Visible light and short wave infrared hybrid sensor

Abstract

The present disclosure relates to visible and short wave infrared (SWIR) hybrid sensors, and methods for constructing such sensors. The method includes forming a first deep trench isolation (DTI), a second DTI, and a third DTI in a silicon substrate. A portion of the silicon substrate positioned between the second DTI and the third DTI forms a silicon photodetector for detecting visible light. The method further includes etching a trench in the silicon substrate between the second DTI and the third DTI. The trench is etched such that another portion of the silicon substrate remains between the second DTI and the third DTI. The method further includes forming a SWIR photodetector within the trench for detecting SWIR light. The method further includes removing another portion of the silicon substrate such that the first DTI, the second DTI, and the third DTI are exposed on one side of the silicon substrate. The method further includes forming a high-K dielectric layer on the silicon substrate.

Description

BACKGROUND

[0001] Image sensors are used in electronic devices such as cellular telephones, cameras, and computers to capture images. Specifically, the electronic devices are provided with an array of image sensor pixels arranged in a grid pattern. Each image sensor pixel receives incoming photons such as light and converts the photons to an electrical signal. Column circuitry is coupled to each column for reading out the sensor signal from each image sensor pixel.

[0002] Time-of-flight (ToF) sensing is used in many industrial applications such as logistics, factory automation, medical, health, and agriculture. ToF sensing is also used in many consumer applications such as augmented reality, virtual reality, gaming, and object scanning. ToF sensing is also used in many automotive applications such as in-car monitoring and light detection and ranging (LIDAR). Indirect ToF (iTOF) is a form of ToF sensing in which distance is measured by collecting reflected infrared light, such as short-wave infrared (SWIR) light, and discerning a phase shift between the emitted infrared light and the reflected infrared light. SUMMARY

[0003] It is desirable to integrate visible and SWIR light sensing into a single sensor. Silicon photodetectors can be used to detect visible light, and other types of photodetectors, such as germanium photodetectors, can be used to detect SWIR light. However, due to the lattice mismatch between silicon and germanium, growing germanium on silicon results in dark current that degrades sensor performance. Accordingly, the present disclosure provides a visible and SWIR hybrid sensor and a method for constructing such a sensor in which such a sensor prevents dark current generated by a SWIR photodetector from flowing into a silicon photodetector.

[0004] The present disclosure provides a method for constructing a visible and short-wave infrared (SWIR) sensor. The method includes forming at least a first deep trench isolation (DTI), a second DTI, and a third DTI on a first side of a silicon substrate. A first portion of the silicon substrate positioned between the second DTI and the third DTI forms a silicon photodetector configured to detect visible light. The method further includes etching a trench on the first side of the silicon substrate between the second DTI and the third DTI. The trench is etched such that a second portion of the silicon substrate remains between the second DTI and the third DTI. The method further includes forming a SWIR photodetector within the trench. The SWIR photodetector is configured to detect SWIR light. The method further includes removing a third portion of the silicon substrate such that the first DTI, the second DTI, and the third DTI are exposed on a second side of the silicon substrate opposite the first side. The method further includes forming a high-K dielectric layer on the second side of the silicon substrate.

[0005] The present disclosure also provides another method for constructing a visible light and SWIR sensor. The method includes etching a trench on a first side of a silicon substrate. The method also includes forming a SWIR photodetector within the trench. The SWIR photodetector is configured to detect SWIR light. The method also includes forming a first DTI on the first side of the silicon substrate. The method also includes forming a second DTI on the first side of the silicon substrate and adjacent to a first side of the SWIR photodetector. A first portion of the silicon substrate positioned between the first DTI and the second DTI forms a silicon photodetector configured to detect visible light. The method also includes forming a third DTI on the first side of the silicon substrate and adjacent to a second side of the SWIR photodetector, the second side of the SWIR photodetector being opposite the first side of the SWIR photodetector. The method also includes removing a second portion of the silicon substrate such that the first DTI, the second DTI, and the third DTI are exposed on a second side of the silicon substrate opposite the first side of the silicon substrate. The method also includes forming a high-K dielectric layer on the second side of the silicon substrate.

[0006] The present disclosure also provides an image sensor for visible light and SWIR sensing. In one implementation, the image sensor includes a first DTI, a second DTI, a third DTI, a silicon photodetector, a SWIR photodetector, and a high-K dielectric layer. The first DTI, the second DTI, and the third DTI are formed in a silicon substrate. The first DTI, the second DTI, and the third DTI are positioned substantially parallel to each other. The silicon photodetector is configured to detect visible light. The silicon photodetector is positioned between the first DTI and the second DTI. The SWIR photodetector is configured to detect SWIR light. The SWIR photodetector is positioned between the second DTI and the third DTI. The high-K dielectric layer is positioned over at least the first DTI, the second DTI, the third DTI, the silicon photodetector, and the SWIR photodetector. A portion of the silicon substrate is positioned between the SWIR photodetector and the high-K dielectric layer. BRIEF DESCRIPTION OF DRAWINGS

[0007] For a detailed description of example implementations, reference will now be made to the accompanying drawings in which:

[0008] Figure 1 is a block diagram of an example of an imaging system according to some implementations;

[0009] Figure 2 is a diagram of an example of an imaging system incorporated into a vehicle according to some implementations;

[0010] Figure 3 is a partial schematic and partial block diagram of an example of an image sensor according to some implementations;

[0011] Figure 4 is a schematic view of an example of a pixel circuit according to some implementations;

[0012] Figure 5 is a view of an example of a color pattern of a pixel according to some implementations;

[0013] Figures 6A-6E is a cross-sectional view of different steps of an example of a method for building a color pattern of Figure 5 according to a first implementation;

[0014] Figure 7 is a cross-sectional view of an example of a color pattern of Figure 5 with a spectral router according to some implementations;

[0015] Figure 8 is a cross-sectional view of an example of a color pattern of Figure 5 with a spectral router and a pyramidal trench according to some implementations;

[0016] Figure 9 is a cross-sectional view of an example of a color pattern of Figure 5 with a spectral router, a spectral filter and a microlens according to some implementations;

[0017] Figure 10 is a cross-sectional view of an example of a color pattern of Figure 5 with a spectral filter and a microlens according to some implementations;

[0018] Figure 11 is a flowchart of an example of a method for building a visible and SWIR sensor according to the first implementation shown in Figures 6A-6E ;

[0019] Figures 12A-12E is a cross-sectional view of different steps of an example of a method for building a color pattern of Figure 5 according to a second implementation; and

[0020] Figure 13 is a flowchart of an example of a method for building a visible and SWIR sensor according to the second implementation shown in Figures 12A-12E .

[0021] Definitions

[0022] Various terminology is used to refer to particular system components. Different companies may refer to a component by different names - this document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to...." Also, the term "couple" is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection can be through a direct connection, or through an indirect connection via other devices and connections.

[0023] As used herein, "a," "an," and "the" mean both singular and plural referents unless the context clearly dictates otherwise. For example, a "processor" that is programmed to perform various functions refers to one processor programmed to perform each function, or more than one processor collectively programmed to perform each of the various functions. For clarity, initial references to "[the referent]" and subsequent references to "the [referent]" should not exclude the possibility that the referent can be plural unless the context clearly dictates otherwise.

[0024] The terms defining a height, such as "above," "below," "upper," and "lower," shall be position terms with respect to the direction of light incident on the pixel array and / or image pixel. Light entry shall be considered to interact with or pass through objects and / or structures that are "above" and "upper" before interacting with or passing through objects and / or structures that are "below" and "lower." Thus, the position terms can have no relationship to the direction of gravity.

[0025] "About" in reference to a recited parameter should mean the recited parameter plus or minus ten percent (+ / - 10%) of the recited parameter.

[0026] "Assert" shall mean to create or maintain a first predetermined state of a Boolean signal. The Boolean signal can be asserted to a high level or have a higher voltage according to the judgment of the circuit designer, and the Boolean signal can be asserted to a low level or have a lower voltage. Similarly, "de-assert" shall mean to create or maintain a second predetermined state of the Boolean opposite the asserted state.

[0027] In reference to electrical devices, whether standalone or as part of an integrated circuit, the terms "input" and "output" refer to electrical connections to the electrical device and should not be construed as verbs requiring action. For example, a differential amplifier such as an operational amplifier can have a first differential input and a second differential input, and these "inputs" define electrical connections to the operational amplifier and should not be construed as requiring a signal input to the operational amplifier.

[0028] “Controller” shall mean, individually or in combination, a sole circuit component, an application specific integrated circuit (ASIC), a microcontroller with control software, a reduced instruction set computer (RISC) with control software, a digital signal processor (DSP) with control software, a processor with control software, a programmable logic device (PLD), a field programmable gate array (FPGA), or a programmable system on a chip (PSOC) configured to read inputs and drive outputs in response to those inputs.

[0029] “Visible light” shall mean light having a wavelength in the range of about 400 nanometers (nm) to 750 nm. “Short wave infrared light” or “SWIR light” shall mean light having a wavelength in the range of about 1,000 nm to 1700 nm. DETAILED DESCRIPTION

[0030] The following discussion relates to various implementations of the application. While one or more of these implementations can be preferred, the disclosed implementations should not be construed as limiting the scope of the present disclosure including the claims. Further, those skilled in the art will appreciate that the description herein is not limited to any particular implementation and is intended to cover any and all modifications, equivalents, and alternatives falling within the scope of the present disclosure including the claims.

[0031] Various examples relate to visible light and short wave infrared (SWIR) hybrid sensors and methods for constructing such hybrid sensors. More specifically, at least some examples relate to sensors having silicon photodetectors for detecting visible light and germanium photodetectors for detecting SWIR light. More specifically, various examples relate to pixels having spectral routers that direct visible light and SWIR light according to wavelength. More specifically, various examples relate to pixels having spectral filters that filter visible light according to wavelength. The specification now turns to example systems to guide the reader.

[0032] Figure 1 An example of an imaging system 100 is shown. In particular, the imaging system 100 can be a portable electronic device with imaging capabilities, such as a camera, a cellular phone, a tablet, a webcam, a camcorder, a video surveillance system, or a video game system. In other cases, the imaging system 100 can be an automotive imaging system. Figure 1The illustrated imaging system 100 includes a camera module 102 that can be used to convert incoming light into digital image data. The camera module 102 can include one or more lenses 104 and one or more corresponding image sensors 106. The lenses 104 can include fixed and / or adjustable lenses. During an image capture operation, light from a scene can be focused by the lenses 104 onto the image sensors 106. The image sensors 106 can include circuitry to convert analog pixel data to corresponding digital image data that will be provided to an imaging controller 108. If desired, the camera module 102 can be provided with an array of lenses 104 and a corresponding array of image sensors 106.

[0033] The imaging controller 108 can include one or more integrated circuits. The imaging circuitry can include image processing circuitry, a microprocessor, and storage devices such as random access memory and non-volatile memory. The imaging controller 108 can be implemented using components separate from the camera module 102 and / or components that form part of the camera module 102 (e.g., circuitry that forms part of the image sensors 106). The imaging controller 108 can be used to process and store digital image data captured by the camera module 102. Processed image data can be provided to external equipment such as a computer, an external display, or other devices using wired and / or wireless communication paths coupled to the imaging controller 108 as desired. The imaging controller 108 can perform light detection and ranging (LIDAR) operations. For example, the digital image data captured by the camera module 102 can include one or more histograms, and the imaging controller 108 can perform analysis of the one or more histograms to determine a combined time of flight of outgoing interrogating infrared light and returning reflected infrared light.

[0034] Figure 2 Another example of an imaging system 100 is shown. Figure 2 The illustrated imaging system 100 includes an automobile or vehicle 200. The vehicle 200 is illustratively shown as a passenger vehicle, but the imaging system 100 can be other types of vehicles including commercial vehicles, on-road vehicles, and off-road vehicles. Commercial vehicles can include buses and tractor-trailer vehicles. Off-road vehicles can include tractors and crop harvesting equipment. In Figure 2In the example of a vehicle 200, the vehicle 200 includes a forward-facing camera module 202 arranged to capture images of a scene in front of the vehicle 200. The forward-facing camera module 202 can be used for any suitable purpose, such as lane-keeping assistance, collision warning systems, cruise control systems, autonomous driving systems, and proximity detection. The example vehicle 200 also includes a rear-facing camera module 204 arranged to capture images of a scene behind the vehicle 200. The rear-facing camera module 204 can be used for any suitable purpose, such as collision warning systems, reverse video, autonomous driving systems, proximity detection, monitoring the position of overtaking vehicles, and backing up. The vehicle 200 also includes a side-facing camera module 206 arranged to capture images of a scene alongside the vehicle 200. The side-facing camera module 206 can be used for any suitable purpose, such as blind spot monitoring, collision warning systems, autonomous driving systems, monitoring the position of overtaking vehicles, lane change detection, and proximity detection. In the case that the imaging system 100 is for a vehicle, the imaging controller 108 can be a controller of the vehicle 200. Turning now to the image sensor 106 in more detail.

[0035] Figure 3 An example of the image sensor 106 is shown. In particular, Figure 3 The image sensor 106 is shown as including a substrate 300 of a semiconductor material (such as silicon) encapsulated within a package to produce a packaged semiconductor device or a packaged semiconductor product. Bond pads or other connection points of the substrate 300 are coupled to terminals of the image sensor 106. These connections can include a serial communication channel 302 coupled to a first terminal 304 and a capture input 306 coupled to a second terminal 308. There will be additional terminals, such as ground terminals, common terminals, or power terminals, but these additional terminals are omitted to not overly complicate the drawing. While a single instance of the substrate 300 is shown, in other implementations multiple substrates can be combined to form the image sensor 106 in a multi-chip module created before or after singulation.

[0036] Figure 3 The image sensor 106 shown includes a pixel array 310 having a plurality of pixels, such as pixel 312. The pixel array 310 can include, for example, hundreds or thousands of rows and hundreds or thousands of columns of pixels 312. Control and readout of the pixel array 310 can be implemented by an image sensor controller 314 coupled to a row controller 316 and a column controller 318. The row controller 316 can receive row addresses from the image sensor controller 314 and provide corresponding row control signals to the pixels 312, such as reset, row select, charge transfer, and readout control signals. The row control signals can be conveyed via one or more conductors, such as row control path 320.

[0037] The column controller 318 can be coupled to the pixel array 310 by one or more conductors, such as column lines 322. The column controller can sometimes be referred to as a column control circuit, a readout circuit, or a column decoder. The column lines 322 can be used to read out pixel signals from the pixels 312 and to provide bias current and / or bias voltage to the pixels 312. If desired, during a readout operation, a row of pixels in the pixel array 310 can be selected using the row controller 316, and pixel signals generated by the pixels 312 in that row of pixels can be read out along the column lines 322. The column controller 318 can include sample-and-hold circuits to sample and temporarily store signals read out from the pixel array 310, amplifier circuits, analog-to-digital conversion (ADC) circuits, bias circuits, column memories, latch circuits to selectively enable or disable column circuits, or other circuits coupled to one or more pixels 312 in the pixel array 310 for operating the pixels 312 and for reading out pixel signals from the pixel array 310. The ADC circuits in the column controller 318 can convert analog pixel values received from the pixel array 310 to corresponding digital data. The column controller 318 can provide the digital data to the image sensor controller 314 and / or the imaging controller 108 via, for example, the serial communication channel 302. Figure 1

[0038] The pixels 312 in the pixel array 310 can include one or more photodiodes, one or more single-photon avalanche detectors (SPADs), one or more silicon photomultipliers (SiPMs), or a combination thereof. Figure 4 is an electrical schematic diagram of an example of one of the pixels 312 in the pixel array 310. Specifically, Figure 4 The pixel 312 shown includes a silicon photodetector 402 in the example form of a photodiode, a blooming light suppression transistor 404, a transfer transistor 406, a floating diffusion region 408, a reset transistor 410, a source follower transistor 412, and a row select transistor 414. The photodetector 402 defines an anode coupled to ground or a common terminal and a cathode coupled to the blooming light suppression transistor 404 and the transfer transistor 406. The blooming light suppression transistor 404 selectively connects the photodetector 402 to a positive pixel supply voltage, such as a supply voltage Vdd. The transfer transistor 406 selectively connects the photodetector 402 to the floating diffusion region 408. The reset transistor 410 selectively connects the floating diffusion region 408 to the positive pixel supply voltage. The source follower transistor 412 buffers a signal associated with charge stored in the floating diffusion region 408. The row select transistor 414 selectively connects the source follower transistor 412 to one of the column lines 322. In some implementations, some or all of the pixels 312 in the pixel array 310 can be in a different configuration than the pixel 312 shown. For example, in some implementations, the pixel 312 can include a different number of transistors, a different number of photodetectors, a different number of floating diffusion regions, or a different number of source follower transistors. Figure 4 ​The illustrated pixel 312 has the same components in the same configuration. In other implementations, some or all of the pixels 312 in the pixel array 310 can have fewer components than the illustrated pixel 312, more components than the illustrated pixel 312, or different components in a different configuration. Figure 4 The illustrated pixel 312 has the same components in the same configuration. In other implementations, some or all of the pixels 312 in the pixel array 310 can have fewer components than the illustrated pixel 312, more components than the illustrated pixel 312, or different components in a different configuration.

[0039] Before obtaining an image, the pixel array 310 is reset. For example, the anti-blooming control signal AB can be asserted to reset the pixel array 310. As shown, Figure 4 As shown, the anti-blooming control signal AB is applied to the gate terminal of the anti-blooming transistor 404. Thus, when the anti-blooming control signal AB is asserted, the anti-blooming transistor 404 is turned on. The anti-blooming transistor 404 is turned on to reset the voltage of the photodetector 402 to be equal to or close to the supply voltage Vdd. In addition, to reset the pixel array 310, the reset control signal RST can be asserted. As shown, Figure 4 As shown, the reset control signal RST is applied to the gate terminal of the reset transistor 410. Thus, when the reset control signal RST is asserted, the reset transistor 410 is turned on. The reset transistor 410 is turned on to reset the voltage of the floating diffusion 408 to be equal to or close to the supply voltage Vdd. After the floating diffusion 408 is reset, the reset control signal RST can be de-asserted to turn off the reset transistor 410.

[0040] After the pixel array 310 is reset, the photodetector 402 collects incoming light during an integration time. The photodetector 402 converts this light into charge. To arrange the pixel array 310 to be sensitive to light during the integration time, the anti-blooming control signal AB can be de-asserted to turn off the anti-blooming transistor 404. After (or during) the integration time, the transfer control signal TX can be asserted. As shown, Figure 4 As shown, the transfer control signal TX is applied to the gate terminal of the transfer transistor 406. Thus, when the transfer control signal TX is asserted, the transfer transistor 406 is turned on. The transfer transistor 406 is turned on to transfer the charge generated by the photodetector 402 to the floating diffusion 408. After the charge is transferred to the floating diffusion 408, the transfer control signal TX can be de-asserted to turn off the transfer transistor 406. Next, the row select control signal RS can be asserted. As shown, Figure 4 As shown, the row select control signal RS is applied to the gate terminal of the row select transistor 414. Thus, when the row select control signal RS is asserted, the row select transistor 414 is turned on. The row select transistor 414 is turned on to output an output signal Vout that characterizes the magnitude of the charge stored in the floating diffusion 408. The output signal Vout is one example of a “pixel signal.” When the row select control signal RS is asserted, one of the column lines 322 can be used to route the output signal Vout to a readout circuit, such as Figure 3The row select control signal RS is asserted to turn on the row select transistor 414. The output signal Vout is output from the column controller 318. After the output signal Vout is output, the row select control signal RS can be de-asserted to turn off the row select transistor 414.

[0041] Figure 5 A view showing an example of a color pattern 500 of pixels is shown. Specifically, Figure 5 The color pattern 500 shown includes a first green pixel 502, a red pixel 504, a blue pixel 506, a second green pixel 508, and a SWIR pixel 510. As Figure 5 shown, a deep trench isolation (DTI) 512 resides between the first green pixel 502, the red pixel 504, the blue pixel 506, the second green pixel 508, and the SWIR pixel 510. The DTI 512 can include silicon dioxide, polysilicon, a metal such as tungsten, or a combination thereof. In some implementations, each of the first green pixel 502, the red pixel 504, the blue pixel 506, and the second green pixel 508 has a pitch of two microns.

[0042] Figures 6A-6E is a cross-sectional view of different steps of an example of a method for constructing Figure 5 the color pattern 500 of Figures 6A-6E The cross-sectional view in Figure 5 is taken along line 5-5 of

[0043] In Figure 6A , a first DTI 602, a second DTI 604, a third DTI 606, and a fourth DTI 608 are formed on a first side 610 of a silicon substrate 612. The first DTI 602, the second DTI 604, the third DTI 606, and the fourth DTI 608 are positioned substantially parallel to each other.

[0044] In Figure 6B , a trench 614 is etched on the first side 610 of the silicon substrate 612. As Figure 6B shown, the trench 614 is etched such that a portion 616 of the silicon substrate 612 remains between the second DTI 604 and the third DTI 606. The portion 616 of the silicon substrate 612 between the second DTI 604 and the third DTI 606 is an example of a “first portion.” Germanium (and other SWIR-detecting materials) cannot be grown directly on the second DTI 604. However, germanium can be grown on silicon. Thus, Figure 6BThe trench 614 is etched such that a portion 618 of the silicon substrate 612 remains between the trench 614 and the second DTI 604. The portion 618 of the silicon substrate 612 located between the trench 614 and the second DTI 604 is an example of a "second portion" and a "fourth portion". Furthermore, germanium cannot be directly grown on the third DTI 606. Therefore, Figure 6B The trench 614 is etched such that a portion 620 of the silicon substrate 612 remains between the trench 614 and the third DTI 606. The portion 620 of the silicon substrate 612 located between the trench 614 and the third DTI 606 is an example of a "third portion" and a "fifth portion".

[0045] exist Figure 6C In this process, a SWIR photodetector 622 is formed (e.g., grown) within trench 614. The SWIR photodetector 622 may comprise germanium, indium, gallium, arsenide, phosphorus, antimony, or any combination thereof. For example, the SWIR photodetector 622 may comprise germanium, indium gallium arsenide (InGaAs), indium arsenide (InAs), gallium arsenide (GaAs), indium antimony (InSb), or indium phosphide (InP). In some specific embodiments, the SWIR photodetector 622 may comprise multiple layers of different compounds. For example, the SWIR photodetector 622 may be created by first forming an InGaAs layer on a silicon substrate 612 within trench 614 and then forming a GaAs layer on top of the InGaAs layer. The SWIR photodetector 622 may comprise other combinations of different compounds, such as InGaAs and gallium phosphide (GaP), InSb and gallium antimony (GaSb), or InP and GaAs.

[0046] exist Figure 6D In this process, a portion of the silicon substrate 612 is removed, exposing the first DTI 602, the second DTI 604, the third DTI 606, and the fourth DTI 608 on the second side 624 of the silicon substrate 612. It should be noted that... Figures 6D-6E The view in the middle relative to Figures 6A-6C The view in the image is flipped vertically. The removed portion of silicon substrate 612 is an example of the "second part" and "third part". Figure 6D As shown, the second side 624 of the silicon substrate 612 is opposite to the first side 610 of the silicon substrate 612.

[0047] exist Figure 6E In this process, a high-k dielectric layer 626 is formed on the second side 624 of the silicon substrate 612. The high-k dielectric layer 626 comprises a high-k dielectric, such as aluminum oxide, hafnium oxide, tantalum pentoxide, or a combination thereof.

[0048] Figure 6EA portion of the silicon substrate 612 in the middle of the first DTI 602 and the second DTI 604 forms a first silicon photodetector 628 configured to detect green light. The first silicon photodetector 628 can be a portion of a first green pixel 502 in the color pattern 500 of Figure 5 Additionally, Figure 6E A portion of the silicon substrate 612 in the middle of the third DTI 606 and the fourth DTI 608 forms a second silicon photodetector 630 configured to detect red light. The second silicon photodetector 630 can be a portion of a red pixel 504 in the color pattern 500 of Figure 5 Additionally, Figure 6E The SWIR photodetector 622 in the middle of the first DTI 602 and the second DTI 604 is configured to detect SWIR light. The SWIR photodetector 622 can be a portion of a SWIR pixel 510 in the color pattern 500 of Figure 5 Additionally,

[0049] As shown in FIG. 6A, the SWIR photodetector 622, the first silicon photodetector 628, and the second silicon photodetector 630 are positioned on a plane that is substantially parallel to the high-K dielectric layer 626. In other words, the SWIR photodetector 622 is not positioned above or below the first silicon photodetector 628 or the second silicon photodetector 630. Positioning the SWIR photodetector below the silicon photodetectors can reduce the detection capabilities of the SWIR photodetector. Additionally, stacking the photodetectors increases the overall size of the pixel array. As shown in FIG. 6B, positioning the SWIR photodetector 622 on the same plane as the first silicon photodetector 628 or the second silicon photodetector 630 improves the detection capabilities of the SWIR photodetector 622 and reduces the overall size of the pixel array 310. Additionally, as shown in FIG. 6C, there is a gap between the SWIR photodetector 622 and the high-K dielectric layer 626. Due to the gap, any dark current generated by the SWIR photodetector 622 is prevented from flowing into the first silicon photodetector 628 or the second silicon photodetector 630. Figure 6E Figure 6E Figure 6E

[0050] In some implementations, additional steps can be performed while building the color pattern 500 of FIG. 6A. For example, after forming the SWIR photodetector 622 in FIG. 6A, a stack of sensor and application-specific integrated circuit (ASIC) layers can be formed on the first side 610 of the silicon substrate 612. These sensor and ASIC layers can include an interlayer dielectric (ILD) that is connected to the SWIR photodetector 622, the first silicon photodetector 628, the second silicon photodetector 630, or a combination thereof. Figure 5 Figure 6C

[0051] ​​​​​In some implementations, incident light entering the pixel array 310 is routed to the photosensitive region via a spectral router. A spectral router (or nanophotonic light guide) is an optical structure that accepts photons incident on an upper surface. The spectral router then diverts the photons from the upper surface to the photosensitive region underneath the photodiode. For example, Figure 7 The green spectral router 702 is shown positioned over the first silicon photodetector 628 and over a portion of the SWIR photodetector 622. The green spectral router 702 is configured to direct incident light in the green wavelength range, such as wavelengths between about 500 nanometers (nm) to 590 nm, to the first silicon photodetector 628. For example, the portion of the green spectral router 702 positioned over the first silicon photodetector 628 is configured to pass incident light in the green wavelength range to the first silicon photodetector 628. For purposes of discussion, consider green light entering the green spectral router 702 over the first silicon photodetector 628. An example of such green light is shown by arrow 704 in Figure 7 The green light initially encounters the portion of the green spectral router 702 positioned over the first silicon photodetector 628, which passes the green light to the first silicon photodetector 628. In addition, the portion of the green spectral router 702 positioned over the SWIR photodetector 622 is configured to direct incident light in the green wavelength range to the first silicon photodetector 628. For purposes of discussion, consider green light entering the green spectral router 702 over the SWIR photodetector 622. An example of such green light is shown by arrow 706 in Figure 7 The green light initially encounters the portion of the green spectral router 702 positioned over the SWIR photodetector 622, which directs the green light to the first silicon photodetector 628.

[0052] The green spectral router 702 is also configured to direct SWIR light to the SWIR photodetector 622. For example, the portion of the green spectral router 702 positioned over the first silicon photodetector 628 is configured to direct SWIR light to the SWIR photodetector 622. For purposes of discussion, consider SWIR light entering the green spectral router 702 over the first silicon photodetector 628. An example of such SWIR light is shown by arrow 708 in Figure 7 The SWIR light initially encounters the portion of the green spectral router 702 positioned over the first silicon photodetector 628, which directs the SWIR light to the SWIR photodetector 622. In addition, the portion of the green spectral router 702 positioned over the SWIR photodetector 622 is configured to pass SWIR light to the SWIR photodetector 622. For purposes of discussion, consider SWIR light entering the green spectral router 702 over the SWIR photodetector 622. An example of such SWIR light is shown by arrow 710 inFigure 7 As indicated by arrow 710. The SWIR light initially encounters the portion of the green spectral router 702 positioned above the SWIR photodetector 622, which transmits the infrared light to the SWIR photodetector 622.

[0053] Figure 7 A red spectral router 712 is also shown positioned above the second silicon photodetector 630 and a portion of the SWIR photodetector 622. The red spectral router 712 is configured to direct incident light in the red wavelength range (such as wavelengths between approximately 590 nm and 690 nm) to the second silicon photodetector 630. For example, the portion of the red spectral router 712 positioned above the second silicon photodetector 630 is configured to deliver incident light in the red wavelength range to the second silicon photodetector 630. For the purposes of discussion, consider red light entering the red spectral router 712 above the second silicon photodetector 630. Examples of such red light are shown in... Figure 7 This is indicated by arrow 714. The red light initially encounters the portion of the red spectral router 712 positioned above the second silicon photodetector 630, which transmits the red light to the second silicon photodetector 630. Furthermore, the portion of the red spectral router 712 positioned above the SWIR photodetector 622 is configured to guide incident light in the red wavelength range to the second silicon photodetector 630. For the purposes of discussion, consider the red light entering the red spectral router 712 above the SWIR photodetector 622. An example of such red light is shown in... Figure 7 As indicated by arrow 716. The red light initially encounters the portion of the red spectral router 712 positioned above the SWIR photodetector 622, which directs the red light to the second silicon photodetector 630.

[0054] The red spectrum router 712 is also configured to direct SWIR light to the SWIR photodetector 622. For example, the portion of the red spectrum router 712 positioned above the second silicon photodetector 630 is configured to direct SWIR light to the SWIR photodetector 622. For the purposes of discussion, consider SWIR light entering the red spectrum router 712 above the second silicon photodetector 630. Examples of such SWIR light are shown in... Figure 7 As indicated by arrow 718. The SWIR light initially encounters the portion of the red spectral router 712 positioned above the second silicon photodetector 630, which directs the SWIR light to the SWIR photodetector 622. Furthermore, the portion of the red spectral router 712 positioned above the SWIR photodetector 622 is configured to deliver SWIR light to the SWIR photodetector 622. For the purposes of discussion, consider the SWIR light entering the red spectral router 712 above the SWIR photodetector 622. An example of such SWIR light is shown in...Figure 8 SWIR light initially encounters the portion of the red spectral router 712 positioned above the SWIR photodetector 622, which passes the SWIR light to the SWIR photodetector 622.

[0055] In some implementations, a dielectric layer 722 is formed between the high-K dielectric layer 626 and the green spectral router 702 and between the high-K dielectric layer 626 and the red spectral router 712. The dielectric layer 722 can include an oxide, such as silicon dioxide, or a nitride, such as silicon nitride.

[0056] In some implementations, the high-K dielectric layer 626 and the dielectric layer 722 are formed to include a light scattering structure that disperses the SWIR light evenly across the photosensitive regions. For example, in Figure 9 In some implementations, the high-K dielectric layer 626 and the dielectric layer 722 include a plurality of pyramids 802 configured to disperse the SWIR light evenly across the SWIR photodetector 622, the first silicon photodetector 628, and the second silicon photodetector 630. The plurality of pyramids 802 is one example of a light scattering structure. In some implementations, the high-K dielectric layer 626 and the dielectric layer 722 can include other light scattering structures, such as vertical trenches.

[0057] In some implementations, a spectral filter is positioned above the spectral router to filter visible light. For example, Figure 9 A green spectral filter 902 is shown positioned above the green spectral router 702. The green spectral filter 902 is configured to pass visible light in the green wavelength range and block (or absorb) visible light outside the green wavelength range. The green spectral filter 902 is also configured to pass SWIR light. The green spectral filter 902 is one example of a “first spectral filter.” Figure 9 A red spectral filter 904 is also shown positioned above the red spectral router 712. The red spectral filter 904 is configured to pass visible light in the red wavelength range and block (or absorb) visible light outside the red wavelength range. The red spectral filter 904 is also configured to pass SWIR light. The red spectral filter 904 is one example of a “second spectral filter.” Figure 9 A plurality of microlenses 906 is also shown positioned above the green spectral filter 902 and the red spectral filter 904, as shown in Figure 10 The plurality of microlenses 906 collimates light entering the pixel array 310.

[0058] In some implementations, instead of spectral routers, only spectral filters are used to control the incident light entering the pixel array 310. For example, in Figure 10In the diagram, the green spectral filter 902 and the red spectral filter 904 are not positioned above the SWIR photodetector 622. Instead, Figure 10 A SWIR spectral filter 1002 is shown positioned above a SWIR photodetector 622. The SWIR spectral filter 1002 is configured to allow SWIR light to pass through and block (or absorb) visible light. The SWIR spectral filter 1002 is an example of a "second spectral filter." In some specific embodiments, multiple microlenses 906 are positioned above a green spectral filter 902, a red spectral filter 904, and the SWIR spectral filter 1002, as shown. Figure 10 As shown. Although in Figure 11 Only two microlenses are shown in the figure, but more than two microlenses can be placed on a 2x2 unit.

[0059] Figures 6A-6E Based on the above... Figure 11 A flowchart illustrating an example of a method 1100 for constructing visible light and SWIR sensors according to the first specific embodiment. For simplicity, method 1100 is described in... Figure 6A The process is depicted and described as a series of operations. However, these operations can be performed in various sequences and / or simultaneously, and / or with other operations not presented and described herein. At block 1102, at least a first deep trench isolation portion (DTI), a second DTI, and a third DTI are formed on a first side of the silicon substrate. For example, a first DTI 602, a second DTI 604, and a third DTI 606 may be formed on a first side 610 of the silicon substrate 612, as shown below. Figure 6B As shown. At frame 1104, a trench is etched between the second DTI and the third DTI on the first side of the silicon substrate. For example, a trench 614 can be etched between the second DTI 604 and the third DTI 606 on the first side 610 of the silicon substrate 612, as shown. Figure 6C As shown. At frame 1106, a SWIR photodetector is formed within a trench. For example, a SWIR photodetector 622 can be formed within trench 614, such as... Figure 6D As shown. At box 1108, a third portion of the silicon substrate is removed, exposing the first DTI, second DTI, and third DTI on a second side of the silicon substrate opposite the first side. For example, a portion of the silicon substrate 612 may be removed, exposing the first DTI 602, second DTI 604, and third DTI 606 on a second side 624 of the silicon substrate 612 opposite the first side 610, as shown. Figure 6E As shown. At frame 1110, a high-k dielectric layer is formed on the second side of the silicon substrate. For example, a high-k dielectric layer 626 can be formed on the second side 624 of the silicon substrate 612, as shown. Figures 12A-12E As shown.

[0060] Figure 5 It is based on the second specific implementation for construction Figures 12A-12E The example of the 500 color pattern method includes cross-sectional views during different steps. Figure 5 The sectional view in the middle is along Figure 12A The line was cut at 5-5. Figure 12B In this process, trenches 1202 are etched on the first side 1204 of the silicon substrate 1206. Figures 6C-6E In this process, a SWIR photodetector 1208 is formed (e.g., grown) within trench 1202. The SWIR photodetector 1208 may include the features described above. Figure 12C The SWIR photodetector 622 shown may be any of the compounds or any combination of compounds described.

[0061] exist Figure 12C In this design, a first DTI 1210, a second DTI 1212, a third DTI 1214, and a fourth DTI 1216 are formed on a first side 1204 of a silicon substrate 1206. The first DTI 1210, the second DTI 1212, the third DTI 1214, and the fourth DTI 1216 are positioned substantially parallel to each other. Figure 12C As shown, a second DTI 1212 and a third DTI 1214 are formed such that a portion 1218 of the silicon substrate 1206 is retained between the second DTI 1212 and the third DTI 1214. Figure 12C The second DTI 1212 is positioned adjacent to the first side 1220 of the SWIR photodetector 1208. Figure 12D The third DTI 1214 is positioned adjacent to the second side 1222 of the SWIR photodetector 1208. The second side 1222 of the SWIR photodetector 1208 is positioned opposite to the first side 1220 of the SWIR photodetector 1208. Forming the SWIR photodetector 1208 within the trench 1202 may damage the portion of the silicon substrate 1206 positioned around the trench 1202. Therefore, the second DTI 1212 and the third DTI 1214 are positioned adjacent to the opposite sides of the SWIR photodetector 1208 such that any damaged portion of the silicon substrate 1206 is removed and replaced by either the second DTI 1212 or the third DTI 1214.

[0062] exist Figures 12D-12E In this process, a portion of the silicon substrate 1206 is removed, exposing the first DTI 1210, the second DTI 1212, the third DTI 1214, and the fourth DTI 1216 on the second side 1224 of the silicon substrate 1206. It should be noted that... Figures 12A-12C The view in the middle relative to Figure 12D The view in the image is flipped vertically. For example...Figure 12E As shown, the second side 1224 of the silicon substrate 1206 is opposite to the first side 1204 of the silicon substrate 1206. Figure 12E In this process, a high-k dielectric layer 1226 is formed on the second side 1224 of the silicon substrate 1206.

[0063] Figure 5 The portion of the silicon substrate 1206 located between the first DTI 1210 and the second DTI 1212 forms a first silicon photodetector 1228 configured to detect green light. The first silicon photodetector 1228 may be... Figure 12E It is part of the first green pixel 502 in the color pattern 500. Furthermore, Figure 5 The portion of the silicon substrate 1206 located between the third DTI 1214 and the fourth DTI 1216 forms a second silicon photodetector 1230 configured to detect red light. The second silicon photodetector 1230 may be... Figure 12E It is part of the red pixel 504 in the color pattern 500. Figure 5 The SWIR photodetector 1208 is configured to detect SWIR light. The SWIR photodetector 1208 can be... Figure 12E A portion of SWIR pixel 510 in color pattern 500. For example... Figure 12E As shown, the SWIR photodetector 1208, the first silicon photodetector 1228, and the second silicon photodetector 1230 are positioned on a plane substantially parallel to the high-k dielectric layer 1226. Figure 12E As shown, compared to positioning the SWIR photodetector 1208 below the first silicon photodetector 1228 or the second silicon photodetector 1230, positioning the SWIR photodetector 1208 on the same plane as the first silicon photodetector 1228 or the second silicon photodetector 1230 improves the detection capability of the SWIR photodetector 1208 and reduces the overall size of the pixel array 310. Furthermore, as... Figure 13 As shown, there is a gap between the SWIR photodetector 1208 and the high-k dielectric layer 1226. This gap prevents any dark current generated by the SWIR photodetector 1208 from flowing into the first silicon photodetector 1228 or the second silicon photodetector 1230.

[0064] Figures 12A-12E Based on the above... Figure 13 The flowchart illustrates an example of a method 1300 for constructing visible light and SWIR sensors according to the second specific embodiment. For simplicity, method 1300 is described below. Figure 12AThe sequence is depicted and described as a series of operations. However, these operations can be performed in various orders and / or simultaneously, and / or with other operations not presented and described herein. At box 1302, trenches are etched on the first side of the silicon substrate. For example, as... Figure 12B As shown, a trench 1202 can be etched on the first side 1204 of the silicon substrate 1206. A SWIR photodetector is formed within the trench at frame 1304. For example, a SWIR photodetector 1208 is formed within the trench 1202, as shown. Figure 12C As shown. At frame 1306, a first DTI is formed on a first side of the silicon substrate. For example, a first DTI 1210 may be formed on a first side 1204 of the silicon substrate 1206, as shown. Figure 12C As shown. At frame 1308, a second DTI is formed on the first side of the silicon substrate and adjacent to the first side of the SWIR photodetector. For example, a second DTI 1212 is formed on the first side 1204 of the silicon substrate 1206 and adjacent to the first side 1220 of the SWIR photodetector 1208, as shown. Figure 12C As shown. At frame 1310, a third DTI is formed on the first side of the silicon substrate and adjacent to the second side of the SWIR photodetector, the second side of which is opposite to the first side of the SWIR photodetector. For example, a third DTI 1214 is formed on the first side 1204 of the silicon substrate 1206 and adjacent to the second side 1222 of the SWIR photodetector 1208, the second side of which is opposite to the first side 1220 of the SWIR photodetector 1208, as shown. Figure 12D As shown. At box 1312, a third portion of the silicon substrate is removed, such that the first DTI, second DTI, and third DTI are exposed on a second side of the silicon substrate opposite to the first side of the silicon substrate. For example, a portion of the silicon substrate 1206 may be removed, such that the first DTI 1210, second DTI 1212, and third DTI 1214 are exposed on a second side 1224 of the silicon substrate 1206 opposite to the first side 1204 of the silicon substrate 1206, as shown. Figure 12E As shown. At frame 1314, a high-k dielectric layer is formed on the second side of the silicon substrate. For example, a high-k dielectric layer 1226 can be formed on the second side 1224 of the silicon substrate 1206, as shown. ​ As shown.

[0065] Many electrical connections in the accompanying drawings are shown as direct couplings without intermediate devices, but this is not explicitly stated in the description above. However, for electrical connections shown in the accompanying drawings without intermediate devices, this paragraph should serve as a preliminary basis for the claims to refer to any electrical connection as a “direct coupling.”

[0066] The above discussion is meant to be illustrative of the principles and various implementations of the present application. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is the intent of the following claims to encompass all such variations and modifications.

Claims

1. A method for constructing a visible light and short-wave infrared (SWIR) sensor, the method comprising: At least a first deep trench isolation portion (DTI), a second DTI, and a third DTI are formed on a first side of a silicon substrate, wherein a silicon photodetector configured to detect visible light is formed in a first portion of the silicon substrate positioned between the second DTI and the third DTI. A trench is etched between the second DTI and the third DTI on the first side of the silicon substrate, wherein the trench is etched such that a second portion of the silicon substrate remains between the second DTI and the third DTI; A SWIR photodetector is formed within the trench, wherein the SWIR photodetector is configured to detect SWIR light; Remove the third portion of the silicon substrate, such that the first DTI, the second DTI, and the third DTI are exposed on the second side of the silicon substrate opposite to the first side; as well as A high-k dielectric layer is formed on the second side of the silicon substrate.

2. The method of claim 1, wherein the trench is further etched such that: The fourth portion of the silicon substrate remains between the trench and the first DTI, and The fifth portion of the silicon substrate remains between the trench and the second DTI.

3. The method of claim 1, further comprising forming a spectral router over the high-k dielectric layer, wherein the spectral router is configured to: Visible light within the color wavelength range is routed to the silicon photodetector, and SWIR light is routed to the SWIR photodetector.

4. The method of claim 3, wherein the high-k dielectric layer is further formed to include one or more light-scattering structures.

5. The method according to claim 3, further comprising: A spectral filter is formed on the spectral router, wherein the spectral filter is configured to block visible light outside the color wavelength range; as well as Microlenses are formed on the spectral filter.

6. The method according to claim 1, further comprising: A first spectral filter is formed on the first portion of the silicon substrate, wherein the first spectral filter is configured to block visible light outside the color wavelength range; A second spectral filter is formed on the SWIR photodetector, wherein the second spectral filter is configured to block the visible light; as well as Microlenses are formed on at least a portion of the second spectral filter and on the first spectral filter.

7. A method for constructing a visible light and short-wave infrared (SWIR) sensor, the method comprising: Trenches are etched on the first side of the silicon substrate; A SWIR photodetector is formed within the trench, wherein the SWIR photodetector is configured to detect SWIR light; A first deep trench isolation portion (DTI) is formed on the first side of the silicon substrate; A second DTI is formed on the first side of the silicon substrate and adjacent to the first side of the SWIR photodetector, wherein the silicon substrate is positioned in a first portion between the first DTI and the second DTI to form a silicon photodetector configured to detect visible light. A third DTI is formed on the first side of the silicon substrate and adjacent to the second side of the SWIR photodetector, wherein the second side of the SWIR photodetector is opposite to the first side of the SWIR photodetector. Remove a second portion of the silicon substrate, such that the first DTI, the second DTI, and the third DTI are exposed on a second side of the silicon substrate opposite to the first side of the silicon substrate; as well as A high-k dielectric layer is formed on the second side of the silicon substrate.

8. The method of claim 7, further comprising forming a spectral router over the high-k dielectric layer, wherein the spectral router is configured to: Visible light within the color wavelength range is routed to the silicon photodetector, and SWIR light is routed to the SWIR photodetector.

9. The method of claim 8, further comprising forming a dielectric layer between the high-k dielectric layer and the spectral router.

10. The method according to claim 8, further comprising: A spectral filter is formed on the spectral router, wherein the spectral filter is configured to block visible light outside the color wavelength range; as well as Microlenses are formed on the spectral filter.

11. The method according to claim 7, further comprising: A first spectral filter is formed on the silicon photodetector, wherein the first spectral filter is configured to block visible light outside the color wavelength range; A second spectral filter is formed on the SWIR photodetector, wherein the second spectral filter is configured to block the visible light; as well as Microlenses are formed on at least a portion of the second spectral filter and on the first spectral filter.

12. An image sensor for sensing visible light and short-wave infrared (SWIR), the image sensor comprising: Pixel array, the pixel array comprising: At least a first deep trench isolation portion (DTI), a second DTI, and a third DTI are formed in a silicon substrate and positioned substantially parallel to each other. A silicon photodetector configured to detect visible light and positioned between a first DTI and a second DTI. A SWIR photodetector, configured to detect SWIR light and positioned between the second DTI and the third DTI. A high-k dielectric layer, wherein the high-k dielectric layer is positioned over at least the first DTI, the second DTI, the third DTI, the silicon photodetector, and the SWIR photodetector, and The silicon substrate is positioned between the SWIR photodetector and the high-k dielectric layer.

13. The image sensor of claim 12, wherein the portion of the silicon substrate positioned between the SWIR photodetector and the high-k dielectric layer is a first portion of the silicon substrate, wherein the pixel array further comprises: The second portion of the silicon substrate, positioned between the SWIR photodetector and the second DTI, and The third portion of the silicon substrate is positioned between the SWIR photodetector and the third DTI.

14. The image sensor of claim 12, wherein the silicon photodetector and the SWIR photodetector are positioned on a plane substantially parallel to the high-k dielectric layer.

15. The image sensor of claim 12, wherein the pixel array further comprises a spectral router positioned over at least a portion of the SWIR photodetector and the silicon photodetector, and wherein the spectral router is configured to: Visible light within the color wavelength range is routed to the silicon photodetector, and SWIR light is routed to the SWIR photodetector.

16. The image sensor of claim 15, wherein the high-k dielectric layer comprises one or more light-scattering structures.

17. The image sensor of claim 15, wherein the pixel array further comprises: A spectral filter, positioned above the spectral router and configured to block visible light outside the color wavelength range, and A microlens, which is positioned above the spectral filter.

18. The image sensor of claim 12, wherein the pixel array further comprises: A first spectral filter, positioned above the silicon photodetector and configured to block visible light outside its color wavelength range, A second spectral filter, positioned above the SWIR photodetector and configured to block the visible light, and A microlens, the microlens being positioned on at least a portion of the second spectral filter and on the first spectral filter.

19. An imaging system, the imaging system comprising: Lens system; The image sensor according to claim 12; and Imaging controller, The image sensor is operationally connected to the lens system and is electrically coupled to the imaging controller.

20. The imaging system of claim 19, wherein the imaging system is at least one selected from the group consisting of: automobiles, vehicles, cameras, cellular phones, tablet computers, webcams, video cameras, video surveillance systems, and video game systems.

Images