Open-hole type micro-bridge structure and preparation method thereof, and focal plane array

Abstract

The invention relates to the technical field of uncooled infrared detectors, and discloses a perforated micro-bridge structure, which comprises a substrate provided with a reading circuit, a heat-sensitive bridge surface electrically connected with the reading circuit, and an umbrella surface layer arranged above the heat-sensitive bridge surface and connected with the heat-sensitive bridge surface through a support hole, and the heat-sensitive bridge surface is provided with a plurality of first through holes; the opening area of the first through hole accounts for 10%-60% of the area of the heat-sensitive bridge floor. Meanwhile, the invention further provides a method for manufacturing the micro-bridge structure and a focal plane array adopting the micro-bridge structure. According to the invention, the absorption area of infrared radiation can be enlarged, a higher filling coefficient can be obtained, and the heat capacity can be reduced, the response speed of the device can be improved and the absorption characteristic can be improved while the infrared absorption is enhanced by forming the plurality of first through holes in the heat-sensitive bridge surface.

Description

Technical Field

[0001] The invention relates to the technical field of uncooled infrared detectors, and in particular to an open-hole microbridge structure and a preparation method thereof, and a focal plane array. Background Art

[0002] Uncooled infrared detectors are mainly based on the thermal effect of infrared radiation. When infrared radiation is incident on the detector, the infrared radiation energy is first converted into thermal energy by the infrared absorption material. This process causes the temperature of the sensitive element to rise. The resistivity of the sensitive element will change with the change of temperature, and then the change of resistivity will be converted into an electrical signal through a certain conversion mechanism. After further processing and measurement, the detection and imaging effect of the target object is finally achieved.

[0003] Among them, the higher the absorption characteristic of the detector to infrared radiation, the more sensitive the device is and the faster the response speed. However, the single-layer microbridge structure can no longer meet the current demand for absorption characteristics, and is gradually being replaced by a double-layer or multi-layer microbridge structure, such as an umbrella-shaped microbridge structure and focal plane array disclosed in Chinese patent CN216899263U. The umbrella-shaped microbridge structure includes a substrate provided with a readout circuit, a thermosensitive bridge deck electrically connected to the readout circuit, and a bridge pier fixed on the substrate to support the thermosensitive bridge deck; an umbrella-shaped absorption layer is provided above the thermosensitive bridge deck; the absorption layer includes a curved absorption layer and a supporting hole connected to the thermosensitive bridge deck; the curved absorption layer is a concave curved surface structure or a convex curved surface structure. The umbrella-shaped microbridge structure of the utility model creatively transforms the traditional planar absorption layer into a dual design of an umbrella-shaped plus curved surface structure, and designs more dense folds to expand the absorption area of ​​the absorption layer and improve the absorption effect of the detector pixel.

[0004] Although the double-layer microbridge structure can provide an extra layer of resonant cavity, it can obtain a higher filling factor, and at the same time, it increases the infrared absorption area and improves the absorption characteristics of the device. However, the double-layer microbridge structure will introduce additional heat capacity, thereby reducing the response speed of the device. Therefore, how to improve the response speed of the device and improve the absorption characteristics is a problem that needs to be solved at present. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems and provide an open-hole microbridge structure, which can not only expand the absorption area of ​​infrared radiation and obtain a higher fill factor, but also reduce the heat capacity while enhancing infrared absorption by opening a plurality of first through holes on the thermally sensitive bridge surface, thereby increasing the response speed of the device and improving the absorption characteristics. At the same time, the present application also provides a method for making the microbridge structure and a focal plane array using the microbridge structure.

[0006] To achieve the above objectives, this application provides the following technical solutions:

[0007] An open-hole microbridge structure comprises a substrate provided with a readout circuit, a thermosensitive bridge surface electrically connected to the readout circuit, and an umbrella surface layer provided above the thermosensitive bridge surface and connected to the thermosensitive bridge surface through a supporting hole, wherein a plurality of first through holes are provided on the thermosensitive bridge surface;

[0008] The opening area of ​​the first through hole accounts for 10% to 60% of the area of ​​the heat-sensitive bridge surface.

[0009] Specifically, the opening area of ​​the first through hole may account for 10%, 20%, 30%, 40%, 50%, or 60% of the area of ​​the thermally sensitive bridge surface, but is not limited to the listed values, and other values ​​not listed are applicable as long as they are within this range.

[0010] Preferably, a plurality of second through holes are provided on the umbrella surface layer, and the second through holes account for no more than 30% of the area of ​​the umbrella surface layer.

[0011] Specifically, the proportion of the second through hole to the area of ​​the umbrella surface layer can be 5%, 10%, 15%, 20%, 25%, or 30%, but is not limited to the listed values, and other unlisted values ​​are applicable as long as they are within this range.

[0012] It should be noted here that the area of ​​the thermally sensitive bridge surface is the area of ​​the thermally sensitive bridge surface minus the portion occupied by the support holes; the area of ​​the umbrella surface layer is the surface of the umbrella surface plus the inner wall of the support holes.

[0013] Preferably, the opening modes of the first through holes and the second through holes are both: arranged in a rectangular array around the support holes. Specifically, the matrix of the first through holes includes but is not limited to 2×2, 3×3, 4×4, 5×5, 6×6, 7×7, etc.; the matrix of the second through holes includes but is not limited to 2×2, 3×3, 4×4, 5×5, 6×6, 7×7, etc.

[0014] It should be noted here that the rectangular array arrangement is only for the convenience of processing and is not used as a limitation on the opening positions.

[0015] Preferably, the first through holes and the second through holes are at least partially staggered.

[0016] Preferably, the electrical property changes of the thermally sensitive bridge deck are transmitted to the readout circuit via the bridge legs connected to the bridge piers; the bridge legs are U-shaped.

[0017] Preferably, a reflective layer is provided on the substrate, a first layer of resonance cavity is provided between the reflective layer and the thermally sensitive bridge surface, and a second layer of resonance cavity is provided between the thermally sensitive bridge surface and the umbrella surface layer.

[0018] Preferably, the height of the first resonant cavity is 2 μm to 2.5 μm; the height of the second resonant cavity is 2 μm to 2.5 μm. Specifically, the height of the first resonant cavity can be 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm; the height of the second resonant cavity can be 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, but it is not limited to the listed values, and other values ​​not listed are applicable as long as they are within this range.

[0019] At the same time, the present application also provides a method for preparing an open-pore microbridge structure, comprising the following steps:

[0020] Step (1): preparing a reflective layer, an insulating dielectric layer, and a first sacrificial layer in sequence on a substrate provided with a readout circuit, and etching the first sacrificial layer to obtain a pier hole;

[0021] Step (2): depositing a first supporting layer, a thermosensitive layer, a first passivation layer, a metal layer and a protective layer on the first sacrificial layer in sequence to form a thermosensitive bridge surface;

[0022] Step (3): etching the thermally sensitive bridge surface to obtain a bridge leg and a thermally sensitive bridge surface having a first through hole;

[0023] Step (4): preparing a second sacrificial layer on the heat-sensitive bridge surface, and etching the second sacrificial layer to obtain a support hole;

[0024] Step (5): depositing a second supporting layer, an absorption layer, and a second passivation layer on the second sacrificial layer in sequence to form an umbrella surface layer, and etching the umbrella surface layer to obtain an umbrella surface layer having a second through hole;

[0025] Step (6): Release the first sacrificial layer and the second sacrificial layer to obtain an open-hole microbridge structure.

[0026] Preferably, the reflective layer is made of aluminum, silver or gold; the thermal sensitive layer is made of vanadium oxide or polysilicon; and the absorption layer is made of silicon nitride, silicon dioxide or porous silicon.

[0027] In addition, the present application also provides a focal plane array, comprising a plurality of open-hole micro-bridge structures as described above, wherein the plurality of open-hole micro-bridge structures are arranged in an array on a two-dimensional plane.

[0028] Compared with the prior art, the beneficial effects of this application are:

[0029] The present application can not only expand the absorption area of ​​infrared radiation and obtain a higher fill factor, but also, by opening a plurality of first through holes on the thermally sensitive bridge surface, it can reduce the heat capacity while enhancing the infrared absorption, thereby increasing the response speed of the device and improving the absorption characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1is a schematic structural diagram of the open-hole microbridge structure of the present invention;

[0031] Figure 2 is a front view of the open-hole microbridge structure of the present invention;

[0032] Figure 3 is a schematic structural diagram of a focal plane array of the present invention;

[0033] Figure 4 is a graph of Example 8 of the present invention;

[0034] Figure 5 It is a curve diagram of Comparative Example 3 of the present invention;

[0035] Figure 6 It is a graph of Comparative Example 5 of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] Before describing Example 1 of the present invention, a method for preparing an open-hole microbridge structure of the present invention is first described. The method comprises the following steps:

[0038] Step (1): preparing a reflective layer 11, an insulating dielectric layer, and a first sacrificial layer in sequence on a substrate 1 provided with a readout circuit, and etching the first sacrificial layer to obtain a bridge pier 5 hole;

[0039] Step (2): depositing a first supporting layer, a thermosensitive layer, a first passivation layer, a metal layer and a protective layer on the first sacrificial layer in sequence to form a thermosensitive bridge surface 2;

[0040] Step (3): etching the thermally sensitive bridge surface 2 to obtain the bridge legs 6 and the thermally sensitive bridge surface 2 having the first through hole 21;

[0041] Step (4): preparing a second sacrificial layer on the heat-sensitive bridge deck 2, and etching the second sacrificial layer to obtain a supporting hole 4;

[0042] Step (5): depositing a second supporting layer, an absorption layer, and a second passivation layer on the second sacrificial layer in sequence to form an umbrella surface layer 3, and etching the umbrella surface layer 3 to obtain an umbrella surface layer 3 having a second through hole 31;

[0043] Step (6): Release the first sacrificial layer and the second sacrificial layer to obtain an open-hole microbridge structure.

[0044] Specific structure reference Figure 1 and Figure 2 .

[0045] Wherein, the first supporting layer and the second supporting layer may be made of silicon nitride;

[0046] The first passivation layer and the second passivation layer may be made of silicon nitride;

[0047] The metal layer may be made of aluminum;

[0048] The first sacrificial layer and the second sacrificial layer may be made of polyimide;

[0049] The protective layer may be made of silicon nitride;

[0050] The insulating dielectric layer may be made of silicon oxide.

[0051] Regarding a focal plane array of the present invention, reference is made to Figure 3 , is formed by arranging the open-hole microbridge structure of the present invention in an array on a two-dimensional plane. Multiple microbridge structures arranged in the focal plane array can monitor the same field of view at the same time, thereby achieving high-resolution imaging. Precise arrangement and design can minimize image interference and noise and improve imaging clarity.

[0052] In the following embodiments, unless otherwise specified, the heights of the first resonant cavity and the second resonant cavity are both 1 / 4λ, and the first through hole 21 and the second through hole 31 are both square holes. The microbridge structures in the following embodiments are simulated by CST software to obtain the absorption rates of the infrared bands 8μm-14μm and 10μm, and except for the structural changes, other parameters are the same.

[0053] Example 1

[0054] An open-hole microbridge structure comprises a substrate 1 provided with a readout circuit, a thermosensitive bridge deck 2 electrically connected to the readout circuit, and an umbrella surface layer 3 provided above the thermosensitive bridge deck 2 and connected to the thermosensitive bridge deck 2 through a supporting hole 4, wherein a plurality of first through holes 21 are provided on the thermosensitive bridge deck 2;

[0055] The opening area of ​​the first through hole 21 accounts for 10% of the area of ​​the thermal sensitive bridge deck 2;

[0056] The first through holes 21 are arranged in a 5*5 matrix rectangular array around the support hole 4;

[0057] The electrical property change of the heat-sensitive bridge deck 2 is transmitted to the readout circuit through the bridge leg 6 connected to the bridge pier 5; the bridge leg 6 is U-shaped;

[0058] A reflective layer 11 is provided on the substrate 1 , a first layer of resonance cavity 7 is provided between the reflective layer 11 and the thermal sensitive bridge surface 2 ; and a second layer of resonance cavity 8 is provided between the thermal sensitive bridge surface 2 and the umbrella surface layer 3 .

[0059] Example 2

[0060] It is basically the same as the first embodiment, except that the first through holes 21 are arranged in a 2*2 matrix rectangular array around the supporting holes 4 .

[0061] Example 3

[0062] It is basically the same as the first embodiment, except that the first through holes 21 are arranged around the supporting holes 4 in an 8*8 matrix rectangular array.

[0063] Example 4

[0064] It is basically the same as the first embodiment, except that the opening area of ​​the first through hole 21 accounts for 30% of the area of ​​the thermal sensitive bridge deck 2 .

[0065] Example 5

[0066] The embodiment is basically the same as the first embodiment, except that the opening area of ​​the first through hole 21 accounts for 60% of the area of ​​the thermal sensitive bridge deck 2 .

[0067] Example 6

[0068] It is basically the same as the first embodiment, except that a plurality of second through holes 31 are provided on the umbrella surface layer 3, and the second through holes 31 account for 10% of the area of ​​the umbrella surface layer 3;

[0069] The second through holes 31 are arranged in a 5*5 matrix rectangular array around the support hole 4;

[0070] The first through holes 21 and the second through holes 31 are partially staggered.

[0071] Example 7

[0072] It is basically the same as the embodiment 5, except that a plurality of second through holes 31 are provided on the umbrella surface layer 3, and the second through holes 31 account for 10% of the area of ​​the umbrella surface layer 3;

[0073] The second through holes 31 are arranged in a rectangular array around the support holes 4;

[0074] The first through holes 21 and the second through holes 31 are partially staggered.

[0075] Example 8

[0076] It is basically the same as Example 7, except that a plurality of second through holes 31 are provided on the umbrella surface layer 3 , and the second through holes 31 account for 30% of the area of ​​the umbrella surface layer 3 .

[0077] Example 9

[0078] It is basically the same as Example 7, except that a plurality of second through holes 31 are provided on the umbrella surface layer 3 , and the second through holes 31 account for 40% of the area of ​​the umbrella surface layer 3 .

[0079] Example 10

[0080] The embodiment is basically the same as the sixth embodiment, except that the first through holes 21 and the second through holes 31 are completely staggered.

[0081] Embodiment 11

[0082] The embodiment is basically the same as the sixth embodiment, except that the first through holes 21 and the second through holes 31 correspond to each other one by one.

[0083] Example 12

[0084] The embodiment is basically the same as the first embodiment, except that a plurality of second through holes 31 are provided on the umbrella surface layer 3, and the second through holes 31 are of the same size as the first through holes 21 and correspond one to one.

[0085] Comparative Example 1

[0086] It is basically the same as the first embodiment, except that the opening area of ​​the first through hole 21 accounts for 5% of the area of ​​the thermal sensitive bridge deck 2 .

[0087] Comparative Example 2

[0088] The embodiment is basically the same as the first embodiment, except that the opening area of ​​the first through hole 21 accounts for 70% of the area of ​​the thermal sensitive bridge deck 2 .

[0089] Comparative Example 3

[0090] The double-layer micro-bridge structure is substantially the same as that of the first embodiment, except that the thermal sensitive bridge surface 2 does not have the first through hole 21 .

[0091] Comparative Example 4

[0092] It is basically the same as Comparative Example 3, except that the thermal sensitive bridge deck 2 does not have the first through hole 21, and the umbrella surface layer 3 has a plurality of second through holes 31, and the second through holes 31 account for 10% of the area of ​​the umbrella surface layer 3.

[0093] Comparative Example 5

[0094] It is basically the same as Comparative Example 3, except that the thermal sensitive bridge deck 2 does not have the first through hole 21, and the umbrella surface layer 3 has a plurality of second through holes 31, and the second through holes 31 account for 30% of the area of ​​the umbrella surface layer 3.

[0095] Comparative Example 6

[0096] It is basically the same as Comparative Example 3, except that the thermal sensitive bridge deck 2 does not have the first through hole 21, and the umbrella surface layer 3 has a plurality of second through holes 31, and the second through holes 31 account for 40% of the area of ​​the umbrella surface layer 3.

[0097] Comparative Example 7

[0098] It is basically the same as the first embodiment, except that the opening area of ​​the first through hole 21 accounts for 70% of the area of ​​the heat-sensitive bridge deck 2 ; the second through hole 31 accounts for 30% of the area of ​​the umbrella surface layer 3 .

[0099] Comparative Example 8

[0100] It is basically the same as the first embodiment, except that the opening area of ​​the first through hole 21 accounts for 70% of the area of ​​the heat-sensitive bridge deck 2 ; the second through hole 31 accounts for 40% of the area of ​​the umbrella surface layer 3 .

[0101] Test method: The open-hole microbridge structures of Examples 1 to 12 and Comparative Examples 1 to 8 were simulated in CST software respectively, and the average absorption rates of the corresponding Examples and Comparative Examples in the infrared band of 8 μm-14 μm and 10 μm were recorded. The simulation results are shown in Table 1.

[0102] Table 1 Simulation results

[0103]

[0104]

[0105] Result analysis:

[0106] 1. From the simulation results of Examples 1 to 3 and Comparative Example 3, it can be seen that the matrix sizes of Example 1, Example 2, and Example 3 increase successively, but in the average absorption rate of 8μm-14μm, the difference among the three is less than 0.2%, and in the absorption rate of 10μm, the difference among the three is even smaller, and the simulation results are closer, indicating that when the first through hole has the same proportion, the size of the matrix has little effect on the result, but they are all better than Comparative Example 3.

[0107] 2. From the simulation results of Example 1, Example 4, Example 5, Comparative Example 1, Comparative Example 2, and Comparative Example 3, it can be seen that when the proportion of the first through holes exceeds the range of 10% to 60%, whether lower or higher than this range, the average absorption rate of 8μm-14μm and the absorption rate of 10μm are significantly reduced, and it can be found that when the proportion of the first through holes reaches 60%, the average absorption rate of 8μm-14μm and the absorption rate of 10μm are most ideal, and are significantly better than Comparative Example 3.

[0108] 3. From the simulation results of Examples 6 to 9 and Comparative Examples 3, 7, and 8, it can be seen that when the first through hole accounts for 10% to 60% and the second through hole accounts for no more than 30%, the absorption rate of 10 μm is slightly improved, and it can also be found that when the proportion of the second through hole gradually increases within the range of no more than 30%, the average absorption rate of 8 μm-14 μm shows an upward trend, and when the proportion of the second through hole reaches 30%, the average absorption rate of 8 μm-14 μm and the absorption rate of 10 μm reach the maximum value;

[0109] When either the first through hole or the second through hole is out of the range, the average absorption rate of 8μm-14μm and the absorption rate of 10μm are significantly reduced; when both are out of the range, the average absorption rate of 8μm-14μm and the absorption rate of 10μm reach the lowest value, further illustrating that the ideal effect can be achieved when the proportion of the first through hole is within the range of 10% to 60% and the proportion of the second through hole is within the range of no more than 30%.

[0110] 4. From the simulation results of Examples 10 to 12 and Comparative Example 3, it can be seen that the effects of the first through hole and the second through hole are very close when they are completely staggered, different in size and corresponding up and down, and the same in size and corresponding up and down. However, perhaps because the proportion of the first through hole and the second through hole is relatively small in the interval, there is still a certain gap with the result of Example 8, which shows that the up and down relationship between the first through hole and the second through hole does not have a big impact on the result, but they are all better than Comparative Example 3.

[0111] 5. Combine Figures 4 to 6 From the simulation results of Example 8 and Comparative Examples 3 to 6, it can be seen that only opening the second through hole on the umbrella surface layer cannot improve the absorption rate, and the simulation results are very close to those of Comparative Example 3. Figure 5 and Figure 6 It can be seen that the curve trend of opening only the first through hole on the umbrella surface is very similar to that of the traditional double-layer micro-bridge structure, with a large overall fluctuation, resulting in a lower average absorption rate of 8μm-14μm. Figure 4 It can be seen that under the synergistic effect of the first through hole and the second through hole, the curve fluctuation is significantly reduced, and it can be found that the absorption rate of 10μm is closer to 100%.

[0112] The reasons for the above results may be:

[0113] 1. The opening of the first through hole and the second through hole can release the first sacrificial layer and the second sacrificial layer more cleanly, thereby reducing the performance impact caused by the residue of the first sacrificial layer and the second sacrificial layer;

[0114] 2. The opening of the first through hole and the second through hole helps to optimize the structure of the corresponding first resonant cavity and the second resonant cavity, and the diffraction effect can be used to enhance the absorption of infrared radiation. When infrared radiation irradiates the thermosensitive layer of the thermosensitive bridge surface, part of the light will be diffracted through the diffraction window formed by the first through hole and the second through hole, so that the infrared radiation that is not directly absorbed by the thermosensitive layer is reflected multiple times in the corresponding first resonant cavity and the second resonant cavity, increasing the path length of the light in the thermosensitive layer and improving the infrared absorption rate;

[0115] 3. If the proportion of the first through hole is too large, the effective absorption area of ​​the thermal sensitive bridge surface will be reduced. Similarly, if the proportion of the second through hole is too large, the effective absorption area of ​​the umbrella surface layer will be reduced, thereby reducing its absorption capacity of infrared radiation. Because the thermal sensitive bridge surface mainly relies on the thermal layer to absorb infrared light and convert the temperature into voltage or current to transmit to the circuit on the substrate, if the proportion is too large, the area of ​​the thermal layer will be reduced, and the conversion of the thermal layer resistance value will be worse, which will directly affect the absorption rate and indirectly affect the imaging effect.

[0116] In summary, the simulation experiment using CST software proves that the perforated microbridge structure in this scheme can greatly improve the detector's absorption rate of infrared light compared to the traditional double-layer microbridge structure. And from the experimental data, it can be seen that under the synergistic effect of the first through hole opened on the thermal sensitive bridge surface and the second through hole opened on the umbrella surface layer, compared with the traditional double-layer microbridge structure, the average absorption rate of 8μm-14μm can be increased by about 13%, and the absorption rate of 10μm is closer to 100%.

[0117] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. An open-hole microbridge structure, comprising a substrate provided with a readout circuit, a thermosensitive bridge surface electrically connected to the readout circuit, and an umbrella surface layer provided above the thermosensitive bridge surface and connected to the thermosensitive bridge surface through a supporting hole, characterized in that: The heat sensitive bridge surface is provided with a plurality of first through holes; The opening area of ​​the first through hole accounts for 10% to 60% of the area of ​​the thermal sensitive bridge surface.

2. The open-hole microbridge structure according to claim 1, characterized in that: The umbrella surface layer is provided with a plurality of second through holes, and the second through holes account for no more than 30% of the area of ​​the umbrella surface layer.

3. The open-hole microbridge structure according to claim 2, characterized in that: The first through holes and the second through holes are both opened in a rectangular array around the supporting holes.

4. The open-hole microbridge structure according to claim 1, characterized in that: The first through holes and the second through holes are at least partially staggered.

5. The open-hole microbridge structure according to claim 1, characterized in that: The electrical property changes of the heat-sensitive bridge deck are transmitted to the readout circuit through the bridge legs connected to the bridge piers; the bridge legs are U-shaped.

6. The open-hole microbridge structure according to claim 1, characterized in that: A reflection layer is arranged on the substrate, a first layer of resonance cavity is arranged between the reflection layer and the heat-sensitive bridge surface, and a second layer of resonance cavity is arranged between the heat-sensitive bridge surface and the umbrella surface layer.

7. The open-hole microbridge structure according to claim 6, characterized in that: The height of the first resonant cavity is 2 μm to 2.5 μm; the height of the second resonant cavity is 2 μm to 2.5 μm.

8. A method for preparing an open-hole microbridge structure, characterized in that: The following steps are involved: Step (1): preparing a reflective layer, an insulating dielectric layer, and a first sacrificial layer in sequence on a substrate provided with a readout circuit, and etching the first sacrificial layer to obtain a bridge pier hole; Step (2): depositing a first supporting layer, a thermosensitive layer, a first passivation layer, a metal layer and a protective layer on the first sacrificial layer in sequence to form a thermosensitive bridge surface; Step (3): etching the thermally sensitive bridge surface to obtain a bridge leg and a thermally sensitive bridge surface having a first through hole; Step (4): preparing a second sacrificial layer on the heat-sensitive bridge surface, and etching the second sacrificial layer to obtain a support hole; Step (5): depositing a second supporting layer, an absorption layer, and a second passivation layer on the second sacrificial layer in sequence to form an umbrella surface layer, and etching the umbrella surface layer to obtain an umbrella surface layer having a second through hole; Step (6): Release the first sacrificial layer and the second sacrificial layer to obtain an open-hole microbridge structure.

9. The method for preparing an open-pore microbridge structure according to claim 8, characterized in that: The material of the reflective layer is aluminum, silver or gold; the material of the thermal sensitive layer is vanadium oxide or polysilicon; the material of the absorption layer is silicon nitride, silicon dioxide, or porous silicon.

10. A focal plane array, characterized in that: It comprises a plurality of open-hole micro-bridge structures as claimed in any one of claims 1 to 7, wherein the plurality of open-hole micro-bridge structures are arranged in an array on a two-dimensional plane.

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