Uncooled focal plane infrared sensor and method of making same

Abstract

A non-cooled focal plane infrared sensor and a preparation method thereof, the non-cooled focal plane infrared sensor comprising: a substrate having a readout circuit therein; a plurality of pixel micro-bridges on the substrate, each of the pixel micro-bridges comprising a first pier, a leg cantilever beam, a second pier and a micro-bridge deck, wherein the first pier is protruded from a surface of the substrate, the leg cantilever beam is supported by the first pier to be suspended above the substrate, the second pier is protruded from a surface of the leg cantilever beam, the micro-bridge deck is supported by the second pier to be suspended above the leg cantilever beam, the micro-bridge deck is electrically connected with the readout circuit through the second pier, the leg cantilever beam and the first pier, and the leg cantilever beam of a single pixel micro-bridge further spans below at least two adjacent micro-bridge decks. The design space of the leg cantilever beam is increased, and the design freedom and the heat insulation performance of the pixel micro-bridge are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sensors, in particular to a non-cooled focal plane infrared sensor and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of optoelectronic technology and products, infrared focal plane sensors are developing towards large array, high sensitivity and low power consumption. Reducing the pixel pitch is an important direction for the development of future focal plane infrared sensors. The pixel pitch of non-cooled focal plane infrared sensors has been reduced from the initial 50μm×50μm to the current 8μm×8μm. With a certain number of pixels, small pixel pitch can reduce the volume and weight of the sensor and expand the application scenarios of infrared sensors.

[0003] However, when the pixel is reduced to a small size such as 10μm or 8μm, how to reduce the thermal conductance of the micro-bridge cantilever under the condition of reducing the pixel pitch and realize high sensitivity detection of infrared signals is a technical problem to be solved. Currently, there are mainly two kinds of micro-bridge structures for commercially available small pixel pitch sensors. One is to set an independent infrared absorption layer above the heat-sensitive layer. This structure can increase the absorption area of infrared radiation and improve the optical fill factor, but the cantilever and the heat-sensitive layer are still on the same bridge surface, the length of the cantilever is insufficient, the thermal conductance of the device is large, and the thermal sensitivity is low. The other is to arrange the cantilever and the heat-sensitive layer in layers, with the cantilever layer below the heat-sensitive layer. However, the bridge pier and the cantilever are placed below the same micro-bridge bridge surface, which limits the arrangement space of the cantilever. At the same time, the cantilever is limited below the current pixel, which is still limited by the small pixel area. Therefore, the above two micro-bridge structures have the problem of heat insulation bottleneck. SUMMARY

[0004] The technical problem to be solved by the present application is how to increase the design space of the micro-bridge cantilever, improve the design freedom and heat insulation performance of the pixel micro-bridge, maximize the arrangement space of the cantilever layer, and solve the limitation of small pixel micro-bridge cantilever design space.

[0005] To solve the above problems, some embodiments of the present application provide a non-cooled focal plane infrared sensor, comprising:

[0006] a substrate having a readout circuit in the substrate;

[0007] a plurality of pixel micro-bridges on the substrate, each of the pixel micro-bridges comprising a first abutment, a leg cantilever beam, a second abutment and a micro-bridge deck, wherein the first abutment is protruded from a surface of the substrate, the leg cantilever beam is suspended above the substrate by the first abutment, the second abutment is protruded from a surface of the leg cantilever beam, and the micro-bridge deck is suspended above the leg cantilever beam by the second abutment, and the micro-bridge deck is electrically connected to the readout circuit through the second abutment, the leg cantilever beam and the first abutment;

[0008] and the leg cantilever beam of a single one of the pixel micro-bridges further spans under at least two adjacent micro-bridge decks.

[0009] In some embodiments, the leg cantilever beam of a single one of the pixel micro-bridges further spans under two adjacent micro-bridge decks, or further spans under three adjacent micro-bridge decks, or further spans under more than three adjacent micro-bridge decks.

[0010] In some embodiments, the number of the first abutment and the second abutment in a single one of the pixel micro-bridges is two, the leg cantilever beam of a single one of the pixel micro-bridges comprises two micro-cantilever beams which are not in contact with each other, the two micro-cantilever beams are respectively located under at least two adjacent micro-bridge decks, the micro-cantilever beam presents a multi-convoluted structure along a direction parallel to the surface of the substrate, one end of a single one of the micro-cantilever beams is connected to a first abutment, and the other end is connected to a second abutment on the same side.

[0011] In some embodiments, the second abutment in a single one of the pixel micro-bridges is located under the micro-bridge deck electrically connected thereto, and the first abutment in the single one of the pixel micro-bridges is located under the micro-bridge deck of an adjacent pixel micro-bridge, and the micro-cantilever beam presents a multi-convoluted structure along a direction parallel to the surface of the substrate from the first abutment to the second abutment.

[0012] In some embodiments, the multi-convoluted structure of the micro-cantilever beam is a double-arc shape, a multi-arc shape, a double-S shape or a multi-S shape; the two micro-cantilever beams in the leg cantilever beam of a single one of the pixel micro-bridges present a symmetrical structure, or present an asymmetrical structure with equal lengths.

[0013] In some embodiments, there are 4, 6, 8 or 2x+2 micro-cantilever beams under a single one of the micro-bridge decks, and x is greater than 3.

[0014] In some embodiments, the upper and lower surfaces of the micro-cantilever beam are parallel to the surface of the substrate, or form an angle with the surface of the substrate.

[0015] In some embodiments, the angles between the upper and lower surfaces of the micro-cantilever beam of different pixel micro-bridges and the surface of the substrate under a single one of the micro-bridge decks are the same or different.

[0016] In some embodiments, the microcantilever beams in the multi-turn structure under the same microbridge deck are at the same height, or at different heights.

[0017] In some embodiments, the first pier and the bridge leg cantilever beam comprise a first support layer, a first electrode layer on the first support layer, and a first passivation layer on the first electrode layer, the second pier comprises a second support layer, a second electrode layer on the second support layer, and a second passivation layer on the second electrode layer, and the second electrode layer is electrically connected to the first electrode layer.

[0018] In some embodiments, the microbridge deck comprises the second support layer, a heat-sensitive layer on part of the second support layer, and a second passivation layer on the heat-sensitive layer and part of the second support layer, and the heat-sensitive layer is electrically connected to the second electrode layer.

[0019] In some embodiments, further comprising: a reflective layer on the surface of the substrate, and the microbridge deck and the reflective layer form a resonant absorption cavity of 1 / 4 absorption wavelength.

[0020] The application also provides a preparation method of a non-cooled focal plane infrared sensor, comprising:

[0021] A substrate is provided, and a readout circuit is formed in the substrate;

[0022] A first sacrificial layer is formed on the substrate;

[0023] A first pier is formed in the first sacrificial layer, and a bridge leg cantilever beam supported by the first pier is formed on the surface of the first sacrificial layer, and the bridge leg cantilever beam spans under at least two adjacent microbridge decks formed subsequently;

[0024] A second sacrificial layer covering the first pier and the bridge leg cantilever beam is formed on the first sacrificial layer;

[0025] A second pier is formed in the second sacrificial layer, the bottom of the second pier is in contact with the surface of the bridge leg cantilever beam, and a microbridge deck supported by the second pier is formed on the surface of the second sacrificial layer;

[0026] The first sacrificial layer and the second sacrificial layer are released, so that the bridge leg cantilever beam is supported by the first pier and suspended above the substrate, and the microbridge deck is supported by the second pier and suspended above the bridge leg cantilever beam.

[0027] In some embodiments, before the first sacrificial layer is formed, a reflective layer is formed on the surface of the substrate, and the reflective layer and the microbridge deck form a resonant absorption cavity of 1 / 4 absorption wavelength.

[0028] In some embodiments, the first pier and cantilever beam includes a first support layer, a first electrode layer on the first support layer, and a first passivation layer on the first electrode layer.

[0029] In some embodiments, the formation process of the first pier and the cantilever beam of the bridge leg includes:

[0030] A first via is formed in the first sacrificial layer to expose a portion of the substrate surface;

[0031] A first support layer is formed on the sidewall and bottom surface of the first through hole and on the surface of the first sacrificial layer;

[0032] A portion of the first support layer at the bottom surface of the first through-hole is removed to form a first opening that exposes a portion of the substrate surface.

[0033] A first electrode layer is formed on the surface of the first support layer and in the first opening, and the first electrode layer is electrically connected to the readout circuit in the substrate.

[0034] A first passivation layer is formed on the first electrode layer, and the first support layer, the first electrode layer and the first passivation layer in the first through hole constitute the first bridge pier;

[0035] Etching removes a portion of the first passivation layer, the first electrode layer, and the first support layer from the surface of the first sacrificial layer, forming a bridge leg cantilever beam with its upper and lower surfaces parallel to the surface of the substrate, and the bridge leg cantilever beam is at the same height.

[0036] In some embodiments, the second pier includes a second support layer, a second electrode layer on the second support layer, and a second passivation layer on the second electrode layer; the microbridge deck includes the second support layer, a heat-sensitive layer on a portion of the second support layer, and a second passivation layer on the heat-sensitive layer and a portion of the second support layer, wherein the heat-sensitive layer is electrically connected to the second electrode layer.

[0037] In some embodiments, the formation process of the second pier and the microbridge deck includes:

[0038] A second through-hole is formed in the second sacrificial layer to expose a portion of the surface of the first passivation layer in the cantilever beam of the bridge leg;

[0039] A second support layer is formed on the sidewall and bottom surface of the second through hole and on the surface of the second sacrificial layer;

[0040] Remove a portion of the second support layer from the bottom surface of the second through hole and a portion of the first passivation layer below the second through hole to form a second opening that exposes a portion of the surface of the first electrode layer in the cantilever beam of the bridge leg.

[0041] forming a second electrode layer on the surface of the second support layer and in the second opening, the second electrode layer being electrically connected with the first electrode layer;

[0042] removing part of the second electrode layer on the surface of the second sacrificial layer to expose the surface of the second support layer;

[0043] forming a heat-sensitive layer on the exposed surface of the second support layer on the second sacrificial layer and on the surface of the part of the second electrode layer, the heat-sensitive layer being electrically connected with the second electrode layer;

[0044] forming a second support layer on the surface of the second electrode layer and on the surface of the heat-sensitive layer, the second support layer, the second electrode layer and the second passivation layer in the second via constituting the first pier, and the second support layer, the heat-sensitive layer and the second passivation layer on the surface of the second sacrificial layer constituting the micro-bridge deck.

[0045] Compared with the prior art, the technical scheme in some embodiments of the present application has the following advantages:

[0046] The bridge leg cantilever beam of the single pixel micro-bridge spans under at least two adjacent micro-bridge decks, i.e. the bridge leg cantilever beam borrows the space under the adjacent pixel micro-bridge, increases the design space of the bridge leg cantilever beam (or micro-cantilever beam), improves the design freedom and heat insulation performance of the pixel micro-bridge, maximizes and optimizes the arrangement space of the bridge leg cantilever beam (or micro-cantilever beam), solves the limitation of small pixel micro-bridge cantilever beam design space, thereby greatly increasing the length of the bridge leg cantilever beam (or micro-cantilever beam), improving the heat insulation performance of the pixel micro-bridge, effectively improving the thermal performance of the device, and realizing high-sensitivity detection of infrared light. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 a structural schematic diagram of a non-refrigeration focal plane infrared sensor in some embodiments of the present application;

[0048] Figures 2-3 a structural schematic diagram of a first pier, a bridge leg cantilever beam and a second pier in some embodiments of the present application;

[0049] Figure 4 a structural schematic diagram of a first pier, a bridge leg cantilever beam and a second pier in some embodiments of the present application;

[0050] Figure 5 a structural schematic diagram of a first pier, a bridge leg cantilever beam and a second pier in some embodiments of the present application;

[0051] Figure 6 a structural schematic diagram of a non-refrigeration focal plane infrared sensor in some embodiments of the present application;

[0052] Figure 7 This is a flowchart illustrating the formation process of an uncooled focal plane infrared sensor in some embodiments of this application. Detailed Implementation

[0053] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. In describing the embodiments of this application in detail, for ease of explanation, the schematic diagrams may be partially enlarged without adhering to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of this application. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0054] Some embodiments of this application first provide an uncooled focal plane infrared sensor, see reference... Figures 1-3 , Figure 2 for Figure 1 A top-view structural diagram of the first pier, the cantilever beam of the bridge leg, and the second pier in the middle section. Figure 3 for Figure 1 A top-view structural diagram of the central section of the miniature bridge, including the bridge deck, the first pier, the cantilever beam of the bridge leg, and the second pier, comprising:

[0055] Substrate 1, wherein the substrate 1 has a readout circuit 10;

[0056] Multiple pixel microbridges 8 are located on the substrate 1. Each pixel microbridge 8 includes a first pier 3, a cantilever beam 4, a second pier 5, and a microbridge deck 9. The first pier 3 protrudes from the surface of the substrate 1. The cantilever beam 4 is suspended above the substrate 1 by the support of the first pier 3. The second pier 5 protrudes from the surface of the cantilever beam 4. The microbridge deck 9 is suspended above the cantilever beam 4 by the support of the second pier 5. The microbridge deck 9 is electrically connected to the readout circuit 10 through the second pier 5, the cantilever beam 4, and the first pier 3.

[0057] Furthermore, the cantilever beam 4 of the leg of a single pixel microbridge 8 also spans across the underside of at least two adjacent microbridge decks 9.

[0058] Specifically, a readout circuit 10 is formed in the substrate 1. The readout circuit 10 is an integrated circuit formed in the substrate 1. The readout circuit 10 is used to process the output signal output by the sensing unit of the uncooled focal plane infrared sensor (e.g., the electrical signal output by the microbridge surface 9 in the pixel microbridge 8 according to the change of infrared radiation of the target object). The processing includes reading out and calibrating the output signal output by the sensing unit.

[0059] The substrate 1 has a plurality of pixel micro-bridges 8, each of which corresponds to a pixel or a sensing unit of a non-cooled focal plane infrared sensor. In some embodiments, the plurality of pixel micro-bridges 8 are arranged in a row-column or array on the substrate 1, such as Figure 2 In some embodiments, the x-axis direction can be regarded as the row direction, and the y-axis direction can be regarded as the column direction. Figure 2 In some embodiments, the positions of four pixel micro-bridges 8 in the column direction are shown, including pixel micro-bridge 8a, pixel micro-bridge 8b, pixel micro-bridge 8c, and pixel micro-bridge 8d from top to bottom along the column direction.

[0060] Each of the pixel micro-bridges 8 includes two first piers 3, a bridge leg cantilever beam 4, two second piers 5, and a micro-bridge deck 9. The first piers 3 are protruded on the surface of the substrate 1, the bottom of the first piers 3 is electrically connected to the readout circuit 10 in the substrate 1, and the top of the first piers 3 is used to support the bridge leg cantilever beam 4, which is used to provide support for the second piers 5 and to electrically connect the first piers 3 and the second piers 5. The second piers 5 are used to support and electrically connect the micro-bridge deck 9. The micro-bridge deck 9 generates a change in thermistor according to the change in infrared radiation of the target object, and converts the change in thermistor into an electrical signal output.

[0061] In some embodiments, the first piers 3 and the bridge leg cantilever beam 4 include a first support layer 11, a first electrode layer 12 on the first support layer 11, and a first passivation layer 13 on the first electrode layer 12. In some embodiments, the material of the first support layer 11 is one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, and silicon carbonitride, the material of the first electrode layer 12 is one or more of titanium, germanium, platinum, nickel-chromium, and titanium nitride, and the material of the first passivation layer 13 is one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, and silicon carbonitride. In other embodiments, the first piers 3 can be metal columns with an outer wall coated with an insulating layer.

[0062] In the present application, the bridge leg cantilever beam 4 of the single pixel micro-bridge 8 also spans under at least two adjacent micro-bridge decks 9, that is, the bridge leg cantilever beam 4 uses the space under the adjacent pixel micro-bridge 8 to increase the design space of the bridge leg cantilever beam 4 (or micro-cantilever beam), improve the design freedom and thermal insulation performance of the pixel micro-bridge, maximize the optimization of the arrangement space of the bridge leg cantilever beam 4 (or micro-cantilever beam), solve the limitation of small pixel micro-bridge cantilever beam design space, thereby greatly increasing the length of the bridge leg cantilever beam 4 (or micro-cantilever beam), improving the thermal insulation performance of the pixel micro-bridge, effectively improving the thermal performance of the device, and realizing high-sensitivity detection of infrared light. In some specific embodiments, the bridge leg cantilever beam 4 of the single pixel micro-bridge 8 spans under two adjacent micro-bridge decks 9, or spans under three adjacent micro-bridge decks 9, or spans under more than three adjacent micro-bridge decks 9.

[0063] In some embodiments, please refer to Figure 2 and Figure 3 , four pixel micro-bridges in the column direction (for example, pixel micro-bridge 8a, pixel micro-bridge 8b, pixel micro-bridge 8c, and pixel micro-bridge 8d) and four micro-bridge decks above the four pixel micro-bridges (for example, micro-bridge deck 9a, micro-bridge deck 9b, micro-bridge deck 9c, and micro-bridge deck 9d) are sequentially arranged in the column direction from top to bottom. Figure 2 and Figure 3 , four pixel micro-bridges in the column direction (for example, pixel micro-bridge 8a, pixel micro-bridge 8b, pixel micro-bridge 8c, and pixel micro-bridge 8d) and four micro-bridge decks above the four pixel micro-bridges (for example, micro-bridge deck 9a, micro-bridge deck 9b, micro-bridge deck 9c, and micro-bridge deck 9d) are sequentially arranged in the column direction from top to bottom. Figure 3 In the present application, the bridge leg cantilever beam 4 of the single pixel micro-bridge 8 also spans under at least two adjacent micro-bridge decks 9, that is, the bridge leg cantilever beam 4 uses the space under the adjacent pixel micro-bridge 8 to increase the design space of the bridge leg cantilever beam 4 (or micro-cantilever beam), improve the design freedom and thermal insulation performance of the pixel micro-bridge, maximize the optimization of the arrangement space of the bridge leg cantilever beam 4 (or micro-cantilever beam), solve the limitation of small pixel micro-bridge cantilever beam design space, thereby greatly increasing the length of the bridge leg cantilever beam 4 (or micro-cantilever beam), improving the thermal insulation performance of the pixel micro-bridge, effectively improving the thermal performance of the device, and realizing high-sensitivity detection of infrared light. In some specific embodiments, the bridge leg cantilever beam 4 of the single pixel micro-bridge 8 spans under two adjacent micro-bridge decks 9, or spans under three adjacent micro-bridge decks 9, or spans under more than three adjacent micro-bridge decks 9.

[0064] In a specific embodiment, please continue to refer to Figure 2 and Figure 3When the leg cantilever beam 4 of a single pixel micro-bridge 8 spans under two adjacent micro-bridge decks 9, the leg cantilever beam 4 of the single pixel micro-bridge 8b (including two micro-cantilever beams 41) spans under two adjacent micro-bridge decks 9b and 9c, for example, the leg cantilever beam 4 of the pixel micro-bridge 8b (including two micro-cantilever beams 41) spans under the micro-bridge deck 9b partially and under the micro-bridge deck 9c partially, and the micro-cantilever beams 41 are in a multi-arcuate structure along the direction parallel to the substrate surface, and a single micro-cantilever beam 41 is connected to a first pier 3 at one end and to a second pier 5 at the other end; for another example, the leg cantilever beam 4 of another pixel micro-bridge 8c (including two micro-cantilever beams 42) spans under two adjacent micro-bridge decks 9c and 9d, i.e. the leg cantilever beam 4 of the pixel micro-bridge 8c (including two micro-cantilever beams 42) spans under the micro-bridge deck 9c partially and under the micro-bridge deck 9d partially, and the micro-cantilever beams 42 are in a multi-arcuate structure along the direction parallel to the substrate surface, and a single micro-cantilever beam 42 is connected to a first pier 3 at one end and to a second pier 5 at the other end.

[0065] With continued reference to Figure 2 and Figure 3 , the two second piers 5 of a single pixel micro-bridge are located under the micro-bridge deck electrically connected thereto, and the two first piers 3 of the single pixel micro-bridge are located under the micro-bridge deck of an adjacent pixel micro-bridge, for example, the two second piers 5 of a single pixel micro-bridge 8b are located under the micro-bridge deck 9b electrically connected thereto, and the two first piers 3 of the single pixel micro-bridge 8b are located under the micro-bridge deck 9c of an adjacent pixel micro-bridge 8c, and a single micro-cantilever beam (41 or 42) is in a multi-arcuate structure along the direction parallel to the substrate surface from a first pier 3 to a second pier 5.

[0066] In some embodiments, the multi-arcuate structure of the micro-cantilever beam (41 or 42) is a double-arcuate structure, a multi-arcuate structure, a double-S structure or a multi-S structure; the two micro-cantilever beams (41 or 42) of the leg cantilever beam 4 of a single pixel micro-bridge 8 are in a symmetrical structure or in an asymmetrical structure with equal lengths.

[0067] The specific arrangement of the leg cantilever beam 4 (or two micro-cantilever beams) of a single pixel micro-bridge 8 when spanning under at least two adjacent micro-bridge decks 9 can be different, and in some embodiments, with continued reference to Figure 2 and Figure 3 , each micro-bridge deck includes a middle region and an edge region surrounding the middle region from three sides, for example Figure 2In the region corresponding to the middle-pixel micro-bridge 8d, the blank region in the middle is the middle region, and the other regions are the edge regions, which surround the middle region from the top, left and right sides. When the bridge leg cantilever beam 4 (or two micro-cantilever beams) of a single pixel micro-bridge 8 is distributed, part of it is located in the middle region below the micro-bridge deck 9 of the pixel micro-bridge 8, and part of it is located in the edge region below the adjacent micro-bridge deck 9. The two second piers 5 are located in the middle region, and the two first piers are located in the edge regions on the left and right sides, respectively. For example, the bridge leg cantilever beam 4 (including two micro-cantilever beams 41) of the pixel micro-bridge 8b is partially located in the middle region below the micro-bridge deck 9b and partially located in the edge region below the micro-bridge deck 9c (the two micro-cantilever beams 41 are distributed in the edge regions on the left and right sides, respectively), and the two micro-cantilever beams 41 have a multiple winding structure in the corresponding region along a direction parallel to the substrate surface. The bridge leg cantilever beam 4 (including two micro-cantilever beams 42) of the pixel micro-bridge 8c is partially located in the middle region below the micro-bridge deck 9c and partially located in the edge region below the micro-bridge deck 9d (the two micro-cantilever beams 42 are distributed in the edge regions on the left and right sides, respectively), and the two micro-cantilever beams 42 have a multiple winding structure in the corresponding region along a direction parallel to the substrate surface.

[0068] In other embodiments, referring to Figure 4 , each micro-bridge deck below includes a middle region and an edge region surrounding the middle region from three sides, such as Figure 4 In the region corresponding to the middle-pixel micro-bridge 8a, the blank region in the middle is the middle region, and the other regions are the edge regions, which surround the middle region from the bottom, left and right sides. When the bridge leg cantilever beam 4 (including two micro-cantilever beams) of a single pixel micro-bridge (8a, 8b, 8c or 8d) is distributed, part of it is located in the edge regions on the left and right sides below the micro-bridge deck (the two second piers are also located in the edge regions on the left and right sides, respectively), and part of it is located in the middle region below the adjacent micro-bridge deck (the two first piers are located in the middle region), and the two micro-cantilever beams have a multiple winding structure in the corresponding region along a direction parallel to the substrate surface. The two second piers are located in the middle region, and the two first piers are located in the edge regions on the left and right sides, respectively.

[0069] In other embodiments, each micro-bridge deck below includes a left-right symmetric first region and a second region. The bridge leg cantilever beam (including two micro-cantilever beams) of one pixel micro-bridge is located in the first region below the two adjacent micro-bridge decks, and the bridge leg cantilever beam (including two micro-cantilever beams) of another adjacent pixel micro-bridge is located in the second region below the two adjacent micro-bridge decks.

[0070] In another embodiment, referring to Figure 5, the bridge leg cantilever beam 4 (including two micro cantilever beams) of the single said pixel micro bridge 8 spans under the adjacent three said micro bridge decks, specifically, the area under each micro bridge deck can include a core area, an intermediate area surrounding the core area from three sides, and an edge area on both sides of the intermediate area, the bridge leg cantilever beam 4 (including two micro cantilever beams) of the single said pixel micro bridge 8 is partially located in the core area under the micro bridge deck of the pixel micro bridge 8, partially located in the intermediate area under the first adjacent micro bridge deck, and partially located in the edge area of the intermediate area under the first adjacent micro bridge deck. Further increase the length of the bridge leg cantilever beam 4 (including two micro cantilever beams).

[0071] Since the bridge leg cantilever beam 4 (including two micro cantilever beams) of the single said pixel micro bridge 8 spans under the adjacent at least two micro bridge decks, there can be 4, 6, 8 or 2x+2 micro cantilever beams under the single said micro bridge deck, x is greater than 3.

[0072] With reference to Figure 1 and Figure 2 , the upper and lower surfaces of the micro cantilever beam (41 or 42) are parallel to the substrate surface. In another embodiment, with reference to Figure 6 , the upper and lower surfaces of the micro cantilever beam (41 or 42) are at an angle to the substrate surface, the angle can range from 40-70 degrees, specifically 60 degrees, which can further optimize the layout space of the micro cantilever beam under the condition of a certain size of the pixel micro bridge, and the single pixel micro bridge obtains more winding times of the micro cantilever beam or more micro cantilever beams of the pixel micro bridge under the single micro bridge deck, further increasing the length of the micro cantilever beam.

[0073] In some embodiments, the included angle between the upper and lower surfaces of the micro cantilever beam of different pixel micro bridges 8 under the single said micro bridge deck 9 and the substrate surface is the same or different.

[0074] In some embodiments, the micro cantilever beam (or bridge leg cantilever beam 4) under the same said micro bridge deck 9 in a multiple winding structure is at the same height or at different heights.

[0075] In some embodiments, with reference to Figure 1The second bridge pier 5 comprises a second support layer 21, a second electrode layer 22 on the second support layer 21, and a second passivation layer 23 on the second electrode layer 22, and the second electrode layer 22 is electrically connected with the first electrode layer 12. In some embodiments, the material of the second support layer 21 is one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, and silicon carbonitride, the material of the second electrode layer 22 is one or more of titanium, germanium, platinum, nickel-chromium, and titanium nitride, and the material of the second passivation layer 23 is one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, and silicon carbonitride. In other embodiments, the second bridge pier 5 can be a metal column with an outer wall coated with an insulating layer.

[0076] In some embodiments, the micro-bridge deck 9 comprises the second support layer 21, a heat-sensitive layer 6 on part of the second support layer 21, and a second passivation layer 23 on the heat-sensitive layer 6 and part of the second support layer 21, and the heat-sensitive layer 6 is electrically connected with the second electrode layer 22.

[0077] The heat-sensitive layer 6 is composed of an infrared heat-sensitive film, and is electrically connected with the second bridge pier 5, the bridge leg cantilever beam 4, the first bridge pier 3, and the readout circuit 10 on the substrate 1. The material of the infrared heat-sensitive film is vanadium oxide, amorphous silicon, copper oxide, manganese oxide, molybdenum oxide, or titanium oxide. The resistance of the heat-sensitive resistor in the heat-sensitive layer 6 changes according to the change of the infrared radiation of the target object, and the change of the electrical signal caused by the change of the resistance is transmitted to the readout circuit 35 through the second bridge pier 5, the bridge leg cantilever beam 4, and the first bridge pier 3, and a result signal is output by the readout circuit 35 to reflect the temperature of the target object.

[0078] In some embodiments, a reflective layer 2 is further provided on the surface of the substrate 10, and the micro-bridge deck 9 and the reflective layer 2 form a resonant absorption cavity with a quarter of the absorption wavelength. The reflective layer 2 is used to reflect the infrared radiation to enhance the absorption capacity of the micro-bridge deck 9 to the infrared radiation. The material of the reflective layer 2 can be one or more of nickel, chromium, gold, silver, and other metals.

[0079] Some embodiments of the present application further provide a preparation method of a non-cooled focal plane infrared sensor, which is combined with reference to the above-mentioned non-cooled focal plane infrared sensor. Figure 7 and Figure 1 , comprising:

[0080] In step S301, a substrate 1 is provided, and a readout circuit 10 is formed in the substrate 1.

[0081] In step S302, a first sacrificial layer (not shown in the figure) is formed on the substrate 1.

[0082] Step S303, forming a first bridge pier 3 in the first sacrificial layer, forming a bridge leg cantilever beam 4 supported by the first bridge pier 3 on the surface of the first sacrificial layer, the bridge leg cantilever beam 4 spanning below the subsequently formed adjacent at least two micro-bridge decks;

[0083] Step S304, forming a second sacrificial layer (not shown in the figure) covering the first bridge pier 3 and the bridge leg cantilever beam 4 on the first sacrificial layer;

[0084] Step S305, forming a second bridge pier 5 in the second sacrificial layer, the bottom of the second bridge pier 5 being in contact with the surface of the bridge leg cantilever beam 4, forming a micro-bridge deck 9 supported by the second bridge pier 5 on the surface of the second sacrificial layer;

[0085] Step S306, releasing the first sacrificial layer and the second sacrificial layer, so that the bridge leg cantilever beam 4 is supported by the first bridge pier 3 and suspended above the substrate 1, so that the micro-bridge deck 9 is supported by the second bridge pier 5 and suspended above the bridge leg cantilever beam 4.

[0086] Specifically, the materials of the first and second sacrificial layers are different from the materials of the first bridge pier 3, the bridge leg cantilever beam 4 and the second bridge pier. The first and second sacrificial layers are formed by deposition or spin coating process. In some embodiments, the materials of the first and second sacrificial layers can be inorganic materials such as amorphous silicon, silicon oxide, silicon nitride, amorphous carbon, polysilicon, germanium silicon, etc. The materials of the first and second sacrificial layers can also be photoresist, or polymers such as polyimide, benzene propyl cyclobutene, acrylic homopolymer, etc.

[0087] In some embodiments, before forming the first sacrificial layer, a reflective layer 2 is formed on the surface of the substrate 1, and the reflective layer 2 forms a 1 / 4 absorption wavelength resonant absorption cavity with the micro-bridge deck 6.

[0088] In some embodiments, the first bridge pier 3 and the bridge leg cantilever beam 4 include a first support layer 11, a first electrode layer 12 on the first support layer 11, and a first passivation layer 13 on the first electrode layer 12.

[0089] In some embodiments, the process of forming the first bridge pier 3 and the bridge leg cantilever beam 4 includes:

[0090] forming a first via in the first sacrificial layer, which exposes part of the surface of the substrate 1;

[0091] forming a first support layer 11 on the sidewall and bottom surface of the first via and the surface of the first sacrificial layer;

[0092] A portion of the first support layer 11 at the bottom surface of the first through hole is removed to form a first opening that exposes a portion of the surface of the substrate 1.

[0093] A first electrode layer 12 is formed on the surface of the first support layer 11 and in the first opening, and the first electrode layer is electrically connected to the readout circuit 10 in the substrate 1.

[0094] A first passivation layer 13 is formed on the first electrode layer 12, and the first support layer 11, the first electrode layer 12 and the first passivation layer 13 in the first through hole constitute the first bridge pier 3.

[0095] Etching removes a portion of the first passivation layer 11, the first electrode layer 12, and the first support layer 13 from the surface of the first sacrificial layer, forming a bridge leg cantilever beam 4 with its upper and lower surfaces parallel to the surface of the substrate 1, and the bridge leg cantilever beam 4 is at the same height.

[0096] In some embodiments, the second pier 5 includes a second support layer 21, a second electrode layer 22 located on the second support layer 21, and a second passivation layer 23 located on the second electrode layer 22; the microbridge deck 9 includes the second support layer 21, a heat-sensitive layer 6 located on a portion of the second support layer 21, and a second passivation layer 23 located on the heat-sensitive layer 6 and a portion of the second support layer 21, wherein the heat-sensitive layer 6 is electrically connected to the second electrode layer 22.

[0097] In some embodiments, the formation process of the second pier 5 and the microbridge deck 9 includes:

[0098] A second through-hole is formed in the second sacrificial layer to expose a portion of the surface of the first passivation layer 13 in the cantilever beam 4 of the bridge leg;

[0099] A second support layer 21 is formed on the sidewall and bottom surface of the second through hole and on the surface of the second sacrificial layer;

[0100] Remove a portion of the second support layer 21 from the bottom surface of the second through hole and a portion of the first passivation layer 13 below the second through hole to form a second opening that exposes a portion of the surface of the first electrode layer 12 in the cantilever beam 4 of the bridge leg.

[0101] A second electrode layer 22 is formed on the surface of the second support layer 21 and in the second opening, and the second electrode layer 22 is electrically connected to the first electrode layer 12.

[0102] A portion of the second electrode layer 22 on the surface of the second sacrificial layer is removed to expose the surface of the second support layer 21;

[0103] A heat-sensitive layer 6 is formed on the exposed surface of the second support layer 21 on the second sacrificial layer and on a portion of the surface of the second electrode layer 22, the heat-sensitive layer 6 being electrically connected to the second electrode layer 22;

[0104] A second support layer 23 is formed on the surface of the second electrode layer 22 and the surface of the heat-sensitive layer 6. The second support layer 21, the second electrode layer 22 and the second passivation layer 23 in the second through hole constitute the second pier 5. The second support layer 21, the heat-sensitive layer 6 and the second passivation layer 23 on the surface of the second sacrificial layer constitute the microbridge deck.

[0105] It should be noted that the terms "comprising" and "having," and their variations, used in this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, unless explicitly indicated by the context. It should be understood that such data used interchangeably where appropriate. Furthermore, the embodiments and features described in these embodiments can be combined with each other unless otherwise specified. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this application. In the various embodiments described above, each embodiment focuses on its differences from other embodiments; similar or identical parts between embodiments can be referred to (or understood) interchangeably.

[0106] Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications to the technical solutions of this application by utilizing the methods and techniques disclosed above without departing from the spirit and scope of this application. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall fall within the protection scope of the technical solutions of this application.

Claims

1. A non-cooled focal plane infrared sensor, characterized by, The application relates to a substrate with a readout circuit, a plurality of pixel micro-bridges on the substrate, each pixel micro-bridge comprising a first bridge pier, a bridge leg cantilever beam, a second bridge pier and a micro-bridge deck, wherein the first bridge pier is protruded from the surface of the substrate, the bridge leg cantilever beam is suspended above the substrate by the first bridge pier, the second bridge pier is protruded from the surface of the bridge leg cantilever beam, the micro-bridge deck is suspended above the bridge leg cantilever beam by the second bridge pier, and the micro-bridge deck is electrically connected to the readout circuit through the second bridge pier, the bridge leg cantilever beam and the first bridge pier; and the bridge leg cantilever beam of a single pixel micro-bridge also spans under at least two adjacent micro-bridge decks. The first bridge pier and the bridge leg cantilever beam comprise a first support layer, a first electrode layer on the first support layer and a first passivation layer on the first electrode layer, the second bridge pier comprises a second support layer, a second electrode layer on the second support layer and a second passivation layer on the second electrode layer, and the second electrode layer is electrically connected to the first electrode layer. A reflective layer is provided on the surface of the substrate, and the micro-bridge deck and the reflective layer form a resonant absorption cavity with a quarter of the absorption wavelength. The bridge leg cantilever beam of a single pixel micro-bridge also spans under two adjacent micro-bridge decks, or three adjacent micro-bridge decks, or more than three adjacent micro-bridge decks. The number of the first bridge pier and the second bridge pier in a single pixel micro-bridge is two, the bridge leg cantilever beam of a single pixel micro-bridge comprises two micro-cantilever beams which are not in contact with each other, the two micro-cantilever beams are arranged under at least two adjacent micro-bridge decks respectively, the micro-cantilever beam presents a multiple meandering structure in the direction parallel to the surface of the substrate, one end of the micro-cantilever beam is connected to a first bridge pier, and the other end is connected to a second bridge pier on the same side. The second bridge pier in a single pixel micro-bridge is arranged under the micro-bridge deck electrically connected to the second bridge pier, and the first bridge pier in the single pixel micro-bridge is arranged under the micro-bridge deck of an adjacent pixel micro-bridge, and the micro-cantilever beam presents a multiple meandering structure in the direction parallel to the surface of the substrate from the first bridge pier to the second bridge pier.

2. The uncooled focal plane infrared sensor of claim 1, wherein, The multiple meandering structure of the micro-cantilever beam is a double arch shape, a multiple arch shape, a double S shape or a multiple S shape; the two micro-cantilever beams in the bridge leg cantilever beam of a single pixel micro-bridge present a symmetrical structure or an asymmetrical structure with equal lengths.

3. The uncooled focal plane infrared sensor according to claim 1 or 2, wherein, There are 4, 6, 8 or 2x+2 micro-cantilever beams under a single micro-bridge deck, and x is greater than 3.

4. The uncooled focal plane infrared sensor of claim 3, wherein, The upper and lower surfaces of the micro-cantilever beam are parallel to the surface of the substrate or form a certain angle with the surface of the substrate.

5. The uncooled focal plane infrared sensor of claim 3, wherein, The angles between the upper and lower surfaces of the micro-cantilever beams of different pixel micro-bridges under a single micro-bridge deck and the surface of the substrate are the same or different.

6. The uncooled focal plane infrared sensor of claim 3, wherein, The micro-cantilever beams with the multiple meandering structure under a single micro-bridge deck are at the same height or at different heights.

7. The uncooled focal plane infrared sensor of claim 4, wherein, ​ 8. The uncooled focal plane infrared sensor of claim 7, wherein, ​ 9. The uncooled focal plane infrared sensor of claim 7, wherein, ​ 10. The uncooled focal plane infrared sensor of claim 1, wherein, The micro-bridge deck comprises the second support layer, a heat-sensitive layer on part of the second support layer, and a second passivation layer on the heat-sensitive layer and part of the second support layer, and the heat-sensitive layer is electrically connected with the second electrode layer.

11. A method of fabricating a non-cooled focal plane infrared sensor, comprising: Comprise: a substrate is provided, and a readout circuit is formed in the substrate; a first sacrificial layer is formed on the substrate; a first pier is formed in the first sacrificial layer, and a bridge leg cantilever beam supported by the first pier is formed on the surface of the first sacrificial layer, the bridge leg cantilever beam is formed in the first sacrificial layer, and the bridge leg cantilever beam supported by the first pier is formed on the surface of the first sacrificial layer, the bridge leg cantilever beam is formed in the first sacrificial layer, and the bridge leg cantilever beam supported by the first pier is formed on the surface of the first sacrificial layer, the bridge leg cantilever beam is formed in the first sacrificial layer, and the bridge leg cantilever beam supported by the first pier is formed on the surface of the first sacrificial layer, the bridge leg cantilever beam 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The method of claim 11, wherein the non-refrigeration focal plane infrared sensor is prepared by the steps of: ​ 13. The method of claim 11, wherein the non-refrigeration focal plane infrared sensor is prepared by a process comprising: ​ 14. The method of claim 13, wherein the non-refrigeration focal plane infrared sensor is prepared by a process comprising: ​ ​ ​ ​ ​ ​ ​ 15. The method for preparing an uncooled focal plane infrared sensor according to claim 13, characterized in that, ​ 16. The method of claim 15, wherein the non-refrigeration focal plane infrared sensor is prepared by the steps of: ​ ​ forming a second support layer on the sidewall and bottom surface of the second via and the surface of the second sacrificial layer; removing part of the second support layer and part of the first passivation layer under the second via from the bottom surface of the second via to form a second opening exposing part of the surface of the first electrode layer in the bridge leg cantilever beam; forming a second electrode layer on the surface of the second support layer and in the second opening, the second electrode layer being electrically connected with the first electrode layer; removing part of the second electrode layer on the surface of the second sacrificial layer to expose the surface of the second support layer; forming a heat-sensitive layer on the exposed surface of the second support layer and part of the surface of the second electrode layer on the second sacrificial layer, the heat-sensitive layer being electrically connected with the second electrode layer; forming a second support layer on the surface of the second electrode layer and the surface of the heat-sensitive layer, the second support layer, the second electrode layer and the second passivation layer in the second via forming the first pier, and the second support layer, the heat-sensitive layer and the second passivation layer on the surface of the second sacrificial layer forming the micro-bridge deck.

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