Metal nanoparticle loaded honeycomb porous silicon thin film and thermopile chip using same

Abstract

The present invention relates to the field of infrared detector chips, and in particular to a metal nanoparticle loaded honeycomb porous silicon thin film and a thermopile chip using same. The metal nanoparticle loaded honeycomb porous silicon thin film is a multifunctional thin film, and is a honeycomb-like porous silicon composite film loaded with nano Ag or Au or Pt noble metal particles and formed by taking a semiconductor silicon thin film as the matrix. By means of the synergistic effect of the light trapping and phonon scattering effect of a honeycomb porous structure and the plasmon and energy filtering effect of metal nanoparticles, the composite film is endowed with wide spectrum, strong absorption and high thermoelectric performance. According to the present invention, the average infrared absorption performance of the thin film in the wavelength range of 2.5-20 μm is as high as 96.56%, and the thermoelectric performance of the present invention is improved by 1.4 times compared with that of conventional silicon thin films. A single film layer replaces an infrared absorption layer, an insulating layer, and a thermocouple layer of a conventional thermopile chip, thereby achieving both efficient light absorption and thermoelectric conversion, greatly reducing the inert heat capacity and energy transmission loss of the chip, and improving the performance of the thermopile chip in lips and bounds.

Description

Metal nanoparticle-loaded honeycomb-like porous silicon film and its thermopile chip Technical Field

[0001] The present invention belongs to the field of infrared detector chips and relates to a thin film and a thermopile chip using the thin film, and specifically relates to a metal nanoparticle-loaded honeycomb porous silicon thin film and a preparation method thereof, and a thermopile chip using the metal nanoparticle-loaded honeycomb porous silicon thin film and a preparation method thereof. Background Art

[0002] Thermopile infrared detectors are a type of uncooled infrared detector. They offer advantages such as no chopping required, long life, excellent stability, low power consumption, and low cost. They are widely used in non-contact temperature measurement and presence sensing, and also have broad application prospects in areas such as non-dispersive infrared gas detection and infrared imaging. As the core component of a thermopile infrared detector, the thermopile chip is primarily composed of thin films such as a support layer, thermocouple, insulation layer, and infrared absorption layer. The infrared absorption layer absorbs infrared radiation, converts it into heat, and transfers it to the thermocouple. Based on the Seebeck (thermoelectric) effect, the thermocouple outputs an electrical signal related to the infrared radiation emitted by the target object. Infrared radiation energy undergoes three processes: light-to-heat conversion, heat transfer, and heat-to-electricity conversion. Chip performance depends on the combined efficiency of these three processes.

[0003] Over the years, researchers have conducted extensive research from the perspectives of thin film materials and chip structures, but the detection rate and response time of thermopile chips have not been able to break through 10 8 cm Hz 1 / 2 / W and millisecond bottlenecks limit the high-end application of thermopile chips. Since the first day of the birth of thermopile chips, light-to-heat and heat-to-electricity conversion have been independently completed by the absorption layer and the thermocouple layer, respectively. This basic configuration has remained unchanged. The efficient light absorption of the absorption layer requires a certain film thickness, and the thick film brings large heat capacity and long response time. This contradiction fundamentally hinders the performance breakthrough of thermopile chips. In addition, this configuration also requires an insulating layer to be arranged between the absorption layer and the thermocouple layer. The light-generated heat needs to be transferred to the thermocouple across the insulating layer, which not only brings additional heat loss but also further prolongs the response time. Summary of the Invention

[0004] In order to solve the technical problem of low thermoelectric performance of existing thermopile chips, the present invention provides a metal nanoparticle-loaded honeycomb porous silicon film and a preparation method thereof, a thermopile chip using the metal nanoparticle-loaded honeycomb porous silicon film and a preparation method thereof.

[0005] The present invention is implemented using the following technical solution: a metal nanoparticle-loaded honeycomb porous silicon film, which is applied to a thermopile chip. The metal nanoparticle-loaded honeycomb porous silicon film is a multifunctional film, which is based on a semiconductor silicon film and constructs a honeycomb porous silicon composite film loaded with nano-Ag, Au or Pt precious metal particles.

[0006] As a further improvement of the above solution, a honeycomb porous silicon composite membrane loaded with nano-Ag, Au or Pt noble metal particles is constructed by a metal-assisted chemical etching method.

[0007] As a further improvement of the above solution, the multifunctional film is a metal nanoparticle-loaded honeycomb-like porous single-crystal silicon, polycrystalline silicon or amorphous silicon film.

[0008] The present invention also provides a thermopile chip, which uses any of the above-mentioned metal nanoparticles to load the honeycomb-like porous silicon film.

[0009] The present invention also provides a method for preparing any of the above-mentioned metal nanoparticle-loaded honeycomb-like porous silicon films, the preparation method comprising the following steps:

[0010] Step 1: Using CVD growth technology to deposit and form a polycrystalline silicon or single crystal silicon thin film;

[0011] Step 2: Using P or B ion implantation process, implantation forms N-type or P-type polysilicon or single crystal silicon thin film;

[0012] Step 3: The deposited N-type or P-type polycrystalline silicon or single crystal silicon film is deposited to form a Ag, Pt or Au particle film by using magnetron sputtering technology or immersing it in a mixed solution of HF, AgNO3 or H2PtCl6 or HAuCl4 and H2O;

[0013] Step 4: Immerse the sample deposited with the precious metal particle film in a mixed solution of HF, H2O2, and H2O, and etch to obtain metal nanoparticle-loaded honeycomb porous silicon, thereby forming the metal nanoparticle-loaded honeycomb porous silicon film as a whole.

[0014] As a further improvement of the above scheme, the preparation method first uses SiH4 as the reaction gas and 630°C as the substrate temperature to grow a polysilicon film; secondly, B ions are implanted with an implantation energy of about 70-100 KeV and an implantation dose of about 2-5×10 20 ions / cm 2, forming a P-type polycrystalline silicon thin film; then, immersing the deposited P-type polycrystalline silicon thin film in a mixed solution of HF, AgNO3 and H2O, wherein the volume ratio of the mixed solution of HF, AgNO3 and H2O is 1: 1: 3, the concentration of the AgNO3 solution is 0.005 mol / L, the concentration of the HF solution is ≥ 40%, the immersion time is 1-5 minutes, and an Ag particle thin film is deposited on the surface; thereafter, the sample deposited with the Ag particle thin film is immersed in a mixed solution of HF, H2O2, and H2O, and etching is performed to obtain a silver nanoparticle-loaded honeycomb porous polycrystalline silicon as the multifunctional thin film.

[0015] As a further improvement of the above scheme, the preparation method first uses SiCl4 and H2 as reaction gases and 1200℃ as substrate temperature to epitaxially grow a single crystal silicon film; secondly, P ions are implanted with an implantation energy of about 70-100 KeV and an implantation dose of about 2-5×10 20 ions / cm 2 , forming an N-type single-crystal silicon thin film; then, using Ag as a target material and argon excitation, a layer of Ag particle film is deposited as an etching metal auxiliary layer; thereafter, the sample deposited with the Ag particle film is immersed in a mixed solution of HF, H2O2, and H2O to etch the silver nanoparticle-loaded honeycomb-like porous single-crystal silicon as the multifunctional film.

[0016] As a further improvement of the above scheme, the preparation method first uses SiH4 as the reaction gas and 630 °C as the substrate temperature to grow a polysilicon film; secondly, B ions are implanted with an implantation energy of about 70-100 KeV and an implantation dose of about 2-5×10 20 ions / cm 2 , forming a P-type polycrystalline silicon film; then, using Au as a target material and argon excitation, a layer of Au particle film is deposited as an etching metal auxiliary layer; thereafter, the sample deposited with the Au particle film is immersed in a mixed solution of HF, H2O2, and H2O to etch the gold nanoparticle-loaded honeycomb porous polycrystalline silicon as the multifunctional film.

[0017] Furthermore, the volume ratio of the HF, H2O2, and H2O mixed solution is 2:5:4, the HF solution concentration is ≥40%, the H2O2 solution concentration is ≥30%, and the immersion time is 1-2 hours.

[0018] The present invention also provides a method for preparing the above-mentioned thermopile chip, which comprises the following steps:

[0019] Using Si(100) as substrate, a layer of SiO2 film is grown as chip support layer;

[0020] The multifunctional film is directly formed on the chip support layer using the above-mentioned preparation method of the metal nanoparticle-loaded honeycomb porous silicon film;

[0021] Using tetraethyl orthosilicate Si(OC2H5)4 as the reaction gas and 700-750°C as the substrate temperature, a layer of SiO2 film is grown as the chip insulation layer;

[0022] The SiO2 film as an insulating layer is patterned to form openings at both ends of the silver nanoparticle-loaded honeycomb porous polycrystalline silicon multifunctional film layer to allow the silver nanoparticle-loaded honeycomb porous polycrystalline silicon to leak out;

[0023] Using AlSi (90% Al) as the target material and argon excitation, a layer of AlSi film is deposited as the chip electrode;

[0024] Using tetraethyl orthosilicate Si(OC2H5)4 as the reaction gas and 700-750°C as the substrate temperature, a layer of SiO2 film is grown as a chip protection layer;

[0025] The SiO2 film, which serves as a protective layer, is patterned to form openings at the solder pads of the thermopile chip, exposing the electrodes made of the Al layer.

[0026] XeF2 is used as a reaction gas and released from the back to etch and remove the silicon substrate under the thermopile to form a suspended structure, thereby obtaining the final base thermopile chip.

[0027] Compared with the existing technology, the present invention adopts a thin film material with both efficient light-heat and heat-electric conversion characteristics, which acts as an infrared absorption layer and a thermocouple at the same time to improve the performance of the thermopile chip. The multifunctional thin film material specifically refers to a metal nanoparticle-loaded honeycomb porous silicon film, which is a honeycomb porous silicon composite film loaded with precious metal particles such as nano-Ag, Au, or Pt, constructed by a metal-assisted chemical etching method using a semiconductor silicon film as a matrix. With the synergistic effect of the light trapping and phonon scattering effects of the honeycomb porous structure and the plasmon and energy filtering effects of the metal nanoparticles, the composite film is endowed with strong wide-spectrum absorption and high thermoelectric performance. The silver nanoparticle-loaded honeycomb porous silicon film disclosed in the embodiment of the present invention has an average infrared absorption performance of up to 96.56% in the wavelength range of 2.5-20 μm, and its thermoelectric performance is 1.4 times higher than that of traditional silicon films. A single film layer replaces the infrared absorption layer, insulation layer, and thermocouple layer of the traditional thermopile chip, while realizing a new concept of efficient light absorption and thermoelectric conversion, significantly reducing the chip's inert heat capacity and energy transfer loss, and bringing a performance leap for thermopile infrared detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a physical and microscopic structure diagram of a multifunctional thin-film-based thermopile chip provided by an embodiment of the present invention.

[0029] FIG2 is a schematic diagram of the preparation process of the multifunctional thin-film-based thermopile chip in FIG1 .

[0030] FIG3 is an infrared absorption spectrum of the thermopile chip in FIG1 after silver nanoparticles are loaded on a honeycomb-like porous silicon film.

[0031] FIG4 is a graph showing the thermoelectric performance of the thermopile chip in FIG1 after silver nanoparticles are loaded on a honeycomb-like porous silicon film. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] Example 1

[0034] Please refer to Figure 1, which discloses the physical object and microscopic structure diagram of the thermopile chip. The thermopile chip adopts a honeycomb porous silicon film loaded with silver nanoparticles. The metal nanoparticle-loaded honeycomb porous silicon film is a single multifunctional film. It is a honeycomb porous silicon composite film loaded with nano-Ag, Au or Pt precious metal particles constructed by a metal-assisted chemical etching method using a semiconductor silicon film as a matrix, preferably loaded with nano-Ag particles. The multifunctional film is a metal nanoparticle-loaded honeycomb porous single-crystal silicon, polycrystalline silicon or amorphous silicon film, preferably single-crystal silicon. This film replaces the three-layer film of the traditional thermopile chip, namely the infrared absorption layer, the insulating layer and the thermocouple layer, and can simultaneously achieve efficient light absorption and thermoelectric conversion.

[0035] Referring to FIG2 , the specific steps of the preparation method of the metal nanoparticle-loaded honeycomb-like porous silicon film are as follows:

[0036] Step 1: Using CVD growth technology, deposit and form polycrystalline silicon or single crystal silicon thin film;

[0037] Step 2: Using P or B ion implantation process, implantation forms N-type or P-type polysilicon or single crystal silicon thin film;

[0038] Step 3: The deposited N-type or P-type polycrystalline silicon or single crystal silicon film is deposited to form a Ag, Pt or Au particle film by using magnetron sputtering technology or immersing it in a mixed solution of HF, AgNO3 or H2PtCl6 or HAuCl4 and H2O;

[0039] Step 4: Immerse the sample deposited with the precious metal particle film in a mixed solution of HF, H2O2, and H2O, and etch to obtain metal nanoparticle-loaded honeycomb-like porous silicon.

[0040] Please refer to Figures 3 and 4. Figure 3 shows the infrared absorption spectrum of the silver nanoparticle-loaded honeycomb porous silicon film used in the thermopile chip in Figure 1, while Figure 4 shows the thermoelectric performance of the silver nanoparticle-loaded honeycomb porous silicon film used in the thermopile chip in Figure 1. Figure 3 shows the infrared absorption spectrum of the silver nanoparticle-loaded honeycomb porous silicon film used in the thermopile chip in Figure 1. The average infrared absorption performance in the 2.5–20 μm wavelength range is as high as 96.56%. Figure 4 shows the thermoelectric performance of the silver nanoparticle-loaded honeycomb porous silicon film used in the thermopile chip in Figure 1. Compared to traditional silicon films, the thermoelectric performance (ZT figure of merit) is improved by 1.4 times.

[0041] It can be seen that the multifunctional thin film material-based thermopile chip of the present invention adopts a thin film material with both efficient light-heat and heat-electric conversion characteristics, which can act as an infrared absorption layer and a thermocouple at the same time, thereby improving the performance of the thermopile chip. The multifunctional thin film material specifically refers to a metal nanoparticle-loaded honeycomb porous silicon film, which is based on a semiconductor silicon film and is constructed by a metal-assisted chemical etching method to construct a honeycomb porous silicon composite film loaded with nano-Ag, Au, Pt and other precious metal particles. With the synergistic effect of the light trapping and phonon scattering effects of the honeycomb porous structure and the plasmon and energy filtering effects of the metal nanoparticles, the composite film is endowed with strong wide-spectrum absorption and high thermoelectric performance. The silver nanoparticle-loaded honeycomb porous silicon film disclosed in the embodiment of the present invention has an average infrared absorption performance of up to 96.56% in the wavelength range of 2.5-20 μm, and its thermoelectric performance is 1.4 times higher than that of traditional silicon films. A single film layer replaces the infrared absorption layer, insulation layer, and thermocouple layer of the traditional thermopile chip, while realizing a new concept of efficient light absorption and thermoelectric conversion, significantly reducing the chip's inert heat capacity and energy transfer loss, and bringing a performance leap for thermopile infrared detectors.

[0042] Next, the manufacturing method of the thermopile chip is introduced in detail by taking an example.

[0043] Example 2

[0044] Step 1: Using Si(100) as the substrate, a SiO2 film with a thickness of about 500nm is grown using a thermal oxidation process as a chip support layer.

[0045] Step 2: Use LPCVD growth technology, SiH4 as the reaction gas, and 630°C as the substrate temperature to grow polysilicon thin film.

[0046] Step 3: Using B ion implantation process, the implantation energy is about 70-100 KeV and the implantation dose is about 2-5×10 20 ions / cm 2 , injected to form a P-type polysilicon film.

[0047] Step 4: Immerse the deposited P-type polysilicon film in a mixed solution of HF, AgNO3 and H2O, where the volume ratio of the mixed solution of HF, AgNO3 and H2O is 1:1:3, the concentration of the AgNO3 solution is 0.005 mol / L, the concentration of the HF solution is ≥ 40%, the immersion time is 1-5 minutes, and a Ag particle film is deposited on the surface.

[0048] Step 5: Immerse the sample deposited with the Ag particle film in a mixed solution of HF, H2O2, and H2O, where the volume ratio of the HF, H2O2, and H2O mixed solution is 2:5:4, the concentration of the HF solution is ≥ 40%, and the concentration of the H2O2 solution is ≥ 30%. The immersion time is 1-2 hours, and silver nanoparticle-loaded honeycomb-like porous polycrystalline silicon is etched to serve as the multifunctional film layer of the chip.

[0049] Step 6: Using LPCVD growth technology, using tetraethyl orthosilicate (Si(OC2H5)4) as the reaction gas and 700-750°C as the substrate temperature, grow a layer of SiO2 film as the chip insulation layer.

[0050] Step 7: Use photolithography and RIE etching processes to pattern the SiO2 film layer serving as the insulating layer, forming openings at both ends of the silver nanoparticle-loaded honeycomb porous polycrystalline silicon multifunctional film layer to expose the silver nanoparticle-loaded honeycomb porous polycrystalline silicon, so as to facilitate ohmic contact with the other thermocouple layer of the subsequent thermopile chip.

[0051] Step 8: Using the measurement-controlled sputtering technology, AlSi (90% Al) is used as the target material and argon excitation to deposit a layer of AlSi film as the other thermocouple layer and electrode of the chip.

[0052] Step 9: Using LPCVD growth technology, using tetraethyl orthosilicate (Si(OC2H5)4) as the reaction gas and 700-750°C as the substrate temperature, grow a layer of SiO2 film as a chip protection layer.

[0053] Step 10: Use photolithography and RIE etching processes to pattern the SiO2 film layer serving as a protective layer, forming openings at the thermopile chip pads to expose the electrodes made of the Al layer, so as to facilitate signal extraction during subsequent thermopile chip packaging.

[0054] Step 11: Use RIE etching process to etch, use XeF2 as the reaction gas, release it from the back, and etch away the silicon substrate under the thermopile to form a suspended structure, thereby obtaining the final new multifunctional thermopile chip.

[0055] Example 3

[0056] Step 1: Using Si(100) as the substrate, a SiO2 film with a thickness of about 500nm is grown using a thermal oxidation process as a chip support layer.

[0057] Step 2: Using LPCVD epitaxial growth technology, SiCl4 and H2 as reaction gases and 1200°C as substrate temperature, epitaxially grow single crystal silicon thin film.

[0058] Step 3: Using P ion implantation process, the implantation energy is about 70-100 KeV and the implantation dose is about 2-5×10 20 ions / cm 2 , injected to form an N-type single crystal silicon thin film.

[0059] Step 4: Using the measurement and control sputtering technology, with Ag as the target material and argon excitation, a layer of Ag particle film is deposited as an etching metal auxiliary layer.

[0060] Step 5: Immerse the sample deposited with the Ag particle film in a mixed solution of HF, H2O2, and H2O, where the volume ratio of the HF, H2O2, and H2O mixed solution is 2:5:4, the concentration of the HF solution is ≥ 40%, and the concentration of the H2O2 solution is ≥ 30%. The immersion time is 2-4 hours, and silver nanoparticle-loaded honeycomb-like porous single crystal silicon is etched.

[0061] Step 6: Using LPCVD growth technology, using tetraethyl orthosilicate (Si(OC2H5)4) as the reaction gas and 700-750°C as the substrate temperature, grow a layer of SiO2 film as the chip insulation layer.

[0062] Step 7: Use photolithography and RIE etching processes to pattern the SiO2 film layer serving as the insulating layer, forming openings at both ends of the silver nanoparticle-loaded honeycomb porous single-crystal silicon multifunctional film layer to expose the silver nanoparticle-loaded honeycomb porous single-crystal silicon, so as to facilitate ohmic contact with the other thermocouple layer of the subsequent thermopile chip.

[0063] Step 8: Using the measurement-controlled sputtering technology, AlSi (90% Al) is used as the target material and argon excitation to deposit a layer of AlSi film as the other thermocouple layer and electrode of the chip.

[0064] Step 9: Using LPCVD growth technology, using tetraethyl orthosilicate (Si(OC2H5)4) as the reaction gas and 700-750°C as the substrate temperature, grow a layer of SiO2 film as a chip protection layer.

[0065] Step 10: Use photolithography and RIE etching processes to pattern the SiO2 film layer serving as a protective layer, forming openings at the thermopile chip pads to expose the electrodes made of the Al layer, so as to facilitate signal extraction during subsequent thermopile chip packaging.

[0066] Step 11: Use RIE etching process to etch, use XeF2 as the reaction gas, release it from the back, and etch away the silicon substrate under the thermopile to form a suspended structure, thereby obtaining the final new multifunctional thermopile chip.

[0067] Example 4

[0068] Step 1: Using Si(100) as the substrate, a SiO2 film with a thickness of about 500nm is grown using a thermal oxidation process as a chip support layer.

[0069] Step 2: Use LPCVD growth technology, SiH4 as the reaction gas, and 630°C as the substrate temperature to grow polysilicon thin film.

[0070] Step 3: Using B ion implantation process, the implantation energy is about 70-100 KeV and the implantation dose is about 2-5×10 20 ions / cm 2 , implanted to form a P-type polysilicon film, which serves as a thermocouple layer on the chip.

[0071] Step 4: Using LPCVD growth technology, using tetraethyl orthosilicate (Si(OC2H5)4) as the reaction gas and 700-750°C as the substrate temperature, grow a layer of SiO2 film as the chip insulation layer.

[0072] Step 5: Use photolithography and RIE etching processes to pattern the SiO2 film layer as an insulating layer, forming openings at both ends of the P-type polysilicon film layer to leak out the P-type polysilicon, so as to facilitate ohmic contact with the other thermocouple layer of the subsequent thermopile chip.

[0073] Step 6: Use LPCVD growth technology, SiH4 as the reaction gas, and 630°C as the substrate temperature to grow polysilicon thin film.

[0074] Step 7: Using P ion implantation process, the implantation energy is about 70-100 KeV and the implantation dose is about 2-5×10 20 ions / cm 2 , implanted to form an N-type polysilicon thin film, which serves as another thermocouple layer of the chip.

[0075] Step 8: Immerse in a mixed solution of HF, AgNO3 and H2O, wherein the volume ratio of the mixed solution of HF, AgNO3 and H2O is 1:1:3, the concentration of the AgNO3 solution is 0.005 mol / L, the concentration of the HF solution is ≥ 40%, the immersion time is 1-5 minutes, and a Ag particle film is deposited on the surface.

[0076] Step 9: Immerse the sample deposited with the Ag particle film in a mixed solution of HF, H2O2, and H2O, where the volume ratio of the HF, H2O2, and H2O mixed solution is 2:5:4, the concentration of the HF solution is ≥ 40%, and the concentration of the H2O2 solution is ≥ 30%. The immersion time is 1-2 hours, and silver nanoparticle-loaded honeycomb-like porous polycrystalline silicon is etched to serve as the multifunctional film layer of the chip.

[0077] Step 10: Using the measurement and control sputtering technology, with AlSi (90% Al) as the target material and argon excitation, a layer of AlSi film is deposited as the chip electrode.

[0078] Step 11: Using LPCVD growth technology, using tetraethyl orthosilicate (Si(OC2H5)4) as the reaction gas and 700-750°C as the substrate temperature, grow a layer of SiO2 film as a chip protection layer.

[0079] Step 12: Use photolithography and RIE etching processes to pattern the SiO2 film layer serving as a protective layer, forming openings at the thermopile chip pads to expose the electrodes made of the Al layer, so as to facilitate signal extraction during subsequent thermopile chip packaging.

[0080] Step 13: Use RIE etching process to etch, use XeF2 as the reaction gas, release it from the back, and etch away the silicon substrate under the thermopile to form a suspended structure, thereby obtaining the final new multifunctional thermopile chip.

[0081] Example 5

[0082] Step 1: Using Si(100) as the substrate, a SiO2 film with a thickness of about 500nm is grown using a thermal oxidation process as a chip support layer.

[0083] Step 2: Use LPCVD growth technology, SiH4 as the reaction gas, and 630°C as the substrate temperature to grow polysilicon thin film.

[0084] Step 3: Using B ion implantation process, the implantation energy is about 70-100 KeV and the implantation dose is about 2-5×10 20 ions / cm 2 , injected to form a P-type polysilicon film.

[0085] Step 4: Using the measurement and control sputtering technology, with Au as the target material and argon excitation, a layer of Au particle film is deposited as an etching metal auxiliary layer.

[0086] Step 5: Immerse the sample deposited with the Au particle film in a mixed solution of HF, H2O2, and H2O, where the volume ratio of the HF, H2O2, and H2O mixed solution is 2:5:4, the concentration of the HF solution is ≥ 40%, and the concentration of the H2O2 solution is ≥ 30%. The immersion time is 1-2 hours, and the gold nanoparticle-loaded honeycomb porous polycrystalline silicon is etched to serve as the multifunctional film layer of the chip.

[0087] Step 6: Using LPCVD growth technology, using tetraethyl orthosilicate (Si(OC2H5)4) as the reaction gas and 700-750°C as the substrate temperature, grow a layer of SiO2 film as the chip insulation layer.

[0088] Step 7: Use photolithography and RIE etching processes to pattern the SiO2 film layer serving as the insulating layer, forming openings at both ends of the gold nanoparticle-loaded honeycomb porous polycrystalline silicon multifunctional film layer to leak out the gold nanoparticle-loaded honeycomb porous polycrystalline silicon, so as to facilitate ohmic contact with the other thermocouple layer of the subsequent thermopile chip.

[0089] Step 8: Using the measurement and control sputtering technology, with AlSi (90% Al) as the target material and argon excitation, a layer of AlSi film is deposited as the other thermocouple layer of the chip.

[0090] Step 9: Using LPCVD growth technology, using tetraethyl orthosilicate (Si(OC2H5)4) as the reaction gas and 700-750°C as the substrate temperature, grow a layer of SiO2 film as a chip protection layer.

[0091] Step 10: Use photolithography and RIE etching processes to pattern the SiO2 film layer serving as a protective layer, forming openings at the thermopile chip pads to expose the electrodes made of the Al layer, so as to facilitate signal extraction during subsequent thermopile chip packaging.

[0092] Step 11: Use RIE etching process to etch, use XeF2 as the reaction gas, release it from the back, and etch away the silicon substrate under the thermopile to form a suspended structure, thereby obtaining the final new multifunctional thermopile chip.

[0093] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the present profession can make slight changes or modifications to equivalent embodiments of equivalent changes using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A metal nanoparticle-loaded honeycomb porous silicon film, which is applied to a thermopile chip, characterized in that: The metal nanoparticle-loaded honeycomb-like porous silicon film is a multifunctional film, which is a honeycomb-like porous silicon composite film loaded with nano Ag, Au or Pt noble metal particles and constructed with a semiconductor silicon film as a matrix.

2. The metal nanoparticle-loaded honeycomb-like porous silicon film according to claim 1, characterized in that: A honeycomb porous silicon composite membrane loaded with nano-Ag, Au or Pt noble metal particles is constructed by a metal-assisted chemical etching method.

3. The metal nanoparticle-loaded honeycomb-like porous silicon film according to claim 1, characterized in that: The multifunctional film is a metal nanoparticle-loaded honeycomb-like porous single-crystal silicon or polycrystalline silicon or amorphous silicon film.

4. A thermopile chip, characterized in that: It adopts the metal nanoparticle-loaded honeycomb porous silicon film as claimed in claim 1, 2 or 3.

5. A method for preparing a metal nanoparticle-loaded honeycomb-like porous silicon film as claimed in claim 1, 2 or 3, characterized in that: The preparation method comprises the following steps: Step 1: Using CVD growth technology to deposit and form a polycrystalline silicon or single crystal silicon thin film; Step 2: Using P or B ion implantation process, implantation forms N-type or P-type polysilicon or single crystal silicon thin film; Step 3: depositing the deposited N-type or P-type polycrystalline silicon or single crystal silicon thin film by magnetron sputtering technology or immersing it in a mixed solution of HF, AgNO3 or H2PtCl6 or HAuCl4 and H2O to form a Ag or Pt or Au particle thin film; Step 4: Immerse the sample deposited with the precious metal particle film in a mixed solution of HF, H2O2, and H2O, and etch to obtain metal nanoparticle-loaded honeycomb porous silicon, thereby forming the metal nanoparticle-loaded honeycomb porous silicon film as a whole.

6. The method for preparing the metal nanoparticle-loaded honeycomb-like porous silicon film according to claim 5, characterized in that: The preparation method firstly uses SiH4 as a reaction gas and 630°C as a substrate temperature to grow a polysilicon film; secondly, B ions are implanted with an implantation energy of about 70-100 KeV and an implantation dose of about 2-5×10 20 ions / cm 2 , forming a P-type polycrystalline silicon film; then, immersing the deposited P-type polycrystalline silicon film in a mixed solution of HF, AgNO3 and H2O, wherein the volume ratio of the mixed solution of HF, AgNO3 and H2O is 1: 1: 3, the concentration of the AgNO3 solution is 0.005 mol / L, the concentration of the HF solution is ≥ 40%, the immersion time is 1-5 minutes, and a Ag particle film is deposited on the surface; thereafter, immersing the sample on which the Ag particle film is deposited, in a mixed solution of HF, H2O2, and H2O, and etching to obtain a honeycomb porous polycrystalline silicon loaded with silver nanoparticles as the multifunctional film.

7. The method for preparing the metal nanoparticle-loaded honeycomb-like porous silicon film according to claim 5, characterized in that: The preparation method firstly uses SiCl4 and H2 as reaction gases and 1200°C as substrate temperature to epitaxially grow a single crystal silicon film; secondly, P ions are implanted with an implantation energy of about 70-100 KeV and an implantation dose of about 2-5×10 20 ions / cm 2 , forming an N-type single-crystalline silicon film; then, using Ag as a target material and exciting argon gas, a layer of Ag particle film is deposited as an etching metal auxiliary layer; thereafter, the sample deposited with the Ag particle film is immersed in a mixed solution of HF, H2O2, and H2O to etch the silver nanoparticle-loaded honeycomb-like porous single-crystalline silicon as the multifunctional film.

8. The method for preparing the metal nanoparticle-loaded honeycomb-like porous silicon film according to claim 5, characterized in that: The preparation method firstly uses SiH4 as a reaction gas and 630°C as a substrate temperature to grow a polysilicon film; secondly, B ions are implanted with an implantation energy of about 70-100 KeV and an implantation dose of about 2-5×10 20 ions / cm 2 , forming a P-type polysilicon film; then, using Au as a target material and argon gas excitation, a layer of Au particle film is deposited as an etching metal auxiliary layer; thereafter, the sample deposited with the Au particle film is immersed in a mixed solution of HF, H2O2, and H2O to etch gold nanoparticle-loaded honeycomb-like porous polysilicon as the multifunctional film.

9. The method for preparing the metal nanoparticle-loaded honeycomb-like porous silicon film according to claim 6, 7 or 8, characterized in that: The volume ratio of HF, H2O2, and H2O mixed solution is 2: 5: 4, the concentration of HF solution is ≥ 40%, the concentration of H2O2 solution is ≥ 30%, and the immersion time is 1-2 hours.

10. A method for preparing a thermopile chip according to claim 4, characterized in that: The method for preparing the thermopile chip comprises the following steps: Using Si(100) as substrate, a layer of SiO2 film is grown as chip support layer; The multifunctional film is prepared on the chip support layer by using the method for preparing the metal nanoparticle-loaded honeycomb porous silicon film as described in claim 6, 7 or 8; Using tetraethyl orthosilicate Si(OC2H5)4 as the reaction gas and 700-750 ℃ ​​as the substrate temperature, a layer of SiO2 film is grown as the chip insulation layer; The SiO2 film as an insulating layer is patterned to form openings at both ends of the metal nanoparticle-loaded honeycomb porous silicon multifunctional film layer to leak out the silver nanoparticle-loaded honeycomb porous polycrystalline silicon; Using AlSi with 90% Al as the target material and argon excitation, a layer of AlSi film is deposited as the chip electrode; Using tetraethyl orthosilicate Si(OC2H5)4 as the reaction gas and 700-750 ℃ ​​as the substrate temperature, a layer of SiO2 film is grown as a chip protection layer; The SiO2 film used as a protective layer is patterned to form openings at the pads of the thermopile chip to expose the electrodes made of the Al layer. XeF2 is used as a reaction gas and released from the back to etch and remove the silicon substrate under the thermopile to form a suspended structure, thereby obtaining the final base thermopile chip.

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