shown Figure 3A The described RGB light sensor and Figure 3A The facade of the components not specifically shown in the image;

[0015] Figures 4A to 4C and Figures 5A to 5BVarious exploded view examples of stacked electromagnetic radiation sensors are shown;

[0016] Figures 6A to 6C Various options for reducing kTC noise are shown when implementing a photodetector array using a photosensitive material (or panchromatic photosensitive layer) separate from the semiconductor substrate that includes its supporting pixel circuitry.

[0017] Figure 7A and Figure 7B An exemplary facade of a stacked electromagnetic radiation sensor is shown, and more specifically, an example of the interconnection between the pixel circuitry and the pixel processing chip of an RGB light sensor (or other visible light sensor) stacked on an IR sensor is shown.

[0018] Figure 8A It shows that it can be used with Figure 7A The interconnection options shown combine interconnection methods to provide a combination of low-resistance metal buses for pixel groups in an RGB light sensor and transparent local connections within pixel groups in an RGB light sensor.

[0019] Figure 8B It shows Figure 8A The arrangement of RGB and IR pixels is shown, but the TSV is routed around the IR pixels within the pixel array of the IR sensor;

[0020] Figures 9A to 9C It shows Figure 7A A portion of the stacked electromagnetic radiation sensor shown, wherein additional interconnection options are used to route signals to / from the RGB pixels of the pixel circuitry in the RGB light sensor.

[0021] Figure 10 A first exemplary configuration of electrical contacts for connecting photosensitive material (or other panchromatic photosensitive layer) to pixel circuitry is shown;

[0022] Figure 11 A second exemplary configuration of electrical contacts for connecting photosensitive material (or other panchromatic photosensitive layer) to pixel circuitry is shown;

[0023] Figure 12 A third exemplary configuration is shown for electrical contacts used to connect a photosensitive material (or other panchromatic photosensitive material) to a pixel circuit.

[0024] Figure 13A A fourth exemplary configuration for connecting a photosensitive material (or other panchromatic photosensitive material) to a pixel circuit is shown;

[0025] Figure 13B It shows Figure 13A The shown is a variation of the interconnection;

[0026] Figures 13C to 13L It shows that it can be used with Figure 13A or Figure 13B Examples of other design features of the structural combination shown;

[0027] Figure 14A An exemplary process for fabricating a stacked electromagnetic radiation sensor is shown;

[0028] Figure 14B and Figure 14C The diagram illustrates the use of different circuits (e.g., pixel circuits) and... Figure 14A An exemplary process for interconnecting the photosensitive layers in the structure shown;

[0029] Figure 15A References are shown Figure 14A Modifications (and simplifications) to the described process;

[0030] Figure 15B The diagram illustrates the use of different circuits (e.g., pixel circuits) and... Figure 15A An exemplary process for interconnecting the photosensitive elements in the structure shown;

[0031] Figure 16A and Figure 16B An example is shown of how longer wavelength photosensitive materials can be deposited on the semiconductor substrate of an IR sensor;

[0032] Figure 17A and Figure 17B Exemplary devices are shown that may include any or more of the stacked or non-stacked electromagnetic radiation sensors described herein;

[0033] Figure 18 An exemplary implementation of the image capture device is shown;

[0034] Figure 19 An exemplary system including a detector using an avalanche diode is shown;

[0035] Figure 20 This demonstrates how multiple images (or image frames) acquired by an electromagnetic radiation sensor (e.g., a visible light sensor or an IR sensor) can be fused to form a single still image; and

[0036] Figure 21 A sample electrical block diagram of an electronic device is shown.

[0037] The use of crosshairs or shading in the accompanying drawings is generally provided to clarify the boundaries between adjacent elements and also to improve the readability of the drawings. Therefore, the presence or absence of crosshairs or shading does not indicate or suggest any preference or requirement for a particular material, material properties, element proportions, element dimensions, commonalities of similar illustrated elements, or any other feature, property, or characteristic of any element shown in the accompanying drawings.

[0038] Furthermore, it should be understood that the proportions and dimensions (relative or absolute) of the various features and elements (as well as their sets and groups), and the boundaries, spacing, and positional relationships therebetween, are provided in the accompanying drawings solely to facilitate understanding of the various embodiments described herein, and may therefore be unnecessarily presented or shown for scaling and are not intended to indicate any preference or requirement for the illustrated embodiments to exclude embodiments in conjunction with them. Detailed Implementation

[0039] Reference will now be made specifically to the representative embodiments shown in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to a single preferred embodiment. Rather, it is intended to cover alternative forms, modifications, and equivalents that may be included within the substance and scope of the embodiments defined by the appended claims.

[0040] As previously mentioned, devices may include visible light sensors and IR sensors integrated on a single silicon substrate. However, integrating such sensors into a single pixel array may provide substandard performance for various reasons. For example, given the sensitivity of the silicon-based photosensitive layer to a wide range of electromagnetic radiation wavelengths, including both visible light and IR radiation, visible light images acquired by a visible light sensor can be contaminated by electromagnetic radiation outside the visible light spectral range. To mitigate this, a dual-band spectral filter that allows only visible light and the desired range of IR wavelengths can be placed above the integrated visible light and IR sensors. However, given the sensitivity of the silicon-based photosensitive layer, IR radiation allowed through the dual-band spectral filter (e.g., through an IR notch defined by the dual-band spectral filter) may still contaminate the visible light pixels (even in the absence of active IR illumination). This can result in a significant reduction in the signal-to-noise ratio (SNR) of the visible light image—especially in low light conditions and for scenarios with abundant IR content (e.g., incandescent lighting, sunset, lighting from candles, illumination from infrared sources on the device, etc.). Although IR radiation blocking filters can be deployed at the pixel level (e.g., above visible light pixels), such filters are limited in their ability to increase the SNR of visible light images and can still degrade the quality of visible light images (e.g., color quality).

[0041] Integrating visible light and IR pixels into a single pixel array can also affect IR sensing. For example, given the sensitivity of silicon-based photosensitive layers to a wide range of electromagnetic radiation wavelengths, including both visible light and IR radiation, IR images acquired by IR sensors can be contaminated by electromagnetic radiation outside the IR spectral range. This can lead to a significant reduction in the SNR of IR images—especially when acquiring IR images outdoors (e.g., in sunlight), under bright lighting conditions, or in the presence of high levels of background light.

[0042] Integrating visible light and IR pixels into a single pixel array can also reduce the spatial resolution of both the visible light sensor and the IR sensor, because some pixels in the visible light sensor's pixel array can be allocated for IR sensing, and some pixels in the IR sensor's pixel array can be allocated for visible light sensing. This fundamentally reduces the quality and / or resolution of both the visible light image and the IR image (or IR depth information).

[0043] This document describes a stacked electromagnetic radiation sensor—that is, a sensor stack in which a first electromagnetic radiation sensor is stacked on top of a second electromagnetic radiation sensor. For the purposes of this specification, labels such as "first" and "second" are used for ease of reference when referring to different instances of the same or similar components. A component referred to as "first" in one drawing may be referred to as "first," "second," or other instances of a component in another drawing or claim.

[0044] The first electromagnetic radiation sensor can be positioned such that electromagnetic radiation incident on the electromagnetic radiation receiving surface of the stacked electromagnetic radiation sensor is typically received by the first electromagnetic radiation sensor before being received by the second electromagnetic radiation sensor. In other words, the first electromagnetic radiation sensor can be positioned within the FoV (field of view) of the second electromagnetic radiation sensor.

[0045] The first electromagnetic radiation sensor may have a high QE (quantum efficiency) for converting a first electromagnetic radiation wavelength range (e.g., visible light) into a first set of electrical signals. The first electromagnetic radiation sensor may also have a low QE for converting a second electromagnetic radiation wavelength range (e.g., IR radiation wavelength range) into a first set of electrical signals. For the purposes of this specification, a high QE for converting electromagnetic radiation wavelengths into a set of signals means that at least 40% of photons in that electromagnetic radiation wavelength range are converted into a set of electrical signals, and preferably more than 50%, more than 60%, more than 70%, more than 80%, or more than 90%. A low QE for converting electromagnetic radiation wavelengths into a set of signals means that less than 15% of photons in that electromagnetic radiation wavelength range are converted into a set of electrical signals, and preferably less than 10% or less than 5%. Alternatively or additionally, the difference between high and low QE may be that the high QE value is at least 30 points larger than the low QE value, and preferably at least 40 points, at least 50 points, at least 60 percentage points, or at least 70 points larger. For example, a high QE can convert 40% of photons, while a low QE can convert 10% (i.e., a difference of 30 points). Generally, a high QE is associated with high sensitivity and high absorption across the entire wavelength range of electromagnetic radiation. Conversely, a low QE is typically associated with low sensitivity and low absorption across the same wavelength range. In some cases, electromagnetic radiation sensors may have an even higher QE for a portion of their high QE range (e.g., a higher QE for green light than for red light).

[0046] The first electromagnetic radiation sensor may also transmit at least partially the second electromagnetic radiation wavelength range, and in some cases, it may transmit a high degree of the second electromagnetic radiation wavelength range (e.g., the IR radiation wavelength range). For the purposes of this specification, the first electromagnetic radiation sensor may transmit 10% or less of the second electromagnetic radiation wavelength range, but may also transmit up to 90% or more of the second electromagnetic radiation wavelength range.

[0047] The second electromagnetic radiation sensor may have a high QE for converting a second electromagnetic radiation wavelength range into a second set of electrical signals.

[0048] The first electromagnetic radiation wavelength range and the second electromagnetic radiation wavelength range can be non-overlapping to reduce the possibility of optical contamination between the first electromagnetic radiation sensor and the second electromagnetic radiation sensor.

[0049] To configure the first and second electromagnetic radiation sensors to have high QE in different non-overlapping electromagnetic radiation wavelength ranges and low QE outside their respective electromagnetic radiation wavelength ranges, it may be useful to configure one or both of the electromagnetic radiation sensors as sensors comprising: 1) a semiconductor substrate (e.g., a silicon substrate) including pixel circuitry for a pixel array, and 2) a photosensitive material deposited on the semiconductor substrate (e.g., a quantum dot film (QF), an organic material, or a material with high α, good mobility, and low-temperature integration with silicon, such as Sb₂Se). (3-x) Te (x) Where x=0 has a direct bandgap of ~1.2 eV, and x>0 tunes the bandgap to lower energies. Photosensitive materials can provide greater flexibility in tuning electromagnetic radiation sensors to a high QE wavelength range (or similarly, a low QE wavelength range). In some cases, the electrical connection array between the pixel circuitry for the pixel array and the photosensitive material may include one or more electrical connections comprising a heterojunction photodiode. The heterojunction photodiode may be formed between the semiconductor substrate and the photosensitive material. In some embodiments, the electrical connection array may at least partially transmit a second electromagnetic radiation wavelength range.

[0050] In some implementations, unstacked electromagnetic radiation sensors can benefit from using photosensitive materials deposited on a semiconductor substrate.

[0051] The following text is for reference only. Figures 1 to 21 These and other embodiments are discussed. However, those skilled in the art will readily understand that the detailed descriptions given herein with respect to the accompanying drawings are for illustrative purposes only and should not be construed as limiting.

[0052] Directional terms such as “top,” “bottom,” “upper,” “lower,” “above,” “below,” “below,” “front,” “rear,” “above,” “below,” “left,” and “right” are used in reference to the orientation of some components in some of the figures described below. Because components in various embodiments may be positioned in multiple different orientations, directional terms are for illustrative purposes only and are not intended to be limiting in any way. Directional terms are intended to be interpreted broadly and should therefore not be construed as excluding components oriented in different ways.

[0053] Figure 1An example of a camera 100 including a stacked electromagnetic radiation sensor 110 (or a stacked electromagnetic radiation imager or sensor stack) is shown, wherein a first electromagnetic radiation sensor 102 is stacked on (e.g., directly on, above, or over) the electromagnetic radiation receiving surface 112 of a second electromagnetic radiation sensor 104. For the purposes of this specification, an element or component stacked on top of another element or component is positioned in the FoV of that other element or component such that electromagnetic radiation will tend to pass through the upper element or component in the stack before passing through the lower element or component in the stack. The element or component stacked on top of another element or component is also connected to the other element or component—directly (e.g., "on another element or component") or indirectly (e.g., via one or more other elements or components in the stack).

[0054] Electromagnetic radiation 122 can be received in the stacked electromagnetic radiation sensor 110 via the first electromagnetic radiation sensor 102, and a portion of the electromagnetic radiation 122 can pass through the first electromagnetic radiation sensor 102 to reach the second electromagnetic radiation sensor 104. The first electromagnetic radiation sensor 102 may have a high QE for converting a first electromagnetic radiation wavelength range (or a first electromagnetic radiation wavelength) into a first set of electrical signals. The first electromagnetic radiation sensor 102 may also at least partially transmit a second electromagnetic radiation wavelength range (or a second electromagnetic radiation wavelength) (or have a low QE for converting the second electromagnetic radiation wavelength range, or have low absorption or no absorption therein). The second electromagnetic radiation sensor 104 may have a high QE for converting a second electromagnetic radiation wavelength range (or a second electromagnetic radiation wavelength) into a second set of electrical signals.

[0055] In some implementations, the first electromagnetic radiation sensor 102 may be a visible light sensor, such as an RGB light sensor. In some cases, the RGB light sensor may include a Bayer patterned color filter. Alternatively, the visible light sensor may take other forms, such as a yellow-cyan-magenta (YCM) light sensor, a yellow-cyan-magenta-white (YCMW) light sensor, a red-blue-green-white (RBGW) light sensor, etc.

[0056] In some embodiments, the second electromagnetic radiation sensor 104 may be an IR sensor. When the second electromagnetic radiation sensor 104 is an IR sensor, and in some examples, the IR sensor may be tuned to detect a narrow range of electromagnetic radiation wavelengths of approximately 940 nm, 1125 nm, 1370 nm, or 1550 nm (e.g., the IR sensor may have a narrow spectral sensitivity of 40-50 nm or less). In other examples, the IR sensor may be tuned to detect a wide range of electromagnetic radiation wavelengths (i.e., having a wide spectral sensitivity). For the IR sensor in the dual-band spectral filter 116 of the camera 100, which includes the stacked electromagnetic radiation sensor 110, a similar narrow or wide passband may be defined.

[0057] When the second electromagnetic radiation sensor 104 is an IR sensor, the IR sensor can be configured in various ways for various purposes. For example, in some cases, the IR sensor can be configured as an image sensor (i.e., a 2D sensor). When configured as an image sensor, the IR sensor can be configured to resemble a typical visible light sensor, but can be sensitive to IR radiation instead of visible light. For example, the IR sensor can be configured to determine how much IR radiation each pixel of the IR sensor absorbs within a specific time window (e.g., using a global shutter or rolling shutter method). In addition, or alternatively, the IR sensor can be configured as a depth sensor, which, depending on its specific implementation, can be considered a 2D sensor or a 3D sensor. When configured as a depth sensor, an IR sensor can be configured to measure the time it takes for a specific photon to be incident on the IR sensor (e.g., the IR sensor may include a single-photon avalanche diode (SPAD) array configured to acquire direct time-of-flight (dToF) measurements, or the IR sensor may include an array of sensor elements (e.g., gated pixels (or simply locked pixels)) configured to acquire indirect time-of-flight measurements (e.g., where the integration time of the sensor elements is gated or modulated synchronously with the modulation of the illumination source)). In some cases, an IR sensor configured as an image sensor can also be configured as a depth sensor. For example, an IR sensor configured as an image sensor can sense IR radiation emitted by a structured illumination source and can provide an output that can be used to derive depth information. Therefore, such an IR sensor can be considered both an image sensor and a depth sensor.

[0058] When the second electromagnetic radiation sensor is an IR sensor, an optional IR illuminator 106 (or multiple IR illuminators) can illuminate the object or the FoV of the IR sensor with IR radiation. IR radiation may include wavelengths (or multiple wavelengths) of IR radiation detected by the IR sensor. The IR illuminator 106 may include one or more electromagnetic radiation sources (e.g., one or more light-emitting diodes (LEDs) or lasers) configured to emit IR radiation. The type of IR illuminator 106 (or multiple IR illuminators) used may depend on the type of IR sensor used, but typically illuminates the entire FoV of the IR sensor (e.g., using floodlighting) or a selected portion of the FoV of the IR sensor (e.g., using patterned structured light or field / point lighting). The IR illuminator 106 can provide fixed or constant illumination, or the IR illuminator 106 can be configured to adjust the spatial positioning (e.g., line scanning or point scanning) or intensity of the IR radiation over time. In some cases, the IR illuminator 106 can provide illumination modulated by one or more of time, space, or intensity modulation. As an example of IR illuminator 106, in a system including an IR depth sensor, IR illuminator 106 can provide structured light illumination and project one or more known illumination patterns into the FoV of the IR depth sensor. As another example, in a system including an IR depth sensor configured to acquire dToF measurements, IR illuminator 106 can project a fixed illumination pattern into the FoV of the IR depth sensor, or can scan an illumination pattern (e.g., rows or groups of dots) across the FoV. As yet another example, in a system including an IR depth sensor configured to acquire indirect ToF (iToF) measurements, IR illuminator 106 can be configured to project flood illumination into the FoV of the IR depth sensor and vary the intensity of the flood illumination over time. As yet another example, in a system including an IR image sensor or an IR depth sensor, IR illuminator 106 can be used as a “flash” during image acquisition in some cases.

[0059] The first electromagnetic radiation sensor 102 and / or the second electromagnetic radiation sensor 104 may optionally be coupled to a pixel processing chip 108 (or a main pixel processing chip), which includes analog and / or digital circuitry (e.g., an analog-to-digital converter (ADC)) for processing the signals generated by both the first electromagnetic radiation sensor 102 and the second electromagnetic radiation sensor 104. In some cases, the pixel processing chip 108 may be formed on a semiconductor substrate shared by the second electromagnetic radiation sensor 104. The first electromagnetic radiation sensor 102 may be electrically connected to the pixel processing chip 108 via a conductor routed through or around the second electromagnetic radiation sensor 104.

[0060] In some embodiments, a stacked electromagnetic radiation sensor 110 (and more specifically, the electromagnetic radiation receiving surface 114 of the first electromagnetic radiation sensor 102) may be positioned behind an optional dual-band spectral filter 116 of the camera 100. The dual-band spectral filter 116 may allow only a range of visible light wavelengths and a range of IR radiation wavelengths to pass through. The first electromagnetic radiation sensor 102 may have a high QE for converting some or all of the visible light wavelength range into a first set of electrical signals, and may have a low QE for converting some or all of the IR radiation wavelength range into the first set of electrical signals. The second electromagnetic radiation sensor 104 may have a high QE for converting some or all of the IR radiation wavelength range into the second set of electrical signals. When the first electromagnetic radiation sensor 102 has a high QE for converting visible light wavelengths into the first set of electrical signals, the dual-band spectral filter 116, in conjunction with the first electromagnetic radiation sensor 102, may help reduce contamination of the second electromagnetic radiation sensor 104 by visible light and / or electromagnetic radiation with wavelengths outside the intended high QE range of the second electromagnetic radiation sensor 104.

[0061] In some embodiments, an optional autofocus (AF) mechanism 118 of the camera 100 may also or alternatively be disposed above the electromagnetic radiation receiving surface 114 of the first electromagnetic radiation sensor 102 (e.g., where a dual-band spectral filter 116 is positioned between the AF mechanism 118 and the first electromagnetic radiation sensor 102). In some cases, the AF mechanism 118 may be a phase detection autofocus (PDAF) mechanism, which includes a metal shield, microlenses, etc. In some cases, the AF mechanism 118 may be located elsewhere in the stacked electromagnetic radiation sensor 110, or may include elements distributed in different layers of the stacked electromagnetic radiation sensor 110. In some cases, the AF mechanism 118 may facilitate focusing electromagnetic radiation received from within the FoV onto the stacked electromagnetic radiation sensor 110, and may be partially or completely positioned outside the path through which the electromagnetic radiation propagates into or through the stacked electromagnetic radiation sensor 110.

[0062] In some embodiments, an optional lens or lens system (e.g., a lens stack) or outer lens 120 of camera 100 may be disposed above the electromagnetic radiation receiving surface 114 of the first electromagnetic radiation sensor 102 (e.g., where a dual-band spectral filter 116 and an AF mechanism 118 are positioned between lens 120 and the first electromagnetic radiation sensor 102). Lens 120 may help form images of desired quality on the first electromagnetic radiation sensor 102 and the second electromagnetic radiation sensor 104.

[0063] In some implementations, other components may be set Figure 1Above, below, or between the components shown. For example, various lenses, filters, or other optical components may be positioned above the electromagnetic radiation receiving surface 114 of the first electromagnetic radiation sensor 102, and / or between the first electromagnetic radiation sensor 102 and the second electromagnetic radiation sensor 104.

[0064] The stacked electromagnetic radiation sensor 110 can be configured differently as a visible image sensor and an IR depth sensor (e.g., an RGB image sensor and an IR depth sensor), a visible image sensor and an IR image sensor (e.g., an RGB image sensor and an IR image sensor), etc.

[0065] Figure 2 An exemplary exploded view of a stacked electromagnetic radiation sensor 200 is shown. Similar to the reference... Figure 1 The described stacked electromagnetic radiation sensor 200 may include a first electromagnetic radiation sensor stacked on top of a second electromagnetic radiation sensor. Therefore, the stacked electromagnetic radiation sensor 200 may include a reference... Figure 1 Some or all aspects of the stacked electromagnetic radiation sensor described.

[0066] By way of example, and for illustrative purposes, the first electromagnetic radiation sensor may be an RGB light sensor 202, and the second electromagnetic radiation sensor may be an IR sensor 204. However, each of the first and second electromagnetic radiation sensors may take other forms, as described in the references. Figure 1 As stated above.

[0067] like Figure 2 As shown, the RGB light sensor 202 may include a lens array 206, a color filter array 208, and a photodetector array 210 including pixel circuitry from the electromagnetic radiation receiving side (or illumination side 220) of the stacked electromagnetic radiation sensor 200. In some embodiments, the lens array 206 may include a microlens array. The microlens array may include individual microlenses positioned above each color pixel defined by the color filter array 208. In some embodiments, the color filter array 208 may include a Bayer patterned color filter, but the color filter array 208 may alternatively include different types of color filters. By way of example, the color filter array 208 is shown defining four pixels. In practical embodiments, the color filter array 208 may define thousands or millions of pixels.

[0068] The IR sensor 204 may be a stacked back-illuminated (BSI) silicon-based sensor. In some embodiments, the stacked BSI sensor may include two silicon layers: a BSI layer 212 comprising a BSI pixel array that absorbs IR radiation within the IR notch spectral band (or at a specific IR radiation wavelength); and a pixel processing chip 214 on which the BSI layer 212 is stacked. The pixel processing chip 214 may include analog and digital circuitry for the IR sensor 204. In alternative embodiments, the IR sensor 204 may be a stacked front-illuminated (FSI) sensor or other types of IR sensor 204. In some embodiments, the IR sensor 204 may include a SPAD array or a gated pixel array, thereby providing, for example, dToF or iToF measurements that can be used to generate depth information.

[0069] In some implementations, the BSI layer 212 can be stacked on and electrically connected to the pixel processing chip 214 using a copper-to-copper hybrid stacking technique. The RGB light sensor 202 can also be stacked on the IR sensor 204 using a wafer-to-wafer stacking technique or a wafer transfer process, as illustrated in the example below. Figures 14A to 15B As described, a connection between the pixel processing chip 214 and the RGB light sensor 202 can be provided using through-silicon vias (TSVs) and / or other electrical connections.

[0070] Pixel processing chip 214 may be connected to the pixel circuitry / array of both RGB light sensor 202 and IR sensor 204 (e.g., to the pixel circuitry of photodetector array 210 and the BSI pixel array of BSI layer 212). Pixel processing chip 214 may include digital and / or analog readout circuitry for both RGB light sensor 202 and IR sensor 204.

[0071] Visible light received by the stacked electromagnetic radiation sensor 200 can be focused by the lens array 206 (e.g., a microlens array), color-separated from the absorptive color filters (e.g., the red, green, and blue filters of a Bayer patterned color filter) of the color filter array 208, and absorbed by the photodetectors of the photodetector array 210. At least some IR radiation can pass through the layers of the RGB light sensor 202 to reach the IR sensor 204. In some embodiments, the stacked electromagnetic radiation sensor 200 may include one or both of the following two additional layers: a focusing element 216 (e.g., a diffractive microlens or any other type of focusing element) and a visible light blocking filter 218. The focusing element 216 and the visible light blocking filter 218 may be disposed between the RGB light sensor 202 and the IR sensor 204 to focus the IR radiation onto the sensitive portions of one or more IR pixels and to block any residual visible light that may pass through the RGB light sensor 202.

[0072] To achieve high performance, the photodetector array 210 may be configured to have a high QE for converting visible light into an electrical signal; components of the RGB light sensor 202 may be configured to have a low QE for converting a range of IR radiation wavelengths into electrical signals (and in some cases, may include the IR notch spectral band of the IR sensor 204 and / or include stacked electromagnetic radiation sensors (e.g., as referenced)). Figure 1 The dual-band spectral filter of the camera (described above) does not absorb any IR radiation (or absorbs only a negligible amount of IR radiation); and all components above the BSI layer 212 (including TSV and routing components in some cases) provide high transmittance of IR radiation in the IR notch spectral band of the IR sensor 204 and / or in the dual-band spectral filter of the camera including the stacked electromagnetic radiation sensor 200. When these conditions are met, the signal generated by the RGB light sensor 202 is not contaminated by IR radiation (or is contaminated to a minimum), thereby improving the SNR and image quality of the RGB light sensor output. This can be particularly useful when imaging low-light scenes with high IR content. In addition, the signal generated by the IR sensor 204 is not contaminated by visible light (or is contaminated to a minimum). In other words, the IR sensor 204 shields visible light through the photodetector array 210 and through the visible light blocking filter 218 (in embodiments including filter 218) with high QE (or absorptivity) of visible light.

[0073] Furthermore, when the above conditions are met, both the RGB light sensor 202 and the IR sensor 204 can have full resolution in their given optical format; the pixel size, pixel architecture, and operating mode of the RGB light sensor 202 and the IR sensor 204 can be selected independently, thus providing great flexibility in the design and architecture of the RGB light sensor 202 and the IR sensor 204; and the RGB light sensor 202 can have a different or smaller pixel size than the IR sensor 204. In some embodiments, the RGB light sensor 202 can be configured to operate in rolling shutter mode or global shutter mode.

[0074] Additionally, when the above conditions are met, the stacked electromagnetic radiation sensor 200 can be used to generate IR image information (e.g., thermal or chromatic information for adjusting visible images) or IR depth information (e.g., depth maps). The IR sensor 204 may include rolling shutter or global shutter pixels, or dToF or iToF pixels (i.e., pixels used to acquire dToF or iToF measurements), having the same or different resolution as their corresponding visible light pixels in the RGB light sensor 202. For example, the size of the IR pixels can be an integer (or non-integer) multiple (or fraction) of the RGB pixels. For the convenience of commonly used readout circuitry, the pixel size of the IR sensor 204 can be a multiple of the pixel size of the RGB light sensor 202. However, this is not a necessary condition. As an example, the IR sensor 204 may have a pixel size (or resolution) of 4µm × 4µm and a pixel array size of 1 megapixel, but the RGB light sensor 202 may have a pixel size (or resolution) of 1µm × 1µm and a pixel array size of 16 megapixels. These two pixel arrays can be used in the same optical format (e.g., 1 / 2.8 inch, 4:3 aspect ratio).

[0075] To achieve optimal performance, the IR notch spectral band of the IR sensor 204 should be selected to have good separation from the visible spectrum to which the RGB light sensor 202 is sensitive, such that the sensitivity of the RGB light sensor 202 does not overlap with or minimally overlaps with the IR notch spectral band. Alternatively, the photosensitive materials and designs of both the RGB light sensor 202 and the IR sensor 204 can be selected to provide no overlap or minimal overlap between their respective electromagnetic radiation sensitivities. In practice, the IR notch spectral band can be determined by the imaging system requirements, thus limiting the selection of photosensitive materials and designs for the RGB light sensor 202 and the IR sensor 204.

[0076] Figure 3A Another exemplary exploded view of the stacked electromagnetic radiation sensor 300 is shown. The stacked electromagnetic radiation sensor 300 is similar to the reference [reference image]. Figure 2 The described stacked electromagnetic radiation sensor, but Figure 2 The photodetector array 210 is implemented using a hybrid design—for example, combining a photosensitive material 302 (or other panchromatic photosensitive layer) with a semiconductor substrate (e.g., a silicon substrate) 304. The semiconductor substrate 304 may include pixel circuitry for the photosensitive material 302. The photosensitive material 302 (or panchromatic photosensitive layer) may, in some cases, include quantum dot (QD) films, organic materials, etc.

[0077] In some embodiments, the photosensitive material 302 can be non-silicon-based, which allows it to transmit more electromagnetic radiation than a silicon-based photodetector array. This improves the operation of the IR sensor 204. For example, consider the case of a stacked RGB-IR sensor with an IR sensor 204 having an IR notch spectral band of approximately 940 nm. The width of the IR notch spectral band can be defined by the system's lenses and other optical parameters, and can be approximately 40-50 nm. To meet reference... Figure 2 Under the described high-performance conditions, the RGB light sensor 202 has no sensitivity or minimal sensitivity (i.e., low QE) for electromagnetic radiation wavelengths above ~900 nm. The IR sensor 204 can be constructed using this assumption and can use silicon as its photosensitive layer. In some cases, the IR sensor 204 may have a BSI stacked silicon sensor design or an FSI stacked silicon sensor design. The use of photosensitive material 302 in the RGB light sensor 202 allows the RGB light sensor 202 to limit its sensitivity (or high QE range) to electromagnetic radiation wavelengths below ~900 nm.

[0078] Figure 3B References are shown Figure 3A The described RGB light sensor 202 and Figure 3A Facade 310, which is an assembly of components not specifically shown in the figure.

[0079] like Figure 3B As shown, a common electrode 312 for the photosensitive material 302 (i.e., the electrode for the entire photosensitive material 302) may be positioned on and electrically contacted with the electromagnetic radiation receiving surface 314 of the photosensitive material 302. Individual electrical contacts 316 (e.g., pixel contacts) may be disposed on the electromagnetic radiation emitting surface 318 of the photosensitive material 302, wherein each individual electrical contact 316 provides electrical contact between a portion of the photosensitive material 302 and the pixel circuitry of the corresponding pixel. The pixel circuitry may be included in a semiconductor substrate 304 and may provide control and signal processing for the photosensitive material 302, including charge acquisition, kTC noise cancellation, etc. In some embodiments, the thickness of the silicon layer (with the pixel circuitry) may be relatively small—approximately one micrometer (e.g., one micrometer ± 10% or ± 1%)—to provide high transmittance of IR radiation to the IR sensor 204. The elements of the pixel circuitry, the contacts of the photosensitive material 302, and the conductive traces providing signal routing may be made of a transparent material that provides high transmittance of IR radiation. Examples of such transparent materials include indium tin oxide (ITO) and polycrystalline silicon.

[0080] As previously described, the photosensitive material 302 may include a QD film (QF) or an organic material. When the photosensitive material 302 includes a QF, the panchromatic photosensitive layer may be formed from a film comprising an array of semiconductor quantum dots. The excitons of each quantum dot may be quantum confined to a volume smaller than the Bohr radius of a bulk semiconductor exciton. The quantum dot size alters the exciton energy, thereby providing the ability to tune the optical absorption initiation point to the desired higher energy. The composition of the photosensitive material may be selected to obtain a desired combination of quantum dot size, size distribution width, optical absorption initiation point, valence band energy, and conduction band energy.

[0081] The advantages of QF-based panchromatic photosensitive layers include: high absorption of electromagnetic radiation within the target spectral range, high quantum efficiency (QE) within the target spectral range, high uniformity and low crosstalk between pixels, low dark current, flexibility in spectral response tuning, low operating voltage, and compatibility with complementary metal-oxide-semiconductor (CMOS) imaging processes. In some cases, the optical absorption threshold of the QF can be tuned to shorter or longer wavelengths by changing the QD size.

[0082] Alternatively, the photosensitive material 302 can be implemented using organic materials. The active layer of the organic material may include, for example, a single type of polymer molecule, or a bulk heterojunction of different polymer molecules (or polymer and non-polymer organic molecules). The pixel architecture and readout circuitry of the photosensitive material 302 based on the organic-based light-absorbing material can be similar to the pixel architecture and readout circuitry of the QF-based photosensitive material 302.

[0083] Photosensitive material 302 (or full-color photosensitive layer) can be deposited using various methods, including spin coating, slot extrusion coating, solution inkjet printing, or vacuum deposition.

[0084] As an alternative, the photosensitive material 302 and the semiconductor substrate 304 can be replaced by a silicon BSI layer comprising a BSI pixel array. However, the silicon BSI layer can be sensitive to IR radiation (or have a high QE), and this IR sensitivity can contaminate the visible light image and reduce the SNR—especially in low light conditions and in the presence of abundant IR. In some cases, from the perspective of color accuracy and / or white balance, the effects of IR contamination in the visible light image can be mitigated by measuring the IR content using the IR sensor 204 and using the output of the IR sensor 204 as input to a color processor (or color processing algorithm). Alternatively, in applications where color accuracy is less critical, the output of the IR sensor 204 can be used to improve luminance sensitivity under very low light conditions.

[0085] Figure 4A Another exemplary exploded view of a stacked electromagnetic radiation sensor 400 is shown. Similar to reference... Figures 1 to 3AThe described stacked electromagnetic radiation sensor 400 may include a first electromagnetic radiation sensor stacked on top of a second electromagnetic radiation sensor. Therefore, the stacked electromagnetic radiation sensor 400 may include a reference... Figures 1 to 3A Some or all aspects of the stacked electromagnetic radiation sensor described.

[0086] As previously mentioned, and in some examples, the first electromagnetic radiation sensor may be a visible light sensor, such as RGB light sensor 402, and the second electromagnetic radiation sensor may be an IR sensor 404. However, each of the first and second electromagnetic radiation sensors may take other forms, as described in the references. Figures 1 to 3B As stated above, and as will be described in further detail herein. Figure 4A As shown, the RGB light sensor 402 can be formed as a semiconductor-based (or silicon-based) pixel array stacked on a QF IR ToF sensor (or other QF IR sensor).

[0087] exist Figure 4A In this embodiment, the RGB light sensor 402 may be a silicon-based RGB sensor and may include a lens array 406, a color filter array 408, and a photodetector array 410 that may include pixel circuitry from the electromagnetic radiation receiving side (or illumination side) of the stacked electromagnetic radiation sensor 400. In some embodiments, the lens array 406 may include a microlens array. The microlens array may include individual microlenses positioned above each color pixel defined by the color filter array 408. In some examples, the photodetector array 410 may be implemented using a hybrid design and may include a photosensitive material (or other panchromatic photosensitive layer) bonded to a semiconductor substrate. The semiconductor substrate may include pixel circuitry for the photosensitive material. In some cases, the photosensitive material (or panchromatic photosensitive layer) may be implemented using QF, organic materials, etc., as will be discussed in further detail herein.

[0088] The IR sensor 404 can be implemented using a separate photosensitive material (e.g., QF 415) that forms a QF / silicon heterojunction at and / or around the interface between the two materials. Additionally, in some examples, the IR sensor 404 may include a pixel processing chip 414. The pixel processing chip 414 may include analog and / or digital circuitry for the IR sensor 404. The QF / silicon heterojunction enables high-speed operation of the IR sensor 404, which may be desirable for depth sensing, or a combination of depth sensing and RGB light sensing, and / or other applications. Furthermore, the QF / silicon heterojunction can be implemented as a tunable bandgap device, which can be used for, for example, dToF and / or iToF depth map acquisition. By tuning the bandgap of the QF, the IR sensor 404 can be made sensitive to electromagnetic radiation exceeding the bandgap of silicon (or tuned to have a high QE). Figure 4AIn the examples, the band gap of QF can be narrower or smaller than that of silicon, and in some cases, it can be less than about 1.1 eV.

[0089] In some examples, QF-based image sensors sensitive to electromagnetic radiation exceeding the bandgap of materials used for RGB imaging allow RGB light sensors 402 to be directly stacked on top of the QF. Furthermore, the RGB light sensor 402 can be stacked on top of the IR sensor 404, allowing the illumination path to pass first through the RGB light sensor 402 and then be received by the IR sensor 404. Even though the RGB light sensor 402 can be directly located on the IR sensor 404, contamination of the RGB light sensor pixels by IR illumination can be mitigated or avoided. Therefore, using QF as the photosensitive material allows for less space in the stacked electromagnetic radiation sensor 400, thus allowing more space within the semiconductor substrate for additional circuitry or a larger maximum well capacity within the semiconductor substrate.

[0090] In some examples, a QF / silicon heterojunction can reduce unwanted capacitance (e.g., capacitance that might slow down the operation of the IR sensor 404). In some examples, the QF may contact the pixel transistor via an indium tin oxide / titanium nitride bottom contact and a copper plug or wire. This indium tin oxide / titanium nitride and copper plug can cause unwanted capacitance and slower operation of the IR sensor 404, making the device too slow for depth sensing applications. By using a QF / silicon heterojunction in the IR sensor 404, capacitance can be significantly reduced to achieve higher operating speeds for depth sensing applications. Heterojunctions are discussed in further detail in this paper.

[0091] The choice of the QF bandgap can be based on a variety of considerations. In some examples, the QF bandgap can be selected to allow laser and / or diode light sources (e.g., IR illuminators) to operate in compliance with safety requirements, which can further lead to higher illumination power and a better SNR ratio. Another consideration for improving SNR is to choose the QF bandgap to be as wide as possible. Doing so reduces dark current, which improves SNR.

[0092] As mentioned above, Figure 4A The IR sensor 404 can be used for ToF depth sensing. To achieve fast operating speed of the IR sensor 404, several factors can be considered. One such factor is the QF response time. The QF response time can depend on any single factor and / or a combination of factors, such as the mobility of the material used for the QF, the thickness of the QF, and the bias voltage that can be applied to the QF.

[0093] Sensor 400 can be used in various environments, including inside buildings or outdoors on sunny days. In external environments where sunlight may be present, the electromagnetic radiation or solar spectrum can at least partially contaminate IR sensor 404. In this example, the bandgap of the QF used in IR sensor 404 can be selected to have a high absorption coefficient at the wavelength where the solar spectrum is minimized. Wavelengths used to minimize absorption of the solar spectrum can include approximately the following: 940 nm or approximately thereafter, 1125 nm or approximately thereafter, 1370 nm or approximately thereafter, and / or 1550 nm or approximately thereafter. Figure 4A In this design, the QF of the IR sensor 404 is sensitive to approximate wavelengths or a range of approximate wavelengths greater than 1100 nm, which helps to minimize solar background illumination absorbed by the IR sensor 404. Furthermore, wavelengths greater than approximately 940 nm allow for lower irradiance limits for laser compliance standards, which can permit more powerful or higher-power emitters.

[0094] Due to the high-speed operation required for ToF sensing, various material properties of the QF can be considered. In some examples, higher external quantum efficiency can be achieved by maximizing the light absorption of the QF. In these cases, the proportion of absorbed incident light can be approximated on a one-way basis as follows:

[0095] %A = 1 - exp(-α d)

[0096] Where A is the proportion of incident light absorbed, α is the film absorption coefficient at the operating wavelength, and d is the QF thickness. In some examples, sufficient absorbent can have a QF of 10000 cm⁻¹. -1 Up to 20000cm -1 The approximate range of α. The operating speed of the QF can be influenced by the photogenerated charge transport time t in the QF. tr The impact of this. Transmission time can be expressed as:

[0097] t tr = d 2 / µV

[0098] Where d is the QF thickness, µ is the charge mobility, and V is the applied bias voltage. Generally, for a QF, µ can be 0.01 cm. 2 V -1 s -1 Up to 1cm 2 V -1 s -1 Within an approximate range. In some examples, to achieve the desired transmission time and quantum efficiency, the corresponding minimum mobility and QF thickness can be determined.

[0099] Figure 4B Another exemplary exploded view of the stacked electromagnetic radiation sensor 400b is shown. Similar to the reference... Figures 1 to 4A The described stacked electromagnetic radiation sensor 400b may include a first electromagnetic radiation sensor stacked on top of a second electromagnetic radiation sensor. Therefore, the stacked electromagnetic radiation sensor 400b may include a reference... Figures 1 to 4A Some or all aspects of the stacked electromagnetic radiation sensor described.

[0100] As previously stated, and in some examples, the first electromagnetic radiation sensor may be a visible light sensor, such as an RGB light sensor 402b, and the second electromagnetic radiation sensor may be an IR sensor 404b. Each of the first and second electromagnetic radiation sensors may take other forms, as described in the references. Figures 1 to 4A As stated above, and as will be described in further detail herein. Figure 4B As shown, QF RGB light sensors can be stacked on top of QF IR ToF sensors (or other QF IR sensors).

[0101] The band gap of the IR absorption QF can be selected to have a high absorption coefficient at the wavelength where the solar spectrum is minimized. Wavelengths used to minimize absorption in the solar spectrum can include approximately the following: 940 nm or approximately, 1125 nm or approximately, 1370 nm or approximately, and / or 1550 nm or approximately. Figure 4B In this context, the QF IR ToF sensor can absorb approximate wavelengths or the approximate wavelength range greater than 940 nm, which can help minimize solar background illumination absorbed by the IR sensor 404b.

[0102] Figure 4B It can include the RGB light sensor 402b, but Figure 4B It may include an RGB light sensor 402 with a separate photosensitive material (e.g., QF407b), instead of... Figure 4A The depicted silicon-based RGB light sensor. Figure 4B In this design, the bandgap of the top RGB QF407b can be selected to be narrow enough to absorb visible light up to about 700 nm, but wider than the bandgap of the bottom IR-absorbing photosensitive material (e.g., another QF). The bandgap can be selected in such a way that the electromagnetic radiation sensed for ToF measurements may not be absorbed by the QF-based RGB light sensor 402.

[0103] also, Figure 4B This may include references Figure 4AThe components discussed include, from the electromagnetic radiation receiving side (or illumination side) of the stacked electromagnetic radiation sensor 400b, a lens array 406b, a color filter array 408b, and a pixel circuit 410b for the QF 407b. In some embodiments, the lens array 406b may include a microlens array. This microlens array may include individual microlenses positioned above each color pixel defined by the color filter array 408b. Figure 4B It may also include other elements, such as those relative to Figure 4A The above is discussed. Furthermore, in some examples, Figure 4A and Figure 4B Elements with similar numbers as depicted can share similar characteristics.

[0104] The IR sensor 404b may include a QF 415b, which may form a QF / silicon heterojunction at and / or around the interface between the two materials. The QF / silicon heterojunction enables high-speed operation of the IR sensor 404b, which may be desirable for depth sensing, or a combination of depth sensing and RGB light sensing, and / or other applications. Furthermore, the QF / silicon heterojunction can be implemented as a tunable bandgap device, which can be used for ToF (e.g., dToF and / or iToF) depth measurement. Figure 4B In the example, the bandgap of the QF-based IR sensor 404 may be narrower or smaller than that of silicon, and in some cases may be less than about 1.1 eV.

[0105] Figure 4C Another exemplary exploded view of the stacked electromagnetic radiation sensor 400c is shown. The stacked electromagnetic radiation sensor 400c can sense or detect IR radiation, similar to the reference sensor. Figures 1 to 4B The described IR sensor. Therefore, the stacked electromagnetic radiation sensor 400c may include a reference. Figures 1 to 4B Some or all aspects of the IR sensor described.

[0106] The IR sensor 404c may include a photosensitive material (e.g., QF 415c) that may form a QF / silicon heterojunction at and / or around the interface between the two materials. The QF / silicon heterojunction enables high-speed operation of the IR sensor 404c, which may be desirable for depth sensing, or a combination of depth sensing and RGB light sensing, and / or other applications. Furthermore, the QF / silicon heterojunction can be implemented as a tunable bandgap device that can be used for ToF (e.g., dToF and / or iToF) depth measurement. Figure 4C In this context, QF-based IR ToF sensors can absorb approximately wavelengths or wavelength ranges around or above 940nm.

[0107] exist Figure 4CIn the examples, the bandgap of the QF 415c can be narrower than or smaller than the bandgap of silicon, and in some embodiments it can be around 1.1 eV or less. By selecting a QF bandgap smaller than that of silicon, the stray light sensitivity in silicon circuits can be reduced (and in some cases eliminated). Furthermore, the QF bandgap can be selected to be within the range of IR radiation, such that illumination provided by an associated IR illuminator may be invisible to the human eye.

[0108] Figure 5A Another exploded view example of a stacked electromagnetic radiation sensor 500 is shown. Similar to the reference. Figures 1 to 4C The described stacked electromagnetic radiation sensor 500 may include a first electromagnetic radiation sensor stacked on top of a second electromagnetic radiation sensor. Therefore, the stacked electromagnetic radiation sensor 500 may include a reference... Figures 1 to 4C Some or all aspects of the stacked electromagnetic radiation sensor described.

[0109] As previously stated, and in some examples, the first electromagnetic radiation sensor may be a visible light sensor, such as RGB light sensor 502, and the second electromagnetic radiation sensor may be an IR sensor 504. However, each of the first and second electromagnetic radiation sensors may take other forms, as described in the references. Figures 1 to 4C As stated above, and as will be described in further detail herein. Figure 5A As shown, the RGB light sensor 502 can be a silicon-based sensor stacked on a QF IR image sensor.

[0110] Similar to Figure 4A The RGB light sensor 502 may be a silicon-based RGB light sensor and may include, for example, relative to at least Figure 4A Similar elements discussed. The stacked electromagnetic radiation sensor 500 may also include an IR sensor 504, which may include a photosensitive material (e.g., QF) forming a QF / silicon heterojunction at and / or around the interface between the QF and a semiconductor substrate (e.g., a silicon substrate), the semiconductor substrate including pixel circuitry for the QF. The QF / silicon heterojunction may be included in an image sensor, and... Figure 5A In some examples, higher quality RGB and IR signals can be generated than those from a Bayer-arranged image sensor employing a color sensor with distributed RGB and IR filters. In some implementations, the stacked electromagnetic radiation sensor 500 structure can be used for facial recognition applications. In some examples, facial recognition can be based on information from IR images and depth information that can be generated by machine learning, or information obtained from any other type of depth sensor.

[0111] Furthermore, the stacked structure of the electromagnetic radiation sensor 500 helps control the floodlight illumination. The IR floodlight illumination used for IR imaging can be selected to avoid contaminating the silicon RGB pixels. Additionally, the floodlight illumination can be located in areas of minimal ambient background illumination around 1125 nm and / or 1370 nm. In some examples of the stacked structure, the silicon-based RGB sensor can transmit IR radiation. Furthermore, the RGB sensor can be stacked on top of the IR sensor, allowing the illumination path to pass through the RGB sensor first and then be received by the IR sensor. Even if the RGB sensor is adjacent to the IR QF sensor, contamination of the RGB sensor pixels by IR illumination can be reduced or avoided.

[0112] Similar to other examples discussed in this paper, the choice of the QF bandgap can be based on a variety of considerations. In some examples, the QF bandgap can be selected to allow the laser and / or diode light source to operate in compliance with safety requirements, which can further lead to higher illumination power and a better signal-to-noise ratio (SNR). Another consideration for improving the SNR ratio is to choose the bandgap of the IR-absorbing QF to be as large or as wide as possible. Doing so reduces dark current, which improves the SNR ratio. In some examples, the QF bandgap can be narrower than or smaller than silicon, and can be around 1.1 eV or less. Furthermore, QF IR radiation absorbers can use less space in image sensing devices, allowing more space within the silicon layer for additional circuitry or a larger maximum well capacity within the silicon layer.

[0113] Figure 5A Image sensing devices can be used in various environments, including inside buildings or outdoors on sunny days. In external environments where sunlight may be present, the electromagnetic radiation or solar spectrum can at least partially contaminate the IR sensor. In this example, the IR absorption QF bandgap can be selected to have a high absorption coefficient at the wavelength where the solar spectrum is minimized. Wavelengths used to minimize absorption of the solar spectrum can include approximately the following amounts: 940 nm, 1125 nm, 1370 nm, and / or 1550 nm or around these. Figure 5A In this context, QF IR sensors can utilize approximate wavelengths or ranges greater than 1100 nm, which helps minimize solar background illumination reaching the IR sensor. Furthermore, wavelengths greater than approximately 940 nm allow for lower irradiance limitations for laser compliance standards, enabling more powerful or higher-power emitters. Additionally, using longer wavelengths minimizes skin reflection compared to using shorter wavelengths in absorbing quantum dot films.

[0114] Figure 5B Another exploded view example of a stacked electromagnetic radiation sensor 500b is shown. Similar to the reference. Figures 1 to 5AThe described electromagnetic radiation sensor 500b may include a first electromagnetic radiation sensor stacked on top of a second electromagnetic radiation sensor. Therefore, the stacked electromagnetic radiation sensor 500b may include a reference... Figures 1 to 5A Some or all aspects of the stacked electromagnetic radiation sensor described.

[0115] As previously stated, and in some examples, the first electromagnetic radiation sensor may be a visible light sensor, such as an RGB light sensor 502b, and the second electromagnetic radiation sensor may be an IR sensor 504b. Each of the first and second electromagnetic radiation sensors may take other forms, as described in the references. Figures 1 to 5A As stated above, and as will be described in further detail herein. Figure 5B As shown, QF RGB sensors can be stacked on top of QF IR sensors. Figure 5B In this context, QF IR sensors can utilize approximate wavelengths or ranges greater than 940 nm, which can help minimize solar background illumination reaching the IR sensor.

[0116] Figure 5B The IR absorption QF bandgap can be selected to have a high absorption coefficient at the wavelength where the solar spectrum is minimized. Wavelengths used to minimize absorption in the solar spectrum can include approximately the following: 940 nm, 1125 nm, 1370 nm, and / or 1550 nm or around these values. Figure 5B In this context, QF IR sensors can utilize approximate wavelengths or ranges greater than 940 nm, which can help minimize solar background illumination reaching the IR sensor.

[0117] Figure 5B It may include the RGB light sensor 502b, but Figure 5B It can include a QF 507b RGB sensor, instead of... Figure 5A The depicted silicon-based RGB sensor. Figure 5B In this design, the band gap of the top RGB QF layer can be selected to be small or narrow enough to absorb visible light up to approximately 700 nm, but wider than the band gap of the bottom IR-absorbing QF layer. The band gap can be selected in a way that prevents electromagnetic radiation or light suitable for IR image acquisition from being absorbed by the RGB QF sensor. Furthermore, Figure 5B May include with Figures 4A to 5A Similar components, and in some examples, Figures 4A to 5A Components with similar numbers as described can share similar characteristics.

[0118] The IR sensor 504b may include a QF 515b, which may form a QF / silicon heterojunction at and / or around the interface between the two materials. Furthermore, the QF / silicon heterojunction can be implemented as a tunable bandgap device that can be used for IR image acquisition. Figure 5B In the example, the bandgap of the QF IR sensor layer can be narrower than or smaller than that of silicon, and can be less than about 1.1 eV. A QF bandgap of less than about 1.1 eV can reduce and / or eliminate stray light sensitivity in silicon circuitry.

[0119] Use it separately from its supporting pixel circuitry (e.g.) Figures 3A to 3B , Figures 4A to 4C ,and Figure 5A and Figure 5B Using photosensitive materials (or panchromatic photosensitive layers) to implement photodetector arrays (as shown) may hinder the inherent ability of silicon-based photodetector arrays to eliminate (or reduce) kTC noise during charge (photocharge) readout. For example, the movement of photodiodes from a silicon semiconductor containing pixel circuitry (e.g., charge accumulation and readout circuitry, or "readout" circuitry) to a separate semiconductor can hinder kTC noise reduction based on correlated double sampling (CDS).

[0120] In contrast to the requirements of typical stacked BSI image sensors, the semiconductor substrate including the pixel circuitry for individual photosensitive materials can comprise both p-channel metal-oxide-semiconductor (PMOS) transistors and n-channel metal-oxide-semiconductor (NMOS) transistors, and the performance of the photodetector is not particularly degraded because light conversion occurs in individual materials. As previously mentioned, the pixelation of the material can be determined by the distribution of electrical contacts on its electromagnetic radiation emitting surface. In some examples, each pixel may have one such electrical contact, which can be electrically connected to a silicon diffusion node (or sensing node (SN)) in the pixel circuitry (or readout circuitry) of the pixel via one or more metal interconnects (e.g., their stacks). Charge generated in the photosensitive material can accumulate on a capacitance formed by the electrical contacts defining the pixel, the metal stack vias connected to the electrical contacts, the SN, and any parasitic capacitances coupled to these structures. Ideally, for efficient collection and before charge accumulation begins, the SN needs to be reset to a high potential (for collecting electrons) or a low potential (for collecting holes). However, a drawback of the aforementioned charge accumulation structure is that the presence of metal in direct contact with the charge accumulation node prevents the charge in the potential well from being completely depleted during a reset. Therefore, the classic CDS and reset operation, widely used for kTC noise reduction in 4T silicon rolling shutter image sensors, cannot be performed.

[0121] Figures 6A to 6CThis illustrates various options for reducing kTC noise when implementing a photodetector array using a photosensitive material (or panchromatic photosensitive layer (PanCh)) separate from the semiconductor substrate containing its supporting pixel circuitry. Reference Figures 6A to 6C The described noise reduction circuitry can be included as part of pixel circuitry within a semiconductor substrate. The noise reduction circuitry can be used, for example, with a visible light sensor or an IR sensor, and when used with a visible light sensor or other sensors stacked on top of an IR sensor, it may (in some embodiments) include components that transmit IR radiation or other types of electromagnetic radiation.

[0122] Figure 6A An example of an in-column noise reduction circuit 600 (i.e., a noise reduction circuit that can be used to provide noise reduction for pixels in a column (or row) of a pixel array) is shown. In circuit 600, a feedback loop 602 is used to regulate the voltage of integrated node 614 during reset. In this feedback loop, column amplifier 604 has an input connected to column readout line 606 and a reference voltage (REF) and an output 608 that provides a voltage to reset transistor 610 under the control of feedback transistor 612. Two capacitors 616 and 618 are required per pixel to reduce the actual reset noise. The attenuation of reset noise is the loop gain A and the two capacitors (C) S 616 and C C A function of the value of 618, and equal to 1 / sqrt(A) C S / C C ) and 1 / (A C C / C SN To achieve good noise reduction, capacitor C S 616 and C C The size of 618 should be approximately 10 × C SN 620, so typically around 10~50 fF. While this solution offers very good noise reduction performance, it may not always provide sufficient IR transparency because achieving large IR transparent capacitors in metal (with metal-insulator-metal (MiM) or 3D structures) or silicon (with trench capacitors) without blocking IR radiation is challenging, and in some cases may require pixels larger than desired.

[0123] Figure 6B An example of an in-pixel noise reduction circuit 630 is shown. Circuit 630 can provide good kTC noise reduction with relatively few devices per pixel (e.g., relatively few transistors) and allows pixels in multiple rows to be reset simultaneously. However, circuit 600 may require larger and higher power PMOS transistors 632 (in addition to smaller and lower power NMOS transistors) to reduce pixel readout time.

[0124] Taking advantage of the fact that both NMOS and PMOS can exist in the readout circuit of the semiconductor substrate supporting the photosensitive material, the amplifier 634 of the feedback circuit moves from column to pixel in circuit 630. Each pixel has a dedicated CMOS amplifier 634, which can be used to regulate the voltage at the integrated node 636 during reset. Also in circuit 630, due to the locality of feedback, Figure 6A The in-pixel capacitors shown can be discarded, but at the cost of potentially lower noise reduction. Specific implementations of the CMOS amplifier 634 use n-wells per pixel. This limits the minimum pixel size, depending on the specific implementation technique. However, the locality of feedback provides a fast reset time because the bandwidth of the reset loop is not affected by... Figure 6A The circuit shown is limited by the long column lines.

[0125] Figure 6C An exemplary pixel column noise reduction circuit 640 is shown. Circuit 640 provides good kTC noise reduction and can be used with reference... Figure 6A and Figure 6B The described circuitry is implemented with fewer components (e.g., only three transistors 642, 644, 646 per pixel). Circuitry 640 also allows for greater flexibility than the reference circuitry. Figure 6A and Figure 6B The described circuit has a smaller pixel size.

[0126] By utilizing column readout transistors, the pixel source follower and selection transistors 644, 646 can be reconfigured to act as a common source amplifier. However, the trade-offs for smaller pixels may be more complex readout circuitry and the inability to simultaneously reset multiple pixels on the same readout bus. If this trade-off is acceptable, circuit 640 utilizes a minimal number of transistors and does not use capacitors to provide noise reduction, which can maximize the IR radiation transmittance even for small pixels.

[0127] For reference Figures 6A to 6C An alternative to the described kTC noise reduction circuitry can be kTC noise reduction implemented on the system side without affecting the pixel-level circuitry. One option is digital CDS. In this mode, all pixels are reset in a rolling shutter manner, and the reset level is converted by an ADC at the array edge and stored in a memory frame somewhere in the image sensor or image signal processor (ISP). After a programmable time controlled by the exposure control, all pixels can be read out in a rolling shutter manner, and each reset level can be digitally subtracted on-chip or in the ISP. This technique completely eliminates the kTC noise contribution in exchange for higher implementation area and power consumption to operate the memory frame. However, system-side kTC noise reduction provides optimal IR radiometric transparency within the pixel circuitry.

[0128] Figure 7A and Figure 7B A stacked electromagnetic radiation sensor 700 is shown. Figure 7A ) or 720 ( Figure 7B The figure illustrates an exemplary elevation of the IR sensor 706, and more specifically shows an example of the interconnection between the pixel circuitry 702 of the RGB light sensor 704 (or other visible light sensor) stacked on top of the IR sensor 706 and the pixel processing chip 708. As shown, components of the IR sensor 706 and optionally other components 710 (e.g., focusing elements and / or visible light blocking filters) may be disposed between the pixel circuitry 702 and the pixel processing chip 708. The RGB light sensor 704 may or may not have a photosensitive material (e.g., layer 730) separate from the semiconductor substrate including the pixel circuitry. Similarly, the IR sensor 706 may or may not have a photosensitive material (not shown) separate from the semiconductor substrate including the pixel circuitry.

[0129] exist Figure 7A In this design, the pixel circuitry 702 of the RGB light sensor 704 can be electrically connected to circuitry in the pixel processing chip 708 using TSVs (including TSVs 712 and 714), which are routed through components / layers disposed between the pixel circuitry 702 and the pixel processing chip 708. TSVs 712 and 714 may be located outside the pixel arrays 716 and 718 of the RGB light sensor 704 and the IR sensor 706, and are arranged around the periphery of the pixel circuitry 702. In some embodiments, this architecture can be implemented via coordinate addressing of the pixels in the pixel circuitry 702. The connection between the transistors of each pixel and the shared TSVs 712 and 714 can be implemented using horizontal and vertical buses that are transparent to IR radiation. Examples of materials that can be used for the horizontal and vertical buses include ITO, polysilicon, etc. Similar materials can be used for local connections between transistors and / or other components of the individual pixels.

[0130] exist Figure 7B In the RGB light sensor 704, the pixel circuit 702 is also electrically connected to the circuitry in the pixel processing chip 708 using TSVs 722, 724, 726, and 728. These TSVs are routed through components / layers located between the pixel circuit 702 and the pixel processing chip 708. However, in Figure 7B In this configuration, TSVs 722, 724, 726, and 728 connect the pixel circuitry of each pixel in the RGB light sensor 704, or the pixel group in the RGB light sensor 704, to the pixel processing chip 708. In this case, TSVs 722, 724, 726, and 728 can be located within the pixel arrays 716 and 71 of the RGB light sensor 704 and the IR sensor 706. Local connections between transistors and / or other components of each pixel can be implemented using materials transparent to IR radiation.

[0131] When the size of the pixels in the IR sensor 706 is an integer multiple of the size of the pixels in the RGB light sensor 704, TSVs 722, 724, 726, and 728 can be positioned along the boundaries of the pixels in the IR sensor 706 to minimize any tendency of the TSVs 722, 724, 726, and 728 to block IR radiation. Alternatively, the TSVs can be positioned in other ways.

[0132] In some implementation schemes, Figure 7A The interconnect options shown can be implemented using the coordinate addressing of the pixels of the RGB light sensor, and may require a low-resistance bus to enable high frame rate operation of the RGB light sensor 704 (or the RGB light sensor may require high frame rate operation for other reasons). Figure 8A The interconnection method shown can be used with Figure 7A The interconnect options shown are used in combination to provide a combination of low-resistance (and possibly opaque) metal buses for pixel groups in the RGB light sensor 704 and transparent local connections within the pixel groups in the RGB light sensor 704. Alternatively, all signal routing between pixels and TSVs can be formed using a transparent material.

[0133] like Figure 8A As shown, the pixel 802 of the RGB light sensor 704 can be smaller than the pixel 804 of the IR sensor 706. A ratio of 4-1, 16-1 (as shown) or other ratios of RGB-IR pixels may be useful, and may be especially useful when the IR sensor 706 is a ToF sensor.

[0134] A low-resistance bus 806, used to provide coordinate addressing for the RGB pixel cluster 802 (e.g., a metal bus), may be located on the periphery of the IR pixel 804. Placing a typically metallic and opaque low-resistance bus 806 on the periphery of the IR pixel 804 may not significantly affect the amount of IR radiation received by the IR pixel 804, because the periphery of the IR pixel 804 is typically not an IR-sensitive area of ​​the IR pixel 804.

[0135] although Figure 8A Only a few horizontal low-resistance buses 806 are shown, but a full-size RGB pixel array can have many more buses, including both horizontal and vertical buses, which connect to all pixels within the pixel array and, in some cases, extend along the entire length or width of the pixel array. The low-resistance buses 806 can be used to connect individual pixels 802 to corresponding TSVs set around the perimeter of the RGB pixel array.

[0136] The transparent bus 808 can locally connect RGB pixels 802 within a group of RGB pixels 802. Compared to the length of the low-resistance bus 806, the transparent bus 808 can be shorter, and therefore using a higher-resistance material (e.g., ITO, polysilicon, etc.) to form the transparent bus 808 can have a relatively small impact on signal settling time and pixel readout time.

[0137] Figure 8B It shows Figure 8A The arrangement of RGB pixels 802 and IR pixels 804 is shown, but TSVs 722, 724, 726, and 728 are routed around IR pixel 804 within the pixel array of the IR sensor, as shown in the reference. Figure 7B As stated above. Figure 8B The interconnect shown combines the low-resistance TSVs 722, 724, 726, 728 at the periphery of the IR pixel 804 with a transparent bus 810, which locally interconnects the TSVs 722, 724, 726, 728 with the pixel circuitry of the RGB pixel 802.

[0138] Figures 9A to 9C Each of them shows Figure 7A A portion of the stacked electromagnetic radiation sensor 700 shown, wherein additional interconnect options are used to route signals to / from the RGB pixels of the pixel circuitry 702 in the RGB light sensor 704. Figure 9A Exemplary interconnection options are shown, in which Figure 8A The low-resistance bus 806 and the transparent bus 808 are both set on the electromagnetic radiation receiving surface 902 of the pixel circuit 702 of the RGB light sensor 704.

[0139] Figure 9BAn exemplary interconnection option is illustrated, wherein a transparent bus 808 is disposed on an electromagnetic radiation receiving surface 902 of pixel circuitry 702, and a low-resistance bus 806 is disposed on an electromagnetic radiation receiving surface 904 of pixel circuitry of IR sensor 706 (e.g., on an electromagnetic radiation receiving surface of a BSI layer). In this example, the transparent bus 808 can be electrically coupled to the low-resistance bus 806 via TSVs 906, 908 extending through RGB pixel circuitry 702 and other components 710 disposed between RGB light sensor 704 and IR sensor 706. TSVs 906, 908 can be formed of a transparent or at least partially transmissive material (e.g., ITO or polysilicon). In some cases, moving the low-resistance bus 806 closer to IR sensor 706 and forming a transparent TSV allows more IR radiation to reach IR sensor 706. The low-resistance bus 806 can be electrically coupled to TSVs 712, 714 surrounding the periphery of pixel circuitry 702 via low-resistance conductive traces (e.g., metal traces). When all electrical connections between pixel circuit 702 and TSV 712, 714 are located on surface 904 of pixel circuit 702, TSV 712, 714 may extend only between pixel processing chip 708 and surface 904 in some cases.

[0140] Figure 9C It shows something similar to Figure 9B The interconnect options shown are exemplary interconnect options. However, the TSVs 906, 908 that couple the transparent bus 808 to the low-resistance bus 806 are formed of an opaque material (e.g., metal). In some cases, moving the low-resistance bus 806 closer to the IR sensor 706 and forming the TSV of an opaque material can help reduce optical crosstalk between IR pixels when IR radiation is scattered while passing through the RGB light sensor 704.

[0141] Figures 10 to 13L Various configurations are shown for connecting pixel circuitry in a semiconductor substrate (e.g., a silicon substrate) to electrical contacts in a separate photosensitive material (or other panchromatic photosensitive layer). The electrical contacts between the pixel circuitry and the photosensitive material (e.g., reference...) Figures 3A to 3B , Figures 4A to 4C , Figures 5A to 5B , Figures 7A to 7B ,or Figures 9A to 9CThe contacts between the pixel circuitry and the photosensitive material shown in any electromagnetic radiation sensor described in any of the above can, in some cases, be configured such that they provide carrier-selective ohmic contacts to the photosensitive material (or panchromatic photosensitive layer). In the case of visible light sensors stacked on top of IR sensors, the electrical contacts can also be highly transparent to the IR radiation sensed by the IR sensor (e.g., near-infrared (NIR) radiation). The electrical contacts can be e-selective (ETL) or h+selective (HTL), depending on the availability of suitable materials and the design of the pixel circuitry. Regardless of which type of electrical contact is chosen for connecting the pixel circuitry to the photosensitive material, the opposite type of electrical contact can be used to connect to the common electrode (e.g., reference electrode) of the electromagnetic radiation receiving surface of the photosensitive material. Figure 3B (Described common electrode 312). For the visible light sensor (or the electromagnetic radiation sensor on top of the stack), the electrical contacts or electrodes connected to the two surfaces of the photosensitive material should have high transparency to the IR radiation sensed by the IR sensor stacked below the visible light sensor (or the electromagnetic radiation sensor at the bottom of the stack), and the electrical contacts or electrodes connected to the electromagnetic radiation receiving surface of the photosensitive material should also have high transmittance to visible (e.g., RGB) light.

[0142] Figure 10 A first exemplary configuration 1000 is shown for connecting a photosensitive material (or other panchromatic photosensitive layer) 1004 to an electrical contact 1002 of a pixel circuit 1006. A via 1008 may be formed in a silicon dioxide (SiO2) layer 1014 and electrically connects the electrical contact 1002 to a metallization (e.g., a conductor) of the pixel circuit 1006. The via 1008 may be formed in the SiO2 layer 1014 using an IR-transparent material such as IR-transparent amorphous silicon (a-Si).

[0143] The electrical contact 1002 may be a multilayer electrical contact and may include a first layer 1010 of ITO or aluminum-doped zinc oxide (AZO) covered by a second layer 1012 configured as an e-transport layer (ETL) or an h+ transport layer (HTL) for ohmic and carrier-selective contact with the photosensitive material 1004.

[0144] When the second layer 1012 is an ETL, such that the electrical contact 1002 is configured to collect electrons (e-), the first layer 1010 can be a deep work function transparent metal (including ITO) or a shallow work function transparent metal (including AZO). It should be noted that shallow work function materials (such as AZO) are more favorable for ohmic contacts, but a deep work function metal (such as ITO) can be used if the second ETL layer 1012 is sufficiently doped to create a sufficiently thin barrier at the ETL / ITO interface for carrier tunneling.

[0145] When the second layer 1012 is HTL, such that the electrical contact 1002 is configured to collect holes (h+), the first layer 1010 may again be a deep work function transparent metal or a shallow work function transparent metal.

[0146] Figure 11 A first exemplary configuration 1100 is shown for connecting a photosensitive material (or other panchromatic photosensitive layer) 1104 to an electrical contact 1102 of a pixel circuit 1106. A via 1108 may be formed in a SiO2 layer 1110 and electrically connects the electrical contact 1102 to a metallization (e.g., a conductor) of the pixel circuit 1106. The via 1108 may be formed in the SiO2 layer 1110 using an IR-transparent material such as IR-transparent amorphous silicon (a-Si).

[0147] The electrical contact 1102 can be a single-layer electrical contact and can be formed using AZO, which provides an e-transport layer (ETL) for ohmic and carrier-selective contact with the photosensitive material 1104.

[0148] Figure 12 A third exemplary configuration 1200 is shown for connecting a photosensitive material (or other panchromatic photosensitive material) 1204 to an electrical contact 1202 of a pixel circuit 1206. A via 1208 may be formed in a SiO2 layer 1214 and electrically connects the electrical contact 1202 to a metallization (e.g., a conductor) of the pixel circuit 1206. The via 1208 may be formed in the SiO2 layer 1214 using an IR-transparent material such as IR-transparent amorphous silicon (a-Si).

[0149] Electrical contact 1202 may be a multilayer electrical contact and may include a first layer 1210 of the same IR transparent amorphous silicon used to form via 1208, the first layer being covered by a second layer 1212 configured as an e-transport layer (ETL) or h+ transport layer (HTL) for ohmic and carrier-selective contact with photosensitive material 1204. In this configuration, a-Si may be selected to minimize any ohmic voltage loss across the entire dimension of electrical contact 1202.

[0150] When the second layer 1212 is an ETL, such that the electrical contact 1202 is configured to collect electrons (e-), the first layer 1210 can be n-doped a-Si. In an alternative embodiment, n-doped a-Si with energy levels aligned with the photosensitive material 1204 can be used without the second layer 1212 (and can be used as the ETL itself).

[0151] When the second layer 1212 is an HTL, such that the electrical contact 1202 is configured to collect holes (h+), the first layer 1210 can be p-doped a-Si. In an alternative embodiment, p-doped a-Si with energy levels aligned with the photosensitive material 1204 can be used without the second layer 1212 (and can be used as the HTL itself).

[0152] exist Figures 10 to 12 In the interconnect configurations shown, suitable ETL materials include zinc oxide (ZnO), titanium dioxide (TiO2), niobium-doped titanium oxide (Nb:TiO2), tin oxide (IV) (SnO2), tin-doped titanium dioxide (Sn:TiO2), or aluminum-doped zinc oxide (Al:ZnO or AZO). Similarly, in... Figures 10 to 12 In the interconnect configuration shown, suitable HTL materials include molybdenum trioxide (MoO3), tungsten trioxide (WO3), vanadium pentoxide (V2O5), nickel(II) oxide (NiO), copper thiocyanate (CuSCN), copper(II) oxide (CuO), or tin-doped indium oxide (Sn:In2O3 or ITO).

[0153] Also in Figures 10 to 12 In the interconnect configuration shown, the vias (which connect to electrical contacts on the bottom surface of the photosensitive material in the visible light sensor (or the electromagnetic radiation sensor on top of the stack) and extend through the semiconductor substrate of the visible light sensor) can be formed using amorphous silicon and / or other conductive materials with high transparency to IR radiation (e.g., NIR radiation) sensed by the IR sensor stacked below the visible light sensor. Amorphous silicon may be a suitable option because it has a wider bandgap than crystalline silicon and good transparency in the NIR wavelength range. It can also be heavily doped as either an n-type or p-type material or both to provide high conductivity, and there are mature processes available for filling high aspect ratio vias formed from amorphous silicon in conventional CMOS fabrication.

[0154] Figure 13A A fourth exemplary configuration 1300 is shown for connecting a photosensitive material (or other panchromatic photosensitive material) 1304 to a pixel circuit 1306. In this configuration, the photosensitive material 1304 is deposited directly on a depleted silicon diode 1308 to form a panchromatic silicon heterojunction photodiode. The heterojunction can be fully depleted to allow zero kTC noise. The depleted silicon diode 1308 can be integrated with a transmission (Tx) gate to allow for fill / drain of the panchromatic silicon heterojunction photodiode.

[0155] like Figure 13AAs further shown, and in some embodiments, the photosensitive material 1304 may be a lightly doped n-type photosensitive material 1304, and may be in direct contact with the lightly doped and depleted p-type silicon layer or region (p-Si) 1310. The back side 1312 of the p-type silicon layer may include an n-type implant 1314 (n-well) that completes the silicon diode 1308 and allows for complete depletion of the lightly doped p-type silicon region (or layer) 1310. In an alternative embodiment, the photosensitive material 1304 may be a lightly doped p-type photosensitive material 1304, and the n-type implant 1314 may completely deplete both the lightly doped p-type silicon region 1310 and the lightly doped p-type photosensitive material 1304.

[0156] Depleted silicon diodes 1308 connected to different pixels can be separated from each other or from other pixel circuitry via the walls of deep trench isolation (DTI) 1320.

[0157] Figure 13B It shows Figure 13A The illustrated variant 1316 of the interconnect includes a heavily doped p-type (P+) implant 1318 provided at the interface between the photosensitive material y 1304 and the lightly doped and depleted p-type silicon region 1310. The purpose of the p-type implant 1318 is to provide a pinned implant for the p-type silicon region 1310, which prevents the p-type silicon region 1310 from being depleted all the way to the full-color silicon interface, where the dangling bond density is high. This reduces the dark current of the full-color silicon heterojunction photodiode. The p-type implant 1318 also helps to deplete the lightly doped n-type photosensitive material 1304.

[0158] Figures 13C to 13L It shows that it can be used with Figure 13A or Figure 13B Examples of other design features of the structural combination shown. Figure 13C An example of a heterojunction 1300c that can be implemented in the QF / silicon heterojunction device described herein is shown. Figure 13C Lightly doped or n-doped silicon regions (or n-wells) 1305c and p-doped silicon regions (or layers) 1310c are depicted. Generally, impurities or dopants can be implanted into silicon to alter and / or control the conductivity of the material. For example... Figure 13C As shown, the p-doped silicon region 1310c can form a heterojunction with the intrinsic QF 1315c. The intrinsic QF 1315c can be adjacent to the p-doped QF 1320c, which can contact the top contact 1325c. The intrinsic QF and the p-doped QF together can form a reference. Figures 3A to 3B , Figures 4A to 4C and Figures 5A to 5BThe QF described. In some examples, QF 1315c may not be intrinsic. Instead, the doping (e.g., n-type or p-type) may be low enough that the material can be completely depleted under the bias applied to the top contact 1325c, allowing the electric field to be uniform across the entire QF layer. Furthermore, in some examples, intrinsic QF 1315c may be a lightly doped QF.

[0159] like Figure 13C As shown, electromagnetic radiation can enter the device from the direction of the top contact 1325c. Furthermore, in Figure 13C In this configuration, a QF bias voltage 1330c can be applied to the top contact 1325c. Furthermore, this device can be a component of the pixels described herein in various image sensor configurations.

[0160] Figure 13C The heterojunction can be combined with one or more transistors to realize a complete pixel. Various pixel configurations can vary and may depend on the intended operating application, such as iToF, dToF, rolling shutter, global shutter, etc. Furthermore, although the various specific implementations discussed herein can be discussed assuming electron transport from QF to silicon and electron collection in silicon, other similar designs can also be implemented such that holes can be transported to silicon and hole collection can occur in the p-doped nodes of silicon.

[0161] like Figure 13C As shown, the heterojunction 1300c may not include a silicon dioxide isolation layer. Even without an isolation layer, electron collection can still occur at the collection node. This can be achieved by an electric field that can be generated at the p / n junction of silicon after a bias voltage is applied to the heterojunction device.

[0162] exist Figure 13C In the example, the p-doped silicon region (or layer) 1310c can be utilized between the n-well 1305c collection node and the intrinsic QF 1315c to minimize and / or prevent silicon depletion at the QF / silicon interface. Furthermore, the energy levels of the material used in the heterojunction 1300c can be selected such that the energy levels are “cascaded.” Cascaded energy levels allow electrons to transport and / or travel across the QF / silicon interface without a barrier. Additionally, electrons can travel from the QF to the n-well 1305c without a barrier. Although each heterojunction in the heterojunction does not include a p+ doped region in the n-well, in some embodiments, the p+ region may be included within the n-well.

[0163] As described herein, even though p-doped silicon can be used to prevent depletion at the QF / silicon interface, dangling bonds can still exist at the interface in some implementations. In this example, the Fermi level can be close enough to the band edge that any dark current generated by the dangling bonds can be generated slowly. Therefore, the heterojunction can be considered well passivated.

[0164] Figure 13D Another example of a heterojunction 1300d that can be implemented in the QF / silicon heterojunction device described herein is shown. Similar to... Figure 13C , Figure 13D The lightly n-doped silicon region, or n-well 1305d, and the p-doped silicon region 1310d are depicted. For example... Figure 13D As shown, the p-doped silicon region (or layer) 1310d can form a heterojunction with the intrinsic QF 1315d, but may also include an intermediate interface passivation layer 1312d. The intrinsic QF 1315d can contact the top contact 1325d. Similar to... Figure 13C For example, light can enter the device from the direction of the top contact 1325d. Furthermore, the device can be a component of the pixels described herein in various image sensor configurations.

[0165] exist Figure 13D In this context, the interface between the p-doped silicon layer and the intrinsic QF 1315d can have dangling bonds. Although, as previously mentioned, relative to... Figure 13C The heterojunction discussed here can be considered a good passivation method, but alternative passivation approaches are discussed in this paper. In some examples, the interface passivation layer 1312d can be used to reduce the dangling bond density at the QF / silicon interface. In one example, the interface passivation layer 1312d can be a dipole, which can include oxides such as, but not limited to, Al2O3 or HFO2, both of which can be used for passivation. In this example, the oxide-containing dipole can have an oxide that is thin enough to allow electron tunneling through, such as about 3 nm, or less.

[0166] As described herein, a dipole-induced layer can be inserted at the QF / silicon interface to at least partially passivate dangling bonds. In one example, when the QF has a small bandgap (e.g., 0.9 eV), an electron collection barrier (Φb) may exist, which is at least in part due to the offset between the conduction band edge of the intrinsic QF and the n-doped silicon. This offset can be addressed by inserting a dipole-induced layer at or around the QF / silicon interface, which alters the vacuum level.

[0167] Another method for passivating the interface at the QF / silicon interface may include using amorphous silicon. In this example, the amorphous silicon can be thicker than a dipole using an oxide passivation method. For example, due to its good electron transport properties, amorphous silicon can be in the approximate range of 3 nm to 100 nm.

[0168] Another method for passivating QF / silicon interfaces can utilize molecularly treated silicon passivation. This method may include alkylation of H-terminated silicon by reaction with alkyl halides, such as iodides and bromides. This method can also be achieved by reaction of H-terminated silicon with alkenes and alkynes, HF hydrogenation, or NH4F hydrogenation.

[0169] Another approach to silicon passivation can involve using different crystalline silicon orientations. Different silicon crystal growth orientations can alter the density of dangling bonds at the QF / silicon interface. The Miller index of Si(111) can have one H bond / silicon atom, while Si(100) can have two H bonds. Changing the silicon crystal growth orientation can affect and / or alter the effectiveness of other passivation strategies.

[0170] Figure 13E An example of a heterojunction 1300e that can be implemented in the QF / silicon heterojunction device described herein is shown. Similar to... Figure 13C , Figure 13E The lightly n-doped silicon region or n-well 1305e and the p-doped silicon region (or layer) 1310e are depicted. For example... Figure 13E As shown, the p-doped silicon region 1310e and p-doped silicon can form a heterojunction with the intrinsic QF 1315e. Figure 13E In this context, the electrically isolated layer 1311e can be a local layer located between the p-doped silicon region 1310e and the intrinsic QF 1315e. Figure 13E Other aspects can be similar to those relative to Figures 13C to 13D The described element.

[0171] exist Figure 13E In this embodiment, the electrically insulating layer 1311e can be any material capable of electrically isolating the intrinsic QF 1315e from the p-doped silicon region 1310e in the region where the electrically insulating layer is located. In some examples, the material can be an oxide, such as silicon dioxide (SiO2). As depicted, the electrically insulating layer partially separates the intrinsic QF 1315e from the p-doped silicon region 1310e. This electrically insulating layer can be used to electrically isolate the pixel from the QF interface and better define the collection node region in silicon. In some examples, the electrically insulating layer can be... Figure 12 Part of the interface passivation layer of D.

[0172] Figure 13F An example of a heterojunction 1300f that can be implemented in the QF / silicon heterojunction device described herein is shown. Similar to... Figures 13C to 13E , Figure 13F The lightly n-doped silicon region or n-well 1305f and the p-doped silicon region (or layer) 1310f are depicted. For example... Figure 13F As shown, p-doped silicon regions 1310f and 1315f can form a heterojunction with intrinsic QF. Figure 13F In this context, the electrically insulating layer 1311f can be a local layer located between the p-doped silicon region 1310f and the intrinsic QF 1315f. Figure 13F In the middle, the electrical isolation layer 1311f can have the same as Figure 13E It has similar properties to the electrical isolation layer 1311e. Furthermore, in Figure 13FIn this process, the electromagnetic radiation shielding layer 1313f can be located between the electrical isolation layer 1311f and the intrinsic QF 1315f. Figure 13F Other aspects can be similar to those relative to Figures 13C to 13E The described element.

[0173] exist Figure 13F In this process, the electromagnetic radiation shielding layer 1313f can be an optically black material (i.e., a material that sufficiently absorbs a range of wavelengths, wherein sufficient absorption is defined as at least 50% absorption, and preferably at least 70%, 80%, or 90% absorption). This layer can be added to the heterojunction 1300f to at least partially shield the effects of electromagnetic radiation and / or light on the readout circuitry. When the incident light can be a wavelength that can be absorbed by silicon (such as approximately 1100 nm, or wavelengths around or below), the shielding layer 1313f can effectively shield the readout circuitry. The shielding layer 1313f can be any optically black material, including but not limited to metals or photosensitive polymers.

[0174] Figure 13G An example of a heterojunction 1300g that can be implemented in the QF / silicon heterojunction device described herein is shown. Similar to... Figures 13C to 13F , Figure 13G The lightly n-doped silicon regions or n-wells 1305g and p-doped silicon regions (or layers) 1310g are depicted. For example... Figure 13G As shown, the p-doped silicon region 1310g and the p-doped silicon can form a heterojunction with the intrinsic QF 1315g, but may also include an intermediate interface passivation layer 1312g. Figure 13G In this context, the electrical isolation layer 1311g can be a local layer positioned adjacent to the interface passivation layer 1312g. Figure 13G In the middle, the electrical isolation layer 1311g can have the same as Figure 13E It has similar characteristics to the 1311E electrical isolation layer. Furthermore, in Figure 13G In this configuration, the electromagnetic radiation shielding layer 1313g can be positioned adjacent to the electrical isolation layer 1311g. Figure 13G The configuration shown is an example, and these layers can be positioned in any other appropriate order. Figure 13G Other aspects can be similar to those relative to Figures 13C to 13F The described element.

[0175] Similar to Figure 13D ,exist Figure 13G In this context, the interface between the p-doped silicon layer and the intrinsic QF 1315g can have dangling bonds. Although, as previously mentioned, relative to... Figure 13CThe heterojunction discussed here can be considered a good passivation method, but alternative passivation approaches are discussed in this paper. In some examples, the interface passivation layer 1312g can be used to reduce the dangling bond density at the QF / silicon interface. In one example, the interface passivation layer 1312g can be a dipole, which can include oxides such as, but not limited to, Al2O3 or HFO2, both of which can be used for passivation. In this example, the oxide-containing dipole can have an oxide that is thin enough to allow electron tunneling through, such as about 3 nm, or less.

[0176] Figure 13H An example of a heterojunction 1300h that can be implemented in the QF / silicon heterojunction device described herein is shown. Figure 13H The lightly n-doped silicon region or n-well 1305h and the p-doped silicon region (or layer) 1310h are depicted. For example... Figure 13H As shown, n-doped silicon can form a heterojunction with intrinsic QF 1315h. Figure 13H Other aspects can be similar to those relative to Figures 13C to 13G The described element.

[0177] like Figure 13H As shown, the heterojunction 1300h may not include a silicon dioxide isolation layer. Therefore, in Figure 13H At the depicted QF / silicon interface, numerous interface states can exist due to the unpassivated silicon dangling bonds. In this example, silicon can be completely depleted at the interface, and the dangling bonds can serve as centers for dark current generation. Furthermore, and as... Figure 13D The heterojunction 1300h discussed may include a passivation layer located between the QF and silicon to mitigate the influence of the interface state at the QF / silicon interface.

[0178] Figure 13I Another example of a heterojunction 1300i that can be implemented in the QF / silicon heterojunction device described herein is shown. Similar to... Figure 13D , Figure 13I The lightly n-doped silicon region, or n-well 1305i, and the p-doped silicon region 1310i are depicted. For example... Figure 13I As shown, the n-well 1305i can form a heterojunction with the intrinsic QF 1315i, but may also include an intermediate interface passivation layer 1312i. The intrinsic QF 1315i can contact the top contact 1325i. Similar to... Figure 13D For example, light can enter the device from the direction of the top contact 1325i. Furthermore, the device can be a component of the pixels described herein in various image sensor configurations.

[0179] Similar to Figure 13D ,exist Figure 13IIn this context, the interface between the n-well layer and the intrinsic QF 1315i can have dangling bonds. In some examples, the interface passivation layer 1312i can be thin enough that electrons can tunnel through it, thereby forming an effective interface between the n-well layer and the intrinsic QF. Although as previously mentioned relative to... Figure 13C The heterojunction discussed here can be considered a good passivation method, but alternative passivation approaches are also discussed. In some examples, the interface passivation layer 1312i can be used to reduce the dangling bond density at the QF / silicon interface. In one example, the interface passivation layer 1312i can be a dipole, which can include oxides such as, but not limited to, Al2O3 or HFO2, both of which can be used for passivation. In this example, the oxide-containing dipole can have an oxide that is thin enough to allow electron tunneling through, such as about 3 nm, or less.

[0180] Figure 13J An example of a heterojunction 1300j that can be implemented in the QF / silicon heterojunction device described herein is shown. Similar to... Figure 13H , Figure 13J The lightly n-doped silicon region or n-well 1305j and the p-doped silicon region (or layer) 1310j are depicted. For example... Figure 13J As shown, n-doped silicon (n-well) can form a heterojunction with intrinsic QF 1315j. Figure 13J Other aspects can be similar to those relative to Figures 13C to 13I The described element.

[0181] exist Figure 13J In this context, the electrically insulating layer 1311j can be any material capable of electrically isolating the intrinsic QF 1315j from the p-doped silicon region 1310j within the region where the electrically insulating layer is located. In some examples, the electrically insulating material can be an oxide, such as silicon dioxide (SiO2). Figure 13J As depicted, the electrically isolated layer partially separates the intrinsic QF 1315j from the n-well 1305j and the p-doped silicon region 1310j. This electrically isolated layer can be used to electrically isolate the pixel from the QF interface and to better define the collection node region in the silicon.

[0182] Figure 13K An example of a heterojunction 1300k that can be implemented in the QF / silicon heterojunction device described herein is shown. Similar to... Figures 13C to 13J , Figure 13K The lightly n-doped silicon region or n-well at 1305k and the p-doped silicon region (or layer) at 1310k are depicted. For example... Figure 13K As shown, n-doped silicon can form a heterojunction with intrinsic QF 1315k. In Figure 13K In this context, the electrically isolated layer 1311k can be a local layer located between the layer comprising the n-well 1305k and the p-doped silicon region 1310k and the intrinsic QF 1315k. Figure 13KIn the middle, the electrical isolation layer 1311k can have the same as Figure 13E It has similar properties to the electrical isolation layer 1311e. Furthermore, in Figure 13K In this context, the electromagnetic radiation shielding layer 1313k can be located between the electrical isolation layer 1311k and the intrinsic QF 1315k. Figure 13K Other aspects can be similar to those relative to Figures 13C to 13J The described element.

[0183] exist Figure 13K In this design, the electromagnetic radiation shielding layer 1313k can be an optically black material. This layer can be added to the heterojunction 1300k to at least partially shield the effects of electromagnetic radiation and / or light on the readout circuitry. When the incident light can be a wavelength that can be absorbed by silicon (such as approximately 1100 nm, or wavelengths around or below), the shielding layer 1313k can effectively shield the readout circuitry. The shielding layer 1313k can be any optically black material, including but not limited to metals or absorbing polymers.

[0184] Figure 13L An example of a heterojunction 1300l that can be implemented in the QF / silicon heterojunction device described herein is shown. Similar to... Figures 13C to 13K , Figure 13L The lightly n-doped silicon region or n-well 1305l and the p-doped silicon region (or layer) 1310l are depicted. For example... Figure 13L As shown, the n-well 1305l can form a heterojunction with the intrinsic QF 1315l, but it can also include an intermediate interface passivation layer 1312l. Figure 13L In this context, the electrical isolation layer 1311l can be a local layer positioned adjacent to the intermediate interface passivation layer 1312l. Figure 13L In the middle, the electrical isolation layer 1311l can have the same as Figure 13E It has similar characteristics to the 1311E electrical isolation layer. Furthermore, in Figure 13L In this process, the electromagnetic radiation shielding layer 1313l may be located between the electrical isolation layer 1311l and the interface passivation layer 1312l. Figure 13L Other aspects can be similar to those relative to Figures 13C to 13K The described element.

[0185] Similar to Figure 13D ,exist Figure 13L In this context, the interface between the n-well layer and the intrinsic QF 1315l can have dangling bonds. In some examples, even if the interface passivation layer 1312l is located between the n-well layer and the intrinsic QF layer, the passivation layer can be thin enough to allow electrons to tunnel through it, effectively making the n-well layer and the intrinsic QF layer adjacent. Although as previously stated... Figure 13CThe heterojunction discussed here can be considered a good passivation method, but alternative passivation approaches are discussed in this paper. In some examples, the interface passivation layer 1312l can be used to reduce the dangling bond density at the QF / silicon interface. In one example, the interface passivation layer 1312l can be a dipole, which can include oxides such as, but not limited to, Al2O3 or HFO2, both of which can be used for passivation. In this example, the oxide-containing dipole can have an oxide that is thin enough to allow electron tunneling through, such as about 3 nm, or less.

[0186] Figure 14A An exemplary process 1400 for fabricating a stacked electromagnetic radiation sensor is illustrated. By way of example, process 1400 is described with reference to an RGB light sensor stacked on an IR sensor, wherein the RGB light sensor includes a photosensitive material deposited on a semiconductor substrate, and the IR sensor is a silicon-based sensor.

[0187] At one step of process 1400, a semiconductor substrate (e.g., a silicon substrate) 1402 of the RGB light sensor may be formed according to an FSI process, wherein its front side 1404 is stacked facing a virtual wafer 1406. The semiconductor substrate 1402 and the virtual wafer 1406 may be bonded using a temporary wafer bonding process. After bonding, the semiconductor substrate 1402 may be thinned to a few micrometers. A semiconductor substrate (e.g., a silicon substrate) 1408 of the IR sensor may be formed according to a BSI process, wherein its front side is stacked together with the front side of a pixel processing chip (e.g., a logic wafer 1410). The semiconductor substrate 1408 and the logic wafer 1410 may be bonded using a wafer bonding process. After bonding, the semiconductor substrate 1408 may be thinned to a few micrometers, and in some cases, a TSV may be formed in the semiconductor substrate 1408. A visible light blocking filter 1412 and a diffractive lens structure 1414 may then be deposited and patterned on the back side of the IR sensor. Next, the IR sensor with pixel processing chip and other structures can be stacked with the RGB light sensor by flipping the RGB light sensor and bonding its wafer to the IR sensor with pixel processing chip and other structures. The dummy wafer 1406 can then be removed. A TSV 1416 can be formed through the semiconductor substrate 1402 of the RGB light sensor, the semiconductor substrate 1408 of the IR sensor, and other structures to connect the metal of the semiconductor substrate 1402 to the metal of the logic wafer 1410. Subsequently, a photosensitive material 1418 (e.g., QF or organic material) can be deposited on the semiconductor substrate 1402 of the RGB light sensor, and color filters and microlenses can be deposited on the photosensitive material 1418.

[0188] Figure 14B and Figure 14C The diagram illustrates the use of different circuits (e.g., pixel circuits) and... Figure 14A Exemplary processes 1420 and 1430 for interconnecting the photosensitive layers in the structure shown. Specifically, Figure 14B and Figure 14C Exemplary processes 1420 and 1430 for forming global TSVs (i.e., TSVs outside the RGB / IR pixel array) and local TSVs (i.e., TSVs within the RGB / IR pixel array) are shown. If desired, global TSVs may have a larger size than local TSVs, but local TSVs may be smaller to achieve better IR transmittance and pixel performance. Alternatively, interconnections between different circuits and the photosensitive layer may be Cu-Cu connections formed as part of a wafer bonding process, or Cu-Cu connections may be used to bond TSVs and / or TSVs to other electrical contacts.

[0189] exist Figure 14B In this configuration, the global TSV 1422 is formed as a single-stage TSV (where TSV 1422 is etched and filled through two layers of silicon) to connect the pixel circuitry of the RGB light sensor to the logic wafer 1410, while the local TSV 1424 is formed as a two-stage TSV. One stage 1424a of the local TSV 1424 is formed through the semiconductor substrate 1408 of the IR sensor before the RGB light sensor is stacked on the semiconductor substrate 1408, and the other stage 1424b of the local TSV 1424 is formed through the semiconductor substrate 1402 of the RGB light sensor after the RGB light sensor has been stacked on the IR sensor. Figure 14C In this context, both global TSV1422 and local TSV1424 are formed as two-level TSVs.

[0190] Figure 15A References are shown Figure 14A Modifications (and simplifications) to the described process. For example, when the RGB light sensor employs a silicon-based photodetector array, process 1500 can be used to stack the RGB light sensor on an IR sensor.

[0191] As shown in the figure, the semiconductor substrate 1408 of the IR sensor can be stacked on a logic chip, as referenced. Figure 14A The semiconductor substrate 1502 of the RGB light sensor can be formed according to the BSI process. The semiconductor substrate 1502 can be stacked on the IR sensor, with its front side 1504 facing the IR sensor, and without using a dummy wafer. The semiconductor substrate 1502 of the RGB light sensor can then be thinned, and a BSI photodetector array 1506 can be formed on the semiconductor substrate 1502. For example, as referenced... Figure 15B As described above, TSVs can be formed in the stack.

[0192] Figure 15BThe diagram illustrates the use of different circuits (e.g., pixel circuits) and... Figure 15A An exemplary process 1510 for interconnecting the photosensitive elements in the structure shown. By way of example, Figure 15B An exemplary process 1510 is shown for forming a combination of a global TSV 1512 and a local TSV 1514. The global TSV 1512 and the local TSV 1514 can be formed as a two-level TSV, as shown in reference. Figure 14C After the semiconductor substrate 1408 of the IR sensor has been stacked and thinned with the logic wafer 1410, a first stage 1512a, 1514a of global TSV 1512 and local TSV 1514 can be formed to connect the back metal of the semiconductor substrate 1408 to the front metal of the semiconductor substrate 1408 and to the metal of the logic wafer 1410. After the visible light blocking filter 1412 and the diffraction lens structure 1414 are deposited on the back side of the IR sensor and patterned, a second stage 1512b, 1514b of global TSV 1512 and local TSV 1514 can be formed to extend the TSV 1512, 1514 to a new top surface of the stack. The semiconductor substrate 1402 of the RGB light sensor can then be stacked on the stack containing the IR sensor, wherein electrical contacts 1516 on the semiconductor substrate are electrically coupled to the TSV 1512, 1514.

[0193] Figure 16A and Figure 16B An example is shown of how a longer-wavelength photosensitive material 1602 can be deposited on a semiconductor substrate 1604 of an IR sensor. This type of IR sensor configuration can be particularly useful when a visible light sensor on top of a stacked electromagnetic radiation sensor uses a silicon-based photodetector array. For example, because silicon is sensitive to a wide range of electromagnetic radiation wavelengths, by depositing the photosensitive material 1602 on the IR sensor, the sensitivity of the IR sensor can be tuned to be outside the sensitivity range of silicon, which absorbs a range of longer electromagnetic radiation wavelengths outside the sensitivity range of silicon (and therefore outside the sensitivity range of a visible light sensor with a silicon-based photodetector array).

[0194] In some examples, Figure 16A and Figure 16B The photosensitive material 1602 shown can be QF or an organic material, as shown in the reference. Figures 4A to 5BThe above describes the process. In other examples, other materials may be used. For example, the IR sensor may be configured to detect electromagnetic radiation wavelengths in the short-wave infrared (SWIR) band (i.e., 1.1 µm to 3 µm electromagnetic radiation wavelengths) when the photosensitive material 1602 is a direct bandgap semiconductor material with a high absorption coefficient. This direct bandgap semiconductor material includes, but is not limited to, group IV materials such as Si / SiGe; group III-V materials, including InGaAs / InP, AlGaAs / GaAs; or group II-VI materials, including CdTe / HgTe. Integration of these materials with the CMOS pixel circuitry in the semiconductor substrate 1604 can be provided by various methods, including but not limited to epitaxy on silicon, pixel-by-pixel hybrid bonding, regrowth on CMOS, and solution deposition of composite semiconductors. The photosensitive material 1602 may also be, or alternatively, a material with high α, good mobility, and low-temperature integration with silicon, such as Sb₂Se. (3-x) Te (x) , where x=0 has a direct bandgap of ~1.2eV, and x>0 tunes the bandgap to a lower energy.

[0195] The aforementioned photosensitive material 1602 can be deposited on the semiconductor substrate 1604 (e.g., a BSI wafer) either pixel-wise (e.g., by coating individual pixels) or as a cladding layer (i.e., by coating all pixels), as shown below. Figure 16A (by pixel) or Figure 16B (As shown in the diagram, which is a cladding layer).

[0196] Extending the spectral sensitivity of IR sensors to longer wavelengths and locating the IR notch band of IR sensors beyond the sensitivity of silicon photodetectors allows for the use of silicon photodetectors (e.g., standard BSI silicon pixel arrays) in visible light sensors. This simplifies visible light sensor design due to the inherent ability of silicon pixel circuitry to perform CDS readout (and mitigate or eliminate kTC noise). Furthermore, visible light sensors benefit from the low dark current of pinned silicon photodiodes and the proven manufacturing technology of BSI silicon sensors.

[0197] Figure 17A and Figure 17BAn exemplary device 1700 is shown that may include any one or more of the stacked or non-stacked electromagnetic radiation sensors described herein. The size and shape factors of the device (including the ratio of the length of its long side to the length of its short side) indicate that device 1700 is a mobile phone (e.g., a smartphone). However, the size and shape factors of the device are arbitrarily chosen, and device 1700 may alternatively be any portable electronic device, including, for example, a mobile phone, tablet computer, portable computer, portable music player, electronic watch, health monitoring device, portable terminal, vehicle navigation system, robot navigation system, or other portable or mobile device. Device 1700 may also be a device that is semi-permanently located (or installed) in a single location. Figure 17A A front isometric view of device 1700 is shown, and Figure 17B A rear isometric view of device 1700 is shown. Device 1700 may include a housing 1702 that at least partially surrounds a display 1704. Housing 1702 may include or support a front cover 1706 or a rear cover 1708. Front cover 1706 may be positioned above display 1704 and may provide a window through which display 1704 can be viewed. In some embodiments, display 1704 may be attached to (or adjacent to) housing 1702 and / or front cover 1706. In alternative embodiments of device 1700, display 1704 may not be included and / or housing 1702 may have an alternative configuration.

[0198] Display 1704 may include one or more light-emitting elements, including, for example, light-emitting diodes (LEDs), organic LEDs (OLEDs), liquid crystal displays (LCDs), electroluminescent displays (ELs), or other types of light-emitting elements. In some embodiments, display 1704 may include one or more touch sensors and / or force sensors, or associated therewith, which are configured to detect touch and / or force applied to the surface of the front cover 1706.

[0199] Various components of housing 1702 may be formed of the same or different materials. For example, sidewall 1718 may be formed of one or more metals (e.g., stainless steel), polymers (e.g., plastics), ceramics, or composite materials (e.g., carbon fiber). In some cases, sidewall 1718 may be a multi-segment sidewall including a set of antennas. Antennas may form structural components of sidewall 1718. Antennas may be structurally connected (connected to each other or to other components) and electrically isolated (electrically isolated from each other or to other components) via one or more non-conductive segments of sidewall 1718. Front cover 1706 may be formed, for example, using one or more of glass, crystal (e.g., sapphire), or transparent polymers (e.g., plastics), which allows a user to view display 1704 through front cover 1706. In some cases, a portion of front cover 1706 (e.g., the peripheral portion of front cover 1706) may be coated with an opaque ink to cover components included within housing 1702. The rear cover 1708 may be formed of the same material used to form the sidewalls 1718 or the front cover 1706. In some cases, the rear cover 1708 may be part of an integral element that also forms the sidewalls 1718 (or, in the case that the sidewalls 1718 are multi-segmented, those portions of the sidewalls 1718 are non-conductive). In other embodiments, all external components of the housing 1702 may be formed of a transparent material, and components within the device 1700 may be covered or uncovered by opaque ink or opaque structures within the housing 1702.

[0200] The front cover 1706 can be mounted to the side wall 1718 to cover the opening defined by the side wall 1718 (i.e., the opening to the internal volume in which various electronic components of the device 1700 (including the display 1704) can be positioned). The front cover 1706 can be mounted to the side wall 1718 using fasteners, adhesives, seals, gaskets or other components.

[0201] A display stack or device stack (hereinafter referred to as the "stack") including display 1704 may be attached (or adjacent to) the inner surface of the front cover 1706 and extend into the internal volume of the device 1700. In some cases, the stack may include a touch sensor (e.g., a grid of capacitive, resistive, strain-based, ultrasonic, or other types of touch sensing elements) or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensor (or part of a touch sensor system) may be configured to detect touches applied to the outer surface of the front cover 1706 (e.g., to the display surface of the device 1700).

[0202] In some cases, the force sensor (or part of a force sensor system) may be located within an internal volume below and / or on the side of the display 1704 (and in some cases, within a device stack). The force sensor (or force sensor system) may be triggered in response to a touch sensor detecting one or more touches on the front cover 1706 (or one or more locations of one or more touches on the front cover 1706), and the magnitude of the force associated with each touch, or the magnitude of the force associated with the entire set of touches, may be determined.

[0203] like Figure 17A As shown, device 1700 may include a variety of other components. For example, the front of device 1700 may include one or more forward-facing cameras 1710 (including one or more image sensors), a speaker 1712, a microphone, or other components 1714 (e.g., audio components, imaging components, and / or sensing components) configured to send signals to or receive signals from device 1700. In some cases, the forward-facing camera 1710 may be configured to operate as a biometric authentication or facial recognition sensor, alone or in combination with other sensors. Device 1700 may also include a variety of input devices, including mechanical or virtual buttons 1716 accessible from the front surface (or display surface) of device 1700.

[0204] Device 1700 may also include buttons or other input devices positioned along a sidewall 1718 and / or on its rear surface. For example, a volume button or multifunction button 1720 may be positioned along the sidewall 1718 and, in some cases, may extend through an opening in the sidewall 1718. The sidewall 1718 may include one or more ports 1722 that allow air, but not liquid, to flow into and out of device 1700. In some embodiments, one or more sensors may be located in or near one of the ports 1722. For example, an ambient pressure sensor, an ambient temperature sensor, an internal / external differential pressure sensor, a gas sensor, a particulate matter concentration sensor, or an air quality sensor may be located in or near one of the ports 1722.

[0205] In some embodiments, the rear surface of device 1700 may include a rear-facing camera 1724 (including one or more image sensors; see [link]). Figure 1 B). A flash or light source 1726 (and in some cases an IR illuminator) may also be positioned along the rear of device 1700 (e.g., near a rear-facing camera). In some embodiments, the IR illuminator may also or alternatively be positioned adjacent to the front-facing camera 1710. In some cases, the rear surface of device 1700 may include multiple rear-facing cameras.

[0206] One or more of the forward-facing camera 1710 or the rear-facing camera 1724 may include stacked or non-stacked electromagnetic radiation sensors as described herein. If the device 1700 is alternatively configured as a vehicle navigation system or some other type of device (and may be configured as a device without a display), the device 1700 may still have at least one camera including stacked or non-stacked electromagnetic radiation sensors as described herein.

[0207] Figure 18 An exemplary embodiment of an image capture device (e.g., camera 1800) is shown, which includes an image sensor 1802, an optional dual-band spectral filter 1808, a lens (or lens stack) 1804, and an AF mechanism 1806. In some embodiments, Figure 18 The components shown can be compared with the reference. Figure 17A and Figure 17B The described forward or backward camera is associated with, or with, any stacked or non-stacked electromagnetic radiation sensor described herein.

[0208] In some cases, the image sensor 1802 may include a non-stacked electromagnetic radiation sensor with multiple pixels, such as multiple pixels arranged in a two-dimensional array. In some cases, multiple (or all) pixels in a pixel may each include a two-dimensional array of subpixels (e.g., a 2x2 array of subpixels), wherein each subpixel includes a photodetector. Configuring most (or more significantly at least 80%, and preferably all) of the pixels to include a 2×2 subpixel array can help improve phase-detection autofocus (PDAF) performance and / or reduce or eliminate the need to correct the output of a pixel with PDAF capability relative to the output of other pixels. The subpixels (or photodetectors) associated with a pixel may be electrically isolated from each other but positioned beneath a shared microlens of the pixel.

[0209] Image sensor 1802 may alternatively include stacked electromagnetic radiation sensors, wherein each of the stacked electromagnetic radiation sensors has a pixel array. Different pixel arrays may have an equal or unequal number of pixels. For example, an IR sensor portion of image sensor 1802 may have pixels spanning multiple pixels of a visible light sensor portion of image sensor 1802, which is stacked on top of the IR sensor portion.

[0210] The dual-band spectral filter 1808 (when present) can pass only a range of visible light wavelengths and a range of IR wavelengths, which precisely or substantially correspond to the range of electromagnetic radiation wavelengths sensed by the sensor of the image sensor 1802.

[0211] Lens 1804 may be adjustable relative to image sensor 1802 to focus an image of scene 1810 onto image sensor 1802. In some embodiments, lens 1804 may be movable relative to image sensor 1802 (e.g., moved to change the distance between lens 1804 and image sensor 1802, moved to change the angle between the plane of lens 1804 and the plane of image sensor 1802, etc.). In other embodiments, image sensor 1802 may be movable relative to lens 1804.

[0212] In some embodiments, the AF mechanism 1806 may include a processor (or the functionality of the AF mechanism 1806 may be provided by a processor). The AF mechanism 1806 may receive signals from the image sensor 1802 and adjust the focus setting of the camera 1800 in response to these signals. In some embodiments, the signals may include PDAF information. The PDAF information may include a horizontal phase detection signal and / or a vertical phase detection signal. In response to the PDAF information (e.g., in response to defocus conditions identified from the PDAF information), the AF mechanism 1806 may adjust the focus setting of the camera 1800 by, for example, adjusting the relationship between the image sensor 1802 and the lens 1804 (e.g., by adjusting the physical position of the lens 1804 or the image sensor 1802).

[0213] Figure 19 An exemplary system 1900 is shown, including a detector 1904 employing an avalanche diode (e.g., SPAD). System 1900 may include a transmitter 1902 and a detector 1904 positioned adjacent to each other and relatively far from a target 1906 (compared to the distance between the transmitter 1902 and detector 1904). In some embodiments, transmitter 1902 and detector 1904 may be provided as a single module. Transmitter 1902 may be positioned to emit photons toward or into the FoV of the target 1906, and detector 1904 may be positioned to detect the reflection of photons from the target 1906. In some embodiments, transmitter 1902 may include an IR illuminator, and detector 1904 may include any stacked or non-stacked electromagnetic radiation sensor described herein.

[0214] Processor 1908 may be operatively connected to transmitter 1902 and detector 1904, and may cause transmitter 1092 to emit photons toward target 1906 (where the emitted photons are indicated by arrow 1910). Photons reflected from target 1906 toward detector 1904 (indicated by arrow 1912) may be detected by detector 1904. Specifically, the reflected photons may induce avalanche events in individual pixels of detector 1904, and the timing of such avalanche events may be recorded and compared with the time when the photons were emitted. Processor 1908 may receive signals output by detector 1904 (e.g., the time of avalanche events), and in some cases may receive photon emission times from transmitter 1902, and may determine the Time of Flight (ToF) of photons emitted by transmitter 1902 and received by pixels of detector 1904. The ToF may be used to determine the distances between individual pixels of detector 1904 and target 1906. These distances may be used to generate depth maps (e.g., a three-dimensional (3D) image of target 1906).

[0215] The operation of the components and system 1900 described are exemplary. In alternative embodiments, system 1900 may include different combinations or configurations of components, or may perform additional or alternative functions.

[0216] System 1900 can be used as part of an electronic device, such as an image sensor in a smartphone (e.g., an image sensor in a smartphone's camera or biosensor (e.g., a facial recognition sensor); in a vehicle navigation system; or in other devices.

[0217] Figure 20 This illustrates how multiple images (or image frames 2000) acquired by an electromagnetic radiation sensor (e.g., a visible light sensor or an IR sensor) can be fused to form a single still image 2002. In some embodiments, image frames within a video stream can be fused to mitigate the higher dark current of the panchromatic photosensitive layer of the visible light sensor.

[0218] Figure 21 A sample electrical block diagram of electronic device 2100 is shown, which may be a reference. Figures 17A to 17B , Figure 18 or Figure 19The described electronic device 2100 may include a display 2102 (e.g., a light-emitting display), a processor 2104, a power supply 2106, a memory 2108 or storage device, a sensor system 2110, or an input / output (I / O) mechanism 2112 (e.g., input / output devices and / or input / output ports). The processor 2104 may control some or all of the operations of the electronic device 2100. The processor 2104 may communicate directly or indirectly with substantially all components of the electronic device 2100. For example, a system bus or other communication mechanism 2114 may provide communication between the processor 2104, the power supply 2106, the memory 2108, the sensor system 2110, and / or the I / O mechanism 2112.

[0219] Processor 2104 may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, processor 2104 may be a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or a combination of such devices. As described herein, the term "processor" is intended to cover a single processor or processing unit, multiple processors, multiple processing units, or one or more other suitably configured computing elements.

[0220] It should be noted that components of electronic device 2100 may be controlled by multiple processors. For example, selection components of electronic device 2100 may be controlled by a first processor, and other components of electronic device 2100 may be controlled by a second processor, wherein the first and second processors may or may not communicate with each other. In some embodiments, processor 2104 may include any of the pixel processing chip or image processor described herein.

[0221] The power source 2106 can be implemented using any device capable of providing power to the electronic device 2100. For example, the power source 2106 can be one or more batteries or rechargeable batteries. Alternatively, the power source 2106 can be a power connector or power cord that connects the electronic device 2100 to another power source, such as a wall socket.

[0222] Memory 2108 may store electrical data that can be used by electronic device 2100. For example, memory 2108 may store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, data structures or databases, image data, or focus settings. Memory 2108 may be configured as any type of memory. By way of example only, memory 2108 may be implemented as random access memory, read-only memory, flash memory, removable memory, other types of storage elements, or combinations of such devices.

[0223] Electronic device 2100 may also include a sensor system 2110, which in turn includes one or more sensors substantially located anywhere on electronic device 2100. The sensors can be configured to sense substantially any type of characteristic, such as, but not limited to, pressure, light, touch, heat, motion, relative motion, biometric data, etc. For example, sensors may include thermal sensors, position sensors, light or optical sensors, accelerometers, pressure transducers, gyroscopes, magnetometers, health monitoring sensors, etc. Furthermore, one or more sensors may utilize any suitable sensing technology, including but not limited to capacitive, ultrasonic, resistive, optical, piezoelectric, and thermal sensing technologies.

[0224] I / O device 2112 can send and / or receive data from a user or another electronic device. I / O devices may include a display, a touch-sensing input surface (such as a touchpad), one or more buttons (e.g., a graphical user interface "home" button), and one or more cameras (e.g., a reference camera). Figures 17A to 17B , Figure 18 or Figure 19 The described camera, or camera including one or more of the stacked or non-stacked electromagnetic radiation sensors described herein, one or more microphones or speakers, one or more ports (such as microphone ports), and / or a keyboard. In addition or alternatively, the I / O devices or ports may transmit electrical signals via communication networks such as wireless and / or wired network connections. Examples of wireless and wired network connections include, but are not limited to, cellular networks, Wi-Fi, Bluetooth, IR, and Ethernet connections.

[0225] The foregoing description uses specific nomenclature to provide a thorough understanding of the described embodiments for the purpose of explanation. However, it will be apparent to those skilled in the art that, after reading this specification, the specific details are not required to practice the described embodiments. Therefore, the foregoing description of specific embodiments described herein is presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to those skilled in the art that, after reading this specification and in light of the teachings above, many modifications and variations are possible.

Claims

1. A sensor stack, the sensor stack comprising: A first electromagnetic radiation sensor, the first electromagnetic radiation sensor having high quantum efficiency for converting a first electromagnetic radiation wavelength range into a first set of electrical signals, and the first electromagnetic radiation sensor comprising a first semiconductor substrate and a first pixel array; as well as A second electromagnetic radiation sensor is located within the field of view of the first electromagnetic radiation sensor. The second electromagnetic radiation sensor includes a second semiconductor substrate and a second pixel array, and the second electromagnetic radiation sensor has: High quantum efficiency for converting a second electromagnetic radiation wavelength range into a second set of electrical signals; and Low quantum efficiency for converting the first electromagnetic radiation wavelength range into the second set of electrical signals; A filter is located between the first electromagnetic radiation sensor and the second electromagnetic radiation sensor. A pixel processing chip is positioned below the first electromagnetic radiation sensor. A set of electrical connections, wherein the set of electrical connections is located between the first electromagnetic radiation sensor and the pixel processing chip; A set of through-silicon vias (TSVs) extends through the first electromagnetic radiation sensor and the filter, beyond the entire first imaging region defined by the first pixel array, and beyond the entire second imaging region defined by the second pixel array, and the set of TSVs is electrically connected to the pixel processing chip. The first set of buses includes one or more opaque low-resistance buses located outside the entire first imaging region and the second imaging region and electrically connected to the TSV; The second set of buses includes one or more IR transparent high-resistance buses electrically connected between the first set of buses and one or more pixels of the second pixel array, wherein: The first electromagnetic radiation wavelength range does not overlap with the second electromagnetic radiation wavelength range; The filter blocks light within the wavelength range of the second electromagnetic radiation. The second electromagnetic radiation sensor at least partially transmits the wavelength range of the first electromagnetic radiation; and At least one of the buses in the second group extends across the first pixel in the second pixel array and is electrically connected to the second pixel in the second pixel array.

2. The sensor stack according to claim 1, wherein the set of TSVs at least partially transmits the first electromagnetic radiation wavelength range.

3. The sensor stack of claim 1, wherein the set of TSVs extends at least partially through the second electromagnetic radiation sensor.

4. The sensor stack according to claim 1, wherein: At least one of the first electromagnetic radiation sensor or the second electromagnetic radiation sensor includes: A semiconductor substrate, the semiconductor substrate including pixel circuitry for a pixel array; Photosensitive material, said photosensitive material being deposited on said semiconductor substrate; and An array of electrical connections between the pixel circuitry and the photosensitive material used in the pixel array.

5. The sensor stack according to claim 4, wherein the photosensitive material comprises a quantum dot film.

6. The sensor stack according to claim 4, wherein the photosensitive material comprises an organic material.

7. The sensor stack according to claim 4, wherein the photosensitive material comprises Sb₂Se. (3-x) Te (x) , where x≥0.

8. The sensor stack according to claim 4, wherein the semiconductor substrate is a silicon substrate.

9. The sensor stack according to claim 4, wherein the electrical connections in the electrical connection array include: A heterojunction photodiode, wherein the heterojunction photodiode is formed between the semiconductor substrate and the photosensitive material.

10. The sensor stack of claim 4, wherein the semiconductor substrate, the photosensitive material, and the electrical connection array are part of the first electromagnetic radiation sensor.

11. The sensor stack according to claim 10, wherein the first electromagnetic radiation sensor is an infrared (IR) sensor.

12. The sensor stack according to claim 11, wherein the IR sensor is an IR image sensor.

13. The sensor stack according to claim 11, wherein the IR sensor is an IR depth sensor.

14. The sensor stack according to claim 11, wherein the second electromagnetic radiation sensor is a visible light sensor.

15. The sensor stack according to claim 14, wherein: The semiconductor substrate is the first semiconductor substrate; The pixel circuit used for the pixel array is a first pixel circuit used for the first IR pixel array; The photosensitive material includes a first photosensitive material; The electrical connection array is a first electrical connection array; and The visible light sensor includes: Second pixel circuit for a second visible light pixel array; A second photosensitive material, wherein the second photosensitive material is deposited on the second semiconductor substrate; and A second electrical connection array between the second pixel circuit and the second photosensitive material for the second visible light pixel array.

16. The sensor stack according to claim 15, wherein: The first photosensitive material includes a first quantum dot film, which has high quantum efficiency for converting the first electromagnetic radiation wavelength range into the first set of electrical signals; and The second photosensitive material includes a second quantum dot film, which has high quantum efficiency for converting the second electromagnetic radiation wavelength range into the second set of electrical signals.

17. The sensor stack of claim 15, wherein the electrical connections in the second electrical connection array include: The second heterojunction photodiode is formed between the second semiconductor substrate and the second photosensitive material.

18. The sensor stack according to claim 14, wherein: The semiconductor substrate is the first semiconductor substrate; The pixel circuit used for the pixel array is a first pixel circuit used for the first IR pixel array; and The second semiconductor substrate includes: Second pixel circuit for a second visible light pixel array; and A photodiode array corresponding to the visible light pixel array.

19. The sensor stack according to claim 4, wherein: The semiconductor substrate is the second semiconductor substrate, and The photosensitive material and the electrical connection array are part of the second electromagnetic radiation sensor.

20. The sensor stack according to claim 4, wherein the second electromagnetic radiation sensor is a visible light sensor.

21. The sensor stack according to claim 20, wherein the first electromagnetic radiation sensor is an infrared (IR) sensor.

22. The sensor stack according to claim 21, wherein: The semiconductor substrate is the first semiconductor substrate; The pixel circuit for the pixel array is a first pixel circuit for a first visible light pixel array, wherein the second semiconductor substrate includes the first pixel circuit.

23. The sensor stack of claim 22, wherein the photosensitive material comprises a quantum dot film having high quantum efficiency for converting the second electromagnetic radiation wavelength range into the second set of electrical signals.

24. The sensor stack according to claim 21, wherein: The filter includes a visible light blocking filter.

25. The sensor stack of claim 21, wherein the electrical connection array at least partially transmits the first electromagnetic radiation wavelength range.

26. The sensor stack of claim 21, wherein the first semiconductor substrate is approximately one micrometer.

27. The sensor stack according to claim 21, wherein the IR sensor is an IR image sensor.

28. The sensor stack of claim 21, wherein the IR sensor is an IR depth sensor.

29. The sensor stack according to claim 4, wherein the pixel circuitry comprises: An in-pixel noise reduction circuit, the in-pixel noise reduction circuit including a p-channel metal-oxide-semiconductor (PMOS) transistor.

30. The sensor stack according to claim 4, wherein the pixel circuitry comprises: Pixel column noise reduction circuit.

31. The sensor stack according to claim 4, wherein the pixel circuitry comprises: In-line noise reduction circuit.

32. The sensor stack according to claim 4, wherein: The photosensitive material includes a quantum dot film; and The semiconductor substrate is a p-doped silicon substrate.

33. The sensor stack of claim 32, wherein the p-doped silicon substrate comprises an n-well.

34. The sensor stack according to claim 33, further comprising: A heterojunction is formed between the p-doped silicon substrate and the quantum dot film.

35. The sensor stack according to claim 34, further comprising: A passivation layer is located between the p-doped silicon substrate and the quantum dot film.

36. The sensor stack according to claim 34, further comprising: An electrical isolation layer is located at a selected location between the p-doped silicon substrate and the quantum dot film, wherein the electrical isolation layer is configured to generate a collection node region in the p-doped silicon substrate.

37. The sensor stack of claim 36, wherein the electrical isolation layer comprises a silicon dioxide layer.

38. The sensor stack according to claim 36, further comprising: An optical black material located at a selected position beneath the electrically insulating layer, wherein the optical black material is configured to sufficiently absorb a predetermined range of wavelengths; and A passivation layer is located above the electrical isolation layer.

39. The sensor stack according to claim 34, further comprising: An optical black material located at a selected position between the p-doped silicon substrate and the quantum dot film, wherein the optical black material is configured to sufficiently absorb a predetermined range of wavelengths.

40. The sensor stack of claim 39, wherein the optical black material comprises an absorptive polymer.

41. The sensor stack according to claim 34, further comprising: A heterojunction is formed between the n-well and the quantum dot film.

42. The sensor stack of claim 41, wherein the quantum dot film is an intrinsic quantum dot film or lightly doped and is configured to be fully depleted under bias.

43. The sensor stack according to claim 41, further comprising: A passivation layer is located between the n-well and the quantum dot film.

44. The sensor stack according to claim 41, further comprising: An electrically insulating layer is located between the n-well and the quantum dot film, wherein the electrically insulating layer is configured to generate a collection node region in the p-doped silicon substrate.

45. The sensor stack of claim 44, wherein the electrical isolation layer comprises a silicon dioxide layer.

46. ​​The sensor stack according to claim 44, further comprising: An optical black material located at a selected position between the n-well and the quantum dot film, wherein the optical black material is configured to sufficiently absorb a predetermined range of wavelengths.

47. The sensor stack of claim 46, wherein the optical black material comprises an absorptive polymer.

48. The sensor stack according to claim 44, further comprising: An optical black material located at a selected position beneath the electrically insulating layer, wherein the optical black material is configured to sufficiently absorb a predetermined range of wavelengths; and A passivation layer is located above the electrical isolation layer.

49. The sensor stack according to claim 33, wherein the quantum dot film is an intrinsic quantum dot film.

50. The sensor stack of claim 33, wherein the quantum dot film is a lightly doped quantum dot film, wherein the lightly doped quantum dot film is completely depleted when a bias voltage is applied.

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