A pixel structure and its manufacturing method, and uncooled infrared polarization detector

Abstract

The present invention relates to the field of infrared imaging and discloses a pixel structure and a manufacturing method thereof, as well as an uncooled infrared polarization detector, comprising: a pixel array and a capping structure, wherein the pixel array includes a plurality of pixels, the capping structure is located above the pixels and vacuum-encapsulates the pixels; the capping structure includes a capping support layer, a micropolarizer structure layer, an infrared window layer, and a channel; the capping support layer is connected to the pixels, and the micropolarizer structure layer and the infrared window layer are sequentially stacked on the upper surface of the capping support layer; the channel penetrates the micropolarizer structure layer and the capping support layer, and the infrared window layer fills the channel; the micropolarizer structure layer has a nanowire grid structure. The capping structure vacuum-encapsulates the pixels, i.e., the present invention adopts pixel-level packaging, avoiding the complex and expensive conventional vacuum packaging process, improving packaging efficiency, reducing packaging costs, and reducing the volume and weight of the detector, making the device miniaturized and lightweight.

Description

Technical Field

[0001] The present invention relates to the field of infrared imaging, and in particular to a pixel structure and a manufacturing method thereof, and a non-cooled infrared polarization detector. Background Art

[0002] Uncooled infrared polarization detectors can simultaneously measure both the intensity and polarization information of space targets, effectively improving the contrast between the target and the background, highlighting the target's details, and enhancing target recognition. Uncooled infrared polarization detectors with split-focal planes, characterized by their high integration and real-time imaging, have become a focus of attention.

[0003] Uncooled infrared polarization detectors with split-focal-plane technology can be manufactured using on-chip integration. This involves fabricating a polarization structure array directly on top of an uncooled infrared pixel array using MEMS (Micro-Electro-Mechanical System) technology. Current uncooled infrared polarization detectors require vacuum packaging, which is costly, complex, and time-consuming, resulting in low production efficiency. Furthermore, these packaged uncooled infrared polarization detectors are relatively large and heavy, hindering their miniaturization and lightweighting.

[0004] Therefore, how to solve the above technical problems should be the focus of those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a pixel structure and a manufacturing method thereof, and an uncooled infrared polarization detector, so as to simplify the packaging process of the pixel structure, improve the manufacturing efficiency, and at the same time make the detector miniaturized and lightweight.

[0006] To solve the above technical problems, the present invention provides a pixel structure of an uncooled infrared polarization detector, comprising:

[0007] A pixel array and a capping structure, wherein the pixel array includes a plurality of pixels, and the capping structure is located above the pixels and vacuum-seales the pixels;

[0008] The capping structure includes a capping support layer, a micropolarizer structure layer, an infrared window layer and a channel; the capping support layer is connected to the pixel, and the micropolarizer structure layer and the infrared window layer are sequentially stacked on the upper surface of the capping support layer; the channel runs through the micropolarizer structure layer and the capping support layer, and the infrared window layer fills the channel; the micropolarizer structure layer has a nanowire grid structure.

[0009] Optionally, the capping structure encapsulates each of the picture elements individually.

[0010] Optionally, also include:

[0011] A first optical blocking layer, wherein the first optical blocking layer is located in the gap between the capping structures corresponding to adjacent pixels; or

[0012] The first optical blocking layer is located between the capping support layer and the micro-polarizer structure layer, and is located on the sidewall of the capping support layer.

[0013] Optionally, a plurality of pixels form a pixel group, the capping structure vacuum-encapsulates each pixel group, and the number of pixels included in the pixel group is an integer multiple of four or six.

[0014] Optionally, the pixel includes a substrate and a microbridge structure, the microbridge structure includes a bridge pier, and the bridge pier includes a first support body, a microbridge support layer and a metal electrode layer;

[0015] The first support body is located on the upper surface of the substrate, the microbridge support layer is located above the first support body and on the side of the first support body, and the metal electrode layer is located above the microbridge support layer and electrically connected to the first support body.

[0016] Optionally, also include:

[0017] A passivation protection layer is located on the upper surface of the metal electrode layer.

[0018] Optionally, the capping structure further includes a second support body, which is located on the upper surface of the bridge pier in the microbridge structure in the pixel.

[0019] Optionally, also include:

[0020] The second optical blocking layer is located around each picture element and between the base of the picture element and the capping support layer.

[0021] Optionally, also include:

[0022] An infrared anti-reflection layer is located on the upper surface of the infrared window layer.

[0023] Optionally, four pixels distributed in two rows and two columns form a pixel set; in each pixel set, there is no micro-polarizer structure layer above one pixel, and the micro-polarizer structure layers corresponding to the other three pixels have the nanowire grid structure, and the transmission axis angles of each nanowire grid structure are different.

[0024] Optionally, four pixels distributed in two rows and two columns form a pixel set; in each of the pixel sets, the micro-polarizer structure layer corresponding to one pixel does not have the nanowire grid structure, and the micro-polarizer structure layers corresponding to the other three pixels have the nanowire grid structure, and the light transmission axis angles of each nanowire grid structure are different.

[0025] Optionally, four pixels distributed in two rows and two columns form a pixel set; in each pixel set, the micro-polarizer structure layer corresponding to one pixel has a circular nanowire grid structure, and the micro-polarizer structure layers corresponding to the other three pixels have a linear nanowire grid structure, and the transmittance axis angles of each linear nanowire grid structure are different.

[0026] Optionally, six pixels distributed in three rows and two columns or two rows and three columns form a pixel set; in each of the pixel sets, the micro-polarizer structure layer corresponding to one or two pixels has a circular nanowire grid structure, and the micro-polarizer structure layer corresponding to the remaining pixels has a linear nanowire grid structure, and the transmittance axis angles of each linear nanowire grid structure are different.

[0027] Optionally, four pixels distributed in two rows and two columns form a pixel set; in each pixel set, the micro-polarizer structure layer corresponding to each pixel has the nanowire grid structure, and the transmission axis angles of each nanowire grid structure are different.

[0028] The present invention also provides a method for manufacturing a pixel structure of an uncooled infrared polarization detector, comprising:

[0029] Preparing a pixel array; the pixel array includes a plurality of pixels;

[0030] Making a capping structure above the pixel, and vacuum-sealing the pixel through the capping structure;

[0031] Among them, the capping structure includes a capping support layer, a micropolarizer structure layer, an infrared window layer and a channel; the capping support layer is connected to the pixel, and the micropolarizer structure layer and the infrared window layer are stacked in sequence on the upper surface of the capping support layer; the channel runs through the micropolarizer structure layer and the capping support layer, and the infrared window layer fills the channel; the micropolarizer structure layer has a nanowire grid structure.

[0032] Optionally, when the capping structure encapsulates each pixel individually, preparing the pixel array includes:

[0033] Prepare a substrate; the substrate includes a substrate, a metal block, a getter layer and an insulating dielectric layer;

[0034] Depositing a first sacrificial layer on the substrate, and etching the first sacrificial layer, wherein the etched area corresponds to the metal block;

[0035] A microbridge structure is fabricated on the first sacrificial layer. The bridge piers of the microbridge structure penetrate the first sacrificial layer and the insulating dielectric layer and are connected to the metal block.

[0036] Optionally, manufacturing a capping structure above the pixel and vacuum-sealing the pixel by using the capping structure includes:

[0037] Depositing a second sacrificial layer on the pixel array having the first sacrificial layer, and etching the first sacrificial layer and the second sacrificial layer between adjacent pixels to expose the insulating dielectric layer;

[0038] depositing a capping support layer, wherein the capping support layer contacts the insulating dielectric layer;

[0039] Depositing a micro-polarizer structure layer on the capping support layer, and etching the micro-polarizer structure layer to form a nanowire grid structure;

[0040] Etching the capping support layer and the micro-polarizer structure layer to form the channel, and releasing the first sacrificial layer and the second sacrificial layer through the channel;

[0041] Under vacuum conditions, an infrared window layer is deposited on the surface of the micro-polarizer structure layer, and the infrared window layer completely fills the channel to form a capping structure.

[0042] Optionally, after forming the capping structure, the following steps are further included:

[0043] A first optical blocking layer is formed in the gaps between the capping structures corresponding to adjacent picture elements.

[0044] Optionally, after depositing the capping support layer on the second sacrificial layer, the method further includes:

[0045] A first optical barrier layer is deposited on the capping support layer, and the first optical barrier layer is etched to retain the first optical barrier layer located on the sidewall of the capping support layer.

[0046] Optionally, when the capping structure vacuum-encapsulates each pixel group, preparing the pixel array includes:

[0047] Prepare a substrate; the substrate includes a substrate, a metal block, a getter layer and an insulating dielectric layer;

[0048] etching the insulating dielectric layer on the metal block to form an opening to expose the metal block;

[0049] depositing a first sacrificial layer and a first hard mask layer in sequence on the substrate;

[0050] Etching the first hard mask layer and the first sacrificial layer to form a first through hole, wherein the first through hole corresponds to the opening;

[0051] Filling the first through hole with a filling material to form a first support body;

[0052] A microbridge structure is fabricated on the first sacrificial layer; the microbridge structure includes a bridge pier, and the bridge pier includes the first support body, a microbridge support layer and a metal electrode layer, the microbridge support layer is located above the first support body and on the side of the first support body, and the metal electrode layer is located above the microbridge support layer and is electrically connected to the first support body.

[0053] Optionally, manufacturing a capping structure above the pixel and vacuum-sealing the pixel by using the capping structure includes:

[0054] sequentially depositing a second sacrificial layer and a second hard mask layer on the pixel array having the first sacrificial layer;

[0055] etching the second hard mask layer and the second sacrificial layer to form a second through hole, wherein the second through hole corresponds to the first through hole;

[0056] Filling the second through hole with a filling material to form a second support body;

[0057] Etching the first sacrificial layer and the second sacrificial layer between adjacent pixel groups to expose the insulating dielectric layer;

[0058] Depositing a capping support layer and a micro-polarizer structure layer in sequence, and etching the micro-polarizer structure layer to form a nanowire grid structure;

[0059] Etching the capping support layer and the micro-polarizer structure layer to form the channel, and releasing the first sacrificial layer and the second sacrificial layer through the channel;

[0060] Under vacuum conditions, an infrared window layer is deposited on the surface of the micro-polarizer structure layer, and the infrared window layer completely fills the channel to form a capping structure.

[0061] Optionally, after sequentially depositing a first sacrificial layer and a first hard mask layer on the substrate, the method further includes:

[0062] etching the first hard mask layer and the first sacrificial layer to form a third through hole;

[0063] Filling the third through hole with a filling material to form a first optical blocking unit layer;

[0064] After sequentially depositing a second sacrificial layer and a second hard mask layer on the pixel array having the first sacrificial layer, the method further includes:

[0065] Etching the second hard mask layer and the second sacrificial layer to form a fourth through hole, wherein the fourth through hole corresponds to the third through hole;

[0066] The fourth through hole is filled with a hole-filling material to form a second optical blocking unit layer.

[0067] The present invention also provides an uncooled infrared polarization detector, comprising any one of the above-mentioned pixel structures of the uncooled infrared polarization detector.

[0068] The present invention provides a pixel structure of an uncooled infrared polarization detector, comprising: a pixel array and a capping structure, wherein the pixel array comprises a plurality of pixels, the capping structure is located above the pixels and vacuum-encapsulates the pixels; the capping structure comprises a capping support layer, a micro-polarizer structure layer, an infrared window layer, and a channel; the capping support layer is connected to the pixels, the micro-polarizer structure layer and the infrared window layer are sequentially stacked on the upper surface of the capping support layer; the channel penetrates the micro-polarizer structure layer and the capping support layer, and the infrared window layer fills the channel; the micro-polarizer structure layer has a nanowire grid structure.

[0069] As can be seen, the pixel structure of the present invention includes a pixel array and a capping structure. The capping structure vacuum-encapsulates the pixels in the pixel array. That is, the present invention adopts pixel-level packaging, avoiding the complex and expensive conventional vacuum packaging process, improving packaging efficiency, and reducing packaging costs. It can also reduce the volume and weight of the uncooled infrared polarization detector, making the device miniaturized and lightweight. The capping structure includes a capping support layer, a micro-polarizer structure layer, and an infrared window layer. In other words, the nanowire grid structure is integrated into the capping structure, eliminating the need to fabricate the nanowire grid structure above the pixel array.

[0070] In addition, the present invention also provides a manufacturing method and a non-cooled infrared polarization detector having the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only 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.

[0072] Figure 1 A cross-sectional diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 1 ;

[0073] Figure 2 A schematic diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention;

[0074] Figure 3 A cross-sectional diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 2 ;

[0075] Figure 4 A cross-sectional diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 3 ;

[0076] Figure 5 for Figure 4 A top view of the pixel structure of the uncooled infrared polarization detector shown;

[0077] Figure 6 A cross-sectional diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 4 ;

[0078] Figure 7 Schematic diagram of the nanowire grid structure provided in the embodiment of this application Figure 1 ;

[0079] Figure 8 Schematic diagram of the nanowire grid structure provided in the embodiment of this application Figure 2 ;

[0080] Figure 9 Schematic diagram of the nanowire grid structure provided in the embodiment of this application Figure 3 ;

[0081] Figure 10 Schematic diagram of the nanowire grid structure provided by the embodiment of the present invention Figure 4 ;

[0082] Figure 11 A schematic diagram of the first step of the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0083] Figure 12 A schematic diagram of the second step of the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0084] Figure 13 A schematic diagram of the third step of the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0085] Figure 14A schematic structural diagram of the fourth step in the first manufacturing process of a pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0086] Figure 15 This is a schematic diagram of the fifth step of the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0087] Figure 16 This is a schematic structural diagram of the sixth step in the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0088] Figure 17 This is a schematic structural diagram of the seventh step in the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0089] Figure 18 This is a schematic structural diagram of a pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application after depositing a first optical blocking layer in a second manufacturing process;

[0090] Figure 19 This is a schematic structural diagram of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application after etching the first optical blocking layer in the second manufacturing process;

[0091] Figure 20 A schematic diagram of the structure of the second to third steps in the third manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0092] Figure 21 This is a schematic diagram of the fourth step of the third manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0093] Figure 22 This is a schematic structural diagram of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application after depositing the hole-filling material in the fifth step of the third manufacturing process;

[0094] Figure 23 This is a schematic structural diagram of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application after removing excess hole-filling material in the fifth step of the third manufacturing process;

[0095] Figure 24 This is a schematic structural diagram of the sixth step in the third manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0096] Figure 25This is a schematic structural diagram of the eighth step in the third manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0097] Figure 26 This is a schematic structural diagram of the ninth step in the third manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0098] Figure 27 This is a schematic diagram of the tenth step of the third manufacturing process of the pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0099] Figure 28 A top view of a substrate in the first step of a fourth manufacturing process for a pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application;

[0100] Figure 29 A top view of a pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application after the micro-bridge structure is manufactured in the fourth manufacturing process;

[0101] Figure 30 This is a schematic structural diagram of a pixel structure of an uncooled infrared polarization detector provided in an embodiment of the present application after forming a second optical blocking unit layer in the fourth manufacturing process;

[0102] In the figure, 1. substrate; 2. metal block; 3. insulating dielectric layer; 4. getter layer; 5. microbridge structure; 6. capping support layer; 7. micropolarizer structure layer; 8. channel; 9. infrared window layer; 10. infrared anti-reflection layer; 11. first optical blocking layer; 13. first sacrificial layer; 14. second sacrificial layer; 15. first hard mask layer; 16. second hard mask layer; 17. first support body; 18. second support body; 19. first through hole; 20. second through hole; 51. bridge deck; 52. bridge leg; 53. bridge pier; 54. microbridge support layer; 55. metal electrode layer; 56. passivation protection layer; 121. first optical blocking unit layer; 122. second optical blocking unit layer. DETAILED DESCRIPTION

[0103] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0104] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0105] As described in the background technology section, the focal plane type uncooled infrared polarization detector in the related art has the defects of high packaging cost, complicated process, low packaging efficiency and being unfavorable for miniaturization and lightweighting.

[0106] In view of this, the present invention provides a pixel structure of an uncooled infrared polarization detector, please refer to Figures 1 to 6 ,include:

[0107] A pixel array and a capping structure, wherein the pixel array includes a plurality of pixels, and the capping structure is located above the pixels and vacuum-seales the pixels;

[0108] The capping structure includes a capping support layer 6, a micropolarizer structure layer 7, an infrared window layer 9 and a channel 8; the capping support layer 6 is connected to the pixel, and the micropolarizer structure layer 7 and the infrared window layer 9 are stacked in sequence on the upper surface of the capping support layer 6; the channel 8 passes through the micropolarizer structure layer 7 and the capping support layer 6, and the infrared window layer 9 fills the channel 8; the micropolarizer structure layer 7 has a nanowire grid structure.

[0109] The pixels in the pixel array are generally arranged in the form of m rows x n columns, where m and n are both integers and may or may not be equal. The pixels are used to detect thermal signals.

[0110] The pixel includes a base 1 and a microbridge structure 5, wherein the base 1 includes a substrate including a readout circuit, a metal block 2, a getter layer 4 and an insulating dielectric layer 3, the metal block 2, the insulating dielectric layer 3 and the getter layer 4 are located on the base, the insulating dielectric layer 3 partially covers the metal block 2, and an opening is provided on the insulating dielectric layer 3 to expose a part of the upper surface of the metal block 2.

[0111] The material of the metal block 2 can be any one of aluminum, titanium, copper and gold, and the thickness of the metal block 2 can range from 50nm to 1000nm; the insulating dielectric layer 3 can be any one of a silicon nitride layer, a silicon oxide layer and a silicon oxynitride layer; the material of the getter layer 4 can be one of titanium-based, zirconium-based, tantalum-based and thorium-based getter materials, and the thickness can range from 50nm to 1000nm.

[0112] The micro-polarizer structure layer 7 corresponding to different pixels has a nanowire grid structure with different patterns, which can simultaneously measure the intensity information and polarization information of the space target, effectively improve the contrast between the target and the background, highlight the detailed features of the target, and enhance the target recognition effect in low thermal contrast application scenarios.

[0113] The capping support layer 6 is connected to the insulating dielectric layer 3 on the substrate 1 to provide mechanical support. The material of the capping support layer 6 includes, but is not limited to, any one of silicon, amorphous silicon, silicon nitride, silicon oxide, and silicon oxynitride. The thickness of the capping support layer 6 can range from 200nm to 1500nm. The micropolarizer structure layer 7 can be any one of a gold layer, a silver layer, a copper layer, an aluminum layer, a tungsten layer, a titanium layer, and a titanium nitride layer, or any combination thereof. The thickness of the micropolarizer structure layer 7 can range from 20nm to 500nm. The material of the infrared window layer 9 can be any one of silicon, germanium, and chalcogenide glass. The thickness of the infrared window layer 9 can range from 500nm to 2500nm.

[0114] Channel 8 serves to release the sacrificial layer during the fabrication process. After release, the sacrificial layer is completely filled and sealed by the infrared window layer 9 in a vacuum environment, forming a vacuum package. Channel 8 can be circular or rectangular, and its dimensions can range from 0.2 μm to 2 μm. The number and location of channels 8 are not limited in this invention and can be determined based on the specific circumstances.

[0115] It should be noted that the present invention does not limit the number of pixels vacuum-encapsulated by the capping structure. Two different methods are described below.

[0116] First way:

[0117] like Figure 1 As shown, the capping structure individually encapsulates each pixel, that is, each pixel is independently sealed and wrapped by a capping structure to achieve vacuum packaging.

[0118] The microbridge structure 5 includes a bridge deck 51, bridge legs 52 and bridge piers 53. The microbridge structure 5 is connected to the metal block 2 through an opening on the insulating dielectric layer 3, thereby achieving electrical connection with the readout circuit in the substrate. The microbridge structure 5 is wrapped by a capping structure to achieve vacuum packaging.

[0119] The pixels in two rows and two columns can be considered as a pixel group, such as Figure 2 As shown, the pixels in three rows and two columns or two rows and three columns are regarded as a pixel group. Each pixel in the pixel group is individually packaged at the pixel level and has a complete and independent microbridge structure 5 and capping structure. Moreover, the microbridge structure 5 of each pixel is consistent, and only the transmission axis angle of the nanowire grid structure in the capping structure is different. For example, the commonly used transmission axis angles are 0°, 45°, 90° and 135°.

[0120] In a pixel group, the sidewalls of the capping structure of each pixel block the light propagation between adjacent pixels, which can reduce the optical crosstalk between adjacent pixels in the pixel group and effectively improve the polarization detection accuracy.

[0121] In order to improve the infrared light transmittance of the capping structure window, in one embodiment of the present invention, it further includes: an infrared transmittance-enhancing layer 10 , and the infrared transmittance-enhancing layer 10 is located on the upper surface of the infrared window layer 9 .

[0122] The material of the infrared anti-reflection layer 10 includes but is not limited to any one or a combination of zinc sulfide and zinc selenide. The thickness of the infrared anti-reflection layer 10 may be in the range of 500 nm to 2500 nm.

[0123] In addition, when the capping structure encapsulates each pixel individually, the side walls of the capping structure around each pixel can reduce the optical crosstalk between adjacent pixels, ensuring that the signals detected by each polarization pixel are independent of each other. This not only solves the problem of the polarization detector's extinction ratio deteriorating due to optical crosstalk, but also provides conditions for achieving more comprehensive and accurate thermal detection and polarization detection functions.

[0124] Second way:

[0125] like Figure 3 As shown, a plurality of pixels form a pixel group, and the capping structure vacuum-encapsulates each pixel group, and the number of pixels included in the pixel group is an integer multiple of four or six. That is, all pixels in each pixel group share a capping structure to seal and encapsulate the pixel group to achieve vacuum encapsulation.

[0126] The number of pixels in a pixel group is an integer multiple of four or six. It should be noted that a pixel group can include all pixels in the pixel array, meaning that all pixels in the pixel structure share a common capping structure. The capping structure corresponding to each pixel in the pixel group differs only in its polarization structure.

[0127] In the first approach, each pixel has an independent capping structure, which occupies a certain amount of space. Therefore, the actual size of the pixel structure of the pixel-level packaged uncooled infrared polarization detector is larger than the size of the thermally isolated microbridge structure 5. Compared with the first approach, the second approach uses a shared capping structure, which keeps the actual size of the pixel structure of the pixel-level packaged uncooled infrared polarization detector consistent with the size of the thermally isolated microbridge structure 5. This minimizes the impact of the pixel-level package capping structure on pixel size and chip area.

[0128] Please refer to Figure 3The pixel includes a substrate 1 and a microbridge structure 5, the microbridge structure 5 includes a bridge pier 53, a bridge deck 51 and a bridge leg 52, the bridge pier 53 includes a first support body 17, a microbridge support layer 54 and a metal electrode layer 55; the first support body 17 is located on the upper surface of the substrate 1, the microbridge support layer 54 is located above the first support body 17 and on the side of the first support body 17, the metal electrode layer 55 is located above the microbridge support layer 54 and is electrically connected to the first support body 17.

[0129] The first support body 17 passes through the microbridge support layer 54 and the insulating dielectric layer 3, and is connected to the metal block 2 on the substrate 1, that is, the first support body 17 is located on the upper surface of the metal block 2 on the substrate 1, and the top of the first support body 17 is connected to the metal electrode layer 55, thereby realizing the electrical connection between the microbridge structure 5 and the readout circuit in the substrate 1, and realizing the mechanical support of the substrate 1 for the microbridge structure 5.

[0130] The material of the microbridge support layer 54 includes but is not limited to any one of silicon nitride, silicon oxide and silicon oxynitride. The material of the metal electrode layer 55 includes but is not limited to any one of titanium, aluminum, copper, gold, vanadium, titanium nitride, nickel-chromium alloy and titanium-aluminum alloy. The material of the first support body 17 can be a conductive metal material such as tungsten, copper, aluminum, gold, titanium and titanium nitride. The shape of the first support body 17 can be cylindrical, and the diameter of the first support body 17 can be 0.5μm~2.5μm, and the height can be 1.0μm~2.5μm.

[0131] As an implementation method, the present invention may further include: a passivation protection layer 56 , wherein the passivation protection layer 56 is located on the upper surface of the metal electrode layer 55 .

[0132] The passivation protection layer 56 can protect the metal electrode layer 55 from being oxidized or corroded, thereby ensuring the reliability of the electrical connection of the microbridge structure 5. The material of the passivation protection layer 56 can be any one of silicon nitride, silicon oxide and silicon oxynitride.

[0133] When the capping structure vacuum-encapsulates each pixel group, in addition to the capping support layer 6, the micro-polarizer structure layer 7, the infrared window layer 9 and the channel 8, the capping structure also includes a second support body 18, which is located on the upper surface of the bridge pier in the micro-bridge structure 5 in the pixel.

[0134] like Figure 3 As shown, the second support body 18 is located above the first support body 17, and the top of the second support body 18 is connected to the capping support layer 6 to provide mechanical support for the shared capping structure. The capping support layer 6 at the edge of the shared capping structure is connected to the edge substrate 1 of the pixel group to provide mechanical support and vacuum sealing for the shared capping structure.

[0135] The material of the second support body 18 can be a conductive metal material such as tungsten, copper, aluminum, gold, titanium and titanium nitride, or a mechanical support material such as amorphous silicon, silicon nitride, silicon oxide and silicon oxynitride, all of which are within the protection scope of the present invention.

[0136] It should be noted that when the material of the second support 18 is a conductive metal material, a passivation protection layer 56 is present between the upper surface of the metal electrode layer 55 and the second support 18 .

[0137] The second support 18 may be cylindrical in shape, with a diameter of 0.5 μm to 2.0 μm and a height of 0.5 μm to 2.5 μm, or may be set to other sizes as needed.

[0138] In order to improve the infrared light transmittance of the capping structure window, in one embodiment of the present invention, it further includes: an infrared transmittance-enhancing layer 10 , and the infrared transmittance-enhancing layer 10 is located on the upper surface of the infrared window layer 9 .

[0139] The material of the infrared anti-reflection layer 10 includes but is not limited to any one or a combination of zinc sulfide and zinc selenide. The thickness of the infrared anti-reflection layer 10 may be in the range of 500 nm to 2500 nm.

[0140] In this embodiment, the pixel structure comprises a pixel array and a capping structure. The capping structure vacuum-encapsulates the pixels in the pixel array. This means that the present invention utilizes pixel-level packaging, avoiding the complex and expensive conventional vacuum packaging process, improving packaging efficiency, and reducing packaging costs. The capping structure includes a capping support layer 6, a micro-polarizer structure layer 7, and an infrared window layer 9. The integration of a nanowire grid structure within the capping structure reduces the volume and weight of the pixel structure, thereby reducing the volume and weight of an uncooled infrared polarization detector, resulting in a miniaturized and lightweight device.

[0141] Based on the above embodiment, in one embodiment of the present invention, when the capping structure encapsulates each pixel separately, the pixel structure of the uncooled infrared polarization detector may further include:

[0142] The first optical blocking layer 11 is located in the gap between the capping structures corresponding to adjacent pixels; or, the first optical blocking layer 11 is located between the capping support layer 6 and the micro-polarizer structure layer 7, and is located on the side wall of the capping support layer 6.

[0143] The first optical barrier layer 11 can be made of any one or any combination of materials with high infrared light absorptivity, such as gold black, carbon nanotubes, silicon nitride, titanium, and titanium nitride. It can also be made of any one or any combination of materials with high infrared light reflectivity, such as gold, silver, copper, aluminum, and tungsten. The thickness of the first optical barrier layer 11 can range from 25 nm to 1000 nm.

[0144] The first optical blocking layer 11 can completely eliminate the optical crosstalk between adjacent pixels, effectively improving the extinction ratio of the polarization detector, thereby obtaining higher polarization detection accuracy.

[0145] When the capping structure encapsulates each pixel individually, there is a groove-shaped gap between the capping structures of adjacent pixels. The first optical barrier layer 11 can be disposed in the gap between the capping structures corresponding to the adjacent pixels, such as Figure 4 and Figure 5 shown.

[0146] The first optical barrier layer 11 can also be arranged in a capping structure, such as Figure 6 As shown, the manufacturing process of the first optical barrier layer 11 is before vacuum packaging, which can improve the process integration.

[0147] It should be noted that when the first optical barrier layer 11 is located between the capping support layer 6 and the micro-polarizer structure layer 7, a small portion of the first optical barrier layer 11 will remain on the upper surface of the capping support layer 6 between adjacent pixels due to the need for alignment margin. Figure 6 shown.

[0148] A first optical barrier layer 11 covers the sidewalls of the capping structure. The first optical barrier layer 11 is absent from the center of the pixel, preventing external infrared light from entering the thermally isolated microbridge structure 5. Above the first optical barrier layer 11 are, in order, the micropolarizer structure layer 7, the channel 8, the infrared window layer 9, and the infrared anti-reflection layer 10. These layers, which are consistent with those of the previous embodiment, are located.

[0149] Based on the above embodiment, in one embodiment of the present invention, when the capping structure vacuum-encapsulates each pixel group, the pixel structure of the uncooled infrared polarization detector further includes:

[0150] The second optical barrier layer is located around each pixel and between the substrate 1 of the pixel and the capping support layer 6 .

[0151] The second optical barrier layer can be made of any one or any combination of materials with high infrared light absorptivity, such as gold black, carbon nanotubes, silicon nitride, titanium, and titanium nitride. It can also be made of any one or any combination of materials with high infrared light reflectivity, such as gold, silver, copper, aluminum, and tungsten. The width of the second optical barrier layer can range from 0.5 μm to 2.0 μm, and the height can range from 1.0 μm to 5.0 μm. The length is determined by the actual pixel size and is not limited in the present invention.

[0152] The second optical blocking layer is located between two adjacent micro-bridge structures 5 and does not contact the bridge deck 51 , bridge legs 52 and bridge piers 53 of the micro-bridge structure 5 , thereby ensuring thermal and electrical insulation.

[0153] The second optical blocking layer can effectively eliminate optical crosstalk between adjacent pixels and effectively improve the extinction ratio of the polarization detector, thereby obtaining higher polarization detection accuracy.

[0154] The second optical barrier layer includes a first optical barrier unit layer 121 and a second optical barrier unit layer 122, which are perpendicular to each other. The first optical barrier unit layer 121 and the second optical barrier unit layer 122 are formed separately during production. The first optical barrier unit layer 121 is formed together with the first support 17, and the second optical barrier unit layer 122 is formed together with the second support 18. The second optical barrier layer can form a self-supporting structure similar to the bridge pier 53, effectively enhancing the mechanical support of the shared capping structure.

[0155] In any of the above embodiments, each capping structure vacuum-encapsulates each pixel individually, or the capping structure vacuum-encapsulates a group of pixels. The micro-polarizer structure layer 7 has a variety of different configurations, which are described below.

[0156] Example 1

[0157] Please refer to Figure 7 , four pixels distributed in two rows and two columns form a pixel set; in each of the pixel sets, one pixel corresponds to no micro-polarizer structure layer 7, and the micro-polarizer structure layers 7 corresponding to the other three pixels have the nanowire grid structure, and the transmission axis angles of the respective nanowire grid structures are different.

[0158] The pixel set in this embodiment can simultaneously realize thermal signal detection and linear polarization signal (S0, S1, S2) detection.

[0159] For the pixel without the micro-polarizer structure layer 7 above, the incident infrared light from the outside can directly pass through the infrared window layer 9 to irradiate the thermally isolated micro-bridge structure 5, thereby obtaining a complete thermal detection signal. The corresponding capping structures above the other three pixels in the pixel set have nanowire grid structures with different light transmission axis angles. Based on the pixel signals of these three nanowire grid structures corresponding to different light transmission axis angles, the linear polarization detection information (S0, S1, S2) can be calculated.

[0160] The present invention does not limit the transmission axis angles of the capping structures corresponding to the other three pixels in the pixel set. The specific angles can be selected based on the Stokes parameter calculation formula. For example, the three different transmission axis angles can be 0°, 45°, and 90°, or 0°, 60°, and 120°.

[0161] Since the side walls of the capping structure and the optical blocking structure eliminate the optical crosstalk between adjacent pixels, the detection signal of each pixel in the pixel set is an independent and accurate signal, and the introduction of the thermal detection pixel will not affect the extinction ratio of the other three polarization detection pixels.

[0162] Example 2

[0163] Please refer to Figure 8 , four pixels distributed in two rows and two columns form a pixel set; in each of the pixel sets, the micro-polarizer structure layer 7 corresponding to one pixel does not have the nanowire grid structure, and the micro-polarizer structure layer 7 corresponding to the other three pixels has the nanowire grid structure, and the transmission axis angles of each nanowire grid structure are different.

[0164] The pixel set in this embodiment can simultaneously detect the reference signal and the linear polarization signal (S0, S1, S2).

[0165] Micropolarizer structure layer 7 lacks a nanowire grid structure—that is, it's not patterned. Therefore, incident infrared light cannot pass through infrared window layer 9 and reach the thermally isolated microbridge structure 5 of this pixel, thereby generating a reference signal. The capping structures corresponding to the other three pixels in the pixel set have nanowire grid structures with different transmission axis angles. Based on the pixel signals corresponding to these three nanowire grid structures with different transmission axis angles, linear polarization detection signals (S0, S1, and S2) can be calculated.

[0166] The detection signal of the uncooled infrared detector pixel is closely related to the ambient temperature, so the polarization detection signal calculated by the thermal detection signal is also easily affected by the ambient temperature. If you want to obtain accurate thermal detection signals and polarization detection signals, the uncooled infrared detector must require strict ambient temperature control. The reference pixel (the pixel whose corresponding micro-polarizer structure layer 7 does not have a nanowire grid structure) completely shields the incident external infrared light, and the presence of the side walls of the capping structure and the optical blocking structure eliminates the optical crosstalk of adjacent pixels. Therefore, the obtained reference signal can accurately characterize the impact of the ambient temperature on the detection signal. Therefore, the polarization detection pixel can obtain a more sensitive and accurate polarization detection signal through the signal feedback of the reference signal, especially when the polarization detection signal response is extremely small (when the polarization angle of the incident light is perpendicular to the transmission axis).

[0167] Example 3

[0168] Please refer to Figure 9, four pixels distributed in two rows and two columns form a pixel set; in each of the pixel sets, the micro-polarizer structure layer 7 corresponding to one pixel has a circular polarization nanowire grid structure, and the micro-polarizer structure layer 7 corresponding to the other three pixels has a linear polarization nanowire grid structure, and the transmission axis angles of each linear polarization nanowire grid structure are different.

[0169] The pixel set in this embodiment can detect full polarization detection signals (S0, S1, S2, S3).

[0170] In this embodiment, the specific type of the circular polarization nanowire grid structure is not limited and can be set at will. For example, the circular polarization nanowire grid structure can be a spiral grating structure, such as Figure 9 As shown, it is either a metasurface polarization detection structure or a linear grating structure combined with a 1 / 4 wavelength material. The metasurface polarization detection structure and the linear grating structure combined with a 1 / 4 wavelength material can be specifically referred to in related technologies and will not be described in detail in this embodiment.

[0171] The incident infrared light from the outside passes through the infrared window layer 9, is modulated by the micro-polarizer structure layer 7, and then irradiates the thermally isolated micro-bridge structure 5, thereby obtaining a circularly polarized detection signal (I l or I r ), the corresponding capping structures above the remaining pixels in the pixel set have linear polarization detection wire grid structures with different transmission axis angles. The linear polarization detection wire grid structure can be a traditional linear wire grid structure. The linear polarization detection signal (S0, S1, S2) can be calculated based on the pixel signals corresponding to the linear polarization nanowire grid structures with different transmission axis angles, and the full Stokes parameters (S0, S1, S2, S3) of the incident light can be further calculated. The specific solution process is well known to those skilled in the art and will not be repeated here.

[0172] Example 4

[0173] Please refer to Figure 10 , six pixels distributed in three rows and two columns or two rows and three columns form a pixel set; in each of the pixel sets, the micro-polarizer structure layer 7 corresponding to one or two pixels has a circular polarization nanowire grid structure, and the micro-polarizer structure layer 7 corresponding to the remaining pixels has a linear polarization nanowire grid structure, and the transmission axis angles of each of the linear nanowire grid structures are different.

[0174] The difference between Example 4 and Example 3 is that the number of pixels having the circularly polarized nanowire grid structure is two. The rest is the same as Example 3 and will not be described in detail here.

[0175] Example 5

[0176] Four picture elements distributed in two rows and two columns form a picture element set; in each picture element set, the micro-polarizer structure layer 7 corresponding to each picture element has the nanowire grid structure, and the light transmission axis angles of the nanowire grid structures are different.

[0177] The transmission axis angles of the nanowire grid structures can be set according to actual conditions and are not limited in the present invention. For example, the transmission axis angles of the nanowire grid structures corresponding to the four pixels in a pixel set can be 0°, 45°, 90°, and 135°, respectively.

[0178] In summary, the pixel structure of the present invention has the following advantages:

[0179] First, compared with the pixel structure of traditional pixel-level packaging:

[0180] (1) The present invention integrates a polarization detection structure into the capping structure used in pixel-level packaging, which can simultaneously measure the intensity information and polarization information of space targets, effectively improve the contrast between the target and the background, highlight the detailed features of the target, and enhance the target recognition effect in low thermal contrast application scenarios;

[0181] (2) The capping structure proposed in the present invention can be an independent capping structure or a shared capping structure. The former has lower difficulty in sealing the pixel vacuum packaging, lower probability of pixel failure, and less impact of pixel failure. The latter has lower pixel size by further reducing the pixel vacuum packaging.

[0182] Second, compared with the traditional focal plane uncooled infrared polarization detection:

[0183] (1) The present invention adopts pixel-level packaging, eliminating the subsequent complicated and tedious vacuum packaging process of traditional uncooled infrared detectors. The entire preparation process has a high degree of integration, which greatly improves the detector packaging efficiency and reduces the packaging cost, device volume and weight;

[0184] (2) The present invention integrates an optical blocking layer between each pixel, eliminating optical crosstalk between adjacent pixels, significantly improving the extinction ratio of the polarization detection pixel, and effectively improving the polarization detection accuracy; in addition, the materials and processes used in the optical blocking layer are compatible with the materials and processes used in the manufacture of pixel-level packaged uncooled infrared polarization detector pixels, and the process integration is high;

[0185] (3) The pixel structure proposed in the present invention can realize more comprehensive and accurate thermal detection and polarization detection functions, and is more flexible in practical applications.

[0186] The present invention also provides a method for manufacturing a pixel structure of an uncooled infrared polarization detector, the method comprising:

[0187] Preparing a pixel array; the pixel array includes a plurality of pixels;

[0188] A capping structure is fabricated above the picture element, and the picture element is vacuum-encapsulated by the capping structure; wherein the capping structure comprises a capping support layer 6, a micro-polarizer structure layer 7, an infrared window layer 9 and a channel 8; the capping support layer 6 is connected to the picture element, and the micro-polarizer structure layer 7 and the infrared window layer 9 are sequentially stacked on the upper surface of the capping support layer 6; the channel 8 passes through the micro-polarizer structure layer 7 and the capping support layer 6, and the infrared window layer 9 fills the channel 8; the micro-polarizer structure layer 7 has a nanowire grid structure.

[0189] When the capping structure encapsulates each pixel individually, the capping support layer directly contacts the insulating medium layer 3 on the substrate 1; when the capping structure vacuum encapsulates each pixel group, the capping support layer contacts the insulating medium layer 3 on the substrate 1 and the second support body 18.

[0190] The following introduces the production method based on the different vacuum packaging forms of the pixel according to the cap structure.

[0191] When the capping structure encapsulates each pixel individually, the method for manufacturing the pixel structure of the uncooled infrared polarization detector includes:

[0192] Step S101 : preparing a substrate 1 ; the substrate 1 includes a substrate, a metal block 2 , a getter layer 4 and an insulating dielectric layer 3 .

[0193] Step S1011: prepare a substrate including a readout circuit, and a metal block 2 and an insulating dielectric layer 3 are formed on the substrate, such as Figure 11 As shown;

[0194] Step S1012: remove the insulating dielectric layer 3 at the center of the pixel and deposit a getter layer 4, such as Figure 12 As shown;

[0195] Step S1013: remove the getter layer 4 outside the pixel center position, such as Figure 13 As shown;

[0196] Step S102 : depositing a first sacrificial layer 13 on the substrate 1 , and etching the first sacrificial layer 13 , wherein the etched area corresponds to the metal block 2 .

[0197] Please refer to Figure 14 , etching penetrates the first sacrificial layer 13 and the insulating dielectric layer 3 , and terminates the upper surface of the metal block 2 .

[0198] The material of the first sacrificial layer 13 may be one of polyimide, polycrystalline carbon and polycrystalline silicon, and the thickness may be 1 μm to 2.5 μm.

[0199] Step S103 : manufacturing a microbridge structure 5 on the first sacrificial layer 13 , wherein the bridge pier 53 of the microbridge structure 5 penetrates the first sacrificial layer 13 and the insulating dielectric layer 3 , and is connected to the metal block 2 .

[0200] Please refer to Figure 14 The bridge pier 53 penetrates the first sacrificial layer 13 and the insulating dielectric layer 3 and terminates at the metal block 2, thereby achieving electrical connection between the microbridge structure 5 and the readout circuit.

[0201] Step S104 : depositing a second sacrificial layer 14 on the pixel array having the first sacrificial layer 13 , and etching the first sacrificial layer 13 and the second sacrificial layer 14 between adjacent pixels to expose the insulating dielectric layer 3 .

[0202] Please refer to Figure 15 The second sacrificial layer 14 is stacked on the upper surface of the first sacrificial layer 13, and the first sacrificial layer 13 and the second sacrificial layer 14 between adjacent pixels are etched so that when the capping structure is subsequently manufactured, each capping structure can vacuum encapsulate one pixel.

[0203] The material of the second sacrificial layer 14 may be polyimide, polysilicon, or polycrystalline carbon, and the thickness may be 0.5 μm to 3 μm.

[0204] Step S105 : depositing a capping support layer, wherein the capping support layer contacts the insulating dielectric layer 3 .

[0205] Please refer to Figure 15 The capping support layer 6 is located on the upper surface of the second sacrificial layer 14, the side surfaces of the first sacrificial layer 13 and the second sacrificial layer 14, and the upper surface of the insulating dielectric layer 3 between adjacent pixels to achieve mechanical support of the capping structure.

[0206] Step S106 : depositing a micro-polarizer structure layer 7 on the capping support layer 6 , and etching the micro-polarizer structure layer 7 to form a nanowire grid structure.

[0207] Please refer to Figure 16 The micro-polarizer structure layer 7 is located on the upper surface of the capping support layer 6, and the corresponding area of ​​each pixel is patterned.

[0208] Step S107 : etching the capping support layer 6 and the micro-polarizer structure layer 7 to form the channel 8 , and releasing the first sacrificial layer 13 and the second sacrificial layer 14 through the channel 8 .

[0209] Please refer to Figure 17 The channel 8 passes through the capping support layer 6 and the micro-polarizer structure layer 7 and ends at the second sacrificial layer 14 .

[0210] In this step, the first sacrificial layer 13 and the second sacrificial layer 14 can be removed by oxygen plasma cleaning, thereby obtaining a suspended thermally isolated microbridge structure 5 and a capping structure.

[0211] Step S108: under vacuum conditions, depositing an infrared window layer 9 on the surface of the micro-polarizer structure layer 7 , wherein the infrared window layer 9 completely fills the channel 8 to form a capping structure.

[0212] Please refer to Figure 1 The infrared window layer 9 is located on the upper surface of the micro-polarizer structure layer 7 and completely fills and seals the through hole.

[0213] It should be noted that after the capping structure is formed, the getter layer 4 needs to be activated to maintain the vacuum level in the vacuum chamber formed by the capping structure. The getter layer 4 can be activated by high-temperature annealing.

[0214] In order to improve the infrared light transmittance of the capping structure window, after forming the capping structure, the following steps may be further included:

[0215] An infrared anti-reflection layer 10 is deposited on the upper surface of the infrared window layer 9, such as Figure 1 shown.

[0216] When the capping structure encapsulates each pixel individually, in order to eliminate optical crosstalk between adjacent pixels, the manufacturing method of the pixel structure may further include preparing a first optical barrier layer 11. There are two ways to manufacture the first optical barrier layer 11, which are introduced below.

[0217] The first type: After forming the cap structure, it also includes:

[0218] A first optical barrier layer 11 is formed in the gaps between the capping structures corresponding to adjacent picture elements.

[0219] The process includes: spin coating photoresist on the pixel structure and performing patterning, then depositing optical blocking material to cover the gap between the capping structures of adjacent pixels; removing the photoresist, and the optical blocking layer material on the photoresist is also removed. Figure 4 As shown, a pixel-level packaged uncooled infrared polarization detector pixel structure with an integrated first optical barrier layer 11 is obtained.

[0220] The second method: after depositing the capping support layer on the second sacrificial layer 14, the method further includes:

[0221] A first optical barrier layer 11 is deposited on the capping support layer, and the first optical barrier layer 11 is etched to retain the first optical barrier layer 11 located on the sidewall of the capping support layer.

[0222] Please refer to Figures 18 and 19After the above step S105, the first optical barrier layer 11 is deposited, and then the first optical barrier layer 11 is patterned to remove the first optical barrier layer 11 at the center of the pixel to obtain an optical barrier layer structure. The subsequent production process refers to the above steps S106 to S108, and the following is obtained: Figure 6 The structure shown.

[0223] When the capping structure vacuum-encapsulates each pixel group, the method for manufacturing the pixel structure of the uncooled infrared polarization detector includes:

[0224] Step S201 : preparing a substrate 1 ; the substrate 1 includes a substrate, a metal block 2 , a getter layer 4 and an insulating dielectric layer 3 .

[0225] Please refer to the above step S101 for this step, which will not be described in detail here.

[0226] Step S202 : etching the insulating dielectric layer 3 on the metal block 2 to form an opening to expose the metal block 2 .

[0227] Please refer to Figure 20 , the local insulating dielectric layer 3 on the metal block 2 is etched.

[0228] Step S203 : depositing a first sacrificial layer 13 and a first hard mask layer 15 in sequence on the substrate 1 .

[0229] Please refer to Figure 20 The first sacrificial layer 13 is located on the upper surface of the substrate 1 , and the first hard mask layer 15 is located on the upper surface of the first sacrificial layer 13 .

[0230] The first sacrificial layer 13 may be made of polyimide, polycrystalline carbon, and polycrystalline silicon, and may have a thickness of 1 μm to 2.5 μm. The first hard mask layer 15 may be made of silicon nitride, silicon oxide, silicon oxynitride, titanium, and titanium nitride.

[0231] Step S204 : etching the first hard mask layer 15 and the first sacrificial layer 13 to form a first through hole 19 ; the first through hole 19 corresponds to the opening.

[0232] Please refer to Figure 21 , the first hard mask layer 15 is patterned, and then the first sacrificial layer 13 is etched to obtain a first through hole 19 with a high aspect ratio. The first through hole 19 passes through the first sacrificial layer 13 and coincides with the opening position on the insulating dielectric layer 3 in step S202, and ends at the metal block 2.

[0233] Step S205 : filling the first through hole 19 with a filling material to form a first support body 17 .

[0234] Please refer to Figures 22 to 23First, a hole-filling material is deposited to fill the first through hole 19 and cover the first hard mask layer 15. Then, excess hole-filling material on the plane of the first sacrificial layer 13 is removed by chemical mechanical polishing (CMP) and etch back. Then, the first hard mask layer 15 is etched away to form a first support body 17.

[0235] The hole filling material in this step can be a conductive metal material such as tungsten, copper, aluminum, gold, titanium and titanium nitride.

[0236] Step S206: A microbridge structure 5 is fabricated on the first sacrificial layer 13; the microbridge structure 5 includes a bridge pier 53, and the bridge pier 53 includes the first support body 17, a microbridge support layer 54 and a metal electrode layer 55. The microbridge support layer 54 is located above the first support body 17 and on the side of the first support body 17. The metal electrode layer 55 is located above the microbridge support layer 54 and is electrically connected to the first support body 17.

[0237] Please refer to Figure 24 A thermally isolated microbridge structure 5 is formed above the first sacrificial layer 13. The pier 53 of the microbridge structure 5 is composed of a first support body 17 and a microbridge support layer 54 and a metal electrode layer 55 deposited above the first support body 17. The microbridge support layer 54 is patterned after deposition, so that the metal electrode layer 55 and the first support body 17 are electrically connected.

[0238] The bridge pier 53 further includes a passivation protection layer 56 located on the metal electrode to prevent the metal electrode layer 55 from being oxidized or corroded during subsequent manufacturing processes.

[0239] Step S207 : sequentially depositing a second sacrificial layer 14 and a second hard mask layer 16 on the pixel array having the first sacrificial layer 13 .

[0240] The material of the second sacrificial layer 14 may be one of polyimide, polycrystalline carbon, and polycrystalline silicon. The material of the second hard mask layer 16 may be one of silicon nitride, silicon oxide, silicon oxynitride, and titanium nitride.

[0241] Step S208 : etching the second hard mask layer 16 and the second sacrificial layer 14 to form a second through hole 20 ; the second through hole 20 corresponds to the first through hole 19 .

[0242] Please refer to Figure 25 The second sacrificial layer 14 and the second hard mask layer 16 are sequentially stacked on the pixel array. The second hard mask layer 16 is first patterned, and then the second sacrificial layer 14 is etched to obtain a second through hole 20 with a high aspect ratio. The second through hole 20 terminates at the passivation protection layer 56.

[0243] Step S209 : filling the second through hole 20 with a filling material to form a second support body 18 .

[0244] Please refer to Figure 26 The second through hole 20 is filled with a filling material and covers the second hard mask layer 16. Then, the excess filling material on the plane of the second sacrificial layer 14 is removed by chemical mechanical polishing and back etching, and the second hard mask layer 16 is etched away to form a second support body 18.

[0245] The hole filling material in this step can be a conductive metal material such as tungsten, copper, aluminum, gold, titanium and titanium nitride, or a mechanical support material such as amorphous silicon, silicon nitride, silicon oxide and silicon oxynitride.

[0246] Step S210 : etching the first sacrificial layer 13 and the second sacrificial layer 14 between adjacent pixel groups to expose the insulating dielectric layer 3 .

[0247] Please refer to Figure 27 In this step, the first sacrificial layer 13 and the second sacrificial layer 14 between adjacent pixel groups are etched so that when a capping structure is subsequently manufactured, each capping structure can perform vacuum packaging on one pixel group.

[0248] Step S211 : depositing a capping support layer 6 and a micro-polarizer structure layer 7 in sequence, and etching the micro-polarizer structure layer 7 to form a nanowire grid structure.

[0249] Step S212 : etching the capping support layer 6 and the micro-polarizer structure layer 7 to form the channel 8 , and releasing the first sacrificial layer 13 and the second sacrificial layer 14 through the channel 8 .

[0250] Please refer to Figure 27 The capping support layer 6 and the micro-polarizer structure layer 7 are patterned to produce a channel 8. The channel 8 passes through the capping support layer 6 and the micro-polarizer structure layer 7 and terminates at the second sacrificial layer 14. The first sacrificial layer 13 and the second sacrificial layer 14 are then removed by oxygen plasma cleaning, thereby obtaining a suspended thermally isolated microbridge structure 5 and a shared capping structure.

[0251] Step S213: under vacuum conditions, depositing an infrared window layer 9 on the surface of the micro-polarizer structure layer 7 , wherein the infrared window layer 9 completely fills the channel 8 to form a capping structure.

[0252] Please refer to Figure 3 , an infrared window layer 9 is deposited under ultra-high vacuum conditions, and the infrared window layer 9 completely fills and seals the channel 8 , thereby achieving vacuum packaging of the thermally isolated microbridge structure 5 .

[0253] It should be noted that after the capping structure is formed, the getter layer 4 needs to be activated to maintain the vacuum level in the vacuum chamber formed by the capping structure. The getter layer 4 can be activated by high-temperature annealing.

[0254] In order to improve the infrared light transmittance of the capping structure window, after forming the capping structure, the following steps may be further included:

[0255] An infrared anti-reflection layer 10 is deposited on the upper surface of the infrared window layer 9, such as Figure 3 shown.

[0256] When the capping structure encapsulates each pixel group, in order to eliminate optical crosstalk between adjacent pixels, the method for manufacturing the pixel structure may further include preparing a second optical barrier layer. When preparing the second optical barrier layer in the pixel structure, the second optical barrier layer includes a first optical barrier unit layer 121 and a second optical barrier unit layer 122 that are vertically corresponding.

[0257] Based on the above embodiment, in one embodiment of the present invention, the preparation process of the second optical barrier layer includes:

[0258] After sequentially depositing the first sacrificial layer 13 and the first hard mask layer 15 on the substrate 1, the method further includes:

[0259] etching the first hard mask layer 15 and the first sacrificial layer 13 to form a third through hole;

[0260] Filling the third through hole with a filling material to form a first optical blocking unit layer 121;

[0261] After sequentially depositing a second sacrificial layer 14 and a second hard mask layer 16 on the pixel array having the first sacrificial layer 13, the method further includes:

[0262] etching the second hard mask layer 16 and the second sacrificial layer 14 to form a fourth through hole, wherein the fourth through hole corresponds to the third through hole;

[0263] The fourth through hole is filled with a hole-filling material to form a second optical blocking unit layer 122 .

[0264] The first optical blocking unit layer 121 and the first support 17 can be manufactured together. That is, during the above steps S201 to S213, the top view of the substrate 1 in step S201 is as shown in FIG. Figure 28 As shown, when the first support 17 is formed in steps S204 and S205, a third through hole is formed by etching at the same time, and a hole-filling material is filled in the third through hole to form a first optical blocking unit layer 121, and the top view after the micro-bridge structure 5 is completed is shown in FIG. Figure 29As shown; in steps S208 and S209, when the second support 18 is formed, a fourth through hole is formed by etching at the same time, and a filling material is filled into the fourth through hole to form a second optical blocking unit layer 122. Further, after forming the micro-polarizer structure layer 7, a top view is shown. Figure 30 As shown, the other processes are the same as the steps in the above embodiment and will not be repeated here.

[0265] The present invention further provides an uncooled infrared polarization detector, comprising the pixel structure of the uncooled infrared polarization detector described in any of the above embodiments.

[0266] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0267] The above describes in detail the pixel structure and its manufacturing method, as well as the uncooled infrared polarization detector provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to help understand the scheme and core concept of the present invention. It should be noted that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A pixel structure of an uncooled infrared polarization detector, characterized in that: include: A pixel array and a capping structure, wherein the pixel array includes a plurality of pixels, and the capping structure is located above the pixels and vacuum-seales the pixels; The pixel comprises a substrate (1) and a microbridge structure (5), wherein the microbridge structure (5) comprises a bridge deck (51), bridge legs (52) and bridge piers (53); the substrate (1) comprises a substrate containing a readout circuit, a metal block (2), a getter layer (4) and an insulating dielectric layer (3); the metal block (2), the insulating dielectric layer (3) and the getter layer (4) are located on the substrate, the insulating dielectric layer (3) partially covers the metal block (2), and an opening is provided on the insulating dielectric layer (3) to expose a part of the upper surface of the metal block (2); the sidewall of the capping structure has the function of reducing optical crosstalk between adjacent pixels; The capping structure comprises a capping support layer (6), a micro-polarizer structure layer (7), an infrared window layer (9) and a channel (8); the capping support layer (6) is connected to the pixel, and the micro-polarizer structure layer (7) and the infrared window layer (9) are sequentially stacked on the upper surface of the capping support layer (6); the channel (8) passes through the micro-polarizer structure layer (7) and the capping support layer (6), and the infrared window layer (9) fills the channel (8); the micro-polarizer structure layer (7) has a nanowire grid structure.

2. The pixel structure of the uncooled infrared polarization detector according to claim 1, characterized in that: The capping structure encapsulates each of the picture elements individually.

3. The pixel structure of the uncooled infrared polarization detector according to claim 2, characterized in that: Also includes: A first optical barrier layer (11), the first optical barrier layer (11) is located in the gap between the capping structures corresponding to adjacent pixels; or The first optical blocking layer (11) is located between the capping support layer (6) and the micro-polarizer structure layer (7), and is located on the side wall of the capping support layer (6).

4. The pixel structure of the uncooled infrared polarization detector according to claim 1, wherein: A plurality of picture elements form a picture element group, the capping structure vacuum-encapsulates each picture element group, and the number of picture elements included in the picture element group is an integer multiple of four or six.

5. The pixel structure of the uncooled infrared polarization detector according to claim 4, characterized in that: The bridge pier (53) includes a first support body (17), a microbridge support layer (54) and a metal electrode layer (55); The first support body (17) is located on the upper surface of the substrate (1), the microbridge support layer (54) is located above the first support body (17) and on the side of the first support body (17), and the metal electrode layer (55) is located above the microbridge support layer (54) and is electrically connected to the first support body (17).

6. The pixel structure of the uncooled infrared polarization detector according to claim 5, characterized in that: Also includes: A passivation protective layer (56), the passivation protective layer (56) is located on the upper surface of the metal electrode layer (55).

7. The pixel structure of the uncooled infrared polarization detector according to claim 4, characterized in that: The capping structure further comprises a second support body (18), and the second support body (18) is located on the upper surface of the bridge pier (53) in the microbridge structure (5) in the pixel.

8. The pixel structure of the uncooled infrared polarization detector according to claim 4, characterized in that: Also includes: A second optical barrier layer is located around each pixel and between the pixel base (1) and the capping support layer (6).

9. The pixel structure of the uncooled infrared polarization detector according to claim 1, characterized in that: Also includes: An infrared transmission-enhancing layer (10), the infrared transmission-enhancing layer (10) being located on the upper surface of the infrared window layer (9).

10. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 9, characterized in that: Four picture elements distributed in two rows and two columns form a picture element set; in each picture element set, one picture element corresponds to a micro-polarizer structure layer (7) without the micro-polarizer structure layer (7), while the micro-polarizer structure layers (7) corresponding to the other three picture elements have the nanowire grid structure, and the light transmission axis angles of the respective nanowire grid structures are different.

11. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 9, characterized in that: Four picture elements distributed in two rows and two columns form a picture element set; in each picture element set, the micro-polarizer structure layer (7) corresponding to one picture element does not have the nanowire grid structure, and the micro-polarizer structure layers (7) corresponding to the other three picture elements have the nanowire grid structure, and the light transmission axis angles of the respective nanowire grid structures are different.

12. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 9, characterized in that: Four picture elements distributed in two rows and two columns form a picture element set; in each picture element set, the micro-polarizer structure layer (7) corresponding to one picture element has a circular nanowire grid structure, and the micro-polarizer structure layers (7) corresponding to the other three picture elements have a linear nanowire grid structure, and the light transmission axis angles of the linear nanowire grid structures are different.

13. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 9, characterized in that: Six picture elements distributed in three rows and two columns or two rows and three columns form a picture element set; in each picture element set, the micro-polarizer structure layer (7) corresponding to one or two picture elements has a circular nanowire grid structure, and the micro-polarizer structure layer (7) corresponding to the remaining picture elements has a linear nanowire grid structure, and the light transmission axis angles of the linear nanowire grid structures are different.

14. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 9, characterized in that: Four picture elements distributed in two rows and two columns form a picture element set; in each picture element set, the micro-polarizer structure layer (7) corresponding to each picture element has the nanowire grid structure, and the light transmission axis angles of the respective nanowire grid structures are different.

15. A method for manufacturing a pixel structure of an uncooled infrared polarization detector, characterized in that: include: Preparing a pixel array; the pixel array includes a plurality of pixels; The pixel comprises a substrate (1) and a microbridge structure (5), wherein the microbridge structure (5) comprises a bridge deck (51), bridge legs (52) and bridge piers (53); the substrate (1) comprises a substrate containing a readout circuit, a metal block (2), a getter layer (4) and an insulating dielectric layer (3); the metal block (2), the insulating dielectric layer (3) and the getter layer (4) are located on the substrate, the insulating dielectric layer (3) partially covers the metal block (2), and an opening is provided on the insulating dielectric layer (3) to expose a part of the upper surface of the metal block (2); A capping structure is fabricated above the pixel, and the pixel is vacuum-encapsulated by the capping structure; the sidewall of the capping structure has the function of reducing optical crosstalk between adjacent pixels; The capping structure comprises a capping support layer (6), a micro-polarizer structure layer (7), an infrared window layer (9) and a channel (8); the capping support layer (6) is connected to the pixel, and the micro-polarizer structure layer (7) and the infrared window layer (9) are sequentially stacked on the upper surface of the capping support layer (6); the channel (8) passes through the micro-polarizer structure layer (7) and the capping support layer (6), and the infrared window layer (9) fills the channel (8); the micro-polarizer structure layer (7) has a nanowire grid structure.

16. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 15, wherein: When the capping structure encapsulates each pixel individually, preparing the pixel array includes: Preparing a substrate (1); the substrate (1) includes a substrate, a metal block (2), a getter layer (4) and an insulating dielectric layer (3); Depositing a first sacrificial layer (13) on the substrate (1), and etching the first sacrificial layer (13), wherein the etched area corresponds to the metal block (2); A microbridge structure (5) is fabricated on the first sacrificial layer (13), wherein a bridge pier (53) of the microbridge structure (5) penetrates the first sacrificial layer (13) and the insulating dielectric layer (3), and is connected to the metal block (2).

17. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 16, wherein: Producing a capping structure above the pixel and vacuum-sealing the pixel by the capping structure includes: Depositing a second sacrificial layer (14) on the pixel array having the first sacrificial layer (13), and etching the first sacrificial layer (13) and the second sacrificial layer (14) between adjacent pixels to expose the insulating dielectric layer (3); Depositing a capping support layer (6), wherein the capping support layer (6) is in contact with the insulating dielectric layer (3); Depositing a micro-polarizer structure layer (7) on the capping support layer (6), and etching the micro-polarizer structure layer (7) to form a nanowire grid structure; Etching the capping support layer (6) and the micro-polarizer structure layer (7) to form the channel (8), and releasing the first sacrificial layer (13) and the second sacrificial layer (14) through the channel (8); Under vacuum conditions, an infrared window layer (9) is deposited on the surface of the micro-polarizer structure layer (7), and the infrared window layer (9) completely fills the channel (8) to form a capping structure.

18. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 17, wherein: After forming the cap structure, it also includes: A first optical blocking layer (11) is formed in the gaps between the capping structures corresponding to adjacent picture elements.

19. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 17, wherein: After depositing the capping support layer (6) on the second sacrificial layer (14), the method further comprises: A first optical barrier layer (11) is deposited on the capping support layer (6), and the first optical barrier layer (11) is etched to retain the first optical barrier layer (11) located on the side wall of the capping support layer (6).

20. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 15, wherein: When the capping structure vacuum-encapsulates each pixel group, preparing the pixel array includes: Preparing a substrate (1); the substrate (1) includes a substrate, a metal block (2), a getter layer (4) and an insulating dielectric layer (3); Etching the insulating dielectric layer (3) located on the metal block (2) to form an opening to expose the metal block (2); Depositing a first sacrificial layer (13) and a first hard mask layer (15) in sequence on the substrate (1); Etching the first hard mask layer (15) and the first sacrificial layer (13) to form a first through hole (19); the first through hole (19) corresponds to the opening; Filling the first through hole (19) with a filling material to form a first support body (17); A microbridge structure (5) is fabricated on the first sacrificial layer (13); the microbridge structure (5) includes a bridge pier (53), the bridge pier (53) includes the first support body (17), a microbridge support layer (54) and a metal electrode layer (55), the microbridge support layer (54) is located above the first support body (17) and on the side of the first support body (17), and the metal electrode layer (55) is located above the microbridge support layer (54) and is electrically connected to the first support body (17).

21. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 20, wherein: Producing a capping structure above the pixel and vacuum-sealing the pixel by the capping structure includes: sequentially depositing a second sacrificial layer (14) and a second hard mask layer (16) on the pixel array having the first sacrificial layer (13); Etching the second hard mask layer (16) and the second sacrificial layer (14) to form a second through hole (20); the second through hole (20) corresponds to the first through hole (19); Filling the second through hole (20) with a filling material to form a second support body (18); Etching the first sacrificial layer (13) and the second sacrificial layer (14) between adjacent pixel groups to expose the insulating dielectric layer (3); sequentially depositing a capping support layer (6) and a micro-polarizer structure layer (7), and etching the micro-polarizer structure layer (7) to form a nanowire grid structure; Etching the capping support layer (6) and the micro-polarizer structure layer (7) to form the channel (8), and releasing the first sacrificial layer (13) and the second sacrificial layer (14) through the channel (8); Under vacuum conditions, an infrared window layer (9) is deposited on the surface of the micro-polarizer structure layer (7), and the infrared window layer (9) completely fills the channel (8) to form a capping structure.

22. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 21, wherein: After sequentially depositing a first sacrificial layer (13) and a first hard mask layer (15) on the substrate (1), the method further comprises: Etching the first hard mask layer (15) and the first sacrificial layer (13) to form a third through hole; Filling the third through hole with a filling material to form a first optical blocking unit layer; After sequentially depositing a second sacrificial layer (14) and a second hard mask layer (16) on the pixel array having the first sacrificial layer (13), the method further includes: Etching the second hard mask layer (16) and the second sacrificial layer (14) to form a fourth through hole, the fourth through hole corresponding to the third through hole; The fourth through hole is filled with a hole-filling material to form a second optical blocking unit layer.

23. An uncooled infrared polarization detector, characterized in that: A pixel structure comprising an uncooled infrared polarization detector as described in any one of claims 1 to 14.

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