High-absorption non-refrigeration optical machine thermal infrared detector and manufacturing method thereof

Abstract

The invention discloses a high-absorption uncooled optical machine thermal infrared detector and a manufacturing method thereof, the optical machine thermal infrared detector comprises a silicon wafer, a first groove and a second groove are formed in the silicon wafer, a movable micro-mirror is arranged in the first groove, and the second groove is exposed out of the lower surface of the movable micro-mirror; the movable micro-mirror comprises an absorption area structure and two micro-bridge structures which are respectively connected to two sides of the absorption area structure; a plurality of micro-nano superstructures are arranged on the upper surface of the absorption region structure; a glass semitransparent mirror is arranged at a notch of the first groove, so that a Fabry-Perot cavity is formed; and an optical filter is arranged at the notch of the second groove. A novel optical-mechanical-thermal detection structure is adopted, the induction speed of a mechanical resonance mode can be increased, and the detection rate can be increased; through the micro-nano superstructure, the absorption efficiency can be improved, and the absorption spectrum range is expanded; in addition, the micro-nano superstructure directly grows on the optical-mechanical thermal structure supporting layer, and thermal transmission between the micro-nano superstructure and the optical-mechanical thermal resonance induction layer is good.

Description

Technical Field

[0001] The invention belongs to the field of infrared detectors, and in particular relates to a high-absorption non-refrigerated optomechanical thermal infrared detector and a manufacturing method thereof. Background Art

[0002] The optomechanical thermal infrared detector is a new type of high-sensitivity uncooled infrared focal plane detector, mainly composed of a MEMS optomechanical thermal conversion pixel array and a (CCD or CIS) image sensor, and is used in infrared guidance, infrared night vision, aerospace / aerospace reconnaissance and other fields. Based on the principle of light → heat → mechanical deformation / resonance conversion, infrared radiation is converted into a mechanical resonance mode (amplitude / frequency change), coupled with (active) visible light, and then detected and read out through a high signal-to-noise ratio charge coupled device (CCD) or CMOS image sensor (CIS), thereby achieving high-speed and high-sensitivity infrared detection imaging.

[0003] Traditional photovoltaic infrared detectors use narrow bandgap semiconductor materials and utilize the photoelectric effect to convert infrared light signals into electrical signals. They operate at temperatures of 77K or lower and require bulky and complex refrigeration equipment. They are large in size, have high maintenance costs, are difficult to miniaturize, and have expensive materials and are difficult to prepare. They are incompatible with CMOS technology, so their development is limited. Traditional thermal resistor type uncooled detectors use the thermal effect of infrared radiation to convert infrared radiation energy into thermal energy. The temperature rise of the sensitive element causes changes in physical parameters, which are then converted into electrical signals or visible light signals through some conversion mechanism for readout. Due to the influence of dark current and other noise sources, the temperature resolution is 1 to 2 orders of magnitude lower than that of the cooling type, and there are problems of slow response speed and low sensitivity. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a high-absorption non-cooled optomechanical thermal infrared detector and a manufacturing method thereof.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A highly absorptive non-cooled optical-mechanical thermal infrared detector comprises a silicon wafer, a first groove is formed on the front side of the silicon wafer, a movable micromirror is arranged at the bottom of the first groove; the movable micromirror comprises an absorption zone structure located in the middle area of ​​the first groove and two microbridge structures respectively connected to the two sides of the absorption zone structure, and the two microbridge structures are connected to the side wall of the first groove; a plurality of micro-nano superstructures are arranged on the upper surface of the absorption zone structure; a glass semi-mirror is fixedly arranged at the notch of the first groove, so as to form a Fabry-Perot cavity between the movable micromirror and the glass semi-mirror; a second groove is arranged on the back side of the silicon wafer corresponding to and directly below the first groove, the second groove exposes the lower surface of the movable micromirror, and a filter is fixedly arranged at the notch of the second groove.

[0007] Furthermore, the absorption zone structure includes a first visible light reflecting layer at the bottom, a first supporting layer arranged on the first visible light reflecting layer, and a surface passivation layer arranged on the supporting layer; the microbridge structure includes a second visible light reflecting layer at the bottom and a second supporting layer arranged on the second visible light reflecting layer.

[0008] Furthermore, the first supporting layer and the second supporting layer are made of materials that can absorb infrared radiation and whose mechanical strength and chemical stability meet the requirements of MEMS processing technology, and the first visible light reflecting layer and the second visible light reflecting layer are made of metal materials that have high reflectivity to visible light and a large difference in thermal expansion coefficient with the materials of the first supporting layer and the second supporting layer.

[0009] Furthermore, the first visible light reflecting layer and the second visible light reflecting layer are made of Au or Al; the first supporting layer and the second supporting layer are made of SiN x or SiO 2 , and its characteristic size is 50nm~500nm.

[0010] Furthermore, the material of the surface passivation layer is Al 2 O 3 or SiO 2 , and its characteristic size is 20nm~200nm.

[0011] Furthermore, the material of the micro-nano superstructure is a combination of any one or more metals selected from Al, Ti, Au and Ag, and its characteristic size is 0.5 μm to 5 μm.

[0012] Furthermore, the microbridge structure includes a first connecting segment, a second connecting segment, a third connecting segment, a fourth connecting segment and a supporting column, the first connecting segment is arranged along the width direction of the absorption area structure and connected to the middle of the side of the absorption area structure; the second connecting segment is arranged along the length direction of the absorption area structure, and the length of the second connecting segment is adapted to half of the length of the absorption area structure, and the first end of the second connecting segment is connected to the first connecting segment; the fourth connecting segment is located on the side of the second connecting segment away from the absorption area structure, and the length of the fourth connecting segment is adapted to the length of the absorption area structure; the first end of the fourth connecting segment is connected to the second end of the second connecting segment through the third connecting segment, the second end of the fourth connecting segment is connected to the supporting column, and the supporting column is fixedly connected to the side wall of the first groove.

[0013] A method for manufacturing a high-absorption uncooled optomechanical thermal infrared detector comprises the following steps:

[0014] S100, taking a silicon wafer, and etching a first groove on the front side of the silicon wafer using a wet etching process;

[0015] S200, manufacturing a movable micromirror and a plurality of micro-nano superstructures in the first groove; the movable micromirror comprises an absorption zone structure located in the middle area of ​​the first groove and two microbridge structures respectively connected to both sides of the absorption zone structure, and the two microbridge structures are both connected to the sidewalls of the first groove; the plurality of micro-nano superstructures are located on the upper surface of the absorption zone structure;

[0016] S300, forming a second groove on the back side of the silicon wafer below the first groove by using double-sided alignment photolithography and deep silicon etching process, wherein the second groove exposes the lower surface of the movable micromirror;

[0017] S400, fixing the glass half mirror at the notch of the first groove by an anodic bonding process, so as to form a Fabry-Perot cavity between the movable micromirror and the glass half mirror;

[0018] S500, fixing the filter at the notch of the second groove by vacuum packaging and bonding.

[0019] Furthermore, the step S200 includes the following sub-steps:

[0020] S210, using a magnetron sputtering process to grow a metal material at the bottom of the first groove to form a visible light reflection layer;

[0021] S220, growing a support layer on the visible light reflection layer by using an LPCVD process;

[0022] S230, growing a surface passivation layer on the surface of the support layer by using a thermal oxidation process;

[0023] S240, patterning the visible light reflecting layer, the supporting layer and the surface passivation layer by using photolithography and etching processes, removing the visible light reflecting layer and the supporting layer in the area outside the absorption region structure and the microbridge structure, and removing the surface passivation layer in the area outside the absorption region structure;

[0024] S250, using PECVD process to deposit metal materials, and using photolithography and etching process to pattern them to form a micro-nano super structure.

[0025] Furthermore, the glass semi-mirror is formed by firstly evaporating aluminum from glass using a PVD process and then patterning it using a photolithography and etching process.

[0026] In the present invention, the detection unit adopts a new type of optomechanical thermal detection structure, which can improve the mechanical resonance mode sensing speed and enhance the detection rate. The micro-nano superstructure is used as the optomechanical thermal infrared detector absorption structure, which can improve the absorption efficiency and expand the absorption spectrum range. In addition, the micro-nano superstructure is directly grown on the optomechanical thermal structure support layer, and the thermal transfer between the micro-nano superstructure and the optomechanical thermal resonance sensing layer is good. In addition, the characteristic size of the micro-nano superstructure is easy to control, and Al, Ti, Au, Ag and other materials compatible with the commonly used silicon-based detector process can be used to improve the structural stability and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 It is a schematic cross-sectional view along the x-axis direction of an embodiment of a high-absorption uncooled optomechanical thermal infrared detector of the present invention.

[0029] Figure 2 Top view after removing the glass half-mirror from the movable micromirror area.

[0030] Figure 3 It is a schematic cross-sectional view along the y-axis direction when the movable micromirror is in a deformed state.

[0031] Figure 4 The flowchart is a method for manufacturing a highly absorbing uncooled optomechanical thermal infrared detector according to an embodiment of the present invention.

[0032] Figure 5 It is a schematic diagram of the structure after the first groove is formed on the silicon wafer.

[0033] Figure 6 This is a schematic diagram of the structure after a movable micromirror and multiple micro-nano superstructures are made in the first groove.

[0034] Figure 7This is a schematic diagram of the structure after removing the silicon below the first groove.

[0035] The accompanying drawings in the specification are as follows:

[0036] Absorption zone structure-1; first visible light reflecting layer-11; first supporting layer-12; surface passivation layer-13; microbridge structure-2; second visible light reflecting layer-21; second supporting layer-22; first connecting section-25; second connecting section-26; third connecting section-27; fourth connecting section-28; supporting column-29; micro-nano superstructure-3; silicon wafer-4; first groove-51; second groove-52; filter-6; glass semi-mirror-7. DETAILED DESCRIPTION

[0037] The following describes the implementation methods of the present invention through specific examples. The illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention. The following embodiments and features in the embodiments may be combined with each other without conflict.

[0038] See also Figure 1 and Figure 2 , Figure 1 Schematic cross-sectional view of an embodiment of a highly absorbing uncooled optomechanical thermal infrared detector of the present invention. The highly absorbing uncooled optomechanical thermal infrared detector of this embodiment comprises a silicon wafer 4, which is generally a double-sided polished silicon wafer. A first groove 51 is formed on the front surface of the silicon wafer 4, and a movable micromirror is arranged in the first groove 51, and the movable micromirror is used to form a MEMS structure.

[0039] The movable micromirror comprises an absorption region structure 1 located in the middle area of ​​the first groove 51 and two microbridge structures 2 respectively connected to both sides of the absorption region structure 1, and the two microbridge structures 2 are connected to the side walls of the first groove 51. Since the movable micromirror needs to absorb infrared radiation and needs to be movable after being irradiated by infrared radiation, and also needs to transmit visible light, the material of the movable micromirror is generally selected to have a high transmittance to visible light and a high absorptivity to infrared radiation, and the structure of the movable micromirror adopts a dual-material cantilever layer structure.

[0040] In this embodiment, the absorption region structure 1 is a three-layer structure, including a first visible light reflecting layer 11 at the bottom, a first supporting layer 12 disposed on the first visible light reflecting layer 11, and a surface passivation layer 13 disposed on the supporting layer. The microbridge structure 2 is a two-layer structure, including a second visible light reflecting layer 21 at the bottom and a second supporting layer 22 disposed on the second visible light reflecting layer 21.

[0041] The first visible light reflecting layer 11 and the second visible light reflecting layer 21 are combined to form a visible light reflecting layer, that is, the first visible light reflecting layer 11 and the second visible light reflecting layer 21 are different regions of the same layer structure. The first supporting layer 12 and the second supporting layer 22 are combined to form a supporting layer, that is, the first supporting layer 12 and the second supporting layer 22 are also different regions of the same layer structure.

[0042] The support layer is one of the material layers of the dual-material cantilever structure, and mainly plays the role of absorbing infrared radiation, causing the dual-material cantilever to deform, and supporting the overall structure. The support layer is made of a material that can absorb infrared radiation and whose mechanical strength and chemical stability meet the requirements of MEMS processing technology.

[0043] The visible light reflecting layer is another material layer of the dual-material cantilever layer structure, and is mainly used to prevent the dual-material cantilever deformation caused by the difference in thermal expansion coefficient after the support layer absorbs infrared radiation, and to reflect visible detection light; the visible light reflecting layer is made of a metal material with high reflectivity to visible light and a large difference in thermal expansion coefficient with the support layer material.

[0044] In order to obtain the best sensitivity of the MEMS structure, the thickness of each film layer can be calculated based on the optical admittance principle and the thermo-mechanical sensitivity theory calculation principle, taking into account the film thickness of the movable micromirror, the cavity length of the Fabry-Perot cavity and the thickness ratio of the dual-material microbridge structure. In addition, when designing the dual-material microbridge structure, in order to obtain a larger thermo-mechanical displacement, the greater the difference in the thermal expansion coefficients of the two materials constituting the dual-material cantilever layer structure, the better.

[0045] For example, the first supporting layer 12 and the second supporting layer 22 may be made of siN x or SiO 2 The material of the first visible light reflection layer 11 and the second visible light reflection layer 21 is Au or Al, and its thickness meets the optical admittance principle (i.e., high reflection design requirements). The surface passivation layer 13 mainly plays the role of surface protection and passivation, and can be made of Al 2 O 3 、SiO 2 Materials such as nanostructured carbon nanotubes have a characteristic size of 20nm to 200nm.

[0046] The upper surface of the absorption zone structure 1 is provided with a plurality of micro-nano superstructures 3, which mainly play the role of enhancing infrared radiation absorption and improving responsiveness. The material of the micro-nano superstructure 3 can be a combination of any one or more metals of Al, Ti, Au and Ag, and the shape of the micro-nano superstructure 3 can be a square, a disk, a triangle, a hole, a column, etc., and its characteristic size is 0.5μm to 5μm.

[0047] The micro-bridge structure 2 may include a first connecting segment 25, a second connecting segment 26, a third connecting segment 27, a fourth connecting segment 28 and a supporting column 29. The first connecting segment 25 is arranged along the width direction of the absorption zone structure 1 and connected to the middle of the side of the absorption zone structure 1. The second connecting segment 26 is arranged along the length direction of the absorption zone structure 1, and the length of the second connecting segment 26 is adapted to half the length of the absorption zone structure 1. The first end of the second connecting segment 26 is connected to the first connecting segment 25. The fourth connecting segment 28 is located on the side of the second connecting segment 26 away from the absorption zone structure 1, and the length of the fourth connecting segment 28 is adapted to the length of the absorption zone structure 1. The first end of the fourth connecting segment 28 is connected to the second end of the second connecting segment 26 through the third connecting segment 27, and the second end of the fourth connecting segment 28 is connected to the supporting column 29. The supporting column 29 is fixedly connected to the side wall of the first groove 51, and mainly plays the role of supporting the movable micromirror.

[0048] A glass half-mirror 7 is fixedly arranged at the notch of the first groove 51 by anodic bonding. The glass half-mirror 7 adopts a semi-transparent and semi-reflective mirror (i.e., it transmits infrared radiation and reflects visible light), and mainly serves as one of the reflectors of the Fabry-Perot cavity, as well as the function of reflecting and detecting visible light. The visible light reflecting layer of the movable micromirror forms the other reflector of the Fabry-Perot cavity, thereby forming a Fabry-Perot cavity between the movable micromirror and the glass half-mirror 7. The Fabry-Perot cavity mainly plays the role of optical readout, and the reflectivity of the two mirror surfaces is directly related to the detection and readout capability.

[0049] A second groove 52 is formed on the back side of the silicon wafer 4 below the first groove 51. The second groove 52 exposes the lower surface of the movable micromirror. A filter 6 is fixedly arranged at the notch of the second groove 52 by vacuum packaging and bonding. The filter 6 mainly plays the role of transmitting visible light and filtering stray light.

[0050] See also Figure 3 After adopting the above structure, when receiving infrared radiation, the absorption area structure 1 is a whole structure, and its area of ​​absorbing infrared radiation is large, so the deformation is also large, and it tilts at a larger angle. The microbridge structure 2 is composed of several thinner sections, and its area is much smaller than the absorption area structure 1, so the deformation is also small, and it will only tilt at a small angle, so that the absorption area structure 1 and the microbridge structure 2 form a certain angle, which is convenient for image sensor detection.

[0051] This embodiment uses the optical-mechanical thermal detection structure + micro-nano superstructure 3 as the infrared detection unit, which has many unique advantages, mainly including the following parts:

[0052] (1) High absorption rate. The structure of this embodiment has a larger effective absorption area and a higher duty cycle than the traditional optomechanical thermal detector structure. By directly growing the micro-nano superstructure 3 on the optomechanical thermal structure support layer, the light-heat-mechanical deformation conversion efficiency is high. In addition, by controlling the parameters of the micro-nano superstructure 3, spectral regulation can be achieved, the spectral absorption efficiency can be improved, and the absorption rate can be greater than 80%, thereby making the optomechanical thermal detector of this embodiment more sensitive.

[0053] (2) Wide absorption spectrum range. This embodiment uses a micro-nano superstructure 3 coupled with an optomechanical thermal detection structure. The micro-nano superstructure 3 can broaden the detection spectrum range, covering short-wave infrared to long-wave infrared bands, and even THz bands, and can achieve extremely wide spectrum detection.

[0054] (3) Fast response speed. The structure of this embodiment is relatively sensitive to deformation. After absorbing infrared radiation, it can produce deformation through the principle of thermal expansion. Compared with the existing heat conduction technology, it reduces the heat conduction process. With the ultra-high absorption efficiency and ultra-low noise optical readout of the micro-nano superstructure 3, the device response speed is greatly improved.

[0055] (4) Good versatility. By controlling the relevant parameters of the micro-nano superstructure 3, the absorption rate from short-wave infrared to long-wave infrared can be greater than 80%, and the structure of this embodiment can be used in optical, mechanical and thermal detection devices in various application scenarios.

[0056] (5) Materials are easily available. The standard silicon process line contains the materials required for the structure of this embodiment, and has low requirements on the manufacturing process platform.

[0057] Based on the above advantages, the optical-mechanical thermal infrared detector of this embodiment is very suitable for applications in the fields of infrared guidance, infrared night vision, aviation / aerospace reconnaissance, etc.

[0058] See also Figure 4 , Figure 4 This is a flow chart of an embodiment of the present invention of a highly absorbing uncooled optical-mechanical thermal infrared detector and a method for manufacturing the same. The highly absorbing uncooled optical-mechanical thermal infrared detector and a method for manufacturing the same in this embodiment include the following steps:

[0059] S100, please refer to Figure 5 , take a silicon wafer 4, which is generally a double-sided polished silicon wafer 4; a first groove 51 is etched on the front side of the silicon wafer 4 by a wet etching process. The size of the first groove 51 can be determined according to the required cavity length of the Fabry-Perot cavity.

[0060] S200, please refer to Figure 6, a movable micromirror and a plurality of micro-nano superstructures 3 are made in the first groove 51. The movable micromirror comprises an absorption zone structure 1 located in the middle area of ​​the first groove 51 and two microbridge structures 2 respectively connected to both sides of the absorption zone structure 1, and the two microbridge structures 2 are both connected to the side walls of the first groove 51; the plurality of micro-nano superstructures 3 are located on the upper surface of the absorption zone structure 1. This step may include the following sub-steps:

[0061] S210, using a magnetron sputtering process, growing a metal material at the bottom of the first groove 51 to form a visible light reflection layer. The visible light reflection layer is made of a metal material with high reflectivity to visible light and a large difference in thermal expansion coefficient with the support layer material. For example, the material of the visible light reflection layer can be Au or Al, and the thickness of the visible light reflection layer can meet the high reflection design requirements.

[0062] S220, using LPCVD process to grow a support layer on the visible light reflection layer. The support layer is made of a material that can absorb infrared radiation and has mechanical strength and chemical stability that meet the requirements of MEMS processing technology. For example, the support layer can be made of siN x or SiO 2 Materials such as nanostructured carbon nanotubes have a characteristic size of 50nm to 500nm.

[0063] S230, using a thermal oxidation process, growing a surface passivation layer 13 on the surface of the support layer. The surface passivation layer 13 mainly plays a role in surface protection and passivation, and can be made of Al 2 O 3 、SiO 2 Materials such as nanostructured carbon nanotubes have a characteristic size of 20nm to 200nm.

[0064] S240, patterning the visible light reflecting layer, the supporting layer and the surface passivation layer 13 by using photolithography and etching processes, removing the visible light reflecting layer and the supporting layer in the area outside the absorption area structure 1 and the microbridge structure 2, and removing the surface passivation layer 13 in the area outside the absorption area structure 1.

[0065] The micro-bridge structure 2 may include a first connecting segment 25, a second connecting segment 26, a third connecting segment 27, a fourth connecting segment 28 and a supporting column 29. The first connecting segment 25 is arranged along the width direction of the absorption zone structure 1 and connected to the middle of the side of the absorption zone structure 1. The second connecting segment 26 is arranged along the length direction of the absorption zone structure 1, and the length of the second connecting segment 26 is adapted to half the length of the absorption zone structure 1. The first end of the second connecting segment 26 is connected to the first connecting segment 25. The fourth connecting segment 28 is located on the side of the second connecting segment 26 away from the absorption zone structure 1, and the length of the fourth connecting segment 28 is adapted to the length of the absorption zone structure 1. The first end of the fourth connecting segment 28 is connected to the second end of the second connecting segment 26 through the third connecting segment 27, and the second end of the fourth connecting segment 28 is connected to the supporting column 29. The supporting column 29 is fixedly connected to the side wall of the first groove 51, and mainly plays the role of supporting the movable micromirror.

[0066] After patterning, the visible light reflecting layer includes a first visible light reflecting layer 11 in the area corresponding to the absorption zone structure 1 and a second visible light reflecting layer 21 in the area corresponding to the microbridge structure 2, the supporting layer includes a first supporting layer 12 in the area corresponding to the absorption zone structure 1 and a supporting layer in the area corresponding to the microbridge structure 2, and the surface passivation layer 13 is only located in the area corresponding to the absorption zone structure 1.

[0067] S250, depositing metal materials by PECVD process, and patterning them by photolithography and etching process to form micro-nano superstructure 3. The micro-nano superstructure 3 mainly plays the role of enhancing infrared radiation absorption and improving responsiveness. The material of the micro-nano superstructure 3 can be a combination of any one or more metals of Al, Ti, Au and Ag. The shape of the micro-nano superstructure 3 can be square, disc, triangle, hole, column, etc., and its characteristic size is 0.5μm to 5μm.

[0068] S300, see Figure 7 A second groove 52 is formed on the back side of the silicon wafer 4 below the first groove 51 by double-sided alignment photolithography and deep silicon etching process. The second groove 52 exposes the lower surface of the movable micromirror, thereby removing the silicon on the back side of the movable micromirror, releasing the movable micromirror, and forming a MEMS structure.

[0069] S400, please continue to read Figure 1The glass half-mirror 7 is fixed to the notch of the first groove 51 by an anodic bonding process, and a Fabry-Perot cavity is formed between the movable micromirror and the glass half-mirror 7 by two reflecting surfaces formed by the surface of the movable micromirror and the lower end surface of the glass half-mirror 7. The glass half-mirror 7 adopts a semi-transparent and semi-reflective mirror, which mainly serves as one of the reflecting mirrors of the Fabry-Perot cavity and reflects and detects visible light. In this embodiment, the glass half-mirror 7 is formed by first evaporating aluminum from glass using a PVD process and then patterning it using a photolithography and etching process.

[0070] S500, please continue to read Figure 1 The filter 6 is fixed to the notch of the second groove 52 by vacuum packaging and bonding, thereby completing the manufacture of the non-cooled optical thermal infrared detector. The filter 6 mainly plays the role of transmitting visible light and filtering stray light.

[0071] The novel optomechanical thermal detection structure manufactured by the method of this embodiment can improve the mechanical resonance mode sensing speed and the detection rate; the micro-nano superstructure 3 is used as the optomechanical thermal infrared detector absorption structure to improve the absorption efficiency and expand the absorption spectrum range. In addition, the micro-nano superstructure 3 is directly grown on the optomechanical thermal structure support layer, and the thermal transfer between the micro-nano superstructure 3 and the optomechanical thermal resonance sensing layer is good. In addition, the characteristic size of the micro-nano superstructure 3 is easy to control, and Al, Ti, Au, Ag and other materials compatible with the commonly used silicon-based detector process can be used to improve the structural stability and reliability.

[0072] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A highly absorbing uncooled optomechanical thermal infrared detector, characterized in that: It includes a silicon wafer, a first groove is formed on the front side of the silicon wafer, and a movable micromirror is arranged at the bottom of the first groove; the movable micromirror includes an absorption zone structure located in the middle area of ​​the first groove and two microbridge structures respectively connected to the two sides of the absorption zone structure, and the two microbridge structures are connected to the side walls of the first groove; a plurality of micro-nano superstructures are arranged on the upper surface of the absorption zone structure; a glass semi-mirror is fixedly arranged at the notch of the first groove, so as to form a Fabry-Perot cavity between the movable micromirror and the glass semi-mirror; a second groove is arranged on the back side of the silicon wafer corresponding to and directly below the first groove, the second groove exposes the lower surface of the movable micromirror, and a filter is fixedly arranged at the notch of the second groove.

2. The high-absorption uncooled optomechanical thermal infrared detector according to claim 1, characterized in that: The absorption zone structure includes a first visible light reflecting layer at the bottom, a first supporting layer arranged on the first visible light reflecting layer, and a surface passivation layer arranged on the supporting layer; the microbridge structure includes a second visible light reflecting layer at the bottom and a second supporting layer arranged on the second visible light reflecting layer.

3. The high-absorption uncooled optical-mechanical thermal infrared detector according to claim 2, characterized in that: The first supporting layer and the second supporting layer are made of materials that can absorb infrared radiation and whose mechanical strength and chemical stability meet the requirements of MEMS processing technology. The first visible light reflecting layer and the second visible light reflecting layer are made of metal materials that have high visible light reflectivity and a large difference in thermal expansion coefficient with the materials of the first supporting layer and the second supporting layer.

4. The high-absorption uncooled optical-mechanical thermal infrared detector according to claim 3, characterized in that: The materials of the first visible light reflecting layer and the second visible light reflecting layer are Au or Al; the materials of the first supporting layer and the second supporting layer are SiN x Or SiO2, its characteristic size is 50nm ~ 500nm.

5. The high-absorption uncooled optical-mechanical thermal infrared detector according to claim 2, characterized in that: The material of the surface passivation layer is Al2O3 or SiO2, and its characteristic size is 20nm-200nm.

6. The high-absorption uncooled optical-mechanical thermal infrared detector according to any one of claims 1 to 5, characterized in that: The material of the micro-nano superstructure is a combination of any one or more metals of Al, Ti, Au and Ag, and its characteristic size is 0.5 μm to 5 μm.

7. The high-absorption uncooled optical-mechanical thermal infrared detector according to any one of claims 1 to 5, characterized in that: The microbridge structure includes a first connecting segment, a second connecting segment, a third connecting segment, a fourth connecting segment and a supporting column. The first connecting segment is arranged along the width direction of the absorption area structure and is connected to the middle of the side of the absorption area structure; the second connecting segment is arranged along the length direction of the absorption area structure, and the length of the second connecting segment is adapted to half of the length of the absorption area structure, and the first end of the second connecting segment is connected to the first connecting segment; the fourth connecting segment is located on the side of the second connecting segment away from the absorption area structure, and the length of the fourth connecting segment is adapted to the length of the absorption area structure; the first end of the fourth connecting segment is connected to the second end of the second connecting segment through the third connecting segment, and the second end of the fourth connecting segment is connected to the supporting column, and the supporting column is fixedly connected to the side wall of the first groove.

8. A method for manufacturing a high-absorption uncooled optomechanical thermal infrared detector, characterized in that: The following steps are involved: S100, taking a silicon wafer, and etching a first groove on the front side of the silicon wafer using a wet etching process; S200, manufacturing a movable micromirror and a plurality of micro-nano superstructures in the first groove; the movable micromirror comprises an absorption zone structure located in the middle of the first groove and two microbridge structures respectively connected to both sides of the absorption zone structure, and the two microbridge structures are both connected to the sidewalls of the first groove; the plurality of micro-nano superstructures are located on the upper surface of the absorption zone structure; S300, forming a second groove on the back side of the silicon wafer below the first groove by using double-sided alignment photolithography and deep silicon etching process, wherein the second groove exposes the lower surface of the movable micromirror; S400, fixing the glass half mirror at the notch of the first groove by an anodic bonding process, so as to form a Fabry-Perot cavity between the movable micromirror and the glass half mirror; S500, fixing the filter at the notch of the second groove by vacuum packaging and bonding.

9. The method for manufacturing a highly absorbing uncooled optical-mechanical thermal infrared detector according to claim 8, characterized in that: The step S200 includes the following sub-steps: S210, using a magnetron sputtering process to grow a metal material at the bottom of the first groove to form a visible light reflection layer; S220, growing a support layer on the visible light reflection layer by using an LPCVD process; S230, growing a surface passivation layer on the surface of the support layer by using a thermal oxidation process; S240, patterning the visible light reflecting layer, the supporting layer and the surface passivation layer by using photolithography and etching processes, removing the visible light reflecting layer and the supporting layer in the area outside the absorption region structure and the microbridge structure, and removing the surface passivation layer in the area outside the absorption region structure; S250, using PECVD process to deposit metal materials, and using photolithography and etching process to pattern them to form a micro-nano super structure.

10. The method for manufacturing a highly absorbing uncooled optical-mechanical thermal infrared detector according to claim 8, characterized in that: The glass half-mirror is formed by firstly evaporating aluminum from glass using a PVD process and then patterning it using a photolithography and etching process.

Images