Bionic visual sensor with pulse coding capability and manufacturing method thereof

Abstract

The invention discloses a bionic visual sensor device with pulse coding capability. When light quantum reaches the device, photo-induced electron-hole pairs are generated. Photo-generated carriers continue to collide with lattice atoms through strong electric field force between the cathode and the anode, and new photo-generated electron-hole pairs are generated. The process is continuously repeated, and then macroscopic current is generated. And an electric field between the cathode and the anode is reduced through voltage division of an external resistor, so that macroscopic current is quenched, and pulse current lasting for several nanoseconds is realized. And after dozens of nanoseconds, the device quickly recovers to an initial state to prepare for detecting the next light quantum. In addition, the inversion layer formed below the polysilicon gate can effectively regulate and control the optical wavelength response of the device, so that the device has reasonable visual color perception capability in biology. Meanwhile, the device is completely compatible with a standard microelectronic process, and a large-scale integrated bionic visual sensor can be realized, so that the development requirements in the fields of bionic robots and the like are met.

Description

Technical Field

[0001] The invention relates to the field of bionic vision technology, and in particular to a bionic vision sensor with pulse coding capability and a manufacturing method thereof. Background Art

[0002] The visual system of humans and animals provides organisms with the core function of obtaining environmental information and is an important basis for perception, decision-making and response. Through efficient visual perception systems, organisms in nature can not only perceive light, color, depth and motion, but also respond quickly in complex environments. Bionics, as a discipline that imitates the structure and function of biological organisms in nature, has been widely used in various fields, among which the research on bionic visual sensors has received significant attention in recent years. Bionic visual sensors provide new technical approaches for intelligent perception and environmental interaction by simulating the perception mechanism of biological visual systems. Taking the human eye as an example, it has extremely strong photosensitivity and dynamic adjustment capabilities, and can obtain clear visual images under different lighting conditions. However, the existing artificial vision system cannot meet the functions of simulating the human eye, especially in low light, dynamic range, fast response, energy consumption and other aspects. In order to overcome these problems, the design of bionic visual sensors not only requires the characteristics of traditional optical sensors such as high sensitivity, wide field of view, and high resolution, but also requires the advantages of biological visual systems such as strong adaptability and low energy consumption. Summary of the invention

[0003] In order to achieve the above object, the present invention provides a bionic visual sensor with pulse coding capability and a manufacturing method thereof, which can realize both color selectivity and pulse coding. In addition, the present invention has a simple structure and is compatible with standard microelectronic processes, is easy to realize large-scale integration and production, and has broad application prospects.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is: a bionic visual sensor with pulse coding capability; an N-type buried layer region (102) is provided on a P-type substrate (101); and an N-type deep well region (103) is provided on the N-type buried layer region (102).

[0005] The N-type deep well region (103) is provided with a first shallow trench isolation region (201), a first N+ heavily doped region (105), a second shallow trench isolation region (202), a first polysilicon gate region (205), a first P+ heavily doped region (106), a second polysilicon gate region (206), a second P+ heavily doped region (107), a third polysilicon gate region (207), a third P+ heavily doped region (108), an N-well region (104), a fourth polysilicon gate region (208), a fourth P+ heavily doped region (109), a fifth polysilicon gate region (209), a fifth P+ heavily doped region (110), a sixth polysilicon gate region (210), a third shallow trench isolation region (203), a second N+ heavily doped region (111), and a fourth shallow trench isolation region (204) in sequence from left to right.

[0006] The first N+ heavily doped region (105) and the second N+ heavily doped region (111) are connected to the cathode through metal leads, and the first to sixth polysilicon gate regions (205, 206, 207, 208, 209, 210) and the first to fifth P+ heavily doped regions (106, 107, 108, 109, 110) are connected to the anode through metal leads.

[0007] The N-well region (104) and the third P+ heavily doped region (108) constitute a deep PN junction; the first P+ heavily doped region (106), the second P+ heavily doped region (107), the fourth P+ heavily doped region (109), the fifth P+ heavily doped region (110) and the N-type deep well region (103) constitute a middle PN junction; the first to sixth polysilicon gate regions (205, 206, 207, 208, 209, 210) and the N-type deep well region (103) constitute a shallow PN junction; the three-layer PN junction realizes the detection of photons of different wavelength bands by controlling the bias voltage of the anode and cathode of the device.

[0008] When a photon is absorbed by the three-layer PN junction, the anode outputs a macroscopic current pulse under the action of the avalanche multiplication region formed by the device N well region (104) and the third P+ heavily doped region (108). Within the same time and light intensity, the current pulse frequency caused by photons of different wavelengths has a huge difference, and the device can achieve color selective perception.

[0009] A method for manufacturing a bionic visual sensor with pulse encoding capability comprises the following steps:

[0010] Step 1: Grow a thin layer of silicon oxide (SiO) on a P-type substrate using oxygen dry oxidation. 2 ) layer, used to protect the silicon wafer surface and control the doping depth, the temperature is about 900℃.

[0011] Step 2: Transfer the pattern on the mask of the N-type buried layer area to the wafer through micro-development technology to form a photoresist pattern in the N-type buried layer area, and retain the photoresist in the non-N-type buried layer area; inject high-energy phosphorus ions to form an N-type buried layer area and remove the photoresist.

[0012] Step 3: Transfer the pattern on the N-type deep well area mask to the wafer through micro-development technology to form a photoresist pattern in the N-type deep well area, and retain the photoresist in the non-N-type deep well area; inject high-energy phosphorus ions to form an N-type deep well area and remove the photoresist.

[0013] Step 4: Apply photoresist on the silicon wafer to form a uniform photoresist layer. Define the first to fourth shallow trench isolation areas, use a mask and ultraviolet light to irradiate the photoresist, and expose to form a pattern. Use dry etching to remove the silicon oxide layer and part of the silicon to form a shallow trench structure. The etching depth is about 0.4μm, and the etching angle is about 10° with the sidewall of the shallow trench. Use low-pressure chemical vapor deposition (LPCVD) technology to fill the groove with about 1.0μm thick silicon oxide. Remove excess silicon oxide material through chemical mechanical polishing (CMP) technology to make the surface of the silicon wafer flat.

[0014] Step 5: Transfer the pattern on the N-well mask to the wafer through micro-development technology to form an N-well photoresist pattern, and retain the photoresist in the non-N-well area; inject high-energy phosphorus ions to form a local N-well and remove the photoresist.

[0015] Step 6: Anneal the ion implanted area, using rapid thermal annealing technology (RTA) to repair ion implantation damage and activate dopants, effectively reducing dopant diffusion, thereby accurately controlling the doping concentration and doping distribution in shallow areas. The temperature is controlled at 1000℃-1300℃ and the duration is about 10-60 seconds.

[0016] Step 7: Grow a thick gate oxide layer. Grow a thick layer of silicon dioxide using dry oxidation at a temperature of about 900°C. Deposit polysilicon with a thickness of about 200nm using LPCVD, form a gate through photolithography and etching, and remove the photoresist.

[0017] Step 8: Apply photoresist on the silicon wafer to define the first and second N+ heavily doped regions, use a mask and ultraviolet light to irradiate the photoresist, and expose to form a pattern. Heavily doped arsenic ions are implanted to form N+ heavily doped regions, and the photoresist is removed.

[0018] Step 9: Apply photoresist on the silicon wafer to define the first to fifth P+ heavily doped regions. Use a mask and ultraviolet light to irradiate the photoresist and expose it to form a pattern. Implant heavily doped boron ions to form P+ heavily doped regions and remove the photoresist. Annealing treatment repairs the crystal damage on the silicon surface caused by ion implantation and eliminates the migration of impurities in the heavily doped regions.

[0019] The beneficial effects of the present invention are:

[0020] 1. The N-well region, P+ injection region, N-type deep well region, P+ injection region, N-type deep well region, and polysilicon gate region in the present invention form three PN junctions of different depths, which improves the photon detection probability of the device and effectively regulates the light wavelength response of the device, thereby meeting the requirements of bionic vision for color perception. In addition, by externally connecting a resistor to divide the voltage, the electric field between the cathode and the anode is reduced, and the macroscopic current is quenched, so that the purpose of pulse encoding can be achieved.

[0021] 2. The manufacturing method of the present invention has a simple manufacturing process and is easy to operate. The bionic visual sensor with pulse coding capability manufactured does not violate the basic design rules of the layout, nor does it use steps other than the standard BCD process. It effectively regulates the light wavelength response of the device and meets the requirements of bionic vision for color perception. At the same time, it is compatible with standard microelectronic processes and is easy to achieve large-scale integration and production, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0023] Figure 1 A cross-sectional view and a circuit connection diagram of a bionic visual sensor with pulse coding capability in an embodiment of the present invention;

[0024] Figure 2 Schematic diagram of the parasitic structure and working principle of the bionic visual sensor with pulse coding capability in an embodiment of the present invention;

[0025] Figure 3 is a top view of a bionic visual sensor with pulse coding capability in an embodiment of the present invention;

[0026] Figure 4 The pulse excitation frequency waveform diagrams for four colors respectively generated by the bionic visual sensor with pulse coding capability in the embodiment of the present invention;

[0027] The figure includes: 1. P-type substrate, 2. N-type buried layer region, 3. N-type deep well region, 4. N-well region, 5. first N+ heavily doped region, 6. second N+ heavily doped region, 7. first P+ heavily doped region, 8. second P+ heavily doped region, 9. third P+ heavily doped region, 10. fourth P+ heavily doped region, 11. fifth P+ heavily doped region, 12. first polysilicon gate region, 13. second polysilicon gate region, 14. third polysilicon gate region, 15. fourth polysilicon gate region, 16. fifth polysilicon gate region, 17. sixth polysilicon gate region, 18. first shallow trench isolation region, 19. second shallow trench isolation region, 20. third shallow trench isolation region, 21. fourth shallow trench isolation region. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The purpose of the present invention is to provide a bionic visual sensor with pulse coding capability and a method for manufacturing the same. The device can convert photons into spike pulses, simulate the human visual perception organ, convert the stimulus into a spike pulse frequency, and then transmit the spike-coded information to the central nervous system for processing. The device is simple to manufacture and can be realized using existing standard microelectronic processes without the need for additional process modifications, and is easy to achieve large-scale array integration.

[0030] In order to make the above-mentioned purposes, features and advantages of the present invention more clear, the present invention is briefly introduced below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the present invention, and for ordinary technicians in this field, other embodiments obtained without creative work belong to the protection scope of the present invention.

[0031] like Figure 1 and Figure 3As shown, the present invention provides a bionic visual sensor with pulse coding capability; a ring-shaped N-type buried layer region (102) is provided on a P-type substrate (101); and a ring-shaped N-type deep well region (103) is provided on the N-type buried layer region (102). The N-type deep well region (103) is provided with an annular first shallow trench isolation region (201), an annular first N+ heavily doped region (105), an annular second shallow trench isolation region (202), an annular first polysilicon gate region (205), an annular first P+ heavily doped region (106), an annular second polysilicon gate region (206), an annular second P+ heavily doped region (107), an annular third polysilicon gate region (207), a circular third P+ heavily doped region (108), a circular N well region (104), an annular fourth polysilicon gate region (208), an annular fourth P+ heavily doped region (109), an annular fifth polysilicon gate region (209), an annular fifth P+ heavily doped region (110), an annular sixth polysilicon gate region (210), an annular third shallow trench isolation region (203), an annular second N+ heavily doped region (111), and an annular fourth shallow trench isolation region (204) in sequence from left to right.

[0032] like Figure 2 As shown, the N-well region (104) and the third P+ heavily doped region (108) constitute a deep PN junction, the first P+ heavily doped region (106), the second P+ heavily doped region (107), the fourth P+ heavily doped region (109), the fifth P+ heavily doped region (110), and the N-type deep well region (103) constitute a middle PN junction, and the first to sixth polysilicon gate regions (205, 206, 207, 208, 209, 210) and the N-type deep well region (103) constitute a shallow PN junction; the three-layer PN junction realizes the detection of photons in different bands by controlling the bias voltage of the anode and cathode of the device. Figure 4 The waveform diagram of pulse excitation frequency generated by the device of the present invention under four similar wavelengths and the same light intensity is shown. The excitation pulse frequencies in response to green, yellow, orange and red are 3.51×10 5 , 2.66×10 5 , 1.87×10 5 and 1.28×10 5 Hz. The difference in the excitation pulse frequency between adjacent colors exceeds 59,000 Hz, indicating that the device has good selectivity in distinguishing different colors of light. By integrating the device into a bionic visual system, it is possible to simulate the human visual perception organ, convert light stimulation into spike pulse frequency, and then transmit the spike-encoded information to the central nervous system for processing.

[0033] The P-type substrate, N-type buried layer region, N-type deep well region, N well region, polysilicon gate region, N+ heavily doped region, P+ heavily doped region, and shallow trench isolation region in the present invention can be realized by using existing standard microelectronics manufacturing processes without the need for additional masks and process modifications.

[0034] The present invention provides a method for manufacturing a bionic visual sensor with pulse coding capability, comprising the following steps:

[0035] Step 1: Grow a thin layer of silicon oxide (SiO) on a P-type substrate using oxygen dry oxidation. 2 ) layer, used to protect the silicon wafer surface and control the doping depth, the temperature is about 900℃;

[0036] Step 2: Transfer the pattern on the mask of the N-type buried layer area to the wafer through micro-development technology to form a photoresist pattern in the N-type buried layer area, and retain the photoresist in the non-N-type buried layer area; inject high-energy phosphorus ions to form an N-type buried layer area and remove the photoresist.

[0037] Step 3: Transfer the pattern on the N-type deep well area mask to the wafer through micro-development technology to form a photoresist pattern in the N-type deep well area, and retain the photoresist in the non-N-type deep well area; inject high-energy phosphorus ions to form an N-type deep well area and remove the photoresist.

[0038] Step 4: Apply photoresist on the silicon wafer to form a uniform photoresist layer. Define the first to fourth shallow trench isolation areas, use a mask and ultraviolet light to irradiate the photoresist, and expose to form a pattern. Use dry etching to remove the silicon oxide layer and part of the silicon to form a shallow trench structure. The etching depth is about 0.4μm, and the etching angle is about 10° with the sidewall of the shallow trench. Use low-pressure chemical vapor deposition (LPCVD) technology to fill the groove with about 1.0μm thick silicon oxide. Remove excess silicon oxide material through chemical mechanical polishing (CMP) technology to make the surface of the silicon wafer flat.

[0039] Step 5: Transfer the pattern on the N-well mask to the wafer through micro-development technology to form an N-well photoresist pattern, and retain the photoresist in the non-N-well area; inject high-energy phosphorus ions to form a local N-well and remove the photoresist.

[0040] Step 6: Anneal the ion implanted area, using rapid thermal annealing technology (RTA) to repair ion implantation damage and activate dopants, effectively reducing dopant diffusion, thereby accurately controlling the doping concentration and doping distribution in shallow areas. The temperature is controlled at 1000℃-1300℃ and the duration is about 10-60 seconds.

[0041] Step 7: Grow a thick gate oxide layer. Grow a thick layer of silicon dioxide using dry oxidation at a temperature of about 900°C. Deposit polysilicon with a thickness of about 200nm using LPCVD, form a gate through photolithography and etching, and remove the photoresist.

[0042] Step 8: Apply photoresist on the silicon wafer to define the first and second N+ heavily doped regions, use a mask and ultraviolet light to irradiate the photoresist, and expose to form a pattern. Heavily doped arsenic ions are implanted to form N+ heavily doped regions, and the photoresist is removed.

[0043] Step 9: Apply photoresist on the silicon wafer to define the first to fifth P+ heavily doped regions. Use a mask and ultraviolet light to irradiate the photoresist and expose it to form a pattern. Implant heavily doped boron ions to form P+ heavily doped regions and remove the photoresist. Annealing treatment repairs the crystal damage on the silicon surface caused by ion implantation and eliminates the migration of impurities in the heavily doped regions.

[0044] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

[0045] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments based on the prior art according to the concept of the present invention still fall within the protection scope of the present invention.

Claims

1. A bionic visual sensor with pulse coding capability, characterized in that: An N-type buried layer region (102) is provided on a P-type substrate (101); An N-type deep well region (103) is provided on the N-type buried layer region (102); The N-type deep well region (103) is provided with a first shallow trench isolation region (201), a first N+ heavily doped region (105), a second shallow trench isolation region (202), a first polysilicon gate region (205), a first P+ heavily doped region (106), a second polysilicon gate region (206), a second P+ heavily doped region (107), a third polysilicon gate region (207), a third P+ heavily doped region (108), an N-well region (104), a fourth polysilicon gate region (208), a fourth P+ heavily doped region (109), a fifth polysilicon gate region (209), a fifth P+ heavily doped region (110), a sixth polysilicon gate region (210), a third shallow trench isolation region (203), a second N+ heavily doped region (111), and a fourth shallow trench isolation region (204) in sequence from left to right; The first N+ heavily doped region (105) and the second N+ heavily doped region (111) are connected to the cathode through metal leads, and the first to sixth polysilicon gate regions (205, 206, 207, 208, 209, 210) and the first to fifth P+ heavily doped regions (106, 107, 108, 109, 110) are connected to the anode through metal leads.

2. A bionic visual sensor with pulse coding capability according to claim 1, characterized in that: The N-well region (104) and the third P+ heavily doped region (108) constitute a deep PN junction; the first P+ heavily doped region (106), the second P+ heavily doped region (107), the fourth P+ heavily doped region (109), the fifth P+ heavily doped region (110) and the N-type deep well region (103) constitute a middle PN junction; the first to sixth polysilicon gate regions (205, 206, 207, 208, 209, 210) and the N-type deep well region (103) constitute a shallow PN junction; the three-layer PN junction realizes the detection of photons of different wavelength bands by controlling the bias voltage of the anode and cathode of the device.

3. A bionic visual sensor with pulse coding capability according to claim 2, characterized in that: When a photon is absorbed by the three-layer PN junction, the anode outputs a macroscopic current pulse under the action of the avalanche multiplication region formed by the device's N-well region (104) and the third P+ heavily doped region (108); within the same time and light intensity, there is a huge difference in the frequency of the current pulse caused by photons of different wavelengths, and the device can achieve color selective perception.

4. A method for manufacturing a bionic visual sensor with pulse coding capability according to any one of claims 1 to 3, comprising the following steps: Step 1: A thin silicon oxide (SiO2) layer is grown on a P-type substrate using oxygen dry oxidation to protect the silicon wafer surface and control the doping depth at a temperature of about 900°C. Step 2: Transfer the pattern on the mask of the N-type buried layer area to the wafer through micro-development technology to form a photoresist pattern in the N-type buried layer area, and retain the photoresist in the non-N-type buried layer area; Implant high-energy phosphorus ions to form an N-type buried layer region and remove the photoresist; Step 3: Transfer the pattern on the N-type deep well area mask to the wafer through micro-development technology to form a photoresist pattern in the N-type deep well area, and retain the photoresist in the non-N-type deep well area; Inject high-energy phosphorus ions to form an N-type deep well region and remove the photoresist; Step 4: coating the photoresist on the silicon wafer to form a uniform photoresist layer, defining the first to fourth shallow trench isolation regions, using a mask and ultraviolet light to irradiate the photoresist, exposing to form a pattern, using dry etching to remove the silicon oxide layer and part of the silicon to form a shallow trench structure, the etching depth is about 0.4 μm, the etching angle is about 10° with the shallow trench sidewall, using low pressure chemical vapor deposition (LPCVD) technology to fill the groove with about 1.0 μm thick silicon oxide, and removing excess silicon oxide material by chemical mechanical polishing (CMP) technology to make the surface of the silicon wafer flat; Step 5: Transfer the pattern on the N-well mask to the wafer through micro-development technology to form a photoresist pattern for the N-well, and retain the photoresist in the non-N-well area; Inject high-energy phosphorus ions to form a local N-well and remove the photoresist; Step 6: Anneal the ion implanted area, using rapid thermal annealing technology (RTA) to repair ion implantation damage and activate dopants, effectively reducing dopant diffusion, thereby accurately controlling doping concentration and doping distribution in shallow areas, with the temperature controlled at 1000°C-1300°C and lasting for about 10-60 seconds; Step 7: growing a thick gate oxide layer, using dry oxidation to grow a thick layer of silicon dioxide at a temperature of about 900°C, using LPCVD to deposit polysilicon with a thickness of about 200nm, forming a gate through photolithography and etching, and removing the photoresist; Step 8: coating a photoresist on the silicon wafer to define the first and second N+ heavily doped regions, using a mask and ultraviolet light to irradiate the photoresist, exposing to form a pattern, implanting heavily doped arsenic ions to form an N+ heavily doped region, and removing the photoresist; Step nine: Apply photoresist on the silicon wafer to define the first to fifth P+ heavily doped regions, use a mask and ultraviolet light to irradiate the photoresist, expose to form a pattern, implant heavily doped boron ions to form P+ heavily doped regions, remove the photoresist, anneal, repair the crystal damage on the silicon surface caused by ion implantation, and eliminate the migration of impurities in the heavily doped regions.

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