CN116558651A - Uncooled focal plane infrared sensor and preparation method thereof - Google Patents

Abstract

An uncooled focal plane infrared sensor and a method of making the same, the uncooled focal plane infrared sensor comprising: a substrate having a readout circuitry therein; the pixel micro-bridges are arranged on the substrate, each pixel micro-bridge comprises a first bridge pier, a bridge leg cantilever beam, a second bridge pier and a micro-bridge deck, wherein the first bridge pier is arranged on the surface of the substrate in a protruding mode, the bridge leg cantilever beam is suspended above the substrate through the first bridge pier support, the second bridge pier is arranged on the surface of the bridge leg cantilever beam in a protruding mode, the micro-bridge deck is suspended above the bridge leg cantilever beam through the second bridge pier support, and the micro-bridge deck is electrically connected with the readout circuit through the second bridge pier, the bridge leg cantilever beam and the first bridge pier; and the cantilever beams of the bridge legs of the pixel microbridge also transversely span and are positioned below at least two adjacent microbridge decks. The design space of the cantilever beam of the bridge leg is increased, and the design freedom degree and the heat insulation performance of the pixel microbridge are improved.

Description

Uncooled focal plane infrared sensor and preparation method thereof

Technical Field

The application relates to the field of sensors, in particular to an uncooled focal plane infrared sensor and a preparation method thereof.

Background

In recent years, with the rapid development of photoelectric technology and products, infrared focal plane sensors are developed towards large area arrays, high sensitivity and low power consumption, and the reduction of pixel spacing is an important direction for the development of future focal plane infrared sensors. The pixel pitch of the uncooled focal plane infrared sensor is reduced from the first 50 μm by 50 μm to the current 8 μm by 8 μm. Under the condition that the pixel number is fixed, the small pixel spacing can reduce the volume and the weight of the sensor, and the application scene of the infrared sensor is expanded.

However, when the pixels are reduced to small sizes of 10 μm, 8 μm, etc., how to reduce the thermal conductance of the micro-bridge cantilever and realize high sensitivity detection of the infrared signal under the condition of reducing the pixel pitch is a technical problem to be solved. Currently, two commercial sensor microbridge structures with small pixel spacing are mainly provided, one is that an independent infrared absorption layer is arranged above a heat sensitive layer, the structure can increase the absorption area of infrared radiation and improve the optical filling coefficient, but a cantilever beam and a heat sensitive layer are still positioned on the same bridge deck, the length of the cantilever beam is insufficient, the heat conductivity of a device is large, and the heat sensitivity is low. The other is that the cantilever beams and the heat sensitive layer are distributed in a layered manner, the cantilever Liang Cengwei is arranged below the heat sensitive layer, but the bridge pier and the cantilever beams are arranged below the same micro-bridge deck, so that the arrangement space of the cantilever beams is limited, and meanwhile, the cantilever beams are limited below the pixel and still limited by the area of the small pixel, so that the two micro-bridge structures have heat insulation bottlenecks.

Disclosure of Invention

The technical problem to be solved by the application is how to increase the design space of the micro-bridge cantilever beam, improve the design freedom degree and the heat insulation performance of the pixel micro-bridge, ensure that the arrangement space of the cantilever beam layer is optimized to the maximum extent, and solve the limitation of narrow design space of the small pixel micro-bridge cantilever beam.

To solve the above-mentioned problems, some embodiments of the present application provide an uncooled focal plane infrared sensor, including:

a substrate having a readout circuitry therein;

the pixel micro-bridges are arranged on the substrate, each pixel micro-bridge comprises a first bridge pier, a bridge leg cantilever beam, a second bridge pier and a micro-bridge deck, wherein the first bridge pier is arranged on the surface of the substrate in a protruding mode, the bridge leg cantilever beam is suspended above the substrate through the first bridge pier support, the second bridge pier is arranged on the surface of the bridge leg cantilever beam in a protruding mode, the micro-bridge deck is suspended above the bridge leg cantilever beam through the second bridge pier support, and the micro-bridge deck is electrically connected with the readout circuit through the second bridge pier, the bridge leg cantilever beam and the first bridge pier;

and the cantilever beams of the bridge legs of the pixel microbridge also transversely span and are positioned below at least two adjacent microbridge decks.

In some embodiments, the bridge leg cantilever of a single said pixel microbridge also spans under two adjacent said microbridge decks, or under three adjacent said microbridge decks, or under more than three adjacent said microbridge decks.

In some embodiments, the number of the first bridge piers and the second bridge piers in the pixel microbridge is two, the bridge leg cantilever beams of the pixel microbridge include two micro cantilever beams which are not contacted with each other, the two micro cantilever beams are respectively arranged below at least two adjacent micro bridge decks, the micro cantilever beams are in multiple circuitous structures along the direction parallel to the surface of the substrate, one end of each micro cantilever beam is connected with one first bridge pier, and the other end of each micro cantilever beam is connected with one second bridge pier on the same side.

In some embodiments, the second bridge pier of the single pixel microbridge is located below the microbridge deck electrically connected with the second bridge pier, and the first bridge pier of the single pixel microbridge is located below the microbridge deck of the adjacent pixel microbridge, and the micro cantilever beam has a multiple roundabout structure from the first bridge pier to the second bridge pier along the direction parallel to the surface of the substrate.

In some embodiments, the multi-detour structure of the micro-cantilever is double-bow, multi-bow, double-S, or multi-S; two micro-cantilever beams in the bridge leg cantilever beams of the single pixel micro-bridge are in a symmetrical structure or in an asymmetrical structure with equal length.

In some embodiments, there are 4, 6, 8, or 2x+2 micro-cantilevers below a single micro-bridge deck, x being greater than 3.

In some embodiments, the upper and lower surfaces of the micro-cantilever are parallel to or at an angle to the substrate surface.

In some embodiments, the angle between the upper and lower surfaces of the micro-cantilever of different pixel micro-bridges below a single micro-bridge deck and the substrate surface is the same or different.

In some embodiments, the micro-cantilevers in multiple roundabout structures under the same micro-bridge deck are at the same height, or at different heights.

In some embodiments, the first bridge pier and the 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 with the first electrode layer.

In some embodiments, the microbridge deck includes the second support layer, a thermally sensitive layer on a portion of the second support layer, and a second passivation layer on the thermally sensitive layer and a portion of the second support layer, the thermally sensitive layer electrically connected to the second electrode layer.

In some embodiments, further comprising: and the reflecting layer is positioned on the surface of the substrate, and the micro-bridge deck and the reflecting layer form a resonance absorption cavity with the absorption wavelength of 1/4.

The application also provides a preparation method of the uncooled focal plane infrared sensor, which comprises the following steps:

providing a substrate, wherein a read-out circuit is formed in the substrate;

forming a first sacrificial layer on the substrate;

forming a first bridge pier in the first sacrificial layer, and forming a bridge leg cantilever beam supported by the first bridge pier on the surface of the first sacrificial layer, wherein the bridge leg cantilever beam spans under at least two adjacent micro-bridge decks formed subsequently;

forming a second sacrificial layer covering the first bridge pier and the cantilever beam of the bridge leg on the first sacrificial layer;

forming a second bridge pier in the second sacrificial layer, wherein the bottom of the second bridge pier is contacted with the surface of the cantilever beam of the bridge leg, and forming a micro-bridge deck supported by the second bridge pier on the surface of the second sacrificial layer;

releasing the first sacrificial layer and the second sacrificial layer, so that the bridge leg cantilever beam is suspended above the substrate by the first bridge pier support, and the micro-bridge deck is suspended above the bridge leg cantilever beam by the second bridge pier support.

In some embodiments, a reflective layer is formed on the surface of the substrate prior to forming the first sacrificial layer, the reflective layer forming a resonant absorption cavity with 1/4 absorption wavelength with the microbridge deck.

In some embodiments, the first bridge pier and the bridge leg cantilever includes a first support layer, a first electrode layer on the first support layer, and a first passivation layer on the first electrode layer.

In some embodiments, the forming of the first bridge pier and the cantilever beam comprises:

forming a first via hole in the first sacrificial layer exposing a surface of the substrate portion;

forming a first supporting layer on the side wall and the bottom surface of the first through hole and the surface of the first sacrificial layer;

removing part of the first supporting layer on the bottom surface of the first through hole to form a first opening exposing part of the surface of the substrate;

forming a first electrode layer on the surface of the first support layer and in the first opening, the first electrode layer being electrically connected to a read circuit in the substrate;

forming a first passivation layer on the first electrode layer, wherein the first support layer, the first electrode layer and the first passivation layer in the first through hole form the first bridge pier;

and etching to remove part of the first passivation layer, the first electrode layer and the first supporting layer on the surface of the first sacrificial layer to form a bridge leg cantilever beam with the upper surface and the lower surface parallel to the surface of the substrate, wherein the bridge leg cantilever beams are at the same height.

In some embodiments, 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; the micro-bridge deck comprises the second supporting layer, a heat-sensitive layer positioned on part of the second supporting layer and a second passivation layer positioned on the heat-sensitive layer and part of the second supporting layer, wherein the heat-sensitive layer is electrically connected with the second electrode layer.

In some embodiments, the forming of the second bridge pier and the micro bridge deck comprises:

forming a second through hole in the second sacrificial layer, wherein the second through hole exposes a part of the surface of the first passivation layer in the bridge leg cantilever;

forming a second supporting layer on the side wall and the bottom surface of the second through hole and on the surface of the second sacrificial layer;

removing part of the second supporting layer on the bottom surface of the second through hole and part of the first passivation layer below the second through hole to form a second opening exposing part of the surface of the first electrode layer of the cantilever beam of the bridge leg;

forming a second electrode layer on the surface of the second support layer and in the second opening, wherein the second electrode layer is 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 supporting layer;

forming a heat sensitive layer on the exposed surface of the second support layer and a portion of the surface of the second electrode layer on the second sacrificial layer, the heat sensitive layer being electrically connected to the second electrode layer;

and forming a second supporting layer on the surface of the second electrode layer and the surface of the heat sensitive layer, wherein the second supporting layer, the second electrode layer and the second passivation layer in the second through hole form the first bridge pier, and the second supporting layer, the heat sensitive layer and the second passivation layer on the surface of the second sacrificial layer form the micro bridge deck.

Compared with the prior art, the technical scheme in some embodiments of the present application has the advantages that:

the bridge leg cantilever beams of the pixel microbridge span at least two adjacent microbridge decks, namely, the bridge leg cantilever beams are used for increasing the design space of the bridge leg cantilever beams (or the micro cantilever beams) by the position adjacent to the lower part of the pixel microbridge, so that the design freedom degree and the heat insulation performance of the pixel microbridge are improved, the arrangement space of the bridge leg cantilever beams (or the micro cantilever beams) is optimized maximally, the limit of narrow design space of the small pixel microbridge cantilever beams is solved, the length of the bridge leg cantilever beams (or the micro cantilever beams) can be greatly increased, the heat insulation performance of the pixel microbridge is improved, the thermal performance of a device is effectively improved, and the high-sensitivity detection of infrared light is realized.

Drawings

Fig. 1 is a schematic structural diagram of an uncooled focal plane infrared sensor in some embodiments of the present application;

fig. 2-3 are schematic structural views of a first bridge pier, a cantilever beam with bridge legs, and a second bridge pier according to some embodiments of the present application;

fig. 4 is a schematic structural diagram of a first bridge pier, a cantilever beam of a bridge leg, and a second bridge pier according to other embodiments of the present application;

fig. 5 is a schematic structural view of a first bridge pier, a cantilever beam of a bridge leg, and a second bridge pier according to other embodiments of the present application;

fig. 6 is a schematic structural diagram of an uncooled focal plane infrared sensor according to other embodiments of the present application;

fig. 7 is a flow chart illustrating a process of forming an uncooled focal plane infrared sensor in some embodiments of the present application.

Detailed Description

The following detailed description of specific embodiments of the present application refers to the accompanying drawings. In describing embodiments of the present application in detail, the schematic drawings are not necessarily to scale and are merely illustrative and should not be taken as limiting the scope of the present application. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.

Some embodiments of the present application first provide an uncooled focal plane infrared sensor, referring to fig. 1 to 3, fig. 2 is a schematic top view structure of a portion of a first bridge pier, a bridge leg cantilever beam, and a second bridge pier in fig. 1.

Fig. 3 is a schematic top view of a portion of the micro bridge deck, the first bridge pier, the cantilever beam with bridge legs, and the second bridge pier in fig. 1, including:

a substrate 1, the substrate 1 having a readout circuitry 10 therein;

a plurality of pixel microbridge 8 located on the substrate 1, each pixel microbridge 8 includes a first bridge pier 3, a bridge leg cantilever beam 4, a second bridge pier 5 and a microbridge bridge 9, wherein the first bridge pier 3 is convexly arranged on the surface of the substrate 1, the bridge leg cantilever beam 4 is convexly arranged on the surface of the bridge leg cantilever beam 4 through the first bridge pier 3, the microbridge bridge 9 is supportively arranged on the upper side of the bridge leg cantilever beam 4 through the second bridge pier 5, and the microbridge bridge 9 is electrically connected with the readout circuit 10 through the second bridge pier 5, the bridge leg cantilever beam 4 and the first bridge pier 3;

and the cantilever beam 4 of the bridge leg of the single pixel microbridge 8 also spans and is positioned below at least two adjacent microbridge decks 9.

Specifically, a readout circuit 10 is formed in the substrate 1, where the readout circuit 1 is an integrated circuit formed in the substrate 1, and the readout circuit 10 is configured to process an output signal (for example, an electrical signal output by a microbridge deck 9 in the pixel microbridge 8 according to an infrared radiation change of a target object) output by a sensing unit of the uncooled focal plane infrared sensor, where the processing includes reading out, calibrating, and so on the output signal output by the sensing unit.

The substrate 1 is provided with a plurality of pixel microbridge 8, and each pixel microbridge 8 corresponds to one pixel or one sensing unit of the uncooled focal plane infrared sensor. In some embodiments, the pixel microbridge 8 is arranged in rows and columns or in an array on the substrate 1, for example, in fig. 2, an x-axis direction may be taken as a row direction, a y-axis direction is taken as a column direction, in fig. 2, positions of the 4 pixel microbridge 8 in the column direction are shown, and the pixel microbridge 8a, the pixel microbridge 8b, the pixel microbridge 8c and the pixel microbridge 8d sequentially include from top to bottom along the column direction.

Each pixel microbridge 8 comprises two first bridge piers 3, a cantilever beam 4 with bridge legs, two second bridge piers 5 and a microbridge bridge deck 9. The first bridge pier 3 is arranged on the surface of the substrate 1 in a protruding mode, the bottom of the first bridge pier 3 is electrically connected with the readout circuit 10 in the substrate 1, the top of the first bridge pier 3 is used for supporting the bridge leg cantilever beam 4, and the bridge leg cantilever beam 4 is used for providing support for the second bridge pier 5 and electrically connecting the first bridge pier 3 and the second bridge pier 5. The second bridge pier 5 is used for supporting the micro-bridge deck 9 and is electrically connected with the micro-bridge deck 9. The microbridge deck 9 generates the change of the thermistor according to the infrared radiation change of a target object, and converts the change of the thermistor into an electric signal to be output.

In some embodiments, the first bridge pier 3 and the cantilever beam 4 comprise 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 supporting 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 bridge pier 3 may be a metal pillar with an outer sidewall coated with an insulating layer.

In this application, the single the bridge leg cantilever beam 4 of pixel microbridge 8 still spanes and is located adjacent two at least microbridge bridge deck 9 below, namely bridge leg cantilever beam 4 borrows the position of adjacent pixel microbridge 8 below, increase the design space of bridge leg cantilever beam 4 (or little cantilever beam), improve the design degree of freedom and the thermal insulation performance of pixel microbridge, make the layout space of bridge leg cantilever beam 4 (or little cantilever beam) obtain the maximize optimization, solve the narrow and small restriction in design space of little pixel microbridge cantilever beam, thereby can increase bridge leg cantilever beam 4 (or little cantilever beam) length by a wide margin, improve the thermal insulation performance of pixel microbridge, effectively promote device thermal behavior, realize the high sensitivity detection to infrared light. In some specific embodiments, the bridge leg cantilever beam 4 of a single said pixel microbridge 8 spans under two adjacent said microbridge decks 9, or spans under three adjacent said microbridge decks 9, or spans under more than three adjacent said microbridge decks 9.

In some embodiments, referring to fig. 2 and fig. 3 in combination, taking as an example four pixel microbridge (including an adjacent pixel microbridge 8a, an adjacent pixel microbridge 8b, an adjacent pixel microbridge 8c, an adjacent pixel microbridge 8 d) in the column direction from top to bottom in fig. 2 and fig. 3) and four microbridge bridges (including an adjacent microbridge 9a, a microbridge 9b, a microbridge 9c, and a microbridge 9 d) above the four pixel microbridge 8 in the column direction in fig. 3), the bridge leg cantilever beam 4 of the single pixel microbridge (such as 8a, 8b, 8c, or 8 d) includes two micro cantilever beams (such as 41 or 42) that do not contact each other, the two micro cantilever beams (41 or 42) are respectively disposed below the adjacent at least two micro bridge bridges (such as 8a, 8b, 8c, or 8 d), the micro cantilever beams (41 or 42) are in a multiple-bypass structure in a direction parallel to the substrate surface, and the other end of the single cantilever beam (such as 8a, 8b, 8c, or 8 d) is connected to the first bridge pier 2.

In a specific embodiment, please continue to refer to fig. 2 and fig. 3, when the bridge leg cantilever beam 4 of the single pixel microbridge 8 spans and is located below two adjacent microbridge bridges 9, the bridge leg cantilever beam 4 (including two micro cantilever beams 41) of the single pixel microbridge 8b spans and is located below two adjacent microbridge bridges 9b and 9c, for example, a part of the bridge leg cantilever beam 4 (including two micro cantilever beams 41) of the pixel microbridge 8b is located below the microbridge bridge 9b, a part of the bridge leg cantilever beam 4 is located below the microbridge bridge 9c, and the micro cantilever beams 41 are in a multiple-bypass structure along a direction parallel to the substrate surface, one end of the single micro cantilever beam 41 is connected with one first bridge pier 3, and the other end of the single micro cantilever beam 41 is connected with one second bridge pier 5; for another example, the bridge leg cantilever beam 4 (including two micro cantilever beams 42) of the other pixel micro bridge 8c spans and is located below the two adjacent micro bridge decks 9c and 9d, that is, a part of the bridge leg cantilever beam 4 (including two micro cantilever beams 42) of the pixel micro bridge 8c is located below the micro bridge deck 9c, a part of the bridge leg cantilever beam 4 is located below the micro bridge deck 9d, and the micro cantilever beams 42 are in multiple circuitous structures along the direction parallel to the surface of the substrate, one end of each micro cantilever beam 42 is connected with one first bridge pier 3, and the other end of each micro cantilever beam 42 is connected with one second bridge pier 5.

With continued reference to fig. 2 and 3, two second bridge piers 5 of a single pixel microbridge are located below the microbridge deck electrically connected thereto, and two first bridge piers 3 of the single pixel microbridge are located below the microbridge deck of an adjacent pixel microbridge, for example, two second bridge piers 5 of a single pixel microbridge 8b are located below the microbridge deck 9b electrically connected thereto, and two first bridge piers 3 of the single pixel microbridge 8b are located below the microbridge deck 9c of an adjacent pixel microbridge 8c, and a single micro cantilever beam (41 or 42) takes a multiple-turn structure from one first bridge pier 3 to one second bridge pier 5 in a direction parallel to the substrate surface.

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

The specific arrangement manner of the bridge leg cantilevers 4 (or two micro-cantilevers) of the single pixel micro-bridge 8 may be different when the bridge leg cantilevers 4 (or two micro-cantilevers) cross under at least two adjacent micro-bridge decks 9, in some embodiments, each micro-bridge deck includes a middle area and an edge area surrounding the middle area from three sides, such as an area corresponding to the pixel micro-bridge 8d in fig. 2, a middle blank area is a middle area, other areas are edge areas, the edge areas surround the middle area from the top, the left side and the right side, when the bridge leg cantilevers 4 (or two micro-cantilevers) of the single pixel micro-bridge 8 are distributed, part of the bridge leg cantilevers 4 (or two micro-cantilevers) are located in the middle area under the micro-bridge decks 9 of the pixel micro-bridge 8, part of the bridge is located in the edge area under the adjacent micro-bridge decks 9, the corresponding two second bridge piers 5 are located in the middle area, the two first bridge piers are respectively located in the edge areas on the left and right sides, such as the two side and the two micro-bridge sides of the corresponding cantilever structures of the two micro-bridge decks 4 b are located in the two parallel to the two micro-bridge deck edge areas 41 (the two parallel to the bottom surfaces 41 of the two micro-bridge decks 9 b) respectively located under the two micro-bridge decks 9 respectively; the bridge leg cantilever beams 4 (including two micro cantilever beams 42) of the pixel micro bridge 8c are partially located in the middle area below the micro bridge deck 9c, partially located in the edge area below the micro bridge deck 9d (the two micro cantilever beams 42 are respectively distributed in the edge areas on the left and right sides), and the two micro cantilever beams 42 are in multiple roundabout structures in the corresponding areas along the direction parallel to the surface of the substrate.

In other embodiments, referring to fig. 4, each micro-bridge deck includes a middle area and edge areas surrounding the middle area from three sides, such as in the area corresponding to the pixel micro-bridge 8a in fig. 4, the middle blank area is the middle area, the other areas are the edge areas, the edge areas surround the middle area from the bottom, the left side and the right side, the bridge leg cantilevers 4 (including two micro-cantilevers) of the single pixel micro-bridge (8 a, 8b, 8c or 8 d) are distributed, the edge areas (corresponding to the two second bridge piers are also respectively located at the left and right side edge areas) of the left and right sides of the micro-bridge deck of the pixel micro-bridge 8 are partially located in the middle area (corresponding to the two first bridge piers are located in the middle area) of the adjacent micro-bridge deck, and the two micro-cantilevers are in multiple roundabout structures along the direction parallel to the substrate surface in the corresponding areas, and the corresponding two second bridge piers are located in the middle area, and the two corresponding first bridge piers are respectively located at the left and right side edge areas and right side areas of the two first bridge piers are respectively located at the left and right side edge areas.

In other embodiments, each of the microbridge surfaces includes a first area and a second area that are bilaterally symmetrical, the bridge leg cantilever beam (including two micro-cantilever beams) of one pixel microbridge is located in the first area below two adjacent microbridge surfaces, and the bridge leg cantilever beam (including two micro-cantilever beams) of another pixel microbridge is located in the second area below two adjacent microbridge surfaces.

In another embodiment, referring to fig. 5, the bridge leg cantilever beams 4 (including two micro-cantilever beams) of the single pixel micro-bridge 8 span under the adjacent 3 micro-bridge decks, specifically, the area under each micro-bridge deck may include a core area, a middle area surrounding the core area from three sides, and edge areas located at two sides of the middle area, and the bridge leg cantilever beams 4 (including two micro-cantilever beams) of the single pixel micro-bridge 8 are partially located in the core area under the micro-bridge deck of the pixel micro-bridge 8, partially located in the middle area under the adjacent first micro-bridge deck, and partially located in the edge area of the middle area under the adjacent first micro-bridge deck. The length of the bridge leg cantilever 4 (comprising two micro-cantilevers) is further increased.

Since the bridge leg cantilever beams 4 (including two micro cantilever beams) of a single pixel micro bridge 8 span under at least two adjacent micro bridge decks, there may be 4, 6, 8 or 2x+2 micro cantilever beams under a single micro bridge deck, x being greater than 3.

With continued reference to fig. 1 and 2, the upper and lower surfaces of the micro-cantilever (41 or 42) are parallel to the substrate surface. In another embodiment, referring to fig. 6, the upper and lower surfaces of the micro-cantilever (41 or 42) form an angle with the surface of the substrate, the angle may be in the range of 40-70 degrees, and may be in the range of 60 degrees, so that the layout space of the micro-cantilever can be further optimized under the condition that the pixel micro-bridge has a certain size, and a single pixel micro-bridge obtains more detour times of the micro-cantilever or places the micro-cantilever of more pixel micro-bridges below a single micro-bridge deck, so that the length of the micro-cantilever is further increased.

In some embodiments, the angle between the upper and lower surfaces of the micro-cantilever of the different pel micro-bridges 8 under the individual micro-bridge deck 9 and the substrate surface is the same or different.

In some embodiments, the micro-cantilevers (or the bridge leg cantilevers 4) in a multiple detour structure under the same micro-bridge deck 9 are at the same height, or at different heights.

In some embodiments, with continued reference to fig. 1, the second bridge pier 5 includes 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 to 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 may be a metal pillar with an outer sidewall coated with an insulating layer.

In some embodiments, the microbridge deck 9 includes the second support layer 21, a thermally sensitive layer 6 on a portion of the second support layer 21, and a second passivation layer 23 on the thermally sensitive layer 6 and a portion of the second support layer 21, the thermally sensitive layer 6 being electrically connected to the second electrode layer 22.

The heat-sensitive layer 6 is composed of an infrared heat-sensitive film, and is electrically connected with the readout circuit 10 on the substrate 1 through the second bridge pier 5, the bridge leg cantilever beam 4 and the first bridge pier 3. The infrared thermosensitive film is made of vanadium oxide, amorphous silicon, copper oxide, manganese oxide, molybdenum oxide or titanium oxide. The resistance value of the thermistor in the heat-sensitive layer 6 changes according to the infrared radiation change of the target object, and the electric signal change caused by the resistance value change 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.

In some embodiments, further comprising: the reflecting layer 2 is arranged on the surface of the substrate 10, and the micro-bridge deck 9 and the reflecting layer 2 form a resonance absorption cavity with an absorption wavelength of 1/4. The reflecting layer 2 is used for reflecting the infrared radiation so as to enhance the absorption capacity of the microbridge deck 9 for the infrared radiation. The material of the reflecting layer 2 may be one or more of nickel, chromium, gold, silver, and the like.

Some embodiments of the present application further provide a method for manufacturing an uncooled focal plane infrared sensor, referring to fig. 7 and fig. 1 in combination, including:

step S301, providing a substrate 1, wherein a readout circuitry 10 is formed in the substrate 1;

step S302, forming a first sacrificial layer (not shown in the figure) on the substrate 1;

step S303, forming a first bridge pier 3 in the first sacrificial layer, and forming a bridge leg cantilever beam 4 supported by the first bridge pier 3 on the surface of the first sacrificial layer, wherein the bridge leg cantilever beam 4 spans under at least two adjacent micro-bridge decks formed subsequently;

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

step S305, forming a second bridge pier 5 in the second sacrificial layer, wherein the bottom of the second bridge pier 5 is contacted with the surface of the cantilever beam 4 of the bridge leg, and forming a micro bridge deck 9 supported by the second bridge pier 5 on the surface of the second sacrificial layer;

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

Specifically, the materials of the first sacrificial layer and the second sacrificial layer are different from the materials of the first bridge pier 3, the bridge leg cantilever 4 and the second bridge pier. The first sacrificial layer and the second sacrificial layer are formed by deposition or spin-coating process, and in some embodiments, the materials of the first sacrificial layer and the second sacrificial layer may be amorphous silicon, silicon oxide, silicon nitride, amorphous carbon, polysilicon, silicon germanium, and other inorganic materials. The materials of the first sacrificial layer and the second sacrificial layer can be photoresist, or polyimide, styrene-acrylic, acrylic acid homopolymer and other polymers.

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 and the microbridge deck 6 form a resonant absorption cavity that absorbs 1/4 of the wavelength.

In some embodiments, the first bridge pier 3 and the cantilever beam 4 comprise 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 forming process of the first bridge pier 3 and the cantilever beam 4 includes:

forming a first through hole exposing a part of the surface of the substrate 1 in the first sacrificial layer;

forming a first support layer 11 on the side wall and bottom surfaces of the first through hole and the surface of the first sacrificial layer;

removing a part of the first supporting layer 11 on the bottom surface of the first through hole to form a first opening exposing a part of the surface of the substrate 1;

forming a first electrode layer 12 on the surface of the first support layer 11 and in the first opening, the first electrode layer being electrically connected to the read circuit 10 in the substrate 1;

forming a first passivation layer 13 on the first electrode layer 12, wherein the first support layer 11, the first electrode layer 12 and the first passivation layer 13 in the first through hole form the first bridge pier 3;

and etching to remove part of the first passivation layer 11, the first electrode layer 12 and the first supporting layer 13 on the surface of the first sacrificial layer to form a bridge cantilever 4 with upper and lower surfaces parallel to the surface of the substrate 1, wherein the bridge cantilever 4 is at the same height.

In some embodiments, the second bridge pier 5 includes 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; the microbridge deck 9 comprises the second support layer 21, a heat-sensitive layer 6 on a part of the second support layer 21, and a second passivation layer 23 on the heat-sensitive layer 6 and a part of the second support layer 21, wherein the heat-sensitive layer 6 is electrically connected with the second electrode layer 22.

In some embodiments, the forming process of the second bridge pier 5 and the micro bridge deck 9 includes:

forming a second through hole in the second sacrificial layer, wherein the second through hole exposes part of the surface of the first passivation layer 13 in the bridge leg cantilever 4;

forming a second support layer 21 on the side wall and bottom surfaces of the second through hole and the surface of the second sacrificial layer;

removing part of the second supporting layer 21 on the bottom surface of the second through hole and part of the first passivation layer 13 below the second through hole to form a second opening exposing part of the surface of the first electrode layer 12 in the cantilever beam 4 of the bridge leg;

forming a second electrode layer 22 on the surface of the second support layer 21 and in the second opening, the second electrode layer 22 being electrically connected to the first electrode layer 12;

removing a portion of the second electrode layer 22 on the surface of the second sacrificial layer to expose the surface of the second support layer 21;

forming a heat sensitive layer 6 on the exposed surface of the second support layer 21 and a part of the surface of the second electrode layer 22 on the second sacrificial layer, the heat sensitive layer 6 being electrically connected to the second electrode layer 22;

a second supporting layer 23 is formed on the surface of the second electrode layer 22 and the surface of the heat sensitive layer 6, the second supporting layer 21, the second electrode layer 22 and the second passivation layer 23 in the second through hole constitute the second bridge pier 5, and the second supporting layer 21, the heat sensitive layer 6 and the second passivation layer 23 on the surface of the second sacrificial layer constitute the micro bridge deck.

It should be noted that the terms "comprising" and "having," and variations thereof, as referred to in this application are intended to cover non-exclusive inclusion. The terms "first," "second," and the like are used to distinguish similar objects and not necessarily to describe a particular order or sequence unless otherwise indicated by context, it should be understood that the data so used may be interchanged where appropriate. In addition, embodiments and features of embodiments in this application may be combined with each other without conflict. In addition, in the above description, descriptions of well-known components and techniques are omitted so as to not unnecessarily obscure the concepts of the present application. In the foregoing embodiments, each embodiment is mainly described for the differences from the other embodiments, and the same/similar parts between the embodiments need to be referred to (or referred to) each other.

Although the present invention has been described with respect to the preferred embodiments, it is not intended to limit the scope of the invention, and any person skilled in the art may make any possible variations and modifications to the technical solution of the present invention using the methods and technical matters disclosed above without departing from the spirit and scope of the present invention, so any simple modifications, equivalent variations and modifications to the above embodiments according to the technical matters of the present invention fall within the scope of the technical matters of the present invention.

Claims (18)

1. An uncooled focal plane infrared sensor, comprising:

a substrate having a readout circuitry therein;

the pixel micro-bridges are arranged on the substrate, each pixel micro-bridge comprises a first bridge pier, a bridge leg cantilever beam, a second bridge pier and a micro-bridge deck, wherein the first bridge pier is arranged on the surface of the substrate in a protruding mode, the bridge leg cantilever beam is suspended above the substrate through the first bridge pier support, the second bridge pier is arranged on the surface of the bridge leg cantilever beam in a protruding mode, the micro-bridge deck is suspended above the bridge leg cantilever beam through the second bridge pier support, and the micro-bridge deck is electrically connected with the readout circuit through the second bridge pier, the bridge leg cantilever beam and the first bridge pier;

and the cantilever beams of the bridge legs of the pixel microbridge also transversely span and are positioned below at least two adjacent microbridge decks.

2. The uncooled focal plane infrared sensor of claim 1, wherein the bridge leg cantilever of a single said pixel microbridge is also positioned across under two adjacent said microbridge decks, or across under three adjacent said microbridge decks, or across under more than three adjacent said microbridge decks.

3. The uncooled focal plane infrared sensor according to claim 1 or 2, wherein the number of the first bridge pier and the second bridge pier in the pixel microbridge is two, the bridge leg cantilever beams of the pixel microbridge comprise two micro cantilever beams which are not contacted with each other, the two micro cantilever beams are respectively arranged below at least two adjacent micro bridge decks, the micro cantilever beams are in a multiple circuitous structure along the direction parallel to the surface of the substrate, one end of each micro cantilever beam is connected with one first bridge pier, and the other end is connected with one second bridge pier on the same side.

4. The uncooled focal plane infrared sensor of claim 3, wherein the second bridge pier of a single pixel microbridge is located below the microbridge deck electrically connected thereto, and the first bridge pier of the single pixel microbridge is located below the microbridge deck of an adjacent pixel microbridge, and the micro cantilever beam has a multiple roundabout structure from the first bridge pier to the second bridge pier along a direction parallel to the surface of the substrate.

5. The uncooled focal plane infrared sensor of claim 3, wherein the multiple detour structure of the micro-cantilever is double-arcuate, multi-arcuate, double-S or multi-S; two micro-cantilever beams in the bridge leg cantilever beams of the single pixel micro-bridge are in a symmetrical structure or in an asymmetrical structure with equal length.

6. The uncooled focal plane infrared sensor of claim 3, wherein there are 4, 6, 8 or 2x+2 micro cantilevers below a single micro bridge deck, x being greater than 3.

7. The uncooled focal plane infrared sensor of claim 4, wherein the upper and lower surfaces of the micro-cantilever are parallel to or at an angle to the substrate surface.

8. The uncooled focal plane infrared sensor of claim 7, wherein the angle between the upper and lower surfaces of the micro-cantilever of different pixel micro-bridges below the individual micro-bridge deck is the same or different from the substrate surface.

9. The uncooled focal plane infrared sensor of claim 7, wherein the micro-cantilevers under the same micro-bridge deck in multiple detours are at the same height or at different heights.

10. The uncooled focal plane infrared sensor of claim 1, wherein the first bridge pier and the bridge leg cantilever 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, the second electrode layer electrically connected to the first electrode layer.

11. The uncooled focal plane infrared sensor of claim 10, wherein the microbridge deck comprises the second support layer, a thermally sensitive layer on a portion of the second support layer, and a second passivation layer on the thermally sensitive layer and a portion of the second support layer, the thermally sensitive layer electrically connected to the second electrode layer.

12. The uncooled focal plane infrared sensor of claim 1, further comprising:

and the reflecting layer is positioned on the surface of the substrate, and the micro-bridge deck and the reflecting layer form a resonance absorption cavity with the absorption wavelength of 1/4.

13. A method for manufacturing an uncooled focal plane infrared sensor, comprising:

providing a substrate, wherein a read-out circuit is formed in the substrate;

forming a first sacrificial layer on the substrate;

forming a first bridge pier in the first sacrificial layer and a bridge leg cantilever beam supported by the first bridge pier, forming a first bridge pier in the first sacrificial layer, and forming a bridge leg cantilever beam supported by the first bridge pier on the surface of the first sacrificial layer, wherein the bridge leg cantilever beam spans and is positioned below at least two adjacent micro-bridge decks formed subsequently;

forming a second sacrificial layer covering the first bridge pier and the cantilever beam of the bridge leg on the first sacrificial layer; forming a second bridge pier in the second sacrificial layer, wherein the bottom of the second bridge pier is contacted with the surface of the cantilever beam of the bridge leg, and forming a micro-bridge deck supported by the second bridge pier on the surface of the second sacrificial layer;

releasing the first sacrificial layer and the second sacrificial layer, so that the bridge leg cantilever beam is suspended above the substrate by the first bridge pier support, and the micro-bridge deck is suspended above the bridge leg cantilever beam by the second bridge pier support.

14. The method of manufacturing an uncooled focal plane infrared sensor of claim 13, wherein a reflective layer is formed on a surface of the substrate before the first sacrificial layer is formed, the reflective layer and the microbridge deck forming a resonant absorption cavity of 1/4 absorption wavelength.

15. The method of claim 13, wherein the first bridge pier and the bridge cantilever comprise a first support layer, a first electrode layer on the first support layer, and a first passivation layer on the first electrode layer.

16. The method of manufacturing an uncooled focal plane infrared sensor of claim 15, wherein the forming of the first bridge pier and the bridge leg cantilever comprises:

forming a first via hole in the first sacrificial layer exposing a surface of the substrate portion;

forming a first supporting layer on the side wall and the bottom surface of the first through hole and the surface of the first sacrificial layer;

removing part of the first supporting layer on the bottom surface of the first through hole to form a first opening exposing part of the surface of the substrate;

forming a first electrode layer on the surface of the first support layer and in the first opening, the first electrode layer being electrically connected to a read circuit in the substrate;

forming a first passivation layer on the first electrode layer, wherein the first support layer, the first electrode layer and the first passivation layer in the first through hole form the first bridge pier;

and etching to remove part of the first passivation layer, the first electrode layer and the first supporting layer on the surface of the first sacrificial layer to form a bridge leg cantilever beam with the upper surface and the lower surface parallel to the surface of the substrate, wherein the bridge leg cantilever beams are at the same height.

17. The method of claim 15, wherein 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; the micro-bridge deck comprises the second supporting layer, a heat-sensitive layer positioned on part of the second supporting layer and a second passivation layer positioned on the heat-sensitive layer and part of the second supporting layer, wherein the heat-sensitive layer is electrically connected with the second electrode layer.

18. The method for manufacturing the uncooled focal plane infrared sensor according to claim 17, wherein the forming process of the second bridge pier and the micro bridge deck comprises:

forming a second through hole in the second sacrificial layer, wherein the second through hole exposes a part of the surface of the first passivation layer in the bridge leg cantilever;

forming a second supporting layer on the side wall and the bottom surface of the second through hole and on the surface of the second sacrificial layer;

removing part of the second supporting layer on the bottom surface of the second through hole and part of the first passivation layer below the second through hole to form a second opening exposing part of the surface of the first electrode layer of the cantilever beam of the bridge leg;

forming a second electrode layer on the surface of the second support layer and in the second opening, wherein the second electrode layer is 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 supporting layer;

forming a heat sensitive layer on the exposed surface of the second support layer and a portion of the surface of the second electrode layer on the second sacrificial layer, the heat sensitive layer being electrically connected to the second electrode layer;

and forming a second supporting layer on the surface of the second electrode layer and the surface of the heat sensitive layer, wherein the second supporting layer, the second electrode layer and the second passivation layer in the second through hole form the first bridge pier, and the second supporting layer, the heat sensitive layer and the second passivation layer on the surface of the second sacrificial layer form the micro bridge deck.