Bi-material micro-cantilever and metasurface compounded infrared detector and preparation method thereof
By introducing a metasurface functional layer into a dual-material micro-cantilever beam infrared detector, the problems of limited application range and low sensitivity of traditional detectors are solved, and efficient absorption and sensitive detection of multiple infrared bands are achieved.
Patent Information
- Application Number
- CN202510489873.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2025-07-22
Smart Images
Figure CN120352031A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of infrared detectors, and particularly to an infrared detector composed of a bimaterial microcantilever and a metasurface and a preparation method thereof. Background Art
[0002] Infrared detection technology is a technology for obtaining and identifying information based on infrared radiation. With the progress of technology, infrared detection technology has been widely used in many fields such as military reconnaissance, environmental monitoring, and medical diagnosis. Traditional infrared detectors mainly work based on quantum effects or thermal effects, but these detectors have deficiencies in some aspects, such as low sensitivity and limited spectral response range. Therefore, the research and development of new infrared detectors have become a current research hotspot.
[0003] A bimaterial microcantilever is a sensitive element of an infrared detector based on the thermally induced bending effect. It is composed of two materials with significantly different thermal expansion coefficients. When exposed to infrared radiation, due to the different thermal expansion coefficients of the two materials, bending deformation will occur. This deformation can be read out through electrical, optical, etc. methods, thereby realizing the detection of infrared radiation. However, traditional bimaterial microcantilever infrared detectors may only be sensitive to specific infrared bands, which limits their application range. Summary of the Invention
[0004] In order to solve the above technical problems, the present invention provides an infrared detector composed of a bimaterial microcantilever and a metasurface with a simple structure and a wide application range, and provides a preparation method thereof.
[0005] The technical solution of the present invention to solve the above technical problems is: an infrared detector composed of a bimaterial microcantilever and a metasurface, including a bimaterial microcantilever, a metasurface functional layer, and a deformation detection module. The bimaterial microcantilever is composed of a thermosensitive layer and a support layer. The metasurface functional layer is integrated on the upper surface of the thermosensitive layer. The deformation detection module is located on the bimaterial microcantilever, and measures the bending deformation of the bimaterial microcantilever through optical or electrical means.
[0006] For the above infrared detector composed of a bimaterial microcantilever and a metasurface, the difference in thermal expansion coefficients between the thermosensitive layer and the support layer is greater than 5×10 -6 / K, the material of the thermosensitive layer is SiN x 、SiO2 or Al, and the material of the support layer is Au, Pt or graphene.
[0007] The above infrared detector with a composite of a bimaterial microcantilever and a metasurface, wherein the functional layer of the metasurface is an array of gold nanorods, the angle between the long axis direction and the incident light polarization direction is adjustable, and the size of the gold nanorods meets the following requirements: the length of the long axis is 500 - 1200 nm, the length of the short axis is 80 - 300 nm, the array period is 1.2 - 2 times the length of the long axis, and the thickness of the gold layer is 30 - 150 nm.
[0008] The above infrared detector with a composite of a bimaterial microcantilever and a metasurface, wherein the functional layer of the metasurface is a substrate-free Au / SiN x / Au patch array, including an Au film located in the lower layer with a thickness of 20 - 50 nm; a SiN x dielectric layer located in the middle with a thickness of 100 - 300 nm; an Au patch array located in the upper layer, the unit size is 1 - 5 μm, the thickness is 50 - 200 nm, and the array period is 1.1 - 1.5 times the unit size.
[0009] The above infrared detector with a composite of a bimaterial microcantilever and a metasurface, wherein the functional layer of the metasurface is a multi-resonant unit combined structure, including a first sub-array and a second sub-array. The first sub-array uses square Au patches with a size of 1 - 3 μm for absorption in the 3 - 5 μm band; the second sub-array uses cross-shaped Au nanorods with a long axis length of 2 - 4 μm for absorption in the 8 - 14 μm band; the spatial arrangement period ratio of the first sub-array and the second sub-array is 1:2 - 1:4.
[0010] The above infrared detector with a composite of a bimaterial microcantilever and a metasurface, wherein a stepped thermal isolation groove is provided at the root of the bimaterial microcantilever. The depth of the thermal isolation groove is 10 - 50 μm, and the thermal isolation groove is filled with porous silica aerogel. The thermal conductivity of the porous silica aerogel is ≤0.015 W / (m·K), and the surface of the thermal isolation groove is covered with a 100 nm thick Al2O3 protective layer.
[0011] A preparation method of an infrared detector with a composite of a bimaterial microcantilever and a metasurface, comprising the following steps:
[0012] S1. Deposit a support layer and a thermosensitive layer on a silicon substrate in sequence to form a bimaterial thin film;
[0013] S2. Use lithography technology to define the pattern of the bimaterial microcantilever, and transfer the pattern to the bimaterial thin film through a reactive ion etching process;
[0014] S3. Prepare a metasurface functional layer on the surface of the thermosensitive layer;
[0015] S4. Release the bimaterial microcantilever structure: Use XeF2 gas etching to remove the silicon substrate.
[0016] The preparation method of the above infrared detector composed of a bimaterial microcantilever and a metasurface. In step S3, if the metasurface functional layer is a gold nanorod array, a nanoimprint lithography + oblique evaporation process is used to control the evaporation angle to adjust the aspect ratio of the gold nanorods. Specifically:
[0017] First, spin-coat a nanoimprint resist, and use a PDMS soft template to imprint to form nano-grooves with a groove width of 80 - 300 nm. Then, deposit a 5 - 20 nm thick Cr adhesion layer at an oblique angle of 30° - 60°. Next, vertically deposit an 80 - 200 nm thick Au layer, and form a gold nanorod array by lift-off.
[0018] The preparation method of the above infrared detector composed of a bimaterial microcantilever and a metasurface. In step S3, if the metasurface functional layer is Au / SiN x / Au patch array, a lift-off process is used to sequentially deposit the lower Au film, the middle SiN x dielectric layer, and the upper Au patch array. Specifically:
[0019] The Au film is deposited by electron beam evaporation, and the rate is The substrate temperature ≤ 100 °C;
[0020] SiN x The dielectric layer is deposited by PECVD, the flow ratio of SiH4 / NH3 is 1:2 - 1:5, and the thickness control accuracy is ±5 nm;
[0021] The Au patch array is deposited by electrochemical deposition, and the current density is 2 - 5 mA / cm 2 , and the surface roughness is Ra ≤ 3 nm.
[0022] The preparation method of the above infrared detector composed of a bimaterial microcantilever and a metasurface. Before releasing the bimaterial microcantilever structure in step S4, the following steps are further included: using deep reactive ion etching (DRIE) to etch a thermal isolation groove with a depth of 10 - 50 μm at the root of the bimaterial microcantilever; forming silica aerogel in the thermal isolation groove through a supercritical drying process; using atomic layer deposition to grow a 100 nm thick Al2O3 protective layer on the surface of the silica aerogel.
[0023] The beneficial effects of the present invention are as follows:
[0024] 1. The bimaterial microcantilever of the present invention is composed of two layers of materials with large differences in thermal expansion coefficients, making the microcantilever very sensitive to temperature changes and capable of efficiently converting infrared radiation into mechanical deformation.
[0025] 2. The metasurface functional layer can adopt three structures (gold nanorod array, Au / SiN x / Au patch array, multi-resonant unit combination structure); If a gold nanorod array is used, when infrared light irradiates the gold nanorods, if the frequency of the light matches the SPR frequency of the gold nanorods, strong resonant absorption will occur; If Au / SiN is used x / Au patch array, when infrared light irradiates the structure, multiple reflections and interferences will occur in the dielectric layer, forming resonant absorption; If a multi-resonant unit combination structure is used, the interaction and coupling effects between different resonant units are utilized to achieve simultaneous absorption of multiple different infrared bands. Therefore, the metasurface functional layer can efficiently absorb specific infrared bands, enhancing the spectral response range and sensitivity of the detector.
[0026] 3. The metasurface functional layer of the present invention can adopt a gold nanorod array, and the angle between the long axis direction of the gold nanorod array and the incident light polarization direction is adjustable, enabling the infrared detector to adjust its absorption characteristics according to requirements and achieving more flexible infrared detection. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 is a schematic structural diagram of an infrared detector with a composite of a bimaterial microcantilever and a metasurface according to the present invention.
[0028] Figure 2 is a flowchart of a preparation method of an infrared detector with a composite of a bimaterial microcantilever and a metasurface according to the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0029] The present invention will be further described below with reference to the drawings and embodiments.
[0030] As Figure 1 shown, an infrared detector with a composite of a bimaterial microcantilever and a metasurface includes a bimaterial microcantilever, a metasurface functional layer, and a deformation detection module. The bimaterial microcantilever is composed of a thermosensitive layer and a support layer. The metasurface functional layer is integrated on the upper surface of the thermosensitive layer, and the deformation detection module is located on the bimaterial microcantilever to measure the bending deformation of the bimaterial microcantilever by optical or electrical means.
[0031] The difference in thermal expansion coefficients between the thermosensitive layer and the support layer is greater than 5×10 -6 / K, the material of the thermosensitive layer is SiN x , SiO2 or Al, and the material of the support layer is Au, Pt or graphene.
[0032] The metasurface functional layer is a gold nanorod array, the angle between its long axis direction and the incident light polarization direction is adjustable, and the size of the gold nanorods meets the requirements: the length of the long axis is 500 - 1200 nm, the length of the short axis is 80 - 300 nm, the array period is 1.2 - 2 times the length of the long axis, and the thickness of the gold layer is 30 - 150 nm.
[0033] The metasurface functional layer is a substrate-free Au / SiN x / Au patch array, including an Au film located in the lower layer with a thickness of 20 - 50 nm; a SiN x dielectric layer located in the middle with a thickness of 100 - 300 nm; an Au patch array located in the upper layer with a unit size of 1 - 5 μm, a thickness of 50 - 200 nm, and an array period that is 1.1 - 1.5 times the unit size.
[0034] The metasurface functional layer is a multi-resonant unit combined structure, including a first sub-array and a second sub-array. The first sub-array uses square Au patches with a size of 1 - 3 μm for absorption in the 3 - 5 μm band; the second sub-array uses cross-shaped Au nanorods with a major axis length of 2 - 4 μm for absorption in the 8 - 14 μm band; the spatial arrangement period ratio of the first sub-array and the second sub-array is 1:2 - 1:4.
[0035] A stepped thermal isolation groove is provided at the root of the bimaterial microcantilever. The depth of the thermal isolation groove is 10 - 50 μm. The thermal isolation groove is filled with porous silica aerogel, and the thermal conductivity of the porous silica aerogel is ≤0.015 W / (m·K). The surface of the thermal isolation groove is covered with a 100 nm thick Al2O3 protective layer.
[0036] A preparation method of an infrared detector composed of a bimaterial microcantilever and a metasurface includes the following steps:
[0037] S1. Deposit a support layer and a thermosensitive layer on a silicon substrate in sequence to form a bimaterial thin film;
[0038] S2. Define the pattern of the bimaterial microcantilever by lithography technology, and transfer the pattern to the bimaterial thin film through a reactive ion etching process;
[0039] S3. Prepare a metasurface functional layer on the surface of the thermosensitive layer;
[0040] If the metasurface functional layer is a gold nanorod array, then use nanoimprint lithography + oblique evaporation process to control the evaporation angle to adjust the aspect ratio of the gold nanorods; specifically:
[0041] First, spin-coat a nanoimprint resist, use a PDMS soft template to imprint to form nano-grooves with a groove width of 80 - 300 nm; then evaporate a 5 - 20 nm thick Cr adhesion layer at an oblique angle of 30° - 60°; then vertically evaporate an 80 - 200 nm thick Au layer, and form a gold nanorod array by lift-off.
[0042] If the metasurface functional layer is an Au / SiN x / Au patch array, then use the lift-off process to deposit the Au film in the lower layer and the SiN in the middle in sequence xThe dielectric layer and the upper Au patch array; specifically:
[0043] The Au film is deposited by electron beam evaporation with a rate of The substrate temperature ≤ 100 °C;
[0044] SiN x The dielectric layer is deposited by PECVD with a SiH4 / NH3 flow ratio of 1:2 - 1:5 and a thickness control accuracy of ±5 nm;
[0045] The Au patch array is deposited electrochemically with a current density of 2 - 5 mA / cm 2 , and the surface roughness is Ra ≤ 3 nm.
[0046] S4. Releasing the bimaterial microcantilever structure: The silicon substrate is removed by XeF2 gas etching.
[0047] In step S4, before releasing the bimaterial microcantilever structure, the following steps are further included: A thermal isolation groove with a depth of 10 - 50 μm is etched at the root of the bimaterial microcantilever by deep reactive ion etching (DRIE); silica aerogel is formed in the thermal isolation groove through a supercritical drying process; a 100 - nm - thick Al2O3 protective layer is grown on the surface of the silica aerogel by atomic layer deposition.
[0048] Example 1
[0049] A preparation method of an infrared detector with a composite of a bimaterial microcantilever and a metasurface, including the following steps:
[0050] S1. Depositing a support layer and a thermosensitive layer on a silicon substrate in sequence to form a bimaterial thin film;
[0051] On the cleaned silicon substrate, first, a 20 - nm - thick Au is deposited as the support layer by electron beam evaporation. Subsequently, a 150 - nm - thick SiN x is deposited as the thermosensitive layer.
[0052] S2. Defining the pattern of the bimaterial microcantilever by lithography technology and transferring the pattern to the bimaterial thin film through a reactive ion etching process;
[0053] S3. Preparing a metasurface functional layer on the surface of the thermosensitive layer;
[0054] By nanoimprint lithography technology, nano - grooves with a width of 150 nm are formed on the thermosensitive layer. A 10 - nm - thick Cr is evaporated at a 45° tilt angle as an adhesion layer, and then a 120 - nm - thick Au is evaporated vertically.
[0055] The excess metal is removed by a lift - off process to form the metasurface functional layer 3.
[0056] S4. Release the bimaterial microcantilever structure: Use XeF2 gas etching to remove the silicon substrate.
[0057] Detection content:
[0058] Use an optical microscope and a scanning electron microscope (SEM) to observe the morphology of the bimaterial microcantilever and the metasurface functional layer. Measure the spectral response of the infrared detector using an infrared spectrometer. Use a laser displacement sensor to measure the bending deformation of the bimaterial microcantilever at different temperatures.
[0059] The detection results are shown in Table 1:
[0060] Table 1
[0061]
[0062] Among them, ΔT is the temperature rise. When the bimaterial microcantilever generates a temperature rise of 10 °C due to absorbing infrared radiation, its thermally induced bending deformation reaches 2.5 μm.
[0063] Example 2
[0064] A preparation method of an infrared detector composed of a composite of a bimaterial microcantilever and a metasurface, comprising the following steps:
[0065] S1. Same as Example 1.
[0066] S2. Same as Example 1.
[0067] S3. Prepare the metasurface functional layer on the surface of the thermosensitive layer:
[0068] Adopt nanoimprint lithography technology to form nano-grooves on the thermosensitive layer, and adjust the groove width to 80 nm. Evaporate a 5-nm-thick Cr adhesion layer at an inclined angle of 30°, and then vertically evaporate an 80-nm-thick Au layer. Remove the excess metal through a lift-off process to form the metasurface functional layer.
[0069] S4. Same as Example 1.
[0070] Detection content:
[0071] Use an optical microscope and a scanning electron microscope (SEM) to observe the morphology of the bimaterial microcantilever and the metasurface functional layer. Pay special attention to the arrangement density and uniformity of the gold nanorod array. Measure the spectral response of the infrared detector using an infrared spectrometer. Use a laser displacement sensor to measure the bending deformation of the bimaterial microcantilever at different temperatures.
[0072] The detection results are shown in Table 2:
[0073] Table 2
[0074]
[0075] Example 3
[0076] A preparation method of an infrared detector composed of a bimaterial microcantilever and a metasurface includes the following steps:
[0077] S1. The same as Example 1.
[0078] S2. The same as Example 1.
[0079] S3. Prepare a metasurface functional layer on the surface of the thermosensitive layer:
[0080] Adopt nanoimprint lithography technology to form nano-grooves on the thermosensitive layer, and adjust the groove width to 300 nm. Evaporate a 20-nm-thick Cr layer as an adhesion layer at an angle of 60°, and then vertically evaporate a 200-nm-thick Au layer. Remove the excess metal through the lift-off process to form the metasurface functional layer.
[0081] S4. The same as Example 1.
[0082] Detection content:
[0083] Use an optical microscope and a scanning electron microscope (SEM) to observe the morphology of the bimaterial microcantilever and the metasurface functional layer. Pay special attention to the spacing and overall coverage of the gold nanorod array. Measure the spectral response of the infrared detector with an infrared spectrometer. Measure the bending deformation of the bimaterial microcantilever at different temperatures with a laser displacement sensor.
[0084] The detection results are shown in Table 3:
[0085] Table 3
[0086]
[0087] Example 4
[0088] A preparation method of an infrared detector composed of a bimaterial microcantilever and a metasurface includes the following steps:
[0089] S1. Deposit a support layer and a thermosensitive layer on a silicon substrate in sequence to form a bimaterial thin film;
[0090] On the cleaned silicon substrate, first deposit a 30-nm-thick Pt layer as the support layer by electron beam evaporation. Subsequently, deposit a 200-nm-thick SiO2 layer as the thermosensitive layer by PECVD.
[0091] S2. Use lithography technology to define the pattern of the bimaterial microcantilever, and transfer the pattern to the bimaterial thin film through the reactive ion etching process;
[0092] S3. Prepare a metasurface functional layer on the surface of the thermosensitive layer;
[0093] Deposit square Au patches using the lift-off process, with a unit size of 2 μm and a thickness of 100 nm; within the same area, prepare a cross-shaped Au nanorod array with a major axis length of 3 μm through a mask and an additional deposition step.
[0094] Preparation of thermal isolation grooves and growth of the protective layer:
[0095] Use deep reactive ion etching (DRIE) to etch thermal isolation grooves with a depth of 30 μm at the beam root. Form silica aerogel in the thermal isolation grooves through supercritical drying. Grow a 100-nm-thick Al2O3 protective layer on the surface of the silica aerogel by atomic layer deposition.
[0096] Remove the excess metal through the lift-off process to form the metasurface functional layer 3.
[0097] S4. Release the bimaterial microcantilever beam structure: Use XeF2 gas etching to remove the silicon substrate.
[0098] Detection content:
[0099] Use SEM and energy-dispersive spectroscopy (EDS) to analyze the multi-resonant unit composition of the metasurface functional layer; measure the thermal conductivity of the thermal isolation grooves with a thermal conductivity meter. The detection results are shown in Table 4:
[0100] Table 4
[0101]
[0102] Example 5:
[0103] A preparation method of a substrate-free Au / SiN x / Au patch array
[0104] Process flow:
[0105] First, substrate preparation:
[0106] Spin-coat photoresist (AR-P5350, thickness 1.2 μm) on the surface of the bimaterial microcantilever beam thermosensitive layer (SiN x , 200 nm), and define the pattern of the lower Au film through ultraviolet lithography (the window size covers the entire cantilever beam area).
[0107] Second, deposit the lower Au film using the electron beam evaporation process:
[0108] Substrate temperature: 80 °C (monitored in real time by a thermocouple);
[0109] Deposition rate: (controlled by a quartz crystal oscillator);
[0110] Final thickness: 30 nm (±2 nm error, verified by profilometer);
[0111] After peeling, a continuous Au film is formed, with surface roughness Ra = 1.2 nm (measured by AFM).
[0112] Third, use PECVD process for intermediate SiN x Dielectric layer deposition:
[0113] Reaction gases: SiH4 / NH3 = 1:3 (flow ratio);
[0114] RF power: 300 W, pressure: 800 mTorr;
[0115] Deposition rate: 12 nm / min, final thickness: 200 nm;
[0116] Refractive index: 2.02 (measured by ellipsometer, 632 nm wavelength);
[0117] Fourth, preparation of upper Au patch array;
[0118] a. Spin-coat electron beam photoresist (PMMA950K, thickness 400 nm);
[0119] b. Electron beam exposure (dose 550 μC / cm 2 , acceleration voltage 100 kV) to define square patch array:
[0120] Unit size: 2 μm × 2 μm
[0121] Array period: 2.4 μm (1.2 times the unit size)
[0122] c. Electrochemical deposition of Au:
[0123] Electrolyte: potassium gold cyanide system (pH = 4.5)
[0124] Current density: 3 mA / cm 2 , deposition time: 15 min
[0125] Final thickness: 120 nm (measured by SEM cross-section)
[0126] d. After peeling, obtain Au patch array, with edge steepness > 85° (characterized by SEM).
[0127] The structural features are verified as shown in Table 5:
[0128] Table 5
[0129]
[0130] Thermal performance test:
[0131] Thermal conductivity gradient:
[0132] Measuring the thermal conductivity of a three-layer structure by time-domain thermoreflectance (TDTR):
[0133] Lower Au film: 318 W / (m·K);
[0134] Intermediate SiN x layer: 1.2 W / (m·K);
[0135] Upper Au patch: 285 W / (m·K);
[0136] Form a significant thermal resistance gradient to promote heat conduction towards the root of the cantilever beam.
[0137] Thermal response time:
[0138] Measured using a pulsed laser (pulse width 10 ns):
[0139] 10%-90% response time: 8.7 ms;
[0140] Recovery time: 12.3 ms;
[0141] Superior to the comparative example (single-layer Au structure without the intermediate SiN x layer) of 15.2 ms / 21.5 ms.
[0142] Proof of technical effect:
[0143] Intermediate SiN x Insertion of the layer enables the upper Au patch and the lower Au film to form a Fabry-Pérot resonance cavity, achieving an absorption rate of 91.3% in the 3-5 μm band.
[0144] The thermal conductivity gradient design of the sandwich structure enables more efficient conversion of temperature changes into bending deformation of the cantilever beam. When ΔT = 10 °C, the deformation amount reaches 3.2 μm.
[0145] The (111) crystal plane preferred orientation of the electrochemically deposited Au patch (XRD full width at half maximum 0.38°) reduces surface scattering loss.
Claims
1. An infrared detector composed of a dual-material microcantilever beam and a metasurface, characterized in that: It includes a bimaterial microcantilever beam, a metasurface functional layer, and a deformation detection module. The bimaterial microcantilever beam is composed of a thermosensitive layer and a support layer combined. The metasurface functional layer is integrated on the upper surface of the thermosensitive layer. The deformation detection module is located on the bimaterial microcantilever beam, and the bending deformation of the bimaterial microcantilever beam is measured by optical or electrical means.
2. The infrared detector with the composite of the bimaterial microcantilever beam and the metasurface according to claim 1, wherein: The difference in the coefficient of thermal expansion between the thermosensitive layer and the support layer is greater than 5×10 -6 / K, and the material of the thermosensitive layer is SiN x , SiO2 or Al, and the material of the support layer is Au, Pt or graphene.
3. The infrared detector with the composite of the dual-material microcantilever and the metasurface according to claim 1, wherein: The metasurface functional layer is an array of gold nanorods, and the included angle between the long axis direction and the incident light polarization direction is adjustable. The size of the gold nanorods meets the following requirements: the long axis length is 500 - 1200 nm, the short axis length is 80 - 300 nm, the array period is 1.2 - 2 times the long axis length, and the gold layer thickness is 30 - 150 nm.
4. The infrared detector composed of a dual-material microcantilever beam and a metasurface according to claim 1, characterized in that: The metasurface functional layer is a substrate-free Au / SiN x / Au patch array, including an Au film located in the lower layer with a thickness of 20-50 nm; a SiN x dielectric layer located in the middle with a thickness of 100-300 nm; an Au patch array located in the upper layer with a unit size of 1-5 μm, a thickness of 50-200 nm, and an array period that is 1.1-1.5 times the unit size.
5. The infrared detector with the composite of the dual-material microcantilever and the metasurface according to claim 1, characterized in that: The metasurface functional layer is a combined structure of multiple resonant units, including a first sub - array and a second sub - array. The first sub - array uses square Au patches with a size of 1 - 3 μm for absorption in the 3 - 5 μm band. The second sub - array uses cross - shaped Au nanorods with a long axis length of 2 - 4 μm for absorption in the 8 - 14 μm band. The spatial arrangement period ratio of the first sub - array and the second sub - array is 1:2 - 1:
4.
6. The infrared detector with a composite of a bimaterial microcantilever and a metasurface according to claim 1, characterized in that: A stepped thermal isolation groove is provided at the root of the bimaterial microcantilever beam. The depth of the thermal isolation groove is 10 - 50 μm. The thermal isolation groove is filled with porous silica aerogel, and the thermal conductivity of the porous silica aerogel is ≤0.015 W / (m·K). The surface of the thermal isolation groove is covered with a 100 - nm - thick Al2O3 protective layer.
7. A method for preparing an infrared detector composed of a composite of a bimaterial microcantilever beam and a metasurface according to any one of claims 1-6, characterized in that, It includes the following steps: S1. Deposit a support layer and a thermosensitive layer on a silicon substrate in sequence to form a bimaterial thin film. S2. Use photolithography technology to define the pattern of the bimaterial microcantilever beam, and transfer the pattern to the bimaterial thin film through a reactive ion etching process. S3. Prepare a metasurface functional layer on the surface of the thermosensitive layer. S4. Release the bimaterial microcantilever beam structure: Use XeF2 gas etching to remove the silicon substrate.
8. The preparation method of the infrared detector composed of the composite of the bimaterial microcantilever beam and the metasurface according to claim 7, characterized in that In step S3, if the metasurface functional layer is an array of gold nanorods, a nanoimprint lithography + oblique evaporation process is used to control the evaporation angle to adjust the aspect ratio of the gold nanorods. Specifically: First, spin - coat a nanoimprint resist, and use a PDMS soft template to imprint to form nano - grooves with a groove width of 80 - 300 nm. Then, deposit a 5 - 20 - nm - thick Cr adhesion layer at an inclined angle of 30° - 60°. Next, vertically deposit an 80 - 200 - nm - thick Au layer, and form an array of gold nanorods through lift - off.
9. The preparation method of the infrared detector composed of a dual-material microcantilever beam and a metasurface according to claim 7, characterized in that, In the step S3, if the metasurface functional layer is an Au / SiN x / Au patch array, the stripping process is used to sequentially deposit the lower Au film, the intermediate SiN x dielectric layer, and the upper Au patch array; specifically: The Au film is deposited by electron beam evaporation at a rate of The substrate temperature ≤ 100 °C; SiN x The dielectric layer is deposited by PECVD, the flow ratio of SiH4 / NH3 is 1:2 - 1:5, and the thickness control accuracy is ±5 nm; The Au patch array is fabricated by electrochemical deposition with a current density of 2 - 5 mA / cm 2 , and the surface roughness is Ra ≤ 3 nm.
10. The preparation method of the infrared detector composed of a bi-material microcantilever and a metasurface according to claim 7, characterized in that, In step S4, before releasing the bimaterial microcantilever beam structure, the following steps are also included: Use deep reactive ion etching (DRIE) to etch a thermal isolation groove with a depth of 10 - 50 μm at the root of the bimaterial microcantilever beam. Form porous silica aerogel in the thermal isolation groove through a supercritical drying process. Use atomic layer deposition to grow a 100 - nm - thick Al2O3 protective layer on the surface of the silica aerogel.