Monolithic heterogeneous integrated transparent infrared image sensing device and preparation method thereof

Abstract

According to the monolithic heterogeneous integrated transparent infrared image sensor and the preparation method thereof, preparation and dynamic real-time imaging of a large-area-array pixel point image sensor can be realized through new material selection and preparation methods, and high-sensitivity infrared detection and good optical transparency can be combined at the same time. The monolithic heterogeneous integrated transparent infrared image sensing device comprises a substrate, a thin film transistor array formed on the substrate, and a photosensitive material formed on the thin film transistor array, the substrate is made of a transparent material; a thin film transistor in the thin film transistor array takes ITO as an electrode, and the thin film transistor array is used for image reading; the pattern of the photosensitive material on the substrate is a line array with fixed line width and line spacing. The invention provides a preparation method of the infrared image sensing device in a targeted manner.

Description

Technical Field

[0001] The present invention relates to the field of image sensing technology, and particularly to a monolithic heterogeneous integrated transparent infrared image sensor device and a preparation method thereof. Background Art

[0002] Infrared sensors, as an important part of modern technology, have characteristics such as non-contact sensing, high-precision measurement, and multi-environment adaptability, and play an irreplaceable role in fields such as military, industry, medical, security, and consumer electronics. In the military, it is used for target reconnaissance and guidance; in industry, it supports temperature detection, equipment maintenance, and automated production; in medical, it realizes non-invasive temperature measurement and thermal imaging diagnosis; in the consumer field, it endows smart home and portable devices with interactive functions. In addition, infrared sensors also provide strong technical support in scientific research, environmental monitoring, and smart city construction, and are an important cornerstone for promoting the intelligence and automation of modern society.

[0003] However, most of the existing image sensing is based on silicon-based CMOS technology and cannot achieve infrared sensing above a light wavelength of 1 micron. Therefore, it is necessary to find suitable infrared photosensitive materials and integrate them with a readout circuit to achieve high-resolution image sensing. Currently, the mature infrared epitaxial materials are mainly InGaAs and HgCdTe. For example, the Shanghai Institute of Technical Physics, Chinese Academy of Sciences successfully developed a planar extended-wavelength InGaAs detector chip with a cut-off wavelength of 2.2 microns by using the method of closed-tube diffusion. However, the process of this sensor is harsh, the cost of large-scale monolithic heterogeneous integration is high, the yield is low, and it is not compatible with the requirements of transparent applications, making it difficult to achieve high-transparency scene applications; in addition, technologies such as solution-processable quantum dots and graphene have been adopted, and these materials can be monolithic heterogeneous integrated. For example, the University of Alberta in Canada integrated PbS colloidal quantum dots onto silicon and constructed an efficient infrared photodiode. However, these materials have poor stability, contain toxic elements, cannot be patterned, and have a high crosstalk in the preparation of image sensors, making it difficult to achieve large-scale industrial promotion.

[0004] Therefore, in the design of infrared image sensor devices, how to simultaneously achieve high-sensitivity infrared detection and good optical transparency is an urgent problem to be solved at present. Summary of the Invention

[0005] In view of this, the present invention provides a monolithic heterogeneous integrated transparent infrared image sensor device and a preparation method thereof, which can realize the preparation of a large-area pixel image sensor and dynamic real-time imaging through new material selection and preparation methods, and can simultaneously combine high-sensitivity infrared detection and good optical transparency.

[0006] To achieve the above object, the technical solution of the present invention is: a monolithic heterogeneous integrated transparent infrared image sensor device, including a substrate, a thin-film transistor array formed on the substrate, and a photosensitive material formed on the thin-film transistor array; the substrate is made of a transparent material; the thin-film transistors in the thin-film transistor array use ITO as electrodes, and the thin-film transistor array is used for image reading; the pattern of the photosensitive material on the substrate is: a line array with a fixed line width and line pitch.

[0007] Further, for the thin-film transistor array, its area array is 16×16 to 256×256, and the size of each pixel is 1 mm×1 mm to 100×100 μm.

[0008] Further, the thin-film transistor chip is equipped with a backend array reading system, and this supporting array reading system reads the current signals collected on the thin-film transistor chip, and finally forms an image on the terminal APP through wireless transmission.

[0009] Further, the photosensitive material is selected as AgBiS2 material, and the photosensitive material is patterned and grown on the substrate by the silver seed layer induction method.

[0010] Further, the range of the line width and line pitch is set to be 5 μm - 20 μm.

[0011] Another embodiment of the present invention also provides a preparation method of a monolithic heterogeneous integrated transparent infrared image sensor device, including the following steps:

[0012] S1: Provide a transparent thin-film transistor chip.

[0013] S2: Clean the transparent thin-film transistor chip.

[0014] S3: Prepare a pixel array pattern on the transparent thin-film transistor chip through a photolithography process; the pixel array pattern includes 16×16 to 64×64 sub-pixel patterns, and each sub-pixel pattern is composed of a number of line arrays with a fixed line width and line pitch.

[0015] S4: Place the chip with the pixel array pattern into a thermal evaporation coating machine to evaporate silver, and after stripping, obtain a silver material pixel array.

[0016] S5: Place the thin-film transistor chip with the silver material into a plasma cleaner and bombard it to oxidize it into silver oxide.

[0017] S6: Spin-coat the AgBiS2 precursor solution onto the silver oxide seed layer.

[0018] S7: Place the chip spin-coated with the AgBiS2 precursor solution in a glove box and heat it.

[0019] Further, in S4, the thickness of the evaporated silver material is 5 - 30 nm.

[0020] Further, the method for preparing the AgBiS2 precursor solution in step S6 is as follows: Weigh AgCl, BiCl3, and thiourea and dissolve them in N,N-dimethylformamide solution, such that the molar ratio of AgCl to BiCl3 is 0 - 2:1, and stir to mix them evenly.

[0021] Further, the spin coating process in S6 is as follows: Place the chip in a spin coater and rotate it at a speed of not less than 2000 revolutions per minute for 10 - 60 seconds. During the rotation, add 15 - 30 μL of the evenly mixed precursor solution dropwise.

[0022] The heating parameters in S7 are as follows: Place the chip on a hot plate at 150 - 200 °C and heat for 3 - 10 minutes.

[0023] During the chip preparation process, repeat the processes of S6 and S7 1 - 5 times to form a uniform and dense AgBiS2 material.

[0024] Further, the final AgBiS2 material only selectively grows on the places where silver material is evaporated on the chip in S4, and does not grow on the places where silver material is not evaporated, thereby forming a 16×16 to 64×64 pixel array pattern on the chip.

[0025] Beneficial effects:

[0026] 1: The present invention provides a monolithic heterogeneous integrated transparent infrared image sensor device, which can be monolithically and heterogeneously integrated on a readout circuit chip such as a thin film transistor array or CMOS on a large scale. The image sensor chip provided by the present invention is prepared based on a low-temperature high-resolution patterning method of AgBiS2 material, and has low processing difficulty. Therefore, it can realize the preparation of a large-area pixel image sensor and dynamic real-time imaging, and can combine high-sensitivity infrared detection and good optical transparency at the same time.

[0027] 2: The present invention provides a monolithic heterogeneous integrated transparent infrared image sensor device, which can realize large-area and dynamic real-time imaging. The image sensor provided by the present invention is prepared by means of a low-temperature patterning method of AgBiS2 material. This patterning method has a relatively high micron-level resolution. Therefore, it can realize the preparation of a large-area pixel image sensor and dynamic real-time imaging.

[0028] 3: The present invention provides a method for fabricating a monolithic heterogeneous integrated transparent infrared image sensor device, which has simple material processes and excellent performance. The AgBiS2 material that can be synthesized by low-temperature patterning is selected as the photosensitive material. Its preparation process is simple and convenient, and only a simple "spin coating - heating" process is required. At the same time, AgBiS2 is an environmentally friendly I-V-VI ternary semiconductor material with a wide spectral response range (300 - 1600 nm), an extremely high light absorption coefficient, and high response and sensitivity in the short-wave infrared band.

[0029] 4: The present invention provides a method for fabricating a monolithic heterogeneous integrated transparent infrared image sensor device, which enables monolithic integration and high-precision patterning. The image sensor provided by the present invention can be prepared at low temperature, and the process is simple. It can overcome the shortcomings of the prior art in monolithic heterogeneous integration, and the patterning of the AgBiS2 material has a micron-level resolution, enabling high-precision patterning. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the simple structure of the monolithic heterogeneous integrated transparent infrared image sensor device in the embodiment of the present invention.

[0031] Figure 2A It is a local scanning electron microscope image of the monolithic heterogeneous integrated transparent infrared image sensor device in the embodiment of the present invention.

[0032] Figure 2B For Figure 2A It is a partially enlarged SEM image of one of the pixel points in

[0033] Figure 3 It is a curve of the photocurrent varying with time of one pixel point in the monolithic heterogeneous integrated transparent infrared image sensor device in the embodiment of the present invention at wavelengths of 360 nm, 520 nm, 808 nm, 1060 nm, 1342 nm, and 1550 nm.

[0034] Figure 4 It is a curve of the photocurrent varying with the optical power density when one pixel point in the monolithic heterogeneous integrated transparent infrared image sensor device in the embodiment of the present invention is irradiated with a laser at a wavelength of 1342 nm.

[0035] Figure 5A It is a schematic diagram of the scanning imaging principle of the single-pixel image sensor in the embodiment of the present invention.

[0036] Figure 5B It is the "key" pattern presented by the single-pixel image sensor in the embodiment of the present invention after penetrating the silicon wafer.

[0037] Figure 5C It is the "paper clip" pattern presented by the single-pixel image sensor in the embodiment of the present invention after penetrating the ink.

[0038] Figure 5D This is the "melon seed kernel" pattern presented by the penetrated melon seeds collected by the single-pixel image sensor in the embodiment of the present invention.

[0039] Figure 6A This is the "giant panda" pattern presented by the ink-penetrated image collected by the 64×64 pixel transparent infrared image sensor in the embodiment of the present invention.

[0040] Figure 6B This is the "Christmas tree" pattern presented by the silicon wafer-penetrated image collected by the 64×64 pixel transparent infrared image sensor in the embodiment of the present invention. Detailed implementation manners

[0041] The present invention will be described in detail below with reference to the accompanying drawings and by way of examples.

[0042] In view of this, the present invention provides a monolithic heterogeneous integrated transparent infrared image sensor device and a preparation method thereof, the transmittance of which can reach 80% in the visible light range, and at the same time can penetrate silicon and specific substances for imaging.

[0043] To achieve the above object, a monolithic heterogeneous integrated transparent infrared image sensor device provided by the present invention, as Figure 1 shown, includes: a substrate 1, a thin-film transistor array 2 formed on the substrate, and a photosensitive material 3 formed on the thin-film transistor array. Among them:

[0044] The image sensor chip uses a transparent glass substrate.

[0045] The thin-film transistors in the thin-film transistor array use ITO as electrodes. The thin-film transistor array is used for image readout, and the area array scale is between 16×16 and 256×256, and the size of each pixel is within the range of 1 mm×1 mm to 100×100 μm.

[0046] The thin-film transistor array is equipped with a backend array readout system, and this supporting array readout system can read the current signals collected on the thin-film transistor array, and finally form an image on the terminal APP through wireless transmission.

[0047] The photosensitive material is selected as AgBiS2 material.

[0048] The photosensitive material is patterned and grown on the thin-film transistor array by a silver seed layer induction method (this method is under patent application, 202410093772.8).

[0049] The pattern of the photosensitive material on the thin-film transistor array is: a line array with a fixed line width and line spacing.

[0050] The innovation lies in monolithic heterogeneous integration. By setting the line width and line spacing range from 5 microns to 20 microns and testing through the transmittance of the image sensor device, it is proved that adjusting the duty cycle of the line width can adjust the transmittance of the device, with a maximum transmittance of 80%.

[0051] The existing most mature infrared monolithic heterogeneous integration technology is complex in process, high in cost, low in yield, and not compatible with transparency.

[0052] The present invention also provides a preparation method for a monolithic heterogeneous integrated transparent infrared image sensor device. The steps of this method include:

[0053] S1: Provide a transparent thin-film transistor array.

[0054] S2: Clean the thin-film transistor array.

[0055] S3: Prepare a pixel array pattern on the thin-film transistor array through photolithography.

[0056] S4: Place the pixel array pattern (the line array pattern corresponding to the photosensitive material) into a thermal evaporation coating machine to evaporate silver, and obtain a silver material pixel array after stripping.

[0057] S5: Place the thin-film transistor chip with the silver material into a plasma cleaner to bombard and oxidize it into silver oxide.

[0058] S6: Spin-coat the AgBiS2 precursor solution onto the silver oxide seed layer.

[0059] S7: Heat the chip spin-coated with the AgBiS2 precursor solution in a glove box.

[0060] In the embodiment of the present invention, cleaning the thin-film transistor chip in step S2 includes: ultrasonically cleaning the thin-film transistor chip with ethanol for 5 - 10 minutes.

[0061] In the embodiment of the present invention, the photolithography process in step S3 includes: spin-coating, pre-baking, exposure, and development.

[0062] In the embodiment of the present invention, the pixel array pattern in step S3 includes 16×16 to 256×256 sub-pixel patterns, and each sub-pixel pattern is composed of a number of line arrays with a fixed line width and line spacing.

[0063] In the embodiment of the present invention, the thickness of the evaporated silver material in step S4 is 5 - 30 nanometers. The purpose of this step is to pattern and arrange a silver seed layer pattern on the thin-film transistor chip for subsequent patterned growth of the AgBiS2 photosensitive material.

[0064] In the embodiment of the present invention, the stripping process in step S4 includes: soaking in acetone for 5 - 20 minutes.

[0065] In the embodiment of the present invention, in step S5, the oxidation parameters for placing the chip in the plasma cleaner are as follows: bombarding the chip coated with silver material for 10 - 30 minutes under an oxygen flow rate of 2 - 10 sccm to oxidize the evaporated silver material into silver oxide.

[0066] In the embodiment of the present invention, in step S6, the method for preparing the AgBiS2 precursor solution is as follows: weighing AgCl, BiCl3, and thiourea and dissolving them in N, N - dimethylformamide solution, with the molar ratio of AgCl to BiCl3 being 0 - 2:1, and stirring to mix them evenly.

[0067] In the embodiment of the present invention, in step S6, the spin - coating process is as follows: placing the chip in a spin coater and rotating it at a speed of not less than 2000 revolutions per minute for 10 - 60 seconds, and dropping 15 - 30 μL of the evenly mixed precursor solution during the rotation.

[0068] In the embodiment of the present invention, in step S7, the heating parameters are as follows: placing the chip on a hot plate at 150 - 200 °C and heating it for 3 - 10 minutes.

[0069] In the embodiment of the present invention, during the chip preparation process, steps S6 and S7 (i.e., spin - coating - heating) need to be repeated 1 - 5 times to form a uniform and dense AgBiS2 material.

[0070] In the embodiment of the present invention, the patterning preparation method of the AgBiS2 material mentioned in this step is realized by the method of stimulating with a silver seed layer, that is, the final AgBiS2 material only selectively grows on the places where the silver material is evaporated on the chip in step S4, and does not grow on the places where the silver material is not evaporated, thereby forming a 16×16 to 64×64 pixel array pattern on the chip.

[0071] As Figure 2A shown in Figure 1 is the scanning electron microscope image of the infrared - transparent image sensor prepared in Figure 2B and Figure 2A is the partially enlarged SEM image of one of the pixel points in . It can be seen that a large - area micron - scale pixel array is neatly and evenly arranged on the image sensor chip. The upper - right inset is the high - resolution scanning electron microscope image of a single pixel point. It can be seen that the patterning preparation process of the AgBiS2 material has an ultra - high micron - scale resolution, and each pixel point is composed of a line - array pattern with a fixed line width and line spacing.

[0072] Next, the performance effect of an infrared - transparent image sensor prepared by the above - mentioned method according to the embodiment of the present invention is verified through actual data examples.

[0073] First, the basic optoelectronic properties of a single pixel point of a monolithic heterogeneously integrated transparent infrared image sensor device were tested.

[0074] As Figure 3 shown, when the bias voltage is 0.5 V, a photodetector is irradiated with lasers having wavelengths of 360 nm, 520 nm, 808 nm, 1060 nm, 1342 nm, and 1550 nm respectively. The device has a higher optical response to the laser with a wavelength of 520 nm. However, the device still has an obvious optical response in the short-wave infrared band of 1550 nm, and the response is relatively stable during 6 dynamic cycles, indicating the application potential of the device in infrared penetration imaging.

[0075] As Figure 4 shown, when the bias voltage is 0.5 V, a photodetector is irradiated with a laser having a wavelength of 1342 nm and different optical power densities. During five dynamic cycles of each of the six light intensities, the changes in photocurrent and dark current are very stable, indicating that the device has good cycle stability. It shows that the AgBiS2 material has photosensitivity and can be continuously excited by short-wave infrared light. As the light intensity increases, the photocurrent of the device becomes larger, and the influence on the dark current can be ignored.

[0076] Secondly, the photodetector is used as a single-pixel image sensor to preliminarily explore its infrared penetration imaging performance.

[0077] As Figure 5A shown in the schematic diagram of single-pixel image sensor scanning imaging, the system includes: an infrared light source 1 with a wavelength of 1342 nm, a silicon wafer 2 for penetration, a photodetector 3, and a two-dimensional motor platform 4.

[0078] The photodetector works in a raster scanning mode on the two-dimensional motor platform. The silicon wafer is placed between the infrared light source and the photodetector for penetration imaging. A key 5 is placed between the light source and the silicon wafer as the pattern for penetration imaging. During the scanning process, the light source, the key, and the silicon wafer remain stationary, and the photodetector moves along the X-axis and Y-axis with the two-dimensional motor platform. Finally, the pattern of the key is projected through the shadow occlusion of the penetrated silicon wafer, as Figure 6B shown.

[0079] Figure 5C is the pattern of a paper clip projected by penetrating ink using the Figure 5B same working mode.

[0080] Figure 5D is the pattern of half a kernel of a melon seed projected by penetrating the melon seed shell using the Figure 5B same working mode, which can be used to identify the defective rate of melon seeds.

[0081] Figure 5AThe single-pixel scanning penetration imaging results shown in A, B, and C all exhibit clear and delicate images. The excellent imaging ability indicates that the single-pixel image sensor has excellent penetration sensing ability. At the same time, the device can withstand ultra-long scanning without affecting its imaging effect, indicating that the device has high stability and reliability.

[0082] Finally, the penetration imaging ability of the 64×64 image sensor chip was tested.

[0083] As Figure 6A shown is the image of a giant panda presented by the penetration of ink collected by the image sensor under the irradiation of an 808-nanometer wavelength laser.

[0084] As Figure 6B shown is the image of a Christmas tree presented by the penetration of a silicon wafer collected by the image sensor under the irradiation of a 1342-nanometer wavelength laser.

[0085] Figure 6A The 64×64 pixel points in A and B make the image clearer and more vivid. The excellent imaging ability shows the high resolution and excellent infrared sensing ability of the image sensor chip.

[0086] In summary, the above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A monolithic heterogeneous integrated transparent infrared image sensor device, characterized in that: include: A substrate, a thin film transistor array formed on the substrate, and a photosensitive material formed on the thin film transistor array; The substrate is made of transparent material; The thin film transistors in the thin film transistor array use ITO as electrodes, and the thin film transistor array is used for image reading; The pattern of the photosensitive material on the substrate is a line array with fixed line width and line spacing.

2. A monolithic heterogeneous integrated transparent infrared image sensor device as claimed in claim 1, characterized in that: The thin film transistor array has an array area of ​​16×16 to 256×256, and a size of each pixel is 1 mm×1 mm to 100×100 microns.

3. The monolithic heterogeneous integrated transparent infrared image sensor device according to claim 1, characterized in that: The thin film transistor chip is equipped with a back-end array reading system, which reads the current signal collected on the thin film transistor chip and finally forms an image on the terminal APP through wireless transmission.

4. The monolithic heterogeneous integrated transparent infrared image sensor device according to claim 1, characterized in that: The photosensitive material is AgBiS2 material, and the photosensitive material is patterned and grown on the substrate by a silver seed layer induction method.

5. The monolithic heterogeneous integrated transparent infrared image sensor device according to claim 1, characterized in that: The line width and line spacing range is set to 5 microns-20 microns.

6. A method for preparing a monolithic heterogeneous integrated transparent infrared image sensor device, characterized in that: The steps include: S1: Provide transparent thin film transistor chips; S2: Cleaning the transparent thin film transistor chip; S3: preparing a pixel array pattern on a transparent thin film transistor chip by a photolithography process; the pixel array pattern includes 16×16 to 64×64 sub-pixel patterns, each sub-pixel pattern is composed of a plurality of line arrays with fixed line width and line spacing; S4: placing the pixel array pattern in a thermal evaporation coating machine to evaporate silver, and obtaining a silver material pixel array after peeling; S5: placing the thin film transistor chip with silver material into a plasma cleaning machine for bombardment and oxidation into silver oxide; S6: spin coating the AgBiS2 precursor solution onto the silver oxide seed layer; S7: Place the chip spin-coated with the AgBiS2 precursor solution in a glove box and heat it.

7. The method for preparing a monolithic heterogeneous integrated transparent infrared image sensor device according to claim 6, characterized in that: The thickness of the evaporated silver material in S4 is 5-30 nanometers.

8. The method for preparing a monolithic heterogeneous integrated transparent infrared image sensor device as claimed in claim 6, characterized in that: The method for preparing the AgBiS2 precursor solution in step S6 is as follows: weigh AgCl, BiCl3, and thiourea, dissolve them in N,N-dimethylformamide solution so that the molar ratio of AgCl to BiCl3 is 0-2:1, and stir to mix them evenly.

9. The method for preparing a monolithic heterogeneous integrated transparent infrared image sensor device according to claim 6, characterized in that: The spin coating process in S6 is as follows: placing the chip in a coating machine and rotating it at a speed of not less than 2000 revolutions per minute for 10-60 seconds, and dropping 15-30 microliters of a well-mixed precursor solution during the rotation process; The heating parameters in S7 are: place the chip on a hot plate at 150-200 degrees Celsius for 3-10 minutes; During the chip preparation process, the S6 and S7 processes are repeated 1-5 times to form a uniform and dense AgBiS2 material.

10. A method for preparing a monolithic heterogeneous integrated transparent infrared image sensor device according to any one of claims 6 to 9, characterized in that: The final AgBiS2 material selectively grows only in the places where silver material is evaporated on the S4 chip, and will not grow in the places where silver material is not evaporated, thereby forming a 16×16 to 64×64 pixel array pattern on the chip.

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