Optical frequency conversion chip and preparation method thereof, and reflective optical frequency conversion system

Abstract

The invention discloses an optical frequency conversion chip and a preparation method thereof, and a reflective optical frequency conversion system, and relates to the technical field of semiconductors, the optical frequency conversion chip comprises a silicon substrate and a plurality of pixel units arranged on the surface in an array; each pixel unit comprises a supporting structure and a radiation absorption layer; the supporting structure comprises a contact layer and two supporting legs; the radiation absorption layer is located on the surface of the side, back on to the silicon substrate, of the contact layer, the projection of the contact layer on the silicon substrate completely covers the projection of the radiation absorption layer on the silicon substrate, and an interval space exists between the contact layer and the silicon substrate; the contact layer is connected with the supporting leg, and the supporting leg is located on the first surface of the silicon substrate and located on the side of the contact layer relative to the vertex angle; and the pixel units are S-shaped. The problem that the apparent temperature is reduced due to the fact that the resolution ratio of a chip is low and the heat dissipation surface of the pixel is large and the temperature is difficult to rise is solved, the temperature rise speed of the pixel unit can be increased, thermal crosstalk between adjacent pixels is reduced, and the refresh frequency, the resolution ratio and the apparent temperature of an image are increased.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an optical frequency conversion chip and a preparation method thereof, and a reflective optical frequency conversion system. Background Art

[0002] Optical frequency conversion chips typically feature an array of pixels with high absorptivity / emissivity, which is related to the resolution of the image being simulated. During operation, the conversion chip is secured in a vacuum environment by a metal clamping ring to minimize the effects of thermal convection. Based on the optical frequency down-conversion method, when a high-resolution visible light image is used to heat the film through a visible light window, the pixels, with their high visible light absorptivity and broadband infrared emissivity, rapidly absorb the heat and heat up, then re-radiate infrared radiation. This radiation passes through the infrared window, is received by the infrared optical system, and is projected onto the entrance pupil of the detector optical system under test.

[0003] In the prior art, to achieve rapid heating while minimizing lateral heat diffusion, optical frequency conversion chips must be extremely thin, typically in the submicron range, resulting in poor mechanical properties. Because the pixel array is two-dimensional, lateral thermal crosstalk still reduces the spatial resolution of the simulated image. Therefore, it is necessary to increase the heating rate of individual pixels and reduce lateral thermal crosstalk between adjacent pixels. Furthermore, during dynamic frame switching, since the thin film relies solely on radiation for heat dissipation and lacks efficient heat conduction channels, this leads to deposited heat within the film, increasing the background temperature of the simulated image environment. This ultimately results in a lower dynamic range for high-frame-rate scene simulations. Related research has proposed a "silicon-based microcavity" structure, which suspends each pixel by etching a microcavity array on a silicon substrate to improve heat dissipation. However, this approach places all four broad sides of each pixel in contact with the silicon substrate, resulting in a large heat dissipation surface and hindering temperature increase. Furthermore, the wider borders occupy a larger area of ​​the pixel, sacrificing the pixel's radiating area, resulting in a lower fill factor and ultimately a lower apparent temperature detected by the detector.

[0004] Therefore, a solution is needed to reduce the deposition heat of the optical frequency conversion chip while increasing the heating rate of a single pixel, reducing the crosstalk between adjacent pixels, and improving the resolution and frame rate of infrared images. Summary of the Invention

[0005] In view of this, the present application provides an optical frequency conversion chip and its preparation method, and a reflective optical frequency conversion system, so as to at least solve the problems in the related art, such as the existence of lateral thermal crosstalk between the pixels of the optical frequency conversion chip, resulting in low spatial resolution of the simulated image, low image dynamic range during high frame rate scene simulation due to excessive deposited heat, and the large heat dissipation surface of the pixel that is difficult to heat up, resulting in a lower apparent temperature recognized by the detector.

[0006] In a first aspect, the present application provides an optical frequency conversion chip, the optical frequency conversion chip comprising: a silicon substrate comprising a first surface and a second surface opposite to each other; A plurality of pixel units arranged in an array are located on the first surface of the silicon substrate; Each pixel unit includes a stacked support structure and a radiation absorbing layer; the radiation absorbing layer is located on the side of the support structure facing away from the silicon substrate; the support structure includes a contact layer and two support legs; the radiation absorbing layer is located on the surface of the contact layer facing away from the silicon substrate, the projection of the contact layer on the silicon substrate completely covers the projection of the radiation absorbing layer on the silicon substrate, and there is a space between the contact layer and the silicon substrate; the contact layer is connected to the support legs, and the support legs are located on the first surface of the silicon substrate and on the side opposite to the top corner of the contact layer; The top view shape of the pixel unit is S-shaped, including a central area and edge areas located on opposite sides of the central area; the edge areas are spaced apart from the sides of the adjacent central area, and the edge areas are connected to one end of the side of the adjacent central area through a transition area; one end of each edge area is connected to the transition area, and the other end is connected to a support leg.

[0007] In a second aspect, the present application further provides a method for preparing an optical frequency conversion chip, which is used to prepare the optical frequency conversion chip of the first aspect. The preparation method comprises: Providing a silicon substrate comprising a first surface and a second surface opposite to each other; A plurality of support structures arranged in an array are formed on the first surface of the silicon substrate; the support structures include a contact layer and two support legs; a space is provided between the contact layer and the silicon substrate; the contact layer is connected to the support legs; the support legs are located on the first surface of the silicon substrate and on the side of the contact layer opposite the top corner; forming a radiation absorbing layer on a side of each support structure facing away from the silicon substrate, the radiation absorbing layer being located on a surface of the contact layer facing away from the silicon substrate; a projection of the contact layer on the silicon substrate completely covering a projection of the radiation absorbing layer on the silicon substrate; Each supporting structure and the corresponding radiation absorbing layer form a pixel unit, and a plurality of supporting structures arranged in an array form a plurality of pixel units arranged in an array; The top view shape of the pixel unit is S-shaped, including a central area and edge areas located on opposite sides of the central area; the edge areas are spaced apart from the sides of the adjacent central area, and the edge areas are connected to one end of the side of the adjacent central area through a transition area; one end of each edge area is connected to the transition area, and the other end is connected to a support leg.

[0008] In a third aspect, the present application further provides an optical frequency conversion system, comprising the optical frequency conversion chip according to the first aspect; The reflective optical frequency conversion system includes: A vacuum chamber, wherein the optical frequency conversion chip is located in the vacuum chamber; a dual-band light-transmitting window is provided on one side of the vacuum chamber, and a radiation-absorbing layer of the optical frequency conversion chip is provided opposite to the dual-band light-transmitting window; a coating is provided on an inner wall of the vacuum chamber, and the infrared emissivity of the coating is greater than 0.8; A cemented prism is provided outside the dual-band light-transmitting window; the cemented prism comprises two triangular prisms cemented together; the interface surface of the two triangular prisms is coated with a visible light reflective and infrared anti-reflective film; the angle between the interface and the dual-band light-transmitting window is 45°; The cemented prism is suitable for refracting the visible light image emitted by the visible light projection device onto the surface of the light frequency conversion chip in the dual-band light-transmitting window through the visible light reflection and infrared anti-reflection film; The optical frequency conversion chip is suitable for converting visible light images into infrared images and emitting them from the dual-band light-transmitting window; The cemented prism is also suitable for transmitting the infrared image emitted by the optical frequency conversion chip through the dual-band light-transmitting window through the visible light reflection and infrared anti-reflection film.

[0009] The optical frequency conversion chip provided by the present invention, on the one hand, has a high thermal conductivity of the silicon substrate and a low thermal conductivity of the support structure. When the radiation absorbing layer is heated, the support structure can reduce the heat dissipation rate of the radiation absorbing film, thereby facilitating heat accumulation and achieving simulation of high-temperature targets. When the radiation absorbing layer is not heated, the heat is rapidly transferred downward along the contact layer and support legs to the silicon substrate, thereby reducing the heat dissipation rate and increasing the heating rate of a single pixel unit. Heat dissipation through the silicon substrate reduces the deposition heat of the radiation absorbing layer, improving the reliability of the chip, enabling the optical frequency conversion chip to heat up and dissipate heat quickly, and improving the resolution and frame rate of infrared images. On the other hand, the support structure includes a contact layer and two support legs. The entire pixel unit is supported only by two support legs in a diagonal direction and is connected to the silicon substrate with high thermal conductivity. Each pixel unit is in contact with the silicon substrate only through two support legs, which greatly reduces the contact area between the support structure and the silicon substrate, reduces the heat conduction rate from the radiation absorbing film to the pixel, can further increase the heating rate of the pixel unit, and reduce thermal crosstalk between adjacent pixels. Therefore, the optical frequency conversion chip provided by the present invention solves the image resolution and dynamic range problems caused by lateral heat diffusion and insufficient heat dissipation channels in the prior art. It can effectively increase the heating rate of the pixel unit and reduce the thermal crosstalk between adjacent pixels. At the same time, the chip is dissipated as a whole through the high thermal conductivity silicon substrate, thereby improving the image refresh frequency, resolution and apparent temperature, and achieving high resolution and high dynamic range performance of infrared images in high frame rate dynamic scenes. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in related technologies, the following briefly introduces the drawings required for use in the specific embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0011] Figure 1 This is a schematic diagram of the structure of a pixel unit in an optical frequency conversion chip according to an embodiment of the present invention; Figure 2A is a schematic top view of the structure of the optical frequency conversion chip in Example 1 according to an embodiment of the present invention; Figure 2B yes Figure 2A Cross-section view at plane AA; Figure 3A is a schematic top view of the structure of the optical frequency conversion chip in Example 2 according to an embodiment of the present invention; Figure 3B yes Figure 3A Cross-section view at plane AA; Figure 4 This is a schematic diagram of the structure of a pixel unit array in an optical frequency conversion chip according to an embodiment of the present invention; Figure 5 is a schematic top view of the structure of a pixel unit array in Example 1 according to an embodiment of the present invention; Figure 6 is a schematic top view of the structure of a pixel unit array in Example 2 according to an embodiment of the present invention; Figure 7 This is a schematic front view of a structure in which the supporting legs of an optical frequency conversion chip are columnar supporting structures according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of a heat sink in an optical frequency conversion chip according to an embodiment of the present invention; Figure 9 This is a schematic front view of the structure of an adhesive layer in an optical frequency conversion chip according to an embodiment of the present invention; Figure 10 is a flow chart of a method for preparing an optical frequency conversion chip according to an embodiment of the present invention; Figure 11 1 is a schematic diagram of a specific process of a method for preparing an optical frequency conversion chip according to an embodiment of the present invention; Figure 12 1 is a schematic structural diagram of forming an initial sacrificial layer in a method for preparing an optical frequency conversion chip according to an embodiment of the present invention; Figure 13 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 12A schematic structural diagram of a first patterned photoresist formed on the basis; Figure 14 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 13 A schematic diagram of a structure in which a sacrificial layer is formed on the base; Figure 15 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 14 Schematic diagram of the structure of forming an initial support layer on the foundation; Figure 16 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 15 Schematic diagram of the structure of forming an initial adhesion layer on the foundation; Figure 17 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 16 A schematic structural diagram of a second patterned photoresist formed on the basis; Figure 18 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 17 Schematic diagram of the structure of forming an adhesion layer on the basis; Figure 19 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 18 A schematic diagram of the structure forming the support structure on the foundation; Figure 20 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 19 A schematic structural diagram of a base with at least the adhesive layer at a position corresponding to the support removed; Figure 21 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 20 Schematic diagram of the structure in which the sacrificial layer is removed to form a separation space; Figure 22 In a method for preparing an optical frequency conversion chip according to an embodiment of the present invention, Figure 21 Schematic diagram of the structure of the radiation absorbing layer formed on the foundation; Figure 23 FIG. 4 is a schematic structural diagram of an optical frequency conversion system according to an embodiment of the present invention.

[0012] Reference numerals: 10. Silicon substrate; 11. Initial support layer; 20. Support structure; 21. Support legs; 22. Contact layer; 30. Radiation absorption layer; 40. Spacing space; 50. Initial sacrificial layer; 51. Sacrificial layer; 60. Adhesion layer; 61. Initial adhesion layer; 91. First patterned photoresist; 92. Second patterned photoresist; 70. Heat sink; 81. Cooling liquid inlet; 82. Cooling liquid outlet; 100. Pixel unit; 101. Central area; 102. Edge area; 103. Transition area; 200. Vacuum chamber; 300. Dual-band light-transmitting window; 400. Triangular prism; 401. Interface; L1. Visible light image; L2. Infrared image. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. It should also be noted that, for the sake of ease of description, only the parts related to the present invention, not all of the structures, are shown in the drawings.

[0014] In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion about the concepts of the present invention. The accompanying drawings illustrate various schematic diagrams of structures according to embodiments of the present invention. These figures are not drawn to scale; certain details are exaggerated and may be omitted for clarity. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions based on actual needs. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intervening layer / element between them. Furthermore, if a layer / element is "on" another layer / element in one orientation, it may be "below" the other layer / element when the orientation is reversed.

[0015] During indoor testing in hardware-in-the-loop simulation and autonomous driving, developers can provide the detector under test with real-time laser, infrared, and multi-mode composite image sources to simulate the optical characteristics of moving targets and backgrounds in real environments. Infrared light, due to its low frequency and long transmission distance, is particularly suitable for use as a detection wavelength in inclement weather. Currently, various technologies for simulating infrared images have been developed in the research community, which can be categorized based on their operating principles as direct radiation and radiation modulation. Direct radiation technology involves the device directly generating infrared images through its own electrical-to-optical, electrical-to-thermal-to-optical, or optical-to-thermal-to-optical conversion. Typical direct radiation devices include resistor arrays, converter chips, and infrared diode arrays. Radiation modulation technology modulates the infrared radiation intensity distribution impinging on the device's working surface by altering its reflection or transmission properties. Typical radiation modulation devices include digital micromirror devices and liquid crystal on silicon spatial light modulators. Currently, mainstream technologies in China include resistor arrays based on electrical-to-thermal-to-optical conversion, digital micromirror devices with reflective spatial light modulation, and converter chips based on optical-to-thermal-to-optical conversion.

[0016] However, resistor arrays are limited by complex CMOS-MEMS processes, making pixel arrays difficult to scale. Digital micromirror devices are affected by long-wave diffraction, resulting in low contrast in long-wave images. With the continuous advancement of microelectromechanical systems (MEMS) technology, converter chip technology has met the current requirements for most infrared scene simulations in terms of array size, simulation temperature, and spectral width. However, its advantages are primarily for static images, and due to the limitations of its heat dissipation structure, it struggles to meet the demands of high-frame-rate dynamic video simulation.

[0017] Traditional optical frequency conversion chips are usually designed as self-suspended composite films with a diameter of 3 inches. The surface of the film is hollowed out and etched with an array of high-absorption / emissivity pixels, which is related to the resolution of the image to be simulated. During operation, the conversion chip needs to be fixed in a vacuum environment by a metal pressure ring to reduce the influence of thermal convection. Based on the optical frequency down-conversion method, when a high-resolution visible light image is used to heat the film through the visible light window, the pixels have high visible light absorptivity and wide-band infrared emissivity, so they can quickly absorb light heat and heat up, and then radiate infrared secondary. The radiation passes through the infrared window, is received by the infrared optical system, and is projected onto the entrance pupil of the optical system of the detector to be measured.

[0018] In related technologies, to achieve rapid heating while minimizing lateral heat diffusion, the converter chip must be very thin, typically in the submicron range, resulting in poor mechanical properties. Because the pixel array is two-dimensional, lateral thermal crosstalk still reduces the spatial resolution of the simulated image. Therefore, it is necessary to increase the heating rate of individual pixels and reduce lateral thermal crosstalk between adjacent pixels. Furthermore, during dynamic frame switching, the thin film relies solely on radiation for heat dissipation, lacking efficient heat conduction channels. This results in deposited heat within the thin film, raising the background temperature of the simulated image environment. This ultimately manifests as a low dynamic range for high-frame-rate scene simulations. Related research has proposed a "silicon-based microcavity" structure, which suspends each pixel by etching a microcavity array on a silicon substrate to improve heat dissipation. However, this approach places all four broad sides of each pixel in contact with the silicon substrate, resulting in a large heat dissipation surface and hindering temperature increase. Furthermore, the wide borders occupy a larger area of ​​the pixel, sacrificing the pixel's radiating area, resulting in a low fill factor and ultimately a lower apparent temperature detected by the detector.

[0019] Therefore, a solution is needed to reduce the deposition heat of the optical frequency conversion chip while increasing the heating rate of a single pixel, reducing the crosstalk between adjacent pixels, and improving the resolution and frame rate of infrared images.

[0020] like Figure 1 As shown, this embodiment provides an optical frequency conversion chip, which includes: The silicon substrate 10 includes a first surface and a second surface opposite to each other; A plurality of pixel units 100 arranged in an array are located on a first surface of a silicon substrate 10; Each pixel unit 100 includes a stacked support structure 20 and a radiation absorbing layer 30; the radiation absorbing layer 30 is located on the side of the support structure 20 facing away from the silicon substrate 10; the support structure 20 includes a contact layer 22 and two support legs 21; the radiation absorbing layer 30 is located on the surface of the contact layer 22 facing away from the silicon substrate 10, the projection of the contact layer 22 on the silicon substrate 10 completely covers the projection of the radiation absorbing layer 30 on the silicon substrate 10, and there is a space 40 between the contact layer 22 and the silicon substrate 10; the contact layer 22 is connected to the support legs 21, and the support legs 21 are located on the first surface of the silicon substrate 10 and on the side opposite the top corner of the contact layer 22; the thermal conductivity of the support structure 20 is lower than that of the silicon substrate; The top view shape of the pixel unit 100 is S-shaped, including a central area 101 and edge areas 102 located on opposite sides of the central area 101; the edge areas 102 are separated from the side of the adjacent central area 101, and the edge areas 102 are connected to one end of the side of the adjacent central area 101 through the transition area 103; one end of each edge area 102 is connected to the transition area 103, and the other end is connected to a support leg 21.

[0021] In a specific implementation, each pixel unit 100 in the pixel array is an independent and unconnected suspended structure. The pixel unit 100 has an S-shaped top view, with a rectangular central region 101 and an elongated edge region 102. The central region 101 comprises, from top to bottom, a radiation absorbing layer 30, a contact layer 22, and a spacing space 40. The edge region 102 and transition region structures include at least a contact layer 22. Support legs 21 are located at one end of the edge region 102 and extend from the contact layer 22 corresponding to the edge region 102 to the first surface of the silicon substrate 10. The two support legs 21 are located at opposite corners of the contact layer 22. The support legs 21 and contact layer 22 are made of a low-thermal-conductivity, flexible, heat-resistant polymer film, which supports the radiation absorbing layer 30. The radiation absorbing layer 30 is made of a sparse, porous metallic black film, which absorbs visible light and radiates infrared light. The radiation-absorbing layer 30 is located at least in the rectangular central region 101. The rectangular design of the radiation-absorbing layer 30 increases the pixel fill factor, thereby improving the apparent temperature detectable by the detector. The edge region 102 is designed as a long strip, connecting the support legs 21 and the central region 101, providing support. By controlling the length of the edge region 102, the thermal resistance can be varied, thereby selectively regulating the pixel end face temperature and thermal response time. The size of a single pixel unit 100 is designed based on the required image resolution.

[0022] Specifically, the top view of the pixel unit 100 is S-shaped, primarily due to the top view of the contact layer 22, which includes a central region 101 and edge regions 102 located on opposite sides of the central region 101. The edge regions 102 are spaced apart from the sides of the adjacent central region 101 and connected to one end of the side of the adjacent central region 101 via a transition region 103. One end of each edge region 102 is connected to the transition region 103, and the other end is connected to a support leg 21. The support legs 21 are located at two opposite corners of the edge region 102 of the contact layer 22, and the radiation absorbing layer 30 at least partially covers the contact layer 22.

[0023] The optical frequency conversion chip provided in this embodiment, on the one hand, has a high thermal conductivity of the silicon substrate and a low thermal conductivity of the support structure. When the radiation absorbing layer is heated, the support structure can reduce the heat dissipation rate of the radiation absorbing film, thereby facilitating heat accumulation and achieving simulation of high-temperature targets. When the radiation absorbing layer is not heated, the heat is rapidly transferred downward along the contact layer and support legs to the silicon substrate, thereby reducing the heat dissipation rate and increasing the heating rate of a single pixel unit. Heat dissipation through the silicon substrate reduces the deposited heat of the radiation absorbing layer, improving chip reliability, enabling rapid heating and heat dissipation of the optical frequency conversion chip, and improving the resolution and frame rate of infrared images. On the other hand, the support structure includes a contact layer and two support legs. The entire pixel unit is supported only by two diagonal support legs and connected to the high-thermal-conductivity silicon substrate. Each pixel unit is in contact with the silicon substrate through only two support legs, which greatly reduces the contact area between the support structure and the silicon substrate, reducing the heat conduction rate from the radiation absorbing film to the silicon substrate, further improving the heating rate of the pixel unit, and reducing thermal crosstalk between adjacent pixels. Therefore, the optical frequency conversion chip provided in this embodiment solves the image resolution and dynamic range problems caused by lateral heat diffusion and insufficient heat dissipation channels in the prior art. It can effectively increase the heating rate of the pixel unit and reduce thermal crosstalk between adjacent pixels. At the same time, the chip is dissipated as a whole through the high thermal conductivity silicon substrate, thereby improving the image refresh frequency, resolution and apparent temperature, and achieving high resolution and high dynamic range performance of infrared images in high frame rate dynamic scenes.

[0024] In some optional embodiments, such as Figure 2A and Figure 3A As shown, the contact layer 22 is located in the central region 101, the edge region 102 and the transition region 103; the projection of the contact layer 22 on the silicon substrate 10 is S-shaped; The radiation absorbing layer 30 is located at least in the central region 101 .

[0025] In a specific implementation, the contact layer 22 has an S-shaped top view and is located simultaneously in the center region 101, the edge region 102, and the transition region 103. The contact layer 22 in each edge region 102 is connected to the contact layer 22 in the transition region 103 at one end and to a support leg 21 at the other end. The radiation absorbing layer 30 is located at least in the center region 101, and the center region 101 is rectangular. The rectangular design of the radiation absorbing layer 30 increases the fill factor of the pixel, thereby improving the apparent temperature that the chip detector can detect. The edge region of the contact layer is used to transfer heat generated by the radiation absorbing layer in the center region to the support legs, and then to the silicon substrate. The provision of the edge region increases the thermal resistance of the heat conduction path and reduces the heat conduction rate from the radiation absorbing film in the center region to the silicon substrate. Generally, the edge region is configured to be elongated to further increase the thermal resistance, thereby reducing the heat conduction rate from the radiation absorbing film to the silicon substrate, thereby increasing the temperature rise rate of the pixel unit and reducing thermal crosstalk between adjacent pixels.

[0026] In some optional embodiments, such as Figure 2A and Figure 2B As shown, in Example 1, the radiation absorbing layer 30 is only located in the central region 101 ; the projection of the radiation absorbing layer 30 on the silicon substrate 10 is a rectangle.

[0027] Specifically, when the radiation absorption layer 30 is only located in the central area 101, the contact layer in the edge area is only used for support and heat conduction, and the thermal resistance is relatively large, so that the heat generated by the radiation absorption layer 30 in the central area 101 needs to be transferred to the silicon substrate through the edge area and the support legs, further reducing the heat conduction speed, which can increase the heating rate of the pixel unit and reduce the thermal crosstalk between adjacent pixels.

[0028] In some optional embodiments, such as Figure 3A and Figure 3B As shown, in Example 2, the radiation absorbing layer 30 is located in the central region 101 , the edge region 102 and the transition region 103 ; the projection of the radiation absorbing layer 30 on the silicon substrate 10 is S-shaped.

[0029] Specifically, the radiation absorbing layer 30 is located in the central region 101 , the edge region 102 and the transition region 103 , which can further increase the fill factor of the radiation absorbing layer, thereby improving the apparent temperature and light conversion efficiency that can be identified by the chip detector.

[0030] In some optional embodiments, the projection of the supporting legs 21 on the silicon substrate 10 does not overlap with the projection of the radiation absorbing layer 30 on the silicon substrate 10 .

[0031] In the optical frequency conversion chip provided in this embodiment, the projection of the supporting legs on the silicon substrate does not overlap with the projection of the radiation absorbing layer on the silicon substrate, thereby avoiding direct heat conduction to the position of the radiation absorbing layer, reducing the interference of the heat conduction path on the performance of the radiation absorbing layer, further increasing the heating rate of the radiation absorbing layer, and improving the resolution and accuracy of the image.

[0032] In some optional embodiments, the plurality of pixel units 100 are arranged in an m×n array on the first surface of the silicon substrate 10 .

[0033] In some optional embodiments, a plurality of pixel units 100 are arranged in a 3×3 array on the first surface of the silicon substrate 10, such as Figure 4 、 Figure 5 and Figure 6 As shown. Figure 4 As can be seen from the main view of , multiple pixels are closely arranged, which can improve the integration of the chip and the fill factor of the pixel unit 100, thereby increasing the apparent temperature that the chip can recognize.

[0034] In some optional embodiments, there is a certain distance between the radiation absorbing layers 30 between adjacent pixel units 100, which can avoid interference between adjacent pixels and reduce thermal crosstalk and thermal diffusion between adjacent pixel units 100, thereby ensuring the thermal isolation effect between the pixel units 100 and improving the resolution of the image.

[0035] In some optional embodiments, such as Figure 5 and Figure 6 As shown, any two adjacent pixel units 100 do not contact each other.

[0036] In the optical frequency conversion chip provided in this embodiment, any two adjacent pixel units do not contact each other, which can reduce thermal crosstalk and mechanical stress transfer between adjacent pixel units, while reducing the impact of heat diffusion on adjacent pixel units, ensuring the thermal isolation effect between pixel units, and thus improving image resolution.

[0037] In some optional embodiments, the support structure 20 includes a contact layer 22 and two support legs 21. The projection of the contact layer 22 on the silicon substrate 10 completely covers the projection of the radiation absorbing layer 30 on the silicon substrate 10, and a space 40 is provided between the contact layer 22 and the silicon substrate 10. The support legs 21 are located at opposite corners of the contact layer 22 and extend to the first surface of the silicon substrate 10. The contact layer 22 has an S-shaped top view, comprising a central region 101 and edge regions 102 located on either side of the central region 101. The edge regions 102 maintain a certain distance from the sides of the adjacent central region 101 and are connected by transition regions 103. Each edge region 102 is connected to a transition region 103 at one end and to a support leg 21 at the other end. The design of the contact layer 22 and support legs 21 not only provides good support for the radiation absorbing layer 30 and improves the mechanical strength of the support structure 20, but also reduces the contact area between the pixel and the silicon substrate 10, slowing down heat conduction and thereby improving the spatial resolution of infrared images and the apparent temperature that can be detected by the chip.

[0038] In some optional embodiments, such as Figure 7 As shown, the support leg 21 is a columnar support structure, which vertically extends from the first surface of the silicon substrate 10 to connect to the side of the contact layer 22 .

[0039] In specific implementations, the columnar support structure can improve the stability of support legs 21, thereby increasing the mechanical stability of the support structure. Furthermore, the columnar support structure has a smaller contact area with the silicon substrate, which can provide stable support while reducing the heat conduction rate of support legs 21, further reducing the heat conduction rate of the support structure. This effectively increases the heating rate of pixel unit 100, prevents thermal crosstalk between adjacent pixels, improves image resolution, and increases the apparent temperature of visible light that the chip can detect.

[0040] In some optional embodiments, such as Figure 1 As shown, the support leg 21 is an arc-shaped support structure, which extends obliquely from the first surface of the silicon substrate 10 in an arc shape to connect to the contact layer 22 .

[0041] During the preparation process, the natural flow of the colloid often produces an arc, resulting in the support leg 21 being an arc-shaped support structure, such as Figure 1 The arc-shaped support structure can also support the pixel unit. At the same time, the arc-shaped support structure can further reduce the volume of the support leg 21 while ensuring the contact area with the silicon wafer, thereby reducing the heat conduction speed of the support leg 21 while providing stable support.

[0042] In some optional embodiments, such as Figure 8 As shown, the optical frequency conversion chip also includes: The heat sink 70 is located on the second surface of the silicon substrate 10 . The heat sink 70 is used to dissipate heat from the silicon substrate 10 .

[0043] In some optional embodiments, a liquid cooling pipe is provided inside the heat sink 70; The heat sink 70 is provided with a cooling liquid inlet 81 and a cooling liquid outlet 82 on the side facing away from the silicon substrate 10; The cooling liquid inlet 81 and the cooling liquid outlet 82 are respectively located at two ends of the liquid cooling pipe.

[0044] In specific implementation, the optical frequency conversion chip is placed vertically in actual operation. When placed vertically, the heat sink 70 and the pixel unit are located on the left and right sides of the silicon substrate respectively; the cooling liquid inlet 81 is located at the bottom of the heat sink, and the cooling liquid outlet 82 is located at the top of the heat sink.

[0045] The optical frequency conversion chip provided in this embodiment dissipates heat from the silicon substrate by disposing a heat sink on the second surface of the silicon substrate, improving the overall heat dissipation capacity of the chip. Heat is transferred along the support legs to the silicon substrate and then to the heat sink, achieving a high frame rate. Furthermore, by providing a liquid cooling channel within the heat sink and connecting it to an external liquid cooler, the heat sink can quickly remove heat accumulated in the silicon substrate, improving heat dissipation efficiency and reducing the impact of deposited heat on the background temperature of the simulated image. This significantly improves the refresh rate, resolution, and apparent temperature of the image using the optical frequency conversion chip.

[0046] In some optional embodiments, such as Figure 9 As shown, each pixel unit 100 also includes: The adhesive layer 60 is located between the radiation absorbing layer 30 and the contact layer 22 and is used to bond the radiation absorbing layer 30 and the contact layer 22 .

[0047] The material selection of the adhesion layer 60 is related to the material of the radiation absorbing layer 30 and the material of the contact layer 22. The adhesion layer 60 can increase the bonding strength between the radiation absorbing layer 30 and the contact layer 22.

[0048] In some optional embodiments, the radiation absorbing layer 30 is a metallic black film, and the material of the adhesion layer 60 is metal; optionally, the material of the adhesion layer 60 is chromium.

[0049] In some optional embodiments, the thermal conductivity of the support structure 20 is less than 0.2 W / (m·K).

[0050] In some optional embodiments, the material of the support structure 20 is a polymer; and the thermal conductivity of the support structure 20 is 0.15 W / (m·K) to 0.2 W / (m·K).

[0051] In practice, both the contact layer 22 and the support legs 21 are made of the same polymer material with low thermal conductivity. The use of a low-thermal-conductivity polymer for the support structure 20 provides efficient thermal isolation, reducing the rate of heat transfer from the radiation-absorbing layer 30 to the silicon substrate 10. This reduces the heat dissipation rate of the radiation-absorbing layer within a single pixel unit, allowing the radiation-absorbing layer 30 to heat up quickly.

[0052] In some optional embodiments, the radiation absorbing layer 30 is a metallic black film.

[0053] In a specific implementation, the radiation absorbing layer 30 is made of a metallic black film, which has a high light absorption conversion efficiency.

[0054] In some optional embodiments, the material of the support structure 20 is polyimide; The radiation absorbing layer 30 is an aluminum black film, a gold black film or a tungsten black film.

[0055] In some optional embodiments, the width of the pixel unit is 15 μm to 100 μm, for example, 15 μm, 30 μm, 50 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0056] In some optional embodiments, the thickness of the radiation absorbing layer 30 is 0.1 μm to 1 μm, for example, 0.1 μm, 0.2 μm, 0.5 μm, 0.6 μm, 0.8 μm or 1 μm.

[0057] In some optional embodiments, the thickness of the radiation absorption layer 30 is greater than or equal to 0.6 μm, and the thickness of the radiation absorption layer 30 is 0.6 μm~1 μm; this can ensure a higher light absorption conversion efficiency, while improving the mechanical properties and reliability of the radiation absorption layer 30, and can improve the light frequency conversion performance of the chip.

[0058] In some optional embodiments, the maximum width of the support leg 21 is 1 μm to 5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, etc.; the height of the support leg 21 is 1 μm to 5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, etc.

[0059] During specific implementation, in order to reduce the heat dissipation rate of the radiation-absorbing layer, it is necessary to minimize the contact area between the support legs 21 and the silicon substrate. The maximum width of the support legs 21 is 1μm~5μm, which can reduce the heat conduction rate of the support structure while providing stable support, so that the pixel unit has a higher heating rate, so that the radiation-absorbing layer can achieve a higher temperature rise when heated by less visible light. The height of the support legs is 1μm~5μm, which can improve the stability of the support legs and thus improve the mechanical stability of the support structure. In practice, other height values ​​can also be set according to the size of the pixel. The height of the support legs has almost no effect on the temperature and frame rate. In one example, the width of the support legs is 3μm and the height is 2μm.

[0060] In some optional embodiments, the width of the edge region 102 is the same as the width of the support leg 21 , which is 1 μm to 5 μm, such as 1 μm, 2 μm, 3 μm, 4 μm or 5 μm.

[0061] Specifically, the edge area needs to be set to be slender to increase thermal resistance. The length of the edge area is set according to the width of the pixel. The width of the edge area 102 is 1μm~5μm. If it is too wide, the temperature rise of the absorbed radiation will be too low, and the thermal conduction rate of the pixel unit will be too fast. If it is too narrow, it may also affect the temperature rise and frame rate. Therefore, setting it to 1μm~5μm can effectively increase thermal resistance, reduce thermal conduction rate, and increase the temperature rise rate of the chip. Specifically, it can be designed according to actual performance requirements and process accuracy.

[0062] In some optional embodiments, the distance between the edge region 102 and the side of the adjacent central region 101 is less than or equal to 3 μm, for example, 3 μm, 2 μm, or 1 μm.

[0063] Specifically, the smaller the distance between the edge region 102 and the side of the adjacent central region 101 , the better, which mainly depends on the process accuracy. The smaller the distance, the larger the fill factor of the pixel, which improves the absorption efficiency of the pixel.

[0064] In some optional embodiments, the thickness of the contact layer 22 is 0.1 μm to 1 μm.

[0065] In specific implementations, while ensuring mechanical strength, the thinner the contact layer 22, the better. The thinner the contact layer 22, the smaller the thermal mass of the pixel, making it easier to heat and cool. The height of the spacing space 40 is the difference between the support leg height and the contact layer thickness. The material and dimensional design of the contact layer 22 and support structure 20 effectively reduces the impact of thermal diffusion on the pixel unit 100, while optimizing the heat conduction path and improving the thermal isolation and mechanical stability of the pixel unit 100. Optionally, the present invention can further reduce the width of the edge region 102, leaving a larger central region 101, provided the process allows.

[0066] In some optional embodiments, the radiation-absorbing layer is an aluminum black film with a thickness of 0.6 μm. To ensure a visible light absorptivity greater than 95% and an emissivity of 0.8, the thickness of the radiation-absorbing layer is as thick as possible; however, from a temporal perspective, a thinner thickness is preferred. Calculations show that the optimal thickness for aluminum black is 0.6 μm.

[0067] In some optional embodiments, the width of the edge region 102 and the width of the support legs are 3 μm, and the height of the support legs is 2 μm. The spacing between each edge region 102 and the center region 101 is 2 μm. The thickness of the contact layer is less than or equal to 0.5 μm. In one example, if the thickness of the contact layer is 0.5 μm, the height of the spacing space is 1.5 μm.

[0068] like Figure 10 As shown, this embodiment provides a method for preparing an optical frequency conversion chip, which includes but is not limited to steps S101 to S103.

[0069] Step S101 : providing a silicon substrate 10 , comprising a first surface and a second surface opposite to each other.

[0070] In step S102, a plurality of support structures 20 arranged in an array are formed on the first surface of the silicon substrate 10; the support structure 20 includes a contact layer 22 and two support legs 21; there is a spacing space 40 between the contact layer 22 and the silicon substrate 10; the contact layer 22 is connected to the support legs 21; the support legs 21 are located on the first surface of the silicon substrate 10 and are located on the side relative to the top corner of the contact layer 22.

[0071] In step S103, a radiation absorbing layer 30 is formed on the side of each support structure 20 facing away from the silicon substrate 10, and the radiation absorbing layer 30 is located on the surface of the contact layer 22 facing away from the silicon substrate 10; the projection of the contact layer 22 on the silicon substrate 10 completely covers the projection of the radiation absorbing layer 30 on the silicon substrate 10; each support structure 20 and the corresponding radiation absorbing layer 30 form a pixel unit 100, and a plurality of support structures 20 arranged in an array form a plurality of pixel units 100 arranged in an array; the top view shape of the pixel unit 100 is S-shaped, including a central area 101 and edge areas 102 located on opposite sides of the central area 101; the edge area 102 is spaced from the side of the adjacent central area 101, and the edge area 102 is connected to one end of the side of the adjacent central area 101 through the transition area 103; one end of each edge area 102 is connected to the transition area 103, and the other end is connected to a support leg 21.

[0072] The method for preparing the optical frequency conversion chip provided in this embodiment, on the one hand, forms a support structure with low thermal conductivity on the first surface of the silicon substrate with high thermal conductivity, and forms a radiation absorption layer on the surface of the contact layer with low thermal conductivity. When the radiation absorption layer is heated, the support structure can reduce the heat dissipation rate of the radiation absorption film, which helps to accumulate heat and achieve the simulation of high-temperature targets. When the radiation absorption layer is not heated, the heat will be rapidly transferred downward along the contact layer and the support legs to the silicon substrate, thereby reducing the heat dissipation rate of a single pixel unit and increasing the heating rate while dissipating heat through the silicon substrate. The invention reduces the deposition heat of the radiation absorbing layer, improves the reliability of the chip, and enables the optical frequency conversion chip to heat up and dissipate heat quickly, thereby improving the resolution and frame rate of infrared images. On the other hand, the support structure includes a contact layer and two support legs. The entire pixel unit is supported only by two support legs in a diagonal direction and connected to the silicon substrate with high thermal conductivity. Each pixel unit is in contact with the silicon substrate with only two support legs, which greatly reduces the contact area between the support structure and the silicon substrate, reduces the heat conduction rate from the radiation absorbing film to the pixel, further improves the heating rate of the pixel unit, and reduces thermal crosstalk between adjacent pixels. Therefore, the preparation method of the optical frequency conversion chip provided in this embodiment solves the image resolution and dynamic range problems caused by lateral heat diffusion and insufficient heat dissipation channels in the prior art. It can effectively improve the heating rate of the pixel unit and reduce thermal crosstalk between adjacent pixels. At the same time, the chip is dissipated as a whole through the high thermal conductivity silicon substrate, thereby improving the image refresh rate, resolution, and apparent temperature, and achieving high resolution and high dynamic range performance of infrared images in high frame rate dynamic scenes.

[0073] In some optional embodiments, the step of forming a plurality of support structures 20 arranged in an array on the first surface of the silicon substrate 10 includes: A plurality of sacrificial layers 51 arranged in an array are formed on the first surface of the silicon substrate 10; the shape of the sacrificial layers 51 is the shape of the separation space 40; A support structure 20 is formed on the side of the sacrificial layer 51 facing away from the silicon substrate 10; The sacrificial layer 51 is removed, and a separation space 40 is formed between the contact layer 22 and the first surface of the silicon substrate 10 .

[0074] The method for preparing the optical frequency conversion chip provided in this embodiment first forms a plurality of sacrificial layers arranged in an array on the first surface of a silicon substrate; the shape of the sacrificial layers is the shape of the spacing space; secondly, a support structure is formed on the side of the sacrificial layer facing away from the silicon substrate; finally, the sacrificial layer is removed to form a spacing space between the contact layer and the first surface of the silicon substrate; the support structure can be integrally formed, thereby improving the stability of the support structure, and at the same time, the process flow can be simplified and the efficiency of the preparation process can be improved.

[0075] In some optional embodiments, the step of forming the support structure 20 on the side of the sacrificial layer 51 facing away from the silicon substrate 10 includes: An initial support layer 11 is formed on the surface of the sacrificial layer 51 facing away from the silicon substrate 10; Forming an initial adhesion layer 61 on the surface of the initial support layer 11 facing away from the silicon substrate 10; Performing a patterning process on the initial adhesion layer 61 and the initial support layer 11 to form an adhesion layer 60 and a support structure 20 respectively; The step of forming the radiation absorbing layer 30 includes: The radiation absorbing layer 30 is formed on the surface of the adhesion layer 60 facing away from the contact layer 22 .

[0076] In some optional embodiments, the step of forming the radiation absorbing layer 30 on the surface of the adhesion layer 60 facing away from the contact layer 22 includes: The radiation absorbing layer 30 is formed by a resistance evaporation coating process; the radiation absorbing layer 30 is a metallic black film; In the resistance evaporation coating process, the metal is heated in a protective gas environment, the working gas pressure and evaporation rate are controlled, and the surface of the adhesion layer 60 facing away from the contact layer 22 is evaporated to form the radiation absorbing layer 30; In some optional embodiments, the material of the radiation absorbing layer is aluminum black film, gold black film or tungsten black film; the metal is aluminum, gold or tungsten; The shielding gas is helium, nitrogen or argon.

[0077] In some optional embodiments, the radiation absorbing layer 30 is made of aluminum black film, the metal is aluminum, the protective gas is helium, the operating pressure is 850-950 Pa, and the evaporation rate is 13 nm / s-17 nm / s. In one example, the operating pressure is 900 Pa, and the evaporation rate is 15 nm / s.

[0078] In some optional embodiments, the material of the radiation absorbing layer 30 is a gold black film; the metal is gold; the protective gas is nitrogen or argon, and the working gas pressure and evaporation rate are set according to actual needs.

[0079] In some optional embodiments, the material of the radiation absorbing layer 30 is tungsten black film; the metal is tungsten; the protective gas is helium, nitrogen or argon, and the working pressure and evaporation rate are set according to actual needs.

[0080] In some optional embodiments, the material of the sacrificial layer 51 is silicon dioxide; The step of removing the sacrificial layer 51 includes: The sacrificial layer 51 is wet-etched multiple times using a hydrofluoric acid buffer solution to remove the sacrificial layer 51 , thereby forming a separation space 40 between the contact layer 22 and the first surface of the silicon substrate 10 , and making the support structure 20 a suspended structure.

[0081] like Figure 11 As shown, the present invention also provides a specific flow chart of a method for preparing an optical frequency conversion chip, including but not limited to steps S201 to S208.

[0082] Step S201 : providing a silicon substrate 10 , comprising a first surface and a second surface opposite to each other.

[0083] During implementation, single-sided polished silicon wafers are first treated to enhance adhesion. The process does not require specific parameters such as the wafer's crystal plane or doping. The wafer serves solely as a substrate for the manufacturing process and as a heat sink. The polished surface of the wafer is referred to as the first surface.

[0084] Step S202: forming a plurality of sacrificial layers 51 arranged in an array on the first surface of the silicon substrate 10; the shape of the sacrificial layers 51 is the shape of the separation space 40, such as Figures 12 to 14 shown.

[0085] In a specific implementation, the material of the sacrificial layer 51 is silicon dioxide. First, an initial sacrificial layer 50 is prepared on the first surface of the silicon wafer using plasma enhanced chemical vapor deposition technology. The thickness of the initial sacrificial layer 50 is the same as the height of the spacing space 40, such as Figure 12 Next, a first patterned photoresist 91 is formed on the surface of the initial sacrificial layer 50, as shown in FIG. Figure 13 Then, the initial sacrificial layer 50 is etched using the first patterned photoresist 91 as a mask to form a sacrificial layer 51 that is consistent with the shape of the space 40, as shown in FIG. Figure 14 shown.

[0086] In some specific examples, the first patterned photoresist 91 is formed by the following process: first, a silicon oxide wafer is placed on a 150°C baking table and heated for 5 to 10 minutes to remove attached water vapor and organic matter; then, a positive photoresist coating is prepared by spin coating, followed by spin coating at a low speed of 500 r / min for 10 seconds and a high speed of 4000 r / min for 60 seconds, and then cured on a 115°C baking table for 1 minute; finally, a UV exposure machine is used for pattern exposure and development, and the pre-designed sacrificial layer 51 pattern on the mask is transferred to the photoresist coating, and then the film is hardened on the baking table for 2 hours to form the first patterned photoresist 91. The etching parameters are g-line (436nm), resolution 0.5μm, and exposure dose 150mJ / cm 2 The developer concentration is 25%, and the main component of the developer is tetramethylammonium hydroxide (TMAH).

[0087] In some specific examples, using the first patterned photoresist 91 as a mask, a hydrofluoric acid buffer solution (40% HF solution: deionized water = 3:7) is used to perform a step-wise wet etching of the exposed portion of the sacrificial layer 51. This involves multiple cycles of etching, rinsing, and hardening to avoid excessive lateral corrosion caused by prolonged etching. Finally, acetone is used to remove the photoresist, and the pattern of the sacrificial layer 51 is transferred to the silicon dioxide sacrificial layer 51.

[0088] Step S203: forming an initial support layer 11 on the surface of the sacrificial layer 51 facing away from the silicon substrate 10. Figure 15 shown.

[0089] In specific implementations, the initial support layer 11 is made of a polymer. The polymer initial support layer 11 is first prepared using a spin coating method. In some examples, the support structure 20 is made of polyimide (PI), using a poly(amic acid) (PAA) solution as the precursor, with a specific gravity of 1.100, a viscosity of 300-400 cps (25°C), a solids content of 12-13%, a pH of 5, and a solvent of N-methylpyrrolidone (NMP). When preparing the polyimide polymer, the initial speed is 800 rpm for 60 seconds, followed by a high speed of 8000 rpm for 180 seconds. The PAA is then imidized in a high-temperature furnace by increasing the temperature stepwise to 100°C, 200°C, and 300°C for 1 hour each, while nitrogen is used as a protective gas, ultimately producing a PI film.

[0090] Step S204: forming an initial adhesion layer 61 on the surface of the initial support layer 11 facing away from the silicon substrate 10. Figure 16 shown.

[0091] In specific implementation, electron beam evaporation coating technology is used to form a 400nm thick chromium metal adhesion layer on the surface of the polymer film as the initial adhesion layer 61. On the one hand, it can serve as a hard mask, and on the other hand, it can be used as the adhesion layer 60 when preparing the final absorption layer.

[0092] Step S205, the initial adhesion layer 61 and the initial support layer 11 are patterned to form an adhesion layer 60 and a support structure 20 respectively; the support structure 20 includes a contact layer 22 and two support legs 21; the contact layer 22 is connected to the support legs 21; the support legs 21 are located on the first surface of the silicon substrate 10 and are located on the side of the contact layer 22 relative to the top corner, such as Figure 19 and as shown.

[0093] In a specific implementation, first, a second patterned photoresist 92 is formed on the surface of the initial adhesion layer 61. The formation process of the second patterned photoresist 92 is the same as that of the first patterned photoresist 91. The pattern of the second patterned photoresist 92 is a pixel pattern, that is, an S-shape. Figure 17 Secondly, the initial adhesion layer 61 is patterned using a second patterned photoresist 92 as a mask to form a plurality of adhesion layers 60 arranged in an array, the pattern of the adhesion layer 60 is S-shaped, as shown. Figure 18 Finally, the initial support layer 11 is patterned using the adhesion layer 60 as a mask to form a plurality of support structures 20 arranged in an array, as shown. Figure 19 shown.

[0094] In some specific examples, the initial adhesion layer 61 is made of chromium. Using a photoresist as a mask, a chromium etching solution consisting of 25g of 99% pure cerium ammonium nitrate powder, 20mL of 36% glacial acetic acid, and 100mL of deionized water is used to etch the chromium adhesion layer, transferring the pixel pattern onto the chromium. Finally, the photoresist is removed using acetone. Subsequently, using the chromium metal adhesion layer 60 as a hard mask, reactive ion beam etching is used to etch the polymer film (initial support layer 11), transferring the pixel pattern onto the polymer film, thereby forming the support structure 20.

[0095] Step S206, at least remove the adhesive layer 60 at the position corresponding to the support leg 21, and the remaining adhesive layer 60 is located on the surface of the contact layer 22, such as Figure 20 shown.

[0096] In practice, photolithography and wet etching processes are used to remove portions of the adhesion layer 60. In Example 1, the adhesion layer 60 corresponding to the support legs 21, as well as the adhesion layer 60 corresponding to the edge region 102 and transition region 103 of the contact layer 22, is removed, leaving only the chromium adhesion layer in the central region 101. In Example 2, only the adhesion layer 60 corresponding to the support legs 21 is removed, leaving the chromium adhesion layer in the central region 101, edge region 102, and transition region 103.

[0097] Step S207: remove the sacrificial layer 51 and form a separation space 40 between the contact layer 22 and the first surface of the silicon substrate 10. Figure 21 shown.

[0098] In specific implementation, the sacrificial layer 51 is wet-etched multiple times using hydrofluoric acid buffer to remove the sacrificial layer 51 and form a separation space 40 between the contact layer 22 and the first surface of the silicon substrate 10, so that the support structure 20 becomes a suspended structure.

[0099] Step S208: forming a radiation absorbing layer 30 on the surface of the adhesion layer 60 facing away from the contact layer 22; the projection of the contact layer 22 on the silicon substrate 10 completely covers the projection of the radiation absorbing layer 30 on the silicon substrate 10; each support structure 20 and the corresponding radiation absorbing layer 30 form a pixel unit 100, and multiple array-arranged support structures 20 form multiple array-arranged pixel units 100, such as Figure 22 shown.

[0100] In practice, the metallic black film is produced using resistance evaporation coating technology. In some examples, high-purity aluminum is used as the raw material. The aluminum is heated in a helium atmosphere, and the operating pressure is adjusted to 900 Pa. The evaporation rate is controlled to evaporate the aluminum black absorptive / radiative film to a desired thickness. In other examples, gold is used as the raw material, and the shielding gas can be nitrogen, argon, or other gases. Different metals and shielding gases have different vacuum pressure requirements and evaporation rates.

[0101] In Example 1, radiation absorbing layer 30 is formed only in central region 101; the projection of radiation absorbing layer 30 on silicon substrate 10 is rectangular. In Example 2, radiation absorbing layer 30 is formed simultaneously in central region 101, edge region 102, and transition region 103; the projection of radiation absorbing layer 30 on silicon substrate 10 is S-shaped.

[0102] like Figure 23 As shown, the present invention also provides a reflective optical frequency conversion system, comprising the above-mentioned optical frequency conversion chip; The reflective optical frequency conversion system includes: A vacuum chamber 200 is provided, wherein the optical frequency conversion chip is located in the vacuum chamber 200; a dual-band light-transmitting window 300 is provided on one side of the vacuum chamber 200, and a radiation-absorbing layer 30 of the optical frequency conversion chip is disposed opposite the dual-band light-transmitting window 300; a coating is provided on the inner wall of the vacuum chamber, and the infrared emissivity of the coating is greater than 0.8; A cemented prism is disposed outside the dual-band light-transmitting window 300. The cemented prism comprises two cemented triangular prisms 400. The interface 401 between the two triangular prisms 400 is coated with a visible light reflective and infrared transmissive film. The angle between the interface 401 and the dual-band light-transmitting window 300 is 45°. The cemented prism is suitable for reflecting the visible light image L1 emitted by the visible light projection device to the surface of the optical frequency conversion chip in the dual-band light-transmitting window 300 through the visible light reflection and infrared anti-reflection film; The optical frequency conversion chip is suitable for converting the visible light image L1 into an infrared image L2 and emitting the infrared image L2 from the dual-band light-transmitting window 300; The cemented prism is also suitable for transmitting the infrared image L2 emitted by the optical frequency conversion chip through the dual-band light-transmitting window 300 through the visible light reflection and infrared anti-reflection film.

[0103] In specific implementation, because the silicon substrate does not have the transmission property for visible light, it is impossible to realize the path of heating by transmission of visible light in the traditional conversion chip. Figure 18 The reflective optical frequency conversion system shown allows visible light to enter the radiation-absorbing layer 30 of the optical frequency conversion chip via a reflective path. The optical frequency conversion chip converts visible light into infrared light, which then transmits the infrared image. The dual-band optical window 300 functions as both a visible light and infrared light-transmitting window, i.e., a visible / infrared dual-band window. A cemented prism is used for both visible light reflection and infrared light projection. The visible light projection device is used to provide visible light images.

[0104] In some embodiments, the visible light reflecting and infrared transmitting film is a stacked visible light reflecting film and infrared transmitting film. In some embodiments, the interface 401 of the two triangular prisms 400 is coated with a high-reflectivity visible light reflecting film with a thickness of 300 nm to 800 nm, and a high-transmittance infrared transmitting film with a thickness of 3 μm to 5 μm or 8 μm to 14 μm.

[0105] The working principle of the optical frequency conversion chip is as follows: first, the high-power, high-resolution visible light image L1 is reflected by the interface 401 of the two triangular prisms 400, passes through the visible light / infrared dual-band window, and irradiates the surface of the pixel array (the surface of the radiation absorption layer 30). The radiation absorption layer 30 of the pixel unit 100 can absorb the heat of visible light and quickly heat up, generating a secondary radiation infrared image L2 that passes through the visible light / infrared dual-band window and is transmitted from the glued prism to form an infrared image L2, realizing rapid optical frequency conversion.

[0106] In addition, the inner wall of the vacuum chamber 200 is coated with a high-emissivity coating. The material of the vacuum chamber 200 is generally copper or stainless steel. The vacuum chamber 200 is a sealed chamber, and the external environment has little impact on the interior of the vacuum chamber 200. However, the optical frequency conversion chip within the vacuum chamber 200 may generate high temperatures during operation. Therefore, by providing the inner wall of the vacuum chamber 200 with a high-emissivity coating, the radiation heat exchange efficiency between the low-temperature vacuum chamber and the film can be increased. It also reduces the reflection of infrared images from the inner wall of the chamber, reduces external interference, and avoids radiation from the inner wall caused by the high temperature inside the chamber.

[0107] In some optional implementations, the optical frequency conversion chip further includes: A heat sink 70 is located on the second surface of the silicon substrate 10; the heat sink 70 is used to dissipate heat from the silicon substrate 10; the optical frequency conversion chip is vertically arranged in the vacuum chamber, and the heat sink and the pixel unit are respectively located on the left and right sides of the silicon substrate; The heat sink 70 is provided with a liquid cooling pipe inside; The heat sink 70 is provided with a cooling liquid inlet 81 and a cooling liquid outlet 82 on the side facing away from the silicon substrate 10; The cooling liquid inlet 81 is located at the bottom end of the liquid cooling pipe; The coolant outlet 82 is located at the top end of the liquid cooling pipe; The chamber wall of the vacuum chamber 200 located on the opposite side of the dual-band light-transmitting window 300 is suitable for setting a heat sink 70; the side wall is provided with a first coolant opening and a second coolant opening, the first coolant opening is correspondingly connected to the coolant inlet 81, and the second coolant opening is correspondingly connected to the coolant outlet 82.

[0108] In order to ensure the low temperature of the silicon substrate, a copper heat sink 70 is designed in this embodiment to conduct heat to the silicon substrate. At the same time, the inner wall of the vacuum chamber is provided with a first coolant opening and a second coolant opening for arranging a coolant inlet 81 and a coolant inlet outlet 82, and the coolant is used as an exchange medium to conduct the heat of the silicon substrate out of the vacuum chamber 200.

[0109] In some optional embodiments, the angle between the interface 401 and the dual-band light-transmitting window 300 is 45°, which can better reflect visible light into the dual-band light-transmitting window 300 and enter the radiation absorption layer 30 of the pixel unit 100.

[0110] In some optional embodiments, a high-power light source is used as a heating source for the visible light image.

[0111] Because optical frequency conversion chips have excellent heat dissipation performance, a high-power light source is used as the heating source for visible light images. Traditional conversion chips typically use LCoS projectors based on LED light sources. In some embodiments, the reflective optical frequency conversion system provided in this embodiment uses DMD projection technology based on high-power visible light lasers.

[0112] In some embodiments, because the optical frequency conversion chip itself achieves optical frequency conversion based on the heat absorption effect, the incident light does not strictly need to be visible light. In some embodiments, when the radiation absorption layer 30 can absorb short-wave infrared light (0.9μm-2.5μm), the metallic black film material of the radiation absorption layer 30 is a broadband absorber of visible and short-wave infrared light. In this case, a short-wave laser is used as the light source for the visible light pattern. At the same time, the transmissive film and reflective film of the dual-band window of the vacuum chamber 200 can be adjusted accordingly to achieve compatibility with the 0.9μm-2.5μm wavelength range.

[0113] In the description of this specification, the reference terms "this embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in an appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless otherwise clearly defined. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise clearly defined.

[0114] While the above description does not provide detailed technical details regarding patterning and etching of each layer, those skilled in the art will appreciate that various technical means can be employed to form layers, regions, and the like in desired shapes. Furthermore, those skilled in the art may devise methods that differ from those described above to form the same structure. Furthermore, while each embodiment has been described separately, this does not mean that the measures in each embodiment cannot be advantageously combined.

[0115] The above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and that various obvious changes, readjustments, combinations, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of protection of the present invention is determined by the scope of the appended claims.

Claims

1. An optical frequency conversion chip, characterized in that: include: a silicon substrate comprising a first surface and a second surface opposite to each other; A plurality of pixel units arranged in an array are located on the first surface of the silicon substrate; Each of the pixel units comprises a stacked support structure and a radiation absorbing layer; the radiation absorbing layer is located on the side of the support structure facing away from the silicon substrate; the support structure comprises a contact layer and two support legs; the radiation absorbing layer is located on the surface of the contact layer facing away from the silicon substrate, the projection of the contact layer on the silicon substrate completely covers the projection of the radiation absorbing layer on the silicon substrate, and there is a space between the contact layer and the silicon substrate; the contact layer is connected to the support legs, and the support legs are located on the first surface of the silicon substrate and on the side of the contact layer opposite to the top corner; The top view shape of the pixel unit is S-shaped, including a central area and edge areas located on opposite sides of the central area; the edge areas are spaced apart from the side of the adjacent central area, and the edge areas are connected to one end of the side of the adjacent central area through a transition area; one end of each of the edge areas is connected to the transition area, and the other end is connected to one of the support legs.

2. The optical frequency conversion chip according to claim 1, characterized in that: The contact layer is located in the central area, the edge area and the transition area; the projection of the contact layer on the silicon substrate is S-shaped; The radiation absorbing layer is located at least in the central region.

3. The optical frequency conversion chip according to claim 2, characterized in that: The radiation absorbing layer is only located in the central area; the projection of the radiation absorbing layer on the silicon substrate is a rectangle.

4. The optical frequency conversion chip according to claim 2, characterized in that: The radiation absorbing layer is located in the central area, the edge area and the transition area; and the projection of the radiation absorbing layer on the silicon substrate is S-shaped.

5. The optical frequency conversion chip according to claim 1, characterized in that: The projection of the supporting legs on the silicon substrate does not overlap with the projection of the radiation absorbing layer on the silicon substrate.

6. The optical frequency conversion chip according to claim 1, characterized in that: Any two adjacent pixel units do not contact each other.

7. The optical frequency conversion chip according to claim 1, characterized in that: The supporting legs are columnar supporting structures, vertically extending from the first surface of the silicon substrate to connect to the side of the contact layer.

8. The optical frequency conversion chip according to claim 1, characterized in that: The optical frequency conversion chip also includes: A heat sink is located on the second surface of the silicon substrate; the heat sink is used to dissipate heat from the silicon substrate.

9. The optical frequency conversion chip according to claim 8, characterized in that: A liquid cooling pipe is provided inside the heat sink; The heat sink is provided with a cooling liquid inlet and a cooling liquid outlet on a side facing away from the silicon substrate; The cooling liquid inlet and the cooling liquid outlet are respectively located at two ends of the liquid cooling pipe.

10. The optical frequency conversion chip according to claim 1, characterized in that: Each of the pixel units further comprises: The adhesive layer is located between the radiation absorbing layer and the contact layer and is used to bond the radiation absorbing layer and the contact layer.

11. The optical frequency conversion chip according to claim 1, characterized in that: The material of the support structure is a polymer; the thermal conductivity of the support structure is 0.15W / (m•K)~0.2W / (m•K); The radiation absorbing layer is a metallic black film.

12. The optical frequency conversion chip according to claim 11, characterized in that: The material of the support structure is polyimide; The radiation absorbing layer is an aluminum black film, a gold black film or a tungsten black film.

13. The optical frequency conversion chip according to claim 11, characterized in that: The width of the pixel unit is 15 μm to 100 μm; The thickness of the radiation absorbing layer is 0.1 μm to 1 μm; The maximum width of the support legs is 1 μm to 5 μm, and the height is 1 μm to 5 μm; The width of the edge area is 1μm~5μm; The spacing between the side of the edge region and the adjacent central region is less than or equal to 3 μm; The thickness of the contact layer is 0.1 μm to 1 μm.

14. A method for preparing an optical frequency conversion chip, characterized in that: include: Providing a silicon substrate comprising a first surface and a second surface opposite to each other; forming a plurality of support structures arranged in an array on the first surface of the silicon substrate; The support structure includes a contact layer and two support legs; there is a spacing space between the contact layer and the silicon substrate; The contact layer is connected to the support leg; The support leg is located on the first surface of the silicon substrate and is located on the side of the contact layer opposite to the top corner; forming a radiation absorbing layer on a side of each of the support structures facing away from the silicon substrate, wherein the radiation absorbing layer is located on a surface of the contact layer facing away from the silicon substrate; The projection of the contact layer on the silicon substrate completely covers the projection of the radiation absorbing layer on the silicon substrate; Each of the support structures and the corresponding radiation absorbing layer forms a pixel unit, and a plurality of support structures arranged in an array form a plurality of pixel units arranged in an array; The top view shape of the pixel unit is S-shaped, including a central area and edge areas located on opposite sides of the central area; the edge areas are spaced apart from the side of the adjacent central area, and the edge areas are connected to one end of the side of the adjacent central area through a transition area; one end of each of the edge areas is connected to the transition area, and the other end is connected to one of the support legs.

15. The method for preparing the optical frequency conversion chip according to claim 14, characterized in that: The step of forming a plurality of support structures arranged in an array on the first surface of the silicon substrate includes: forming a plurality of sacrificial layers arranged in an array on the first surface of the silicon substrate; the shape of the sacrificial layers is the shape of the separation space; forming a support structure on a side of the sacrificial layer facing away from the silicon substrate; The sacrificial layer is removed to form a separation space between the contact layer and the first surface of the silicon substrate.

16. The method for preparing the optical frequency conversion chip according to claim 15, characterized in that: The step of forming a support structure on the side of the sacrificial layer facing away from the silicon substrate comprises: forming an initial supporting layer on a surface of the sacrificial layer facing away from the silicon substrate; forming an initial adhesion layer on the surface of the initial support layer facing away from the silicon substrate; Performing a patterning process on the initial adhesion layer and the initial support layer to form an adhesion layer and a support structure respectively; The step of forming the radiation absorbing layer includes: A radiation absorbing layer is formed on a surface of the adhesion layer facing away from the contact layer.

17. The method for preparing the optical frequency conversion chip according to claim 16, wherein: The step of forming a radiation absorbing layer on the surface of the adhesion layer facing away from the contact layer comprises: A resistance evaporation coating process is used to form a radiation absorbing layer; In the resistance evaporation coating process, the metal is heated in a protective gas environment, the working gas pressure and the evaporation rate are controlled, and the surface of the adhesion layer facing away from the contact layer is evaporated to form a radiation absorbing layer; The material of the radiation absorbing layer is aluminum black film, gold black film or tungsten black film; the metal is aluminum, gold or tungsten respectively; The protective gas is helium, nitrogen or argon.

18. The method for preparing the optical frequency conversion chip according to claim 15, wherein: The material of the sacrificial layer is silicon dioxide; The step of removing the sacrificial layer includes: The sacrificial layer is wet-etched multiple times using a hydrofluoric acid buffer solution to remove the sacrificial layer, thereby forming a spacing space between the contact layer and the first surface of the silicon substrate, so that the support structure becomes a suspended structure.

19. A reflective optical frequency conversion system, characterized in that: The optical frequency conversion chip comprising any one of claims 1 to 13; The reflective optical frequency conversion system comprises: A vacuum chamber, wherein the optical frequency conversion chip is located in the vacuum chamber; a dual-band light-transmitting window is provided on one side of the vacuum chamber, and a radiation-absorbing layer of the optical frequency conversion chip is disposed opposite the dual-band light-transmitting window; and a coating is provided on the inner wall of the vacuum chamber, wherein the infrared emissivity of the coating is greater than 0.8; A cemented prism is provided on the outside of the dual-band light-transmitting window; the cemented prism comprises two glued triangular prisms; the interface surface of the two triangular prisms is coated with a visible light reflective and infrared anti-reflective film; the angle between the interface and the dual-band light-transmitting window is 45°; The cemented prism is adapted to reflect the visible light image emitted by the visible light projection device onto the surface of the light frequency conversion chip in the dual-band light-transmitting window through the visible light reflection and infrared anti-reflection film; The optical frequency conversion chip is suitable for converting visible light images into infrared images and emitting them from the dual-band light-transmitting window; The cemented prism is also suitable for transmitting the infrared image emitted by the optical frequency conversion chip through the dual-band light-transmitting window through visible light reflection and infrared anti-reflection film.

20. The reflective optical frequency conversion system according to claim 19, wherein: The optical frequency conversion chip also includes: A heat sink is located on the second surface of the silicon substrate; the heat sink is used to dissipate heat from the silicon substrate; the optical frequency conversion chip is vertically arranged in the vacuum chamber, and the heat sink and the pixel unit are respectively located on the left and right sides of the silicon substrate; A liquid cooling pipe is provided inside the heat sink; The heat sink is provided with a cooling liquid inlet and a cooling liquid outlet on a side facing away from the silicon substrate; The cooling liquid inlet is located at the bottom end of the liquid cooling pipe; The coolant outlet is located at the top end of the liquid cooling pipe; The chamber wall of the vacuum chamber located on the opposite side of the dual-band light-transmitting window is suitable for arranging the heat sink; the side wall is provided with a first coolant opening and a second coolant opening, the first coolant opening is correspondingly connected to the coolant inlet, and the second coolant opening is correspondingly connected to the coolant outlet.

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