Pixel structure, manufacturing method thereof and uncooled infrared polarization detector

Abstract

The invention relates to the field of infrared imaging, and discloses a pixel structure and a manufacturing method thereof, and an uncooled infrared polarization detector, and the pixel structure comprises a pixel array, a packaging structure, and an optical isolator. The pixel array comprises a plurality of pixels, and the packaging structure is located above the pixels and packages the pixels; the packaging structure comprises a packaging base body layer and a micro-polaroid structure layer, the packaging base body layer is connected with the pixel, and the micro-polaroid structure layer is located on the upper surface of the packaging base body layer; the micro-polaroid structure layer is provided with a nanowire grid structure; and the optical isolator is positioned between two adjacent pixels. The optical isolator is arranged between the adjacent pixels, so that optical crosstalk between the adjacent pixels can be effectively reduced or even eliminated, the extinction ratio of the polarization detector is effectively improved, and higher polarization detection precision is obtained.

Description

Technical Field

[0001] The 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 the intensity and polarization information of space targets, effectively improving the contrast between the target and the background, highlighting the details of the target, and enhancing the target recognition effect. The focal plane type uncooled infrared polarization detector has the characteristics of high integration and real-time imaging, and has become the focus of attention.

[0003] The polarization detection of the uncooled infrared polarization detector is realized by a focal plane type polarization detection pixel group composed of two adjacent rows and two columns of pixels. The pixel groups are arranged in sequence to form an uncooled infrared polarization detector focal plane array. The thermal insulation microbridges of the pixels in the focal plane array are closely adjacent, and there is a polarization structure corresponding to different transmission axis angles directly above. The polarization structure will perform different polarization modulation on the intensity of incident light with different polarization angles (following Malus's law). Due to reflection and diffraction, the light passing through the polarization structure will inevitably propagate to and be absorbed by adjacent pixels, thereby generating optical crosstalk. This problem will cause the extinction ratio of the detector to decrease, thereby affecting the polarization detection accuracy of the detector.

[0004] Therefore, how to solve the optical crosstalk in the polarization detector should be a technical problem that needs to be solved urgently by 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, which can reduce or even eliminate optical crosstalk between adjacent pixels and improve polarization detection accuracy.

[0006] In order to solve the above technical problems, the present invention provides a pixel structure of an uncooled infrared polarization detector, comprising: a pixel array, a packaging structure and an optical isolator; The pixel array includes a plurality of pixels, and the packaging structure is located above the pixels and packages the pixels; The packaging structure comprises a packaging substrate layer and a micro-polarizer structure layer, wherein the packaging substrate layer is connected to the pixel, and the micro-polarizer structure layer is located on the upper surface of the packaging substrate layer; the micro-polarizer structure layer has a nanowire grid structure; The optical isolator is located between two adjacent picture elements.

[0007] Optionally, a plurality of pixels form a pixel group, the encapsulation structure encapsulates each of the pixel groups, and the number of pixels included in the pixel group is an integer multiple of four or six.

[0008] Optionally, the optical isolator is located around each pixel, and the optical isolator includes a first isolation unit body and a second isolation unit body; The pixel comprises a microbridge structure, the bridge pier of the microbridge structure comprises a microbridge support column, the packaging structure further comprises a packaging support column, the packaging support column is located directly above the microbridge support column and between the upper surface of the bridge pier and the packaging substrate layer; The first isolation unit body is located outside the micro-bridge support column and is flush with the upper surface of the micro-bridge support column; the second isolation unit body is located outside the package support column and is flush with the upper surface of the package support column.

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

[0010] Optionally, the optical isolator is located in the gap between the packaging structures corresponding to adjacent picture elements.

[0011] Optionally, the optical isolator is located between the packaging substrate layer and the micro-polarizer structure layer, and is located on a side wall of the packaging substrate layer.

[0012] Optionally, the packaging structure further includes an infrared window layer, wherein the infrared window layer is located on the upper surface of the micro-polarizer structure layer and in an opening, and the opening runs through the packaging base layer and the micro-polarizer structure layer.

[0013] Optionally, it also includes: an infrared transmittance-enhancing layer, wherein the infrared transmittance-enhancing layer is located on the upper surface of the infrared window layer.

[0014] Optionally, four pixels distributed in two rows and two columns form a pixel set; in each of the pixel sets, 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 light transmission axis angles of each nanowire grid structure are different.

[0015] 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.

[0016] 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 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 of the linear nanowire grid structures are different.

[0017] 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.

[0018] Optionally, four picture elements distributed in two rows and two columns form a picture element set; in each of the picture element sets, the micro-polarizer structure layer corresponding to each picture element has the nanowire grid structure, and the light transmission axis angles of each nanowire grid structure are different.

[0019] The present invention also provides a method for manufacturing a pixel structure of an uncooled infrared polarization detector, comprising: Prepare a pixel array; the pixel array includes a plurality of pixels; Making a packaging structure above the pixel, and packaging the pixel by the packaging structure; Producing an optical isolator between two adjacent picture elements; The packaging structure comprises a packaging substrate layer and a micro-polarizer structure layer, the packaging substrate layer is connected to the picture element, and the micro-polarizer structure layer is located on the upper surface of the packaging substrate layer; the micro-polarizer structure layer has a nanowire grid structure.

[0020] Optionally, when the encapsulation structure encapsulates each pixel group, preparing the pixel array includes: Preparing a substrate; the substrate comprises a substrate, a metal block and an insulating dielectric layer; Etching the insulating dielectric layer on the metal block to form an opening to expose the metal block; sequentially depositing a first sacrificial layer and a first hard mask layer on the substrate; Etching the first hard mask layer and the first sacrificial layer to form a first through hole; the first through hole corresponds to the opening; Filling the first through hole with a filling material to form a microbridge support column; A microbridge structure is fabricated on the first sacrificial layer; the microbridge structure includes a bridge pier, and the bridge pier includes the microbridge support column, a microbridge support layer and a metal electrode layer, the microbridge support layer is located above the microbridge support column and on the side of the microbridge support column, and the metal electrode layer is located above the microbridge support layer and is electrically connected to the microbridge support column.

[0021] Optionally, making an optical isolator between two adjacent picture elements includes: After sequentially depositing a first sacrificial layer and a first hard mask layer on the substrate, etching the first hard mask layer and the first sacrificial layer to form a third through hole; Filling the third through hole with a filling material to form a first isolation unit body; After sequentially depositing a second sacrificial layer and a second hard mask layer on the pixel array having the first sacrificial layer, 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; The fourth through hole is filled with a hole-filling material to form a second isolation unit body.

[0022] Optionally, when the packaging structure packages each pixel individually, making an optical isolator between two adjacent pixels includes: An optical isolator is formed in the gap between the packaging structures corresponding to adjacent picture elements.

[0023] Optionally, when the packaging structure packages each pixel individually, making an optical isolator between two adjacent pixels includes: After the encapsulation base layer is formed, an optical insulator is deposited on the encapsulation base layer, and the optical insulator is etched to retain the optical insulator located on the side wall of the encapsulation base layer.

[0024] Optionally, also include: 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 opening to form a packaging structure.

[0025] 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.

[0026] The present invention provides a pixel structure of an uncooled infrared polarization detector, comprising: a pixel array, a packaging structure and an optical isolator; the pixel array comprises a plurality of pixels, the packaging structure is located above the pixels and packages the pixels; the packaging structure comprises a packaging substrate layer and a micro-polarizer structure layer, the packaging substrate layer is connected to the pixels, the micro-polarizer structure layer is located on the upper surface of the packaging substrate layer; the micro-polarizer structure layer has a nanowire grid structure; the optical isolator is located between two adjacent pixels.

[0027] It can be seen that the pixel structure in the present invention includes a pixel array, a packaging structure and an optical isolator. The packaging structure can encapsulate the pixel, and the micro-polarizer structure layer in the packaging structure can enable the pixel to achieve polarization detection. An optical isolator is provided between adjacent pixels, which can effectively reduce or even eliminate the optical crosstalk between adjacent pixels, effectively improve the extinction ratio of the polarization detector, and thus obtain higher polarization detection accuracy.

[0028] In addition, the present invention also provides a manufacturing method and a non-cooling infrared polarization detector having the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0030] 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 ; Figure 2 A schematic diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; 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 ; Figure 4 for Figure 3 A top view of the pixel structure of the uncooled infrared polarization detector shown; Figure 5 A cross-sectional diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 3 ; 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 ; Figure 7 A cross-sectional diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 5 ; Figure 8 A cross-sectional diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 6 ; Fig. 9 A cross-sectional diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 7 ; Fig.10 Schematic diagram of the nanowire grid structure provided by the embodiment of the present invention Figure 1 ; Fig.11 Schematic diagram of the nanowire grid structure provided by the embodiment of the present invention Figure 2 ; Fig.12 Schematic diagram of the nanowire grid structure provided by the embodiment of the present invention Figure 3 ; Fig.13 Schematic diagram of the nanowire grid structure provided by the embodiment of the present invention Figure 4 ; Fig.14 A schematic diagram of the first step of the first manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.15 A schematic diagram of the second step of the first manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.16 A schematic diagram of the third step of the first manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.17 A schematic diagram of the fourth step of the first manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.18 A schematic diagram of the fifth step of the first manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.19 A schematic diagram of the sixth step of the first manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig. 20 A schematic diagram of the seventh step of the first manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.21 A schematic diagram of a second manufacturing process for a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention, wherein an optical isolator is deposited after the fifth step; Fig. 22 A schematic diagram of the second manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention after etching the optical isolator after the fifth step; Fig.23 A schematic top view of a substrate in the first step of a third manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.24 A schematic diagram of the structure of the second step to the third step in the third manufacturing process of the pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.25 A schematic diagram of the fourth step of the third manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.26 A schematic diagram of the structure after depositing the hole-filling material in the fifth step of the third manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig. 27 A schematic structural diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention after removing excess hole-filling material in the fifth step of the third manufacturing process; Fig.28 A schematic structural diagram of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention after a micro-bridge structure is formed in the sixth step of the third manufacturing process; Fig.29 A schematic top view of a micro-bridge structure in the sixth step of the third manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.30 A schematic diagram of the eighth step of the third manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.31 A schematic diagram of the ninth step of the third manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.32 A schematic diagram of the tenth step of the third manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; Fig.33 A schematic structural diagram of the eleventh step in the third manufacturing process of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention; In the figure, 1, substrate; 2, metal block; 3, insulating dielectric layer; 4, getter layer; 5, microbridge structure; 6, packaging base layer; 7, micropolarizer structure layer; 8, opening; 9, infrared window layer; 10, infrared anti-reflection layer; 11, optical isolator; 12, first sacrificial layer; 13, second sacrificial layer; 14, first hard mask layer; 15, second hard mask layer; 16, microbridge support column; 17, packaging support column; 18, first through hole; 19, second through hole; 51, bridge deck; 52, bridge leg; 53, bridge pier; 54, microbridge support layer; 55, metal electrode layer; 56, passivation protection layer; 111, first isolation unit body; 112, second isolation unit body. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and 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.

[0033] As described in the background technology section, light passing through the polarization structure will inevitably propagate to and be absorbed by adjacent pixels, thereby generating optical crosstalk. This problem will cause the extinction ratio of the detector to decrease, thereby affecting the polarization detection accuracy of the detector.

[0034] Optical crosstalk has a particularly serious impact on the pixel response when the polarization angle of the incident light is perpendicular to the transmission axis. The response of the pixel should reach its minimum value at this time, but because the transmission axis of the adjacent pixels is not perpendicular to the polarization angle of the incident light at this time, the transmittance of the polarization structure of these adjacent pixels remains at a high level. Part of the light transmitted from the adjacent pixels will be absorbed by the pixel after propagating to it, so its response is high and the extinction ratio of the detector will be reduced.

[0035] In view of this, the present invention provides a pixel structure of an uncooled infrared polarization detector, please refer to Figures 1 to 6 , comprising: a pixel array, a packaging structure and an optical isolator 11; The pixel array includes a plurality of pixels, and the packaging structure is located above the pixels and packages the pixels; The packaging structure includes a packaging substrate layer 6 and a micro-polarizer structure layer 7, wherein the packaging substrate layer 6 is connected to the pixel, and the micro-polarizer structure layer 7 is located on the upper surface of the packaging substrate layer 6; the micro-polarizer structure layer 7 has a nanowire grid structure; The optical isolator 11 is located between two adjacent picture elements.

[0036] The pixels in the pixel array are generally arranged in the form of x rows × y columns, where x and y are both integers, and x and y may be equal or unequal. The pixels are used to detect thermal signals.

[0037] The pixel includes a substrate 1 and a microbridge structure 5, wherein the substrate 1 includes a substrate including a readout circuit, a metal block 2 and an insulating dielectric layer 3, the metal block 2 and the insulating dielectric layer 3 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.

[0038] 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.

[0039] The micro-polarizer structure layer 7 corresponding to different pixels has nanowire grid structures 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.

[0040] The encapsulation base layer 6 is connected to the insulating dielectric layer 3 on the substrate 1 to achieve mechanical support. The material of the encapsulation base 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 encapsulation base layer 6 can range from 100nm to 1500nm. The micro-polarizer 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 micro-polarizer structure layer 7 can range from 20nm to 500nm.

[0041] In this embodiment, non-vacuum packaging of the pixel can be achieved through the packaging substrate layer 6 and the micro-polarizer structure layer 7 .

[0042] The pixel structure also includes an opening 8, which penetrates the encapsulation substrate layer 6 and the micro-polarizer structure layer 7, connects to the outside world, and is used to release the sacrificial layer. The shape of the opening 8 can be circular or rectangular, etc., and the size range can be 0.2μm~2μm. The number and position of the opening 8 are not limited in the present invention and can be determined according to the situation.

[0043] The optical isolator 11 is located between two adjacent picture elements. The specific position of the optical isolator 11 varies according to the number of picture elements packaged by the packaging structure, which will be introduced below.

[0044] It should be pointed out that the present invention does not limit the number of pixels that are non-vacuum packaged by the packaging structure. Two different methods are introduced below.

[0045] First method like Figure 1 As shown, the packaging structure packages each pixel separately, that is, each pixel is independently packaged by a packaging structure.

[0046] The microbridge structure 5 includes a bridge deck, bridge legs and bridge piers. 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 the packaging structure to achieve packaging.

[0047] 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 packaging structure, and the microbridge structure 5 of each pixel is consistent. Only the light transmission axis angle of the nanowire grid structure in the packaging structure is different. For example, the commonly used light transmission axis angles are 0°, 45°, 90° and 135°.

[0048] In a pixel group, the sidewalls of the packaging structure of each pixel play a role in blocking the propagation of light between adjacent pixels, which can block the optical crosstalk between adjacent pixels in the pixel group, effectively improving the polarization detection accuracy. At the same time, the optical isolator 11 is set to further ensure that the signals detected by each polarization pixel are independent of each other, which can not only solve the problem of the deterioration of the extinction ratio of the polarization detector due to optical crosstalk, but also provide conditions for realizing more comprehensive and accurate thermal detection and polarization detection functions.

[0049] When the packaging structure packages each pixel individually, the optical isolator 11 can have different setting positions. Two different methods are introduced below.

[0050] Mode 1: The optical isolator 11 is located in the gap between the packaging structures corresponding to adjacent pixels.

[0051] When the packaging structure packages each pixel separately, there is a groove-shaped gap between the packaging structures of adjacent pixels, and the optical isolator 11 can be arranged in the gap between the packaging structures corresponding to the adjacent pixels, such as Figure 1 , Figure 3 , Figure 4 shown.

[0052] Mode 2: As shown, the optical isolator 11 is located between the packaging substrate layer 6 and the micro-polarizer structure layer 7 , and is located on the side wall of the packaging substrate layer 6 .

[0053] The optical isolator 11 can also be arranged in a packaging structure, such as Figure 5 As shown, at this time, the manufacturing process of the optical isolator 11 can improve the process integration before the packaging is completed.

[0054] It should be noted that when the optical isolator 11 is located between the encapsulation substrate layer 6 and the micro-polarizer structure layer 7, a small portion of the optical isolator 11 will also be left on the upper surface of the encapsulation substrate layer 6 between adjacent pixels due to the need for alignment margin. Figure 5 shown.

[0055] The optical isolator 11 covers the side walls of the packaging structure. There is no optical isolator 11 in the central area of ​​the pixel, which does not affect the external infrared light from being incident on the thermally isolated microbridge structure 5.

[0056] The optical isolator 11 can be one or any combination of material films with high infrared light absorption rate such as gold black, carbon nanotubes, silicon nitride, titanium and titanium nitride, or one or any combination of material films with high infrared light reflection rate such as gold, silver, copper, aluminum, tungsten, etc. The thickness of the optical isolator 11 can range from 25nm to 1000nm.

[0057] The optical isolator 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.

[0058] Second method like Figure 6 As shown, a plurality of pixels form a pixel group, the encapsulation structure 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 encapsulation structure to seal and encapsulate.

[0059] The number of pixels included in the pixel group is an integer multiple of four or six. It should be noted that the pixel group can include all pixels in the pixel array, that is, all pixels in the pixel structure share a packaging structure. The corresponding packaging structure above each pixel in the pixel group only differs in the polarization structure.

[0060] In the first method, the independent packaging structure of each pixel will occupy a certain space, so the actual size of the pixel structure of the uncooled infrared polarization detector is larger than the size of the thermally isolated microbridge structure 5. Compared with the first method, the second method adopts a shared packaging structure, and the actual size of the pixel structure of the pixel-level packaged uncooled infrared polarization detector is consistent with the size of the thermally isolated microbridge structure 5, which can minimize the impact of the packaging structure on the pixel size and chip area.

[0061] Please refer to Figure 6The 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 microbridge support column 16, a microbridge support layer 54 and a metal electrode layer 55; the microbridge support column 16 is located on the upper surface of the substrate 1, the microbridge support layer 54 is located above the microbridge support column 16 and on the side of the microbridge support column 16, the metal electrode layer 55 is located above the microbridge support layer 54, and is electrically connected to the microbridge support column 16.

[0062] The microbridge support column 16 passes through the microbridge support layer 54 and the insulating medium layer 3, and is connected to the metal block 2 on the substrate 1, that is, the microbridge support column 16 is located on the upper surface of the metal block 2 on the substrate 1, and the top of the microbridge support column 16 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 to the microbridge structure 5.

[0063] 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 microbridge support column 16 can be a conductive metal material such as tungsten, copper, aluminum, gold, titanium and titanium nitride. The shape of the microbridge support column 16 can be cylindrical, and the diameter of the microbridge support column 16 can be 0.5μm~2.5μm, and the height can be 1.0μm~2.5μm.

[0064] As an implementation method, it 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 .

[0065] 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.

[0066] When the packaging structure vacuum packages each pixel group, the packaging structure includes not only the packaging base layer 6 and the micro-polarizer structure layer 7, but also a packaging support column 17, which is located on the upper surface of the bridge pier in the micro-bridge structure 5 in the pixel.

[0067] like Figure 6 As shown, the packaging support column 17 is located above the micro-bridge support column 16, and the top of the packaging support column 17 is connected to the packaging base layer 6 to provide mechanical support for the shared packaging structure. The packaging base layer 6 at the edge of the shared packaging structure is connected to the edge substrate 1 of the pixel group to provide mechanical support and vacuum sealing for the shared packaging structure.

[0068] The material of the package support column 17 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.

[0069] It should be noted that when the material of the package support column 17 is a conductive metal material, a passivation protection layer 56 exists between the upper surface of the metal electrode layer 55 and the package support column 17 .

[0070] The package support column 17 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 required.

[0071] When the packaging structure packages each pixel group, the optical isolator 11 is located around each pixel, and the optical isolator 11 includes a first isolation unit body 111 and a second isolation unit body 112; The pixel comprises a microbridge structure, the bridge pier of the microbridge structure comprises a microbridge support column, the packaging structure further comprises a packaging support column, the packaging support column is located directly above the microbridge support column and between the upper surface of the bridge pier and the packaging substrate layer 6; The first isolation unit body 111 is located outside the micro-bridge support column and is flush with the upper surface of the micro-bridge support column; the second isolation unit body 112 is located outside the package support column and is flush with the upper surface of the package support column 17.

[0072] In the second mode, the optical isolator 11 can be one or any combination of material films with high infrared light absorption rate such as gold black, carbon nanotubes, silicon nitride, titanium and titanium nitride, or one or any combination of material films with high infrared light reflectivity such as gold, silver, copper, aluminum, tungsten, etc. The width of the optical isolator 11 can range from 0.5μm to 2.0μm, the height can range from 1.0μm to 5.0μm, and the length is determined according to the actual size of the pixel, which is not limited in the present invention.

[0073] The optical isolator 11 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 insulation and electrical insulation.

[0074] The optical isolator 11 can effectively eliminate the optical crosstalk between adjacent pixels and effectively improve the extinction ratio of the polarization detector, thereby obtaining higher polarization detection accuracy.

[0075] The first isolation unit body 111 and the second isolation unit body 112 are vertically arranged and are separately manufactured during manufacturing. The first isolation unit body 111 is manufactured together with the microbridge support column 16, and the second isolation unit body 112 is manufactured together with the package support column 17. The optical isolator 11 can form a self-supporting structure similar to the bridge pier 53, effectively enhancing the mechanical support of the shared package structure.

[0076] The pixel structure in this embodiment includes a pixel array, a packaging structure and an optical isolator 11. The packaging structure can encapsulate the pixel, and the micro-polarizer structure layer 7 in the packaging structure can enable the pixel to realize polarization detection. The optical isolator 11 is provided between adjacent pixels, which can effectively reduce or even eliminate the optical crosstalk between adjacent pixels, effectively improve the extinction ratio of the polarization detector, and thus obtain higher polarization detection accuracy.

[0077] Please refer to Figure 7 , Figure 8 and Fig. 9 On the basis of the above embodiments, in one embodiment of the present invention, the packaging structure may further include an infrared window layer 9, wherein the infrared window layer 9 is located on the upper surface of the micro-polarizer structure layer 7 and in the opening 8, and the opening 8 passes through the packaging base layer 6 and the micro-polarizer structure layer 7.

[0078] The function of the opening 8 is to release the sacrificial layer during the manufacturing process. After the sacrificial layer is released, it is completely filled and sealed by the infrared window layer 9 in a vacuum environment to form a vacuum package.

[0079] In this embodiment, when vacuum packaging is implemented, the substrate 1 further includes a getter layer 4 to maintain the internal vacuum. The getter layer 4 may be made of titanium-based, zirconium-based, tantalum-based and thorium-based getter materials, and the thickness may range from 50nm to 1000nm. The material of the infrared window layer 9 may be one of silicon, germanium and chalcogenide glass, and the thickness of the infrared window layer 9 may be in the range of 500 nm to 2500 nm.

[0080] In this embodiment, vacuum packaging of the pixel can be realized, avoiding the complicated and expensive conventional vacuum packaging process, improving packaging efficiency and reducing packaging costs. In addition, the nanowire grid structure is integrated into the packaging structure, which can reduce the volume and weight of the pixel structure, thereby reducing the volume and weight of the uncooled infrared polarization detector, making the device miniaturized and lightweight.

[0081] On the basis of the above embodiment, in one embodiment of the present invention, it may further include: 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 .

[0082] The material of the infrared transmission-enhancing layer 10 includes but is not limited to any one or a combination of zinc sulfide and zinc selenide. The thickness of the infrared transmission-enhancing layer 10 may be in the range of 500 nm to 2500 nm.

[0083] For any of the above embodiments, each packaging structure individually packages each pixel, or the packaging structure packages a pixel group, and the micro-polarizer structure layer 7 has a variety of different configurations, which are described below.

[0084] Example 1 Please refer to Fig.10 , 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 light transmission axis angles of each nanowire grid structure are different.

[0085] The pixel set in this embodiment can realize thermal signal detection and linear polarization signal (S0, S1, S2) detection at the same time.

[0086] For the pixels without the micro-polarizer structure layer 7 above, the incident infrared light from the outside can directly irradiate the thermally isolated micro-bridge structure 5 through the infrared window layer 9 to obtain a complete thermal detection signal. The corresponding packaging structures above the other three pixels in the pixel set have nanowire grid structures with different light transmission axis angles. The linear polarization detection information (S0, S1, S2) can be calculated based on the pixel signals of these three nanowire grid structures corresponding to different light transmission axis angles.

[0087] The light transmission axis angles of the packaging structures corresponding to the other three pixels in the pixel set are not limited in the present invention, and the specific angles can be selected according to the Stokes parameter calculation formula. For example, the three different light transmission axis angles can be 0°, 45° and 90°, or 0°, 60° and 120°.

[0088] Since the side walls of the packaging structure and the optical isolator 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 remaining three polarization detection pixels.

[0089] Example 2 Please refer to Fig.11 , four picture elements distributed in two rows and two columns form a picture element set; in each of the picture element sets, the micro-polarizer structure layer 7 corresponding to one picture element does not have the nanowire grid structure, and the micro-polarizer structure layer 7 corresponding to the other three picture elements has the nanowire grid structure, and the light transmission axis angles of each nanowire grid structure are different.

[0090] The pixel set in this embodiment can detect the reference signal and the linear polarization signal (S0, S1, S2) simultaneously.

[0091] The micro-polarizer structure layer 7 does not have a nanowire grid structure, that is, the micro-polarizer structure layer 7 is not patterned, and the external incident infrared light cannot pass through the infrared window layer 9 to irradiate the microbridge structure 5 of the thermal isolation of the pixel, thereby obtaining a reference signal. The corresponding packaging structures above the other three pixels in the pixel set have nanowire grid structures with different light transmission axis angles. The linear polarization detection signals (S0, S1, S2) can be calculated based on the pixel signals corresponding to the three nanowire grid structures with different light transmission axis angles.

[0092] 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 corresponding micro-polarizer structure layer 7 does not have a nanowire grid structure pixel) completely shields the incident infrared light from the outside, and the presence of the side walls of the packaging structure and the optical blocking structure eliminates the optical crosstalk of adjacent pixels, so the obtained reference signal can accurately characterize the influence 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 light transmission axis).

[0093] Example 3 Please refer to Fig.12 , 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.

[0094] The pixel set in this embodiment can detect full polarization detection signals (S0, S1, S2, S3).

[0095] 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 linear grating structure, such as Fig. 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 the relevant technology, and will not be described in detail in this embodiment.

[0096] The external incident infrared light passes through the infrared window layer 9, and then is modulated by the micro-polarizer structure layer 7 and irradiated to the thermally isolated microbridge structure 5, thereby obtaining a circular polarization detection signal (Il or Ir). The corresponding packaging structure above the remaining pixels in the pixel set has a linear polarization detection wire grid structure with different light transmission axis angles. The linear polarization detection wire grid structure can be a traditional linear wire grid structure. According to the pixel signal corresponding to the linear polarization nanowire grid structure with different light transmission axis angles, the linear polarization detection signal (S0, S1, S2) can be calculated, and then the full Stokes parameters (S0, S1, S2, S3) of the incident light can be obtained. The specific solution process is well known to those skilled in the art and will not be described in detail here.

[0097] Example 4 Please refer to Fig.13 , six picture elements distributed in three rows and two columns or two rows and three columns form a picture element set; in each of the picture element sets, the micro-polarizer structure layer 7 corresponding to one or two picture elements has a circular polarization nanowire grid structure, and the micro-polarizer structure layer 7 corresponding to the remaining picture elements has a linear polarization nanowire grid structure, and the light transmission axis angles of each of the linear nanowire grid structures are different.

[0098] The difference between Example 4 and Example 3 is that the number of pixels having the circular polarization nanowire grid structure is two, and the rest is the same as Example 3, which will not be described in detail here.

[0099] Example 5 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 each nanowire grid structure are different.

[0100] The light transmission axis angle of each nanowire grid structure can be set according to actual conditions, and is not limited in the present invention. For example, the light transmission axis angles of the nanowire grid structures corresponding to four pixels in a pixel set can be 0°, 45°, 90°, and 135°, respectively.

[0101] In summary, the pixel structure of the present invention has the following advantages: First, compared with the traditional focal plane uncooled infrared polarization detection: (1) The present invention integrates an optical isolator between each pixel, eliminating the optical crosstalk between adjacent pixels, greatly improving the extinction ratio of the polarization detection pixel, and effectively improving the polarization detection accuracy; in addition, the materials and processes used for the optical isolator are compatible with the materials and processes used for manufacturing the pixel of the pixel-level packaged uncooled infrared polarization detector, and the process integration is high; (2) The present invention can adopt pixel-level packaging, eliminating the subsequent complicated and cumbersome vacuum packaging process of traditional uncooled infrared detectors. The entire preparation process has a high degree of integration, greatly improving the detector packaging efficiency and reducing the packaging cost, device volume and weight; (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.

[0102] Second, compared with the pixel structure of traditional pixel-level packaging: (1) The present invention integrates a polarization detection structure in the packaging structure used for 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; (2) The packaging structure proposed in the present invention can be an independent packaging structure or a shared packaging 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 vacuum packaging that can further reduce the pixel size.

[0103] The present invention also provides a method for manufacturing a pixel structure of an uncooled infrared polarization detector, the method comprising: Prepare a pixel array; the pixel array includes a plurality of pixels; Making a packaging structure above the pixel, and packaging the pixel by the packaging structure; Producing an optical isolator between two adjacent picture elements; The packaging structure comprises a packaging substrate layer and a micro-polarizer structure layer, the packaging substrate layer is connected to the picture element, and the micro-polarizer structure layer is located on the upper surface of the packaging substrate layer; the micro-polarizer structure layer has a nanowire grid structure.

[0104] When the packaging structure encapsulates each pixel individually, the packaging base layer directly contacts the insulating medium layer on the substrate; when the packaging structure performs vacuum packaging on each pixel group, the packaging base layer contacts the insulating medium layer on the substrate and the packaging support column.

[0105] The following introduces the production method of different vacuum packaging forms for pixels according to the packaging structure.

[0106] When the packaging structure packages each pixel separately, as an implementable method, a method for manufacturing a pixel structure of an uncooled infrared polarization detector includes: Step S101: preparing a substrate; the substrate includes a substrate, a metal block and an insulating dielectric layer.

[0107] 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 Fig.14 As shown; Step S1012: removing the insulating dielectric layer 3 at the center of the pixel. Fig.15 When vacuum packaging is performed, a getter layer 4 needs to be deposited; Step S1013: When vacuum packaging is performed, the getter layer 4 outside the center of the pixel is removed, such as Fig.16 As shown; Step S102: depositing a first sacrificial layer on the substrate, and etching the first sacrificial layer, wherein the etching area corresponds to the metal block.

[0108] Please refer to Fig.17 , etching penetrates the first sacrificial layer 12 and the insulating dielectric layer 3 , and terminates the upper surface of the metal block 2 .

[0109] The material of the first sacrificial layer 12 may be one of polyimide, polycrystalline carbon and polycrystalline silicon, and the thickness may be 1 μm to 2.5 μm.

[0110] Step S103: manufacturing a microbridge structure on the first sacrificial layer, wherein a bridge pier of the microbridge structure penetrates the first sacrificial layer and the insulating dielectric layer and is connected to the metal block.

[0111] Please refer to Fig.17 The bridge pier 53 penetrates the first sacrificial layer 12 and the insulating dielectric layer 3 and terminates at the metal block 2, thereby realizing the electrical connection between the microbridge structure 5 and the readout circuit.

[0112] Step S104: 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 medium layer.

[0113] Please refer to Fig.18 The second sacrificial layer 13 is stacked on the upper surface of the first sacrificial layer 12, and the first sacrificial layer 12 and the second sacrificial layer 13 between adjacent pixels are etched so that when the packaging structure is subsequently manufactured, each packaging structure can perform vacuum packaging on one pixel.

[0114] The material of the second sacrificial layer 13 may be polyimide, polysilicon or polycrystalline carbon, and the thickness may be 0.5 μm to 3 μm.

[0115] Step S105: depositing a package base layer, wherein the package base layer is in contact with the insulating medium layer.

[0116] Please refer to Fig.18The packaging base layer 6 is located on the upper surface of the second sacrificial layer 13, the side surfaces of the first sacrificial layer 12 and the second sacrificial layer 13, and the upper surface of the insulating medium layer 3 between adjacent pixels to achieve mechanical support of the packaging structure.

[0117] Step S106: depositing a micro-polarizer structure layer on the packaging substrate layer, and etching the micro-polarizer structure layer to form a nanowire grid structure.

[0118] Please refer to Fig.19 The micro-polarizer structure layer 7 is located on the upper surface of the packaging substrate layer 6, and a patterning process is performed on the corresponding area of ​​each pixel.

[0119] Step S107 : etching the packaging base layer and the micro-polarizer structure layer to form the opening 8 , and releasing the first sacrificial layer and the second sacrificial layer through the opening 8 .

[0120] Please refer to Fig. 20 The opening 8 penetrates the packaging substrate layer 6 and the micro-polarizer structure layer 7 and ends at the second sacrificial layer 13 .

[0121] In this step, the first sacrificial layer 12 and the second sacrificial layer 13 can be removed by oxygen plasma cleaning, thereby obtaining a suspended thermally isolated microbridge structure 5 and a packaging structure.

[0122] Step S108: forming an optical isolator in the gap between the packaging structures corresponding to adjacent pixels.

[0123] The process includes: spin coating photoresist on the pixel structure and patterning it, then depositing optical blocking material to cover the gap between the packaging structures of adjacent pixels; removing the photoresist, and the optical isolator material on the photoresist is also removed, such as Figure 3 , Figure 4 As shown, a pixel-level packaged uncooled infrared polarization detector pixel structure with an integrated optical isolator 11 is obtained.

[0124] When the packaging structure packages each pixel separately, as another possible implementation method, a method for manufacturing a pixel structure of an uncooled infrared polarization detector includes: Step S201: preparing a substrate; the substrate includes a substrate, a metal block and an insulating dielectric layer.

[0125] When vacuum packaging is performed, the substrate also includes a getter layer.

[0126] Step S202: depositing a first sacrificial layer on the substrate, and etching the first sacrificial layer, wherein the etching area corresponds to the metal block.

[0127] Step S203: manufacturing a microbridge structure on the first sacrificial layer, wherein a bridge pier of the microbridge structure penetrates the first sacrificial layer and the insulating dielectric layer and is connected to the metal block.

[0128] Step S204: 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 medium layer.

[0129] Step S205: depositing a package base layer, wherein the package base layer is in contact with the insulating medium layer.

[0130] Step S206: depositing an optical isolator on the packaging substrate layer, and etching the optical isolator to retain the optical isolator located on the side wall of the packaging substrate layer.

[0131] Please refer to Figure 21 to Figure 22 After the above step S105, the optical isolator 11 is deposited, and then the optical isolator 11 is patterned to remove the optical isolator 11 at the center of the pixel to obtain the optical isolator structure. Please refer to the above steps S106 to S108 for the subsequent production process. Figure 5 The structure shown.

[0132] Step S207: depositing a micro-polarizer structure layer on the packaging substrate layer, and etching the micro-polarizer structure layer to form a nanowire grid structure.

[0133] Step S208: etching the packaging base layer and the micro-polarizer structure layer to form the opening, and releasing the first sacrificial layer and the second sacrificial layer through the opening.

[0134] When the packaging structure packages each pixel group, as an implementable method, the manufacturing method of the pixel structure of the uncooled infrared polarization detector includes: Step S301: preparing a substrate; the substrate includes a substrate, a metal block and an insulating dielectric layer.

[0135] When vacuum packaging is performed, the substrate also includes a getter layer.

[0136] Please refer to the above step S101 for this step, and no further details will be given here. Fig.23 shown.

[0137] Step S302: etching the insulating dielectric layer on the metal block to form an opening to expose the metal block.

[0138] Please refer to Fig.24 , the local insulating dielectric layer 3 on the metal block 2 is etched.

[0139] Step S303: depositing a first sacrificial layer and a first hard mask layer in sequence on the substrate.

[0140] Please refer to Fig.24 , the first sacrificial layer 12 is located on the upper surface of the substrate 1 , and the first hard mask layer 14 is located on the upper surface of the first sacrificial layer 12 .

[0141] The material of the first sacrificial layer 12 may be one of polyimide, polycrystalline carbon and polycrystalline silicon, and the thickness may be 1 μm to 2.5 μm. The material of the first hard mask layer 14 may be one of silicon nitride, silicon oxide, silicon oxynitride, titanium and titanium nitride.

[0142] Step S304: etching the first hard mask layer and the first sacrificial layer to form a first through hole and a third through hole; the first through hole corresponds to the opening.

[0143] Please refer to Fig.25 , the first hard mask layer 14 is patterned, and then the first sacrificial layer 12 is etched to obtain a first through hole 18 and a third through hole with a high aspect ratio. The first through hole 18 and the third through hole penetrate the first sacrificial layer 12. The first through hole 18 coincides with the opening position on the insulating dielectric layer 3 in step S202 and ends at the metal block 2.

[0144] Step S305: Filling the first through hole and the third through hole with a filling material to form a micro-bridge support column and a first isolation unit body.

[0145] Please refer to Figure 26 to Figure 27 First, a hole-filling material is deposited to fill the first through hole 18 and the third through hole and cover the first hard mask layer 14. Then, the excess hole-filling material on the plane of the first sacrificial layer 12 is removed by chemical mechanical polishing (CMP) and etch back, and then the first hard mask layer 14 is etched away to form a microbridge support column 16 and a first isolation unit body.

[0146] The hole filling material in this step can be a conductive metal material such as tungsten, copper, aluminum, gold, titanium and titanium nitride.

[0147] Step S306: making a microbridge structure on the first sacrificial layer; the microbridge structure includes a bridge pier, and the bridge pier includes the microbridge support column, a microbridge support layer and a metal electrode layer, the microbridge support layer is located above the microbridge support column and on the side of the microbridge support column, and the metal electrode layer is located above the microbridge support layer and is electrically connected to the microbridge support column.

[0148] Please refer to Fig.28A microbridge structure 5 for thermal isolation is fabricated on the first sacrificial layer 12. The bridge pier 53 of the microbridge structure 5 is composed of a microbridge support column 16, a microbridge support layer 54 deposited on the microbridge support column 16, and a metal electrode layer 55. The microbridge support layer 54 is patterned after deposition, so that the metal electrode layer 55 and the microbridge support column 16 are electrically connected. Fig.29 As shown, a first isolation unit body 111 is formed around the pixel.

[0149] 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.

[0150] Step S307: sequentially depositing a second sacrificial layer and a second hard mask layer on the pixel array having the first sacrificial layer.

[0151] The material of the second sacrificial layer 13 may be one of polyimide, polycrystalline carbon and polycrystalline silicon, and the material of the second hard mask layer 15 may be one of silicon nitride, silicon oxide, silicon oxynitride and titanium nitride.

[0152] Step S308: etching the second hard mask layer and the second sacrificial layer to form a second through hole and a fourth through hole, wherein the second through hole corresponds to the first through hole, and the fourth through hole corresponds to the third through hole; Please refer to Fig.30 The second sacrificial layer 13 and the second hard mask layer 15 are sequentially stacked on the pixel array. The second hard mask layer 15 is firstly patterned, and then the second sacrificial layer 13 is etched to obtain the second through hole 19 and the fourth through hole with a high aspect ratio. The second through hole 19 and the fourth through hole are terminated at the passivation protection layer 56.

[0153] Step S309 : filling the second through hole and the fourth through hole with a filling material to form a package support column and a second isolation unit body 112 .

[0154] Please refer to Fig.31 The second through hole 19 and the fourth through hole are filled with the filling material and cover the second hard mask layer 15. Then, the excess filling material on the plane of the second sacrificial layer 13 is removed by chemical mechanical polishing and back etching, and then the second hard mask layer 15 is etched away to form a package support column 17.

[0155] 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.

[0156] Step S310: etching the first sacrificial layer and the second sacrificial layer between adjacent pixel groups to expose the insulating medium layer.

[0157] Please refer to Fig.32 In this step, the first sacrificial layer 12 and the second sacrificial layer 13 between adjacent pixel groups are etched so that when a packaging structure is subsequently manufactured, each packaging structure can perform vacuum packaging on one pixel group.

[0158] Step S311: depositing a packaging substrate layer and a micro-polarizer structure layer in sequence, and etching the micro-polarizer structure layer to form a nanowire grid structure.

[0159] Please refer to Fig.33 A second isolation unit body 112 is formed around the pixel.

[0160] Step S312: etching the packaging base layer and the micro-polarizer structure layer to form the opening, and releasing the first sacrificial layer and the second sacrificial layer through the opening.

[0161] Please refer to Fig.32 The packaging substrate layer 6 and the micro-polarizer structure layer 7 are patterned to produce an opening 8, which penetrates the packaging substrate layer 6 and the micro-polarizer structure layer 7 and ends at the second sacrificial layer 13. The first sacrificial layer 12 and the second sacrificial layer 13 are then removed by oxygen plasma cleaning, thereby obtaining a suspended thermally isolated microbridge structure 5 and a shared packaging structure.

[0162] Based on any of the above embodiments, in one embodiment of the present invention, after releasing the first sacrificial layer and the second sacrificial layer, the method may further include: Under vacuum conditions, an infrared window layer is deposited on the surface, and the infrared window layer completely fills the opening to form a packaging structure.

[0163] Please refer to Figures 7 to 9 , an infrared window layer 9 is deposited in a vacuum state, the infrared window layer 9 is located on the upper surface of the micro-polarizer structure layer 7, and the openings are completely filled and sealed, thereby realizing vacuum packaging of the thermally isolated micro-bridge structure 5.

[0164] It should be noted that after the packaging structure is formed, the getter layer needs to be activated to maintain the vacuum degree in the vacuum chamber formed by the packaging structure. The getter layer can be activated by high temperature annealing.

[0165] In order to improve the infrared light transmittance of the packaging structure window, after forming the packaging structure, the following steps may also be included: An infrared anti-reflection layer 10 is deposited on the upper surface of the infrared window layer 9, such as Figures 7 to 9 shown.

[0166] The present invention also provides an uncooled infrared polarization detector, comprising the pixel structure of the uncooled infrared polarization detector described in any of the above embodiments.

[0167] 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.

[0168] The pixel structure and its manufacturing method, and the uncooled infrared polarization detector provided by the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the scheme of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle 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: Pixel array, packaging structure and optical isolator (11); The pixel array includes a plurality of pixels, and the packaging structure is located above the pixels and packages the pixels; The packaging structure comprises a packaging substrate layer (6) and a micro-polarizer structure layer (7); the packaging substrate layer (6) is connected to the pixel, and the micro-polarizer structure layer (7) is located on the upper surface of the packaging substrate layer (6); the micro-polarizer structure layer (7) has a nanowire grid structure; The optical isolator (11) is located between two adjacent picture elements.

2. The pixel structure of the uncooled infrared polarization detector according to claim 1, characterized in that: A plurality of pixels form a pixel group, the encapsulation structure encapsulates each of the pixel groups, and the number of pixels included in the pixel group is an integer multiple of four or six.

3. The pixel structure of the uncooled infrared polarization detector according to claim 2, characterized in that: The optical isolator (11) is located around each pixel, and the optical isolator (11) comprises a first isolation unit body and a second isolation unit body; The pixel comprises a microbridge structure (5), the bridge pier of the microbridge structure (5) comprises a microbridge support column (16), the packaging structure further comprises a packaging support column (17), and the packaging support column (17) is located directly above the microbridge support column (16) and between the upper surface of the bridge pier and the packaging substrate layer (6); The first isolation unit body is located outside the microbridge support column (16) and is flush with the upper surface of the microbridge support column (16); the second isolation unit body is located outside the package support column (17) and is flush with the upper surface of the package support column (17).

4. The pixel structure of the uncooled infrared polarization detector according to claim 1, characterized in that: The packaging structure packages each of the picture elements separately.

5. The pixel structure of the uncooled infrared polarization detector according to claim 4, characterized in that: The optical isolator (11) is located in the gap between the packaging structures corresponding to adjacent pixels.

6. The pixel structure of the uncooled infrared polarization detector according to claim 4, characterized in that: The optical isolator (11) is located between the packaging substrate layer (6) and the micro-polarizer structure layer (7), and is located on the side wall of the packaging substrate layer (6).

7. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 6, 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 has no micro-polarizer structure layer (7) above it, 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 nanowire grid structures are different.

8. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 6, 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 nanowire grid structures are different.

9. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 6, 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.

10. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 6, 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.

11. The pixel structure of the uncooled infrared polarization detector according to any one of claims 1 to 6, 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 nanowire grid structures are different.

12. A method for manufacturing a pixel structure of an uncooled infrared polarization detector, characterized in that: include: Prepare pixel array; The pixel array includes a plurality of pixels; Making a packaging structure above the pixel, and packaging the pixel by the packaging structure; Producing an optical isolator (11) between two adjacent picture elements; The packaging structure comprises a packaging substrate layer (6) and a micro-polarizer structure layer (7); the packaging substrate layer (6) is connected to the picture element; the micro-polarizer structure layer (7) is located on the upper surface of the packaging substrate layer (6); and the micro-polarizer structure layer (7) has a nanowire grid structure.

13. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 12, characterized in that: When the encapsulation structure encapsulates each pixel group, preparing the pixel array includes: Preparing a substrate (1); the substrate (1) comprises a substrate, a metal block (2) 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 (12) and a first hard mask layer (14) in sequence on the substrate (1); Etching the first hard mask layer (14) and the first sacrificial layer (12) to form a first through hole (18); the first through hole (18) corresponds to the opening; Filling the first through hole (18) with a hole-filling material to form a microbridge support column (16); A microbridge structure (5) is fabricated on the first sacrificial layer (12); the microbridge structure (5) comprises a bridge pier (53); the bridge pier (53) comprises the microbridge support column (16), a microbridge support layer (54) and a metal electrode layer (55); the microbridge support layer (54) is located above the microbridge support column (16) and on the side of the microbridge support column (16); the metal electrode layer (55) is located above the microbridge support layer (54) and is electrically connected to the microbridge support column (16).

14. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 13, characterized in that: Producing an optical isolator (11) between two adjacent picture elements comprises: After sequentially depositing a first sacrificial layer (12) and a first hard mask layer (14) on the substrate (1), etching the first hard mask layer (14) and the first sacrificial layer (12) to form a third through hole; Filling the third through hole with a filling material to form a first isolation unit body; After sequentially depositing a second sacrificial layer (13) and a second hard mask layer (15) on the pixel array having the first sacrificial layer (12), etching the second hard mask layer (15) and the second sacrificial layer (13) 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 isolation unit body (112).

15. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 12, characterized in that: When the packaging structure packages each pixel individually, making an optical isolator (11) between two adjacent pixels includes: An optical isolator (11) is formed in the gap between the packaging structures corresponding to adjacent picture elements.

16. The method for manufacturing a pixel structure of an uncooled infrared polarization detector according to claim 12, characterized in that: When the packaging structure packages each pixel individually, making an optical isolator (11) between two adjacent pixels includes: After the encapsulation base layer (6) is formed, an optical isolator (11) is deposited on the encapsulation base layer (6), and the optical isolator (11) is etched to retain the optical isolator (11) located on the side wall of the encapsulation base layer (6).

17. 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 11.

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