A pixel structure, a manufacturing method thereof, and an uncooled infrared polarization detector

Abstract

The present invention relates to the field of infrared imaging, and discloses a pixel structure, a manufacturing method thereof, and an uncooled infrared polarization detector, including: a pixel array, a packaging structure, and an optical isolator; the pixel array includes a plurality of pixels, the packaging structure is located above the pixels and packages the pixels; the packaging structure includes a packaging matrix layer and a micro-polarizer structure layer, the packaging matrix layer is connected to the pixels, and the micro-polarizer structure layer is located on the upper surface of the packaging matrix layer; the micro-polarizer structure layer has a nanowire grid structure; the optical isolator is located between two adjacent pixels. The present invention is provided with an optical isolator 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.

Description

Technical Field

[0001] The present invention relates to the field of infrared imaging, and particularly to a pixel structure, a manufacturing method thereof, and an uncooled infrared polarization detector. Background Art

[0002] The uncooled infrared polarization detector can simultaneously measure the intensity information and polarization information of a spatial target, effectively improve the contrast between the target and the background, highlight the detailed features of the target, and enhance the target recognition effect. The split focal plane type uncooled infrared polarization detector, with characteristics such as high integration and real-time imaging, has become the focus of attention.

[0003] The polarization detection of the uncooled infrared polarization detector is realized by a split focal plane type polarization detection pixel group composed of two rows and two columns of adjacent pixels. The pixel groups are arranged in sequence to form the focal plane array of the uncooled infrared polarization detector. The thermal insulation microbridges of the pixels in the focal plane array are closely adjacent, and a polarization structure with different light transmission axis angles is provided directly above. The polarization structure will perform different polarization modulations on the light intensities of incident light with different polarization angles (following Malus' law). Due to reflection and diffraction, the light transmitted through the polarization structure will inevitably propagate to adjacent pixels and be absorbed by them, thus generating optical crosstalk. This problem will lead to a decrease in the extinction ratio of the detector, and further affect the polarization detection accuracy of the detector.

[0004] Therefore, how to solve the optical crosstalk in the polarization detector should be a technical problem urgently to be solved by those skilled in the art. Summary of the Invention

[0005] The object of the present invention is to provide a pixel structure, a manufacturing method thereof, and an uncooled infrared polarization detector, which can reduce or even eliminate the optical crosstalk between adjacent pixels and improve the polarization detection accuracy.

[0006] To solve the above technical problem, the present invention provides a pixel structure of an uncooled infrared polarization detector, including: a pixel array, a packaging structure, and an optical isolator;

[0007] The pixel array includes a plurality of pixels, and the packaging structure is located above the pixels and packages the pixels;

[0008] The packaging structure includes a packaging matrix layer and a micro-polarizer structure layer. The packaging matrix layer is connected to the pixels, and the micro-polarizer structure layer is located on the upper surface of the packaging matrix layer; the micro-polarizer structure layer has a nanowire grid structure;

[0009] The optical isolator is located between two adjacent pixels.

[0010] Optionally, a plurality of pixels form a pixel group, and the encapsulation structure encapsulates each pixel group. The number of pixels included in the pixel group is an integer multiple of four or six.

[0011] Optionally, the optical isolator is located around each pixel. The optical isolator includes a first isolation unit body and a second isolation unit body.

[0012] The pixel includes a microbridge structure. The piers of the microbridge structure include microbridge support columns. The encapsulation structure further includes encapsulation support columns, which are located directly above the microbridge support columns and between the upper surface of the piers and the encapsulation matrix layer.

[0013] The first isolation unit body is located outside the microbridge support column and flush with the upper surface of the microbridge support column. The second isolation unit body is located outside the encapsulation support column and flush with the upper surface of the encapsulation support column.

[0014] Optionally, the encapsulation structure encapsulates each pixel individually.

[0015] Optionally, the optical isolator is located in the gap between the encapsulation structures corresponding to adjacent pixels.

[0016] Optionally, the optical isolator is located between the encapsulation matrix layer and the micro-polarizer structure layer and on the side wall of the encapsulation matrix layer.

[0017] Optionally, the encapsulation structure further includes an infrared window layer, which is located on the upper surface of the micro-polarizer structure layer and in the openings that penetrate through the encapsulation matrix layer and the micro-polarizer structure layer.

[0018] Optionally, it further includes an infrared antireflection layer, which is located on the upper surface of the infrared window layer.

[0019] 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 corresponding to one pixel above, and the micro-polarizer structure layers corresponding to the other three pixels have the nanowire grid structure, and the light transmission axis angles of the respective nanowire grid structures are different.

[0020] 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 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 the respective nanowire grid structures are different.

[0021] 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 linear nanowire grid structures, and the light transmission axis angles of the respective linear nanowire grid structures are different from each other.

[0022] 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 layers corresponding to the remaining pixels have linear nanowire grid structures, and the light transmission axis angles of the respective linear nanowire grid structures are different from each other.

[0023] 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 each pixel has the nanowire grid structure, and the light transmission axis angles of the respective nanowire grid structures are different from each other.

[0024] The present invention also provides a method for manufacturing a pixel structure of an uncooled infrared polarization detector, including:

[0025] Prepare a pixel array; the pixel array includes a plurality of pixels;

[0026] Fabricate a packaging structure above the pixels and encapsulate the pixels through the packaging structure;

[0027] Fabricate an optical isolator between two adjacent pixels;

[0028] The packaging structure includes a packaging substrate layer and a micro-polarizer structure layer. The packaging substrate layer is connected to the pixels, 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.

[0029] Optionally, when the packaging structure encapsulates each pixel group, preparing the pixel array includes:

[0030] Prepare a substrate; the substrate includes a substrate, a metal block, and an insulating dielectric layer;

[0031] Etch the insulating dielectric layer located on the metal block to form an opening to expose the metal block;

[0032] Deposit a first sacrificial layer and a first hard mask layer on the substrate in sequence;

[0033] Etch the first hard mask layer and the first sacrificial layer to form a first through hole; the first through hole corresponds to the opening;

[0034] Fill the first through-hole with a filling material to form a micro-bridge support column;

[0035] Fabricate a micro-bridge structure on the first sacrificial layer; the micro-bridge structure includes bridge piers, and the bridge piers include the micro-bridge support columns, a micro-bridge support layer, and a metal electrode layer. The micro-bridge support layer is located above and on the sides of the micro-bridge support columns, and the metal electrode layer is located above the micro-bridge support layer and is electrically connected to the micro-bridge support columns.

[0036] Optionally, fabricating an optical isolator between two adjacent pixels includes:

[0037] After sequentially depositing a first sacrificial layer and a first hard mask layer on the substrate, etch the first hard mask layer and the first sacrificial layer to form a third through-hole;

[0038] Fill the third through-hole with a filling material to form a first isolation unit;

[0039] After sequentially depositing a second sacrificial layer and a second hard mask layer on the pixel array having the first sacrificial layer, etch the second hard mask layer and the second sacrificial layer to form a fourth through-hole, and the fourth through-hole corresponds to the third through-hole;

[0040] Fill the fourth through-hole with a filling material to form a second isolation unit.

[0041] Optionally, when the packaging structure individually packages each pixel, fabricating an optical isolator between two adjacent pixels includes:

[0042] Form an optical isolator in the gap between the packaging structures corresponding to adjacent pixels.

[0043] Optionally, when the packaging structure individually packages each pixel, fabricating an optical isolator between two adjacent pixels includes:

[0044] After fabricating and forming a packaging matrix layer, deposit an optical isolator on the packaging matrix layer and etch the optical isolator to retain the optical isolator on the sidewalls of the packaging matrix layer.

[0045] Optionally, further includes:

[0046] Under vacuum conditions, deposit an infrared window layer on the surface of the micro-polarizer structure layer, and the infrared window layer completely fills the opening to form a packaging structure.

[0047] The present invention also provides a non-cooled infrared polarization detector, including the pixel structure of any one of the above-mentioned non-cooled infrared polarization detectors.

[0048] The pixel structure of a non-cooled infrared polarization detector provided by the present invention includes: 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 includes a packaging substrate layer and a micro-polarizer structure layer, the packaging substrate layer is connected to the pixels, 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 pixels.

[0049] 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 package the pixels, and the micro-polarizer structure layer in the packaging structure can enable the pixels 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.

[0050] In addition, the present invention also provides a manufacturing method and a non-cooled infrared polarization detector with the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0052] Figure 1 is a cross-sectional schematic diagram of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention Figure 1 ;

[0053] Figure 2 is a schematic diagram of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0054] Figure 3 is a cross-sectional schematic diagram of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention Figure 2 ;

[0055] Figure 4 is Figure 3 a top view of the pixel structure of the non-cooled infrared polarization detector shown;

[0056] Figure 5 is a cross-sectional schematic diagram of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention Figure 3 ;

[0057] Figure 6 Cross-sectional schematic of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 4 ;

[0058] Figure 7 Cross-sectional schematic of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 5 ;

[0059] Figure 8 Cross-sectional schematic of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 6 ;

[0060] Figure 9 Cross-sectional schematic of a pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention Figure 7 ;

[0061] Figure 10 Schematic of the nanowire grating structure provided by an embodiment of the present invention Figure 1 ;

[0062] Figure 11 Schematic of the nanowire grating structure provided by an embodiment of the present invention Figure 2 ;

[0063] Figure 12 Schematic of the nanowire grating structure provided by an embodiment of the present invention Figure 3 ;

[0064] Figure 13 Schematic of the nanowire grating structure provided by an embodiment of the present invention Figure 4 ;

[0065] Figure 14 Schematic of the first step of the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention;

[0066] Figure 15 Schematic of the second step of the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention;

[0067] Figure 16 Schematic of the third step of the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention;

[0068] Figure 17 Schematic of the fourth step of the first manufacturing process of the pixel structure of an uncooled infrared polarization detector provided by an embodiment of the present invention;

[0069] Figure 18Schematic diagram of the fifth step in the first manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0070] Figure 19 Schematic diagram of the sixth step in the first manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0071] Figure 20 Schematic diagram of the seventh step in the first manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0072] Figure 21 Schematic diagram of depositing an optical isolator after the fifth step in the second manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0073] Figure 22 Schematic diagram after etching the optical isolator after the fifth step in the second manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0074] Figure 23 Top view schematic diagram of the substrate in the first step of the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0075] Figure 24 Schematic diagrams of the second to third steps in the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0076] Figure 25 Schematic diagram of the fourth step in the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0077] Figure 26 Schematic diagram of the structure after depositing hole-filling material in the fifth step of the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0078] Figure 27 Schematic diagram of the structure after removing the excess hole-filling material in the fifth step of the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0079] Figure 28 Schematic diagram of the structure after forming a micro-bridge structure in the sixth step of the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0080] Figure 29It is a top view schematic diagram after the micro-bridge structure in the sixth step of the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0081] Figure 30 It is a schematic diagram of the eighth step in the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0082] Figure 31 It is a schematic diagram of the ninth step in the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0083] Figure 32 It is a schematic diagram of the tenth step in the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0084] Figure 33 It is a schematic diagram of the eleventh step in the third manufacturing process of the pixel structure of a non-cooled infrared polarization detector provided by an embodiment of the present invention;

[0085] In the figure, 1, substrate; 2, metal block; 3, insulating dielectric layer; 4, getter layer; 5, micro-bridge structure; 6, encapsulation matrix layer; 7, micro-polarizer 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, micro-bridge support column; 17, encapsulation support column; 18, first through hole; 19, second through hole; 51, bridge deck; 52, bridge leg; 53, bridge pier; 54, micro-bridge support layer; 55, metal electrode layer; 56, passivation protection layer; 111, first isolation unit body; 112, second isolation unit body. Detailed implementation manners

[0086] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0087] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention, but the present invention may be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0088] As described in the background art section, the light passing through the polarization structure will inevitably propagate to adjacent pixels and be absorbed by them, thus generating optical crosstalk. This problem will lead to a decrease in the extinction ratio of the detector, thereby affecting the polarization detection accuracy of the detector.

[0089] Optical crosstalk has a particularly serious impact on the response of the pixel when the polarization angle of the incident light is perpendicular to the transmission axis. The response of this pixel should reach the minimum value at this time, but because the transmission axes of the adjacent pixels are not perpendicular to the polarization angle of the incident light at this time, the transmittance of the polarization structures of these adjacent pixels still remains at a relatively high level. A part of the light transmitted from the adjacent pixels will be absorbed by this pixel after propagating to it, so its response is on the high side, and the extinction ratio of the detector will also decrease accordingly.

[0090] In view of this, the present invention provides a pixel structure of an uncooled infrared polarization detector. Please refer to Figures 1 to 6 , including: a pixel array, a packaging structure, and an optical isolator 11;

[0091] The pixel array includes a plurality of pixels, and the packaging structure is located above the pixels and packages the pixels.

[0092] The packaging structure includes a packaging matrix layer 6 and a micropolarizer structure layer 7. The packaging matrix layer 6 is connected to the pixels, and the micropolarizer structure layer 7 is located on the upper surface of the packaging matrix layer 6; the micropolarizer structure layer 7 has a nanowire grid structure.

[0093] The optical isolator 11 is located between two adjacent pixels.

[0094] The pixels in the pixel array are generally arranged in the form of x rows × y columns, where both x and y are integers, and x and y can be equal or not equal. The pixels are used to detect thermal signals.

[0095] The pixel includes a substrate 1 and a microbridge structure 5. Among them, the substrate 1 includes a substrate containing 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, and the insulating dielectric layer 3 partially covers the metal block 2. An opening is provided on the insulating dielectric layer 3 to expose a part of the upper surface of the metal block 2.

[0096] The material of the metal block 2 can be any one of aluminum, titanium, copper, and gold, and the thickness range of the metal block 2 can be 50 nm to 1000 nm; the insulating dielectric layer 3 can be any one of a silicon nitride layer, a silicon oxide layer, and a silicon oxynitride layer.

[0097] The nanowire grid structures corresponding to different pixels in the micro-polarizer structure layer 7 have different patterns, which can simultaneously measure the intensity information and polarization information of a spatial 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.

[0098] The encapsulation matrix layer 6 is connected to the insulating dielectric layer 3 on the substrate 1 to achieve mechanical support. The material of the encapsulation matrix layer 6 includes but is not limited to any one of silicon, amorphous silicon, silicon nitride, silicon oxide, and silicon oxynitride. The thickness range of the encapsulation matrix layer 6 can be 100 nm to 1500 nm. The micro-polarizer structure layer 7 can be any one or any combination of a gold layer, a silver layer, a copper layer, an aluminum layer, a tungsten layer, a titanium layer, and a titanium nitride layer. The thickness range of the micro-polarizer structure layer 7 can be 20 nm to 500 nm.

[0099] In this embodiment, non-vacuum encapsulation of the pixel can be achieved through the encapsulation matrix layer 6 and the micro-polarizer structure layer 7.

[0100] The pixel structure further includes an opening 8. The opening 8 penetrates through the encapsulation matrix layer 6 and the micro-polarizer structure layer 7 to communicate with the outside world and is used for the release of the sacrificial layer. The shape of the opening 8 can be circular or rectangular, etc., and the size range can be 0.2 μm to 2 μm. The number and position of the openings 8 are not limited in the present invention and can be determined according to the situation.

[0101] The optical isolator 11 is located between two adjacent pixels. The specific position of the optical isolator 11 is different according to the number of pixels encapsulated by the encapsulation structure, and the following will be introduced separately.

[0102] It should be noted that the number of pixels encapsulated by the encapsulation structure in a non-vacuum manner is not limited in the present invention, and the following introduces two different methods.

[0103] The first method

[0104] As Figure 1 shown, the encapsulation structure encapsulates each pixel separately. That is, each pixel is independently encapsulated by an encapsulation structure.

[0105] The micro-bridge structure 5 includes a bridge deck, bridge legs, and bridge piers. The micro-bridge structure 5 is connected to the metal block 2 through an opening in the insulating dielectric layer 3, thereby realizing electrical connection with the readout circuit in the substrate. The micro-bridge structure 5 is encapsulated by the encapsulation structure.

[0106] Pixels arranged in two rows and two columns can be regarded as a pixel group, as Figure 2As shown, or the pixels in a three-row two-column or two-row three-column arrangement are regarded as a pixel group. Each pixel within the pixel group is individually encapsulated at the pixel level and has a complete and independent microbridge structure 5 and encapsulation structure. Moreover, the microbridge structures 5 of each pixel are identical, and only the light-transmitting axis angles of the nanowire grid structures in the encapsulation structure are different. For example, the commonly used light-transmitting axis angles are 0°, 45°, 90°, and 135°.

[0107] Within a pixel group, the sidewalls of the encapsulation structures of each pixel play a role in blocking the light propagation between adjacent pixels, which can block the optical crosstalk between adjacent pixels within the pixel group and effectively improve the polarization detection accuracy. At the same time, by setting the optical isolator 11, it can be further ensured that the signals detected by each polarization pixel are independent of each other. This can not only solve the problem of the extinction ratio deterioration of the polarization detector caused by optical crosstalk but also provide conditions for realizing more comprehensive and accurate thermal detection and polarization detection functions.

[0108] When the encapsulation structure individually encapsulates each pixel, the optical isolator 11 can be set at different positions. Two different methods are introduced below.

[0109] Method 1: The optical isolator 11 is located in the gap between the encapsulation structures corresponding to adjacent pixels.

[0110] When the encapsulation structure individually encapsulates each pixel, there is a groove-shaped gap between the encapsulation structures of adjacent pixels, and the optical isolator 11 can be arranged in the gap between the encapsulation structures corresponding to adjacent pixels, as shown in Figure 1 、 Figure 3 、 Figure 4 shown.

[0111] Method 2: As shown, the optical isolator 11 is located between the encapsulation matrix layer 6 and the micro-polarizer structure layer 7 and on the sidewall of the encapsulation matrix layer 6.

[0112] The optical isolator 11 can also be set in the encapsulation structure. As shown in Figure 5 shown, in this case, the manufacturing process of the optical isolator 11 can improve the process integration before the encapsulation is completed.

[0113] It should be noted that when the optical isolator 11 is located between the encapsulation matrix layer 6 and the micro-polarizer structure layer 7, because alignment margins are required, a small part of the optical isolator 11 will also remain on the upper surface of the encapsulation matrix layer 6 between adjacent pixels, as shown in Figure 5 shown.

[0114] The optical isolator 11 covers the sidewalls of the encapsulation structure and there is no optical isolator 11 in the central area of the pixel, which does not affect the incidence of external infrared light on the thermally isolated microbridge structure 5.

[0115] The optical isolator 11 can be one or any combination of material films such as gold black, carbon nanotubes, silicon nitride, titanium, and titanium nitride that have a high absorption rate for infrared light, or one or any combination of material films such as gold, silver, copper, aluminum, and tungsten that have a high reflectivity for infrared light. The thickness range of the optical isolator 11 can be 25 nm to 1000 nm.

[0116] The optical isolator 11 can completely eliminate the optical crosstalk between adjacent pixels, effectively improve the extinction ratio of the polarization detector, and thus obtain higher polarization detection accuracy.

[0117] The second method

[0118] As Figure 6 shown, multiple pixels form a pixel group, and the packaging structure packages each pixel group. The number of pixels included in the pixel group is an integer multiple of four or six. That is, all the pixels in each pixel group share one packaging structure to be hermetically wrapped for packaging.

[0119] 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 the pixels in the pixel array, that is, all the pixels in the pixel structure share one packaging structure. The polarization structures of the packaging structures corresponding to each pixel above in the pixel group are only different.

[0120] In the first method, the independent packaging structure owned by each pixel will occupy a certain space. Therefore, the actual size of the non-cooled infrared polarization detector pixel structure is larger than the size of the thermal isolation microbridge structure 5. Compared with the first method, in the second method, a shared packaging structure is adopted, and the actual size of the pixel-level packaged non-cooled infrared polarization detector pixel structure is the same as the size of the thermal isolation microbridge structure 5, which can minimize the influence of the packaging structure on the pixel size and chip area.

[0121] Please refer to Figure 6 , the pixel includes a substrate 1 and a microbridge structure 5. The microbridge structure 5 includes a pier 53, a bridge deck 51, and bridge legs 52. The 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.

[0122] The micro-bridge support pillar 16 penetrates through the micro-bridge support layer 54 and the insulating dielectric layer 3 and is connected to the metal block 2 on the substrate 1, that is, the micro-bridge support pillar 16 is located on the upper surface of the metal block 2 on the substrate 1, and the top of the micro-bridge support pillar 16 is connected to the metal electrode layer 55, thereby realizing the electrical connection between the micro-bridge structure 5 and the readout circuit in the substrate 1 and realizing the mechanical support of the substrate 1 for the micro-bridge structure 5.

[0123] The material of the micro-bridge 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 micro-bridge support pillar 16 can be a conductive metal material such as tungsten, copper, aluminum, gold, titanium, and titanium nitride. The shape of the micro-bridge support pillar 16 can be cylindrical, the diameter of the micro-bridge support pillar 16 can be 0.5 μm to 2.5 μm, and the height is 1.0 μm to 2.5 μm.

[0124] As an implementable embodiment, it may further include: a passivation protection layer 56, and the passivation protection layer 56 is located on the upper surface of the metal electrode layer 55.

[0125] 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 micro-bridge structure 5. The material of the passivation protection layer 56 can be any one of silicon nitride, silicon oxide, and silicon oxynitride.

[0126] When the packaging structure performs vacuum packaging on each pixel group, in addition to including the packaging matrix layer 6 and the micro-polarizer structure layer 7, the packaging structure further includes a packaging support pillar 17, and the packaging support pillar 17 is located on the upper surface of the pier in the micro-bridge structure 5 in the pixel.

[0127] As Figure 6 shown, the packaging support pillar 17 is located above the micro-bridge support pillar 16, and the top of the packaging support pillar 17 is connected to the packaging matrix layer 6 to provide mechanical support for the shared packaging structure. The packaging matrix layer 6 at the edge of the shared packaging structure is connected to the substrate 1 at the edge of the pixel group to provide mechanical support and vacuum sealing for the shared packaging structure.

[0128] The material of the packaging support pillar 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, which are all within the protection scope of the present invention.

[0129] It should be noted that when the material of the packaging support pillar 17 is a conductive metal material, there is a passivation protection layer 56 between the upper surface of the metal electrode layer 55 and the packaging support pillar 17.

[0130] The shape of the encapsulation support pillar 17 can be cylindrical, the diameter of the encapsulation support pillar 17 can be 0.5μm to 2.0μm, and the height can be 0.5μm to 2.5μm. It can also be set to other sizes according to needs.

[0131] When the encapsulation structure encapsulates each pixel group, the optical isolator 11 is located around each pixel. The optical isolator 11 includes a first isolation unit body 111 and a second isolation unit body 112;

[0132] The pixel includes a microbridge structure. The piers of the microbridge structure include microbridge support pillars. The encapsulation structure further includes an encapsulation support pillar. The encapsulation support pillar is located directly above the microbridge support pillar and between the upper surface of the pier and the encapsulation matrix layer 6;

[0133] The first isolation unit body 111 is located outside the microbridge support pillar and is flush with the upper surface of the microbridge support pillar; the second isolation unit body 112 is located outside the encapsulation support pillar and is flush with the upper surface of the encapsulation support pillar 17.

[0134] In the second method, the optical isolator 11 can be one or any combination of material films such as gold black, carbon nanotubes, silicon nitride, titanium, and titanium nitride that have a high absorption rate for infrared light, or it can be one or any combination of material films such as gold, silver, copper, aluminum, and tungsten that have a high reflectivity for infrared light. The width range of the optical isolator 11 can be 0.5μm to 2.0μm, the height range can be 1.0μm to 5.0μm, and the length is determined according to the actual size of the pixel and is not limited in the present invention.

[0135] The optical isolator 11 is located between two adjacent microbridge structures 5 and does not contact the bridge deck 51, bridge legs 52, and piers 53 of the microbridge structure 5, ensuring thermal insulation and electrical insulation.

[0136] The optical isolator 11 can effectively eliminate optical crosstalk between adjacent pixels, effectively improve the extinction ratio of the polarization detector, and thus obtain higher polarization detection accuracy.

[0137] The first isolation unit body 111 and the second isolation unit body 112 are vertically arranged and are separately manufactured during production. The first isolation unit body 111 is formed together with the microbridge support pillar 16, and the second isolation unit body 112 is formed together with the encapsulation support pillar 17. The optical isolator 11 can form a self-supporting structure similar to the pier 53, effectively enhancing the mechanical support of the shared encapsulation structure.

[0138] The pixel structure in this embodiment includes a pixel array, a packaging structure, and an optical isolator 11. The packaging structure can package the pixels, and the micropolarizer structure layer 7 in the packaging structure enables the pixels to achieve polarization detection. An 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.

[0139] Please refer to Figure 7 、 Figure 8 and Figure 9 , on the basis of the above embodiment, in an embodiment of the present invention, the packaging structure may further include an infrared window layer 9, and the infrared window layer 9 is located on the upper surface of the micropolarizer structure layer 7 and in the opening 8, and the opening 8 penetrates through the packaging substrate layer 6 and the micropolarizer structure layer 7.

[0140] 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.

[0141] When realizing the vacuum package in this embodiment, the substrate 1 further includes a getter layer 4 to maintain the internal vacuum degree. 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 range can be 50nm - 1000nm

[0142] The material of the infrared window layer 9 can be one of silicon, germanium, and chalcogenide glass, and the thickness range of the infrared window layer 9 can be 500nm - 2500nm.

[0143] In this embodiment, the vacuum package of the pixels can be realized, avoiding the complicated and expensive conventional vacuum packaging process, improving the packaging efficiency, and reducing the packaging cost. And integrating the nanowire grid structure in the packaging structure can reduce the volume and weight of the pixel structure, and further reduce the volume and weight of the uncooled infrared polarization detector, making the device have the characteristics of miniaturization and light weight.

[0144] On the basis of the above embodiment, in an embodiment of the present invention, it may further include: an infrared antireflection layer 10, and the infrared antireflection layer 10 is located on the upper surface of the infrared window layer 9.

[0145] The material of the infrared antireflection layer 10 includes but is not limited to any one or combination of zinc sulfide and zinc selenide, and the thickness range of the infrared antireflection layer 10 can be 500nm - 2500nm.

[0146] For any of the above embodiments, each packaging structure individually packages each pixel, or the packaging structure packages a pixel group. The micropolarizer structure layer 7 has a variety of different setting methods, which will be introduced separately below.

[0147] Example 1

[0148] Please refer to Figure 10 , 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 7 above one pixel, and the micro-polarizer structure layer 7 corresponding to the other three pixels has the nanowire grid structure, and the light transmission axis angles of the respective nanowire grid structures are different from each other.

[0149] The pixel set in this embodiment can simultaneously realize thermal signal detection and linearly polarized signal (S0, S1, S2) detection.

[0150] 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 and irradiate the thermally isolated micro-bridge structure 5 to obtain a complete thermal detection signal. The encapsulation structures corresponding to the other three pixels in the pixel set have nanowire grid structures with different light transmission axis angles. According to the signals of these three pixels corresponding to different light transmission axis angles of the nanowire grid structures, linearly polarized detection information (S0, S1, S2) can be calculated.

[0151] The light transmission axis angles of the encapsulation 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°.

[0152] Due to the presence of the side walls of the encapsulation structure and the optical isolator, the optical crosstalk between adjacent pixels is eliminated. Therefore, the detection signals of each pixel in the pixel set are independent and accurate signals, and the introduction of the thermal detection pixel will not affect the extinction ratio of the remaining three polarization detection pixels.

[0153] Example 2

[0154] Please refer to Figure 11 , 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 light transmission axis angles of the respective nanowire grid structures are different from each other.

[0155] The pixel set in this embodiment can simultaneously detect the reference signal and the linearly polarized signal (S0, S1, S2).

[0156] The micro-polarizer structure layer 7 does not have a nanowire grid structure, that is, the micro-polarizer structure layer 7 is not patterned. The incident external infrared light cannot irradiate the micro-bridge structure 5 isolated by the pixel through the infrared window layer 9, so as to obtain a reference signal. The encapsulation structures corresponding to the other three pixels in the pixel set have nanowire grid structures with different light transmission axis angles. The linearly polarized detection signals (S0, S1, S2) can be calculated according to the signals of these three pixels corresponding to the nanowire grid structures with different light transmission axis angles.

[0157] The detection signal of the uncooled infrared detector pixel is closely related to the ambient temperature. Therefore, the polarization detection signal calculated from the thermal detection signal is also easily affected by the ambient temperature. If accurate thermal detection signals and polarization detection signals are to be obtained, the uncooled infrared detector must require strict ambient temperature control. The reference pixel (the pixel corresponding to the micro-polarizer structure layer 7 without a nanowire grid structure) completely shields the incident external infrared light, and the presence of the side wall of the encapsulation structure and the optical blocking structure eliminates the optical crosstalk between adjacent pixels. Therefore, 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 in the case where the response of the polarization detection signal is extremely small (when the polarization angle of the incident light is perpendicular to the light transmission axis).

[0158] Example 3

[0159] Please refer to Figure 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 circularly polarized nanowire grid structure, and the micro-polarizer structure layers 7 corresponding to the other three pixels have linearly polarized nanowire grid structures, and the light transmission axis angles of the respective linearly polarized nanowire grid structures are different.

[0160] The pixel set in this embodiment can detect full polarization detection signals (S0, S1, S2, S3).

[0161] In this embodiment, the specific type of the circularly polarized nanowire grid structure is not limited and can be set by itself. For example, the circularly polarized nanowire grid structure can be a spiral grating structure, as Figure 9 shown, or a metasurface polarization detection structure, or a linear grating structure combined with a quarter-wavelength material. The metasurface polarization detection structure and the linear grating structure combined with a quarter-wavelength material can be specifically referred to the related technologies, and will not be introduced in detail in this embodiment.

[0162] The incident external infrared light passes through the infrared window layer 9, and after being modulated by the micro-polarizer structure layer 7, it irradiates the thermally isolated micro-bridge structure 5, thereby obtaining a circularly polarized detection signal (Il or Ir). The packaging structures corresponding to the remaining pixels in the pixel set have linear polarization detection grating structures with different light transmission axis angles. The linear polarization detection grating structure can be a traditional linear grating structure. According to the pixel signals corresponding to the linear polarization nanowire grating structures with different light transmission axis angles, linear polarization detection signals (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 elaborated here in detail.

[0163] Example 4

[0164] Please refer to Figure 13 , 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, one or two pixels corresponding to the micro-polarizer structure layer 7 have circular polarization nanowire grating structures, and the remaining pixels corresponding to the micro-polarizer structure layer 7 have linear polarization nanowire grating structures, and the light transmission axis angles of the respective linear nanowire grating structures are different.

[0165] The difference between Example 4 and Example 3 is that the number of pixels with circular polarization nanowire grating structures is two, and the others are the same as in Example 3, which will not be elaborated here in detail.

[0166] Example 5

[0167] Four pixels distributed in two rows and two columns form a pixel set; in each of the pixel sets, each pixel corresponding to the micro-polarizer structure layer 7 has the nanowire grating structure, and the light transmission axis angles of the respective nanowire grating structures are different.

[0168] The light transmission axis angles of the respective nanowire grating structures can be set according to the actual situation and are not limited in the present invention. For example, the light transmission axis angles of the nanowire grating structures corresponding to the four pixels in a pixel set can be 0°, 45°, 90°, and 135° respectively.

[0169] In summary, the pixel structure of the present invention has the following advantages:

[0170] First, compared with the traditional split focal plane type uncooled infrared polarization detection:

[0171] (1) In the present invention, an optical isolator is integrated between each pixel, eliminating the optical crosstalk between adjacent pixels, greatly improving the extinction ratio of the polarization detection pixels, 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 pixels of the pixel-level packaged uncooled infrared polarization detector, and the process integration degree is high;

[0172] (2) The present invention can adopt pixel-level packaging, eliminating the subsequent complex and cumbersome vacuum packaging process of traditional uncooled infrared detectors. The entire preparation process has a high degree of process integration, greatly improving the packaging efficiency of the detector, and reducing the packaging cost, device volume, and weight.

[0173] (3) The pixel structure proposed by the present invention can achieve more comprehensive and accurate thermal detection and polarization detection functions, and is more flexible in practical applications.

[0174] Second, compared with the pixel structure of traditional pixel-level packaging:

[0175] (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 spatial targets, effectively improving the contrast between the target and the background, highlighting the detailed features of the target, and enhancing the target recognition effect in low thermal contrast application scenarios.

[0176] (2) The packaging structure proposed by the present invention can be an independent packaging structure or a shared packaging structure. The former has a lower sealing difficulty for pixel vacuum packaging, a lower probability of pixel failure, and a smaller impact on pixel failure. The latter can further reduce the pixel size for pixel vacuum packaging.

[0177] The present invention also provides a manufacturing method for the pixel structure of an uncooled infrared polarization detector, which includes:

[0178] Prepare a pixel array; the pixel array includes a plurality of pixels.

[0179] Fabricate a packaging structure above the pixel and package the pixel through the packaging structure.

[0180] Fabricate an optical isolator between two adjacent pixels.

[0181] The packaging structure includes a packaging matrix layer and a micro-polarizer structure layer. The packaging matrix layer is connected to the pixel, and the micro-polarizer structure layer is located on the upper surface of the packaging matrix layer; the micro-polarizer structure layer has a nanowire grid structure.

[0182] When the packaging structure individually packages each pixel, the packaging matrix layer directly contacts the insulating dielectric layer on the substrate; when the packaging structure performs vacuum packaging on each pixel group, the packaging matrix layer contacts the insulating dielectric layer on the substrate and the packaging support posts.

[0183] The following introduces the manufacturing method according to different vacuum packaging forms of the pixel by the packaging structure.

[0184] When the packaging structure individually packages each pixel, as an implementable manner, the manufacturing method for the pixel structure of an uncooled infrared polarization detector includes:

[0185] Step S101: Prepare a substrate; the substrate includes a substrate, a metal block, and an insulating dielectric layer.

[0186] 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, as Figure 14 shown;

[0187] Step S1012: Remove the insulating dielectric layer 3 at the center position of the pixel as Figure 15 shown. When performing vacuum packaging, an additional getter layer 4 needs to be deposited;

[0188] Step S1013: When performing vacuum packaging, remove the getter layer 4 outside the center position of the pixel, as Figure 16 shown;

[0189] Step S102: Deposit a first sacrificial layer on the substrate and etch the first sacrificial layer, and the etching area corresponds to the metal block.

[0190] Please refer to Figure 17 , etch through the first sacrificial layer 12 and the insulating dielectric layer 3 and terminate at the upper surface of the metal block 2.

[0191] The material of the first sacrificial layer 12 can be one of polyimide, polycrystalline carbon, and polysilicon, and the thickness can be 1 μm to 2.5 μm.

[0192] Step S103: Fabricate a microbridge structure on the first sacrificial layer, and the piers of the microbridge structure penetrate through the first sacrificial layer and the insulating dielectric layer and are connected to the metal block.

[0193] Please refer to Figure 17 , the pier 53 penetrates through 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.

[0194] Step S104: Deposit a second sacrificial layer on the pixel array with the first sacrificial layer, and etch the first sacrificial layer and the second sacrificial layer between adjacent pixels to expose the insulating dielectric layer.

[0195] Please refer to Figure 18 , the second sacrificial layer 13 is laminated 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 fabricating the packaging structure later, each packaging structure performs vacuum packaging on one pixel.

[0196] The material of the second sacrificial layer 13 can be polyimide or polysilicon or polycrystalline carbon, and the thickness can be 0.5 μm to 3 μm.

[0197] Step S105: Deposit an encapsulation matrix layer, and the encapsulation matrix layer is in contact with the insulating dielectric layer.

[0198] Please refer to Figure 18 , the encapsulation matrix layer 6 is located on the upper surface of the second sacrificial layer 13, the sides of the first sacrificial layer 12 and the second sacrificial layer 13, and the upper surface of the insulating dielectric layer 3 between adjacent pixels, realizing the mechanical support of the encapsulation structure.

[0199] Step S106: Deposit a micro-polarizer structure layer on the encapsulation matrix layer, and etch the micro-polarizer structure layer to form a nanowire grid structure.

[0200] Please refer to Figure 19 , the micro-polarizer structure layer 7 is located on the upper surface of the encapsulation matrix layer 6, and patterning is performed on the corresponding area of each pixel.

[0201] Step S107: Etch the encapsulation matrix layer and the micro-polarizer structure layer to form the opening 8, and release the first sacrificial layer and the second sacrificial layer through the opening 8.

[0202] Please refer to Figure 20 , the opening 8 penetrates through the encapsulation matrix layer 6 and the micro-polarizer structure layer 7 and terminates at the second sacrificial layer 13.

[0203] In this step, the first sacrificial layer 12 and the second sacrificial layer 13 can be removed by means of oxygen plasma cleaning, so as to obtain the suspended thermally isolated micro-bridge structure 5 and the encapsulation structure.

[0204] Step S108: Form an optical isolator in the gap between the encapsulation structures corresponding to adjacent pixels.

[0205] The process includes: spin-coating photoresist on the pixel structure and performing patterning, then depositing an optical barrier material to cover the gap between the encapsulation structures of adjacent pixels; removing the photoresist, and the optical isolator material on the photoresist is also removed accordingly, as shown in Figure 3 , Figure 4 , so as to obtain the pixel-level packaged uncooled infrared polarization detector pixel structure integrated with the optical isolator 11.

[0206] When the encapsulation structure encapsulates each pixel separately, as another implementable manner, the manufacturing method of the pixel structure of the uncooled infrared polarization detector includes:

[0207] Step S201: Prepare a substrate; the substrate includes a substrate, a metal block, and an insulating dielectric layer.

[0208] When performing vacuum encapsulation, the substrate further includes a getter layer.

[0209] Step S202: Deposit a first sacrificial layer on the substrate, and etch the first sacrificial layer, with the etched area corresponding to the metal block.

[0210] Step S203: Fabricate a micro-bridge structure on the first sacrificial layer, where the piers of the micro-bridge structure penetrate through the first sacrificial layer and the insulating dielectric layer and are connected to the metal block.

[0211] Step S204: Deposit a second sacrificial layer on the pixel array with the first sacrificial layer, and etch the first sacrificial layer and the second sacrificial layer between adjacent pixels to expose the insulating dielectric layer.

[0212] Step S205: Deposit a packaging matrix layer, and the packaging matrix layer is in contact with the insulating dielectric layer.

[0213] Step S206: Deposit an optical isolator on the packaging matrix layer, and etch the optical isolator, leaving the optical isolator on the sidewall of the packaging matrix layer.

[0214] Please refer to Figures 21 to 22 , after the above step S105, deposit an optical isolator 11, and then perform patterning on the optical isolator 11 to remove the optical isolator 11 at the pixel center to obtain an optical isolator structure. For the subsequent manufacturing process, please refer to the above steps S106 to S108 to obtain the structure as Figure 5 shown.

[0215] Step S207: Deposit a micro-polarizer structure layer on the packaging matrix layer, and etch the micro-polarizer structure layer to form a nanowire grid structure.

[0216] Step S208: Etch the packaging matrix layer and the micro-polarizer structure layer to form the opening, and release the first sacrificial layer and the second sacrificial layer through the opening.

[0217] When the packaging structure encapsulates each pixel group, as an implementable manner, the manufacturing method of the pixel structure of the uncooled infrared polarimeter includes:

[0218] Step S301: Prepare a substrate; the substrate includes a substrate, a metal block, and an insulating dielectric layer.

[0219] When performing vacuum packaging, the substrate further includes a getter layer.

[0220] For this step, please refer to the above step S101, and it will not be elaborated here in detail. The top view of the substrate 1 is as Figure 23 shown.

[0221] Step S302: Etch the insulating dielectric layer on the metal block to form an opening to expose the metal block.

[0222] Please refer to Figure 24 , and etch the local insulating dielectric layer 3 on the metal block 2.

[0223] Step S303: Deposit a first sacrificial layer and a first hard mask layer on the substrate in sequence.

[0224] Please refer to Figure 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.

[0225] The material of the first sacrificial layer 12 can be one of polyimide, polycrystalline carbon, and polysilicon, and the thickness can be 1μm - 2.5μm. The material of the first hard mask layer 14 can be one of silicon nitride, silicon oxide, silicon oxynitride, titanium, and titanium nitride.

[0226] Step S304: Etch 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.

[0227] Please refer to Figure 25 , pattern the first hard mask layer 14, and then etch the first sacrificial layer 12 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 terminates at the metal block 2.

[0228] Step S305: Fill the first through hole and the third through hole with a filling material to form a micro-bridge support pillar and a first isolation unit.

[0229] Please refer to Figures 26 to 27 , first deposit the filling material. The filling material fills the first through hole 18 and the third through hole and covers the first hard mask layer 14. Then, remove the excess filling material on the plane of the first sacrificial layer 12 by chemical mechanical polishing (CMP) and etch back, and then etch away the first hard mask layer 14 to form a micro-bridge support pillar 16 and a first isolation unit.

[0230] In this step, the filling material can be a conductive metal material such as tungsten, copper, aluminum, gold, titanium, and titanium nitride.

[0231] Step S306: Fabricate a microbridge structure on the first sacrificial layer; the microbridge structure includes bridge piers, and the bridge piers include the microbridge support columns, a microbridge support layer, and a metal electrode layer. The microbridge support layer is located above and on the sides of the microbridge support columns, and the metal electrode layer is located above the microbridge support layer and is electrically connected to the microbridge support columns.

[0232] Please refer to Figure 28 , a thermally isolated microbridge structure 5 is fabricated above the first sacrificial layer 12. The bridge piers 53 of the microbridge structure 5 are composed of microbridge support columns 16, a microbridge support layer 54 deposited above the microbridge support columns 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 columns 16 are electrically connected. The top view is as shown in Figure 29 . A first isolation unit 111 is formed around the pixel.

[0233] The bridge pier 53 further includes a passivation protection layer 56 on the metal electrode to prevent the metal electrode layer 55 from being oxidized or corroded during subsequent fabrication.

[0234] Step S307: Sequentially deposit a second sacrificial layer and a second hard mask layer on the pixel array having the first sacrificial layer.

[0235] The material of the second sacrificial layer 13 can be one of polyimide, polycrystalline carbon, and polysilicon, and the material of the second hard mask layer 15 can be one of silicon nitride, silicon oxide, silicon oxynitride, and titanium nitride.

[0236] Step S308: Etch the second hard mask layer and the second sacrificial layer to form a second through-hole and a fourth through-hole. The second through-hole corresponds to the first through-hole, and the fourth through-hole corresponds to the third through-hole.

[0237] Please refer to Figure 30 , the second sacrificial layer 13 and the second hard mask layer 15 are sequentially stacked on the pixel array. First, the second hard mask layer 15 is patterned, and then the second sacrificial layer 13 is etched to obtain high-aspect-ratio second through-holes 19 and fourth through-holes. The second through-holes 19 and the fourth through-holes terminate at the passivation protection layer 56.

[0238] Step S309: Fill the second through-hole and the fourth through-hole with a filling material to form encapsulation support columns and a second isolation unit 112.

[0239] Please refer to Figure 31, The via filling material fills the second via 19 and the fourth via, and covers the second hard mask layer 15. Then, the excess via 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 the encapsulation support pillar 17.

[0240] In this step, the via filling material can be conductive metal materials such as tungsten, copper, aluminum, gold, titanium, and titanium nitride, or mechanical support materials such as amorphous silicon, silicon nitride, silicon oxide, and silicon oxynitride.

[0241] Step S310: Etch the first sacrificial layer and the second sacrificial layer between adjacent pixel groups to expose the insulating dielectric layer.

[0242] Please refer to Figure 32 , In this step, the first sacrificial layer 12 and the second sacrificial layer 13 between adjacent pixel groups are etched so that when fabricating the encapsulation structure subsequently, each encapsulation structure can perform vacuum encapsulation on one pixel group.

[0243] Step S311: Deposit the encapsulation matrix layer and the micro-polarizer structure layer in sequence, and etch the micro-polarizer structure layer to form a nanowire grid structure.

[0244] Please refer to Figure 33 , A second isolation unit body 112 is formed around the pixel.

[0245] Step S312: Etch the encapsulation matrix layer and the micro-polarizer structure layer to form the opening, and release the first sacrificial layer and the second sacrificial layer through the opening.

[0246] Please refer to Figure 32 , The encapsulation matrix layer 6 and the micro-polarizer structure layer 7 are patterned to fabricate the opening 8. The opening 8 penetrates through the encapsulation matrix layer 6 and the micro-polarizer structure layer 7 and terminates at the second sacrificial layer 13. Then, the first sacrificial layer 12 and the second sacrificial layer 13 are removed by oxygen plasma cleaning, thereby obtaining the suspended thermally isolated micro-bridge structure 5 and the shared encapsulation structure.

[0247] Based on any of the above embodiments, in an embodiment of the present invention, after releasing the first sacrificial layer and the second sacrificial layer, it may further include:

[0248] Under vacuum conditions, deposit an infrared window layer on the surface. The infrared window layer completely fills the opening to form an encapsulation structure.

[0249] Please refer to Figures 7 to 9 , Deposit the infrared window layer 9 under vacuum. The infrared window layer 9 is located on the upper surface of the micro-polarizer structure layer 7 and completely fills and closes the opening, thereby realizing the vacuum encapsulation of the thermally isolated micro-bridge structure 5.

[0250] It should be noted that after the encapsulation structure is formed, the getter layer needs to be activated to maintain the vacuum degree in the vacuum chamber formed by the encapsulation structure. The activation method of the getter layer can be by means of high-temperature annealing treatment.

[0251] In order to improve the infrared light transmittance of the window of the encapsulation structure, after the encapsulation structure is formed, it may further include:

[0252] Depositing an infrared antireflection layer 10 on the upper surface of the infrared window layer 9, as Figures 7 to 9 shown.

[0253] The present invention also provides a non-cooled infrared polarization detector, including the pixel structure of the non-cooled infrared polarization detector described in any one of the above embodiments.

[0254] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0255] The pixel structure, its manufacturing method, and the non-cooled infrared polarization detector provided by the present invention have been introduced in detail above. Specific examples are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the solution and the core idea of the present invention. It should be noted that for those of ordinary skill in the art 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 protection scope 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; 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; 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).

2. The pixel structure of the uncooled infrared polarization detector according to claim 1, 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.

3. The pixel structure of the uncooled infrared polarization detector according to claim 1, 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.

4. The pixel structure of the uncooled infrared polarization detector according to claim 1, 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.

5. The pixel structure of the uncooled infrared polarization detector according to claim 1, 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.

6. The pixel structure of the uncooled infrared polarization detector according to claim 1, 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.

7. 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 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; Wherein, 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); 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).

8. 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 6.

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