A MEMS thermopile ultraviolet detector and a preparation method thereof

Abstract

The application discloses a MEMS thermoelectric pile ultraviolet detector and a preparation method thereof, and relates to the technical field of semiconductors. The MEMS thermoelectric pile ultraviolet detector comprises a MEMS thermoelectric pile ultraviolet detection unit, a nano forest unit and a metal particle unit arranged on the surface of the four sides of the nano forest unit, wherein the nano forest unit is arranged above the MEMS thermoelectric pile ultraviolet detection unit; the metal particle unit is used for increasing the ultraviolet radiation absorption rate, thereby improving the high-sensitivity detection of ultraviolet radiation in the 10-400 nm wave band, and expanding the detection range while improving the detection sensitivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a MEMS thermopile ultraviolet detector and a preparation method thereof. BACKGROUND

[0002] With the development of the technical field of semiconductor, the ultraviolet detector as an important part has also been rapidly developed. The ultraviolet detector can be divided into two categories, one is a thermal detector, and the other is a photoelectric detector. The representative of the thermal detector is a thermopile, and the photoelectric detector can be divided into a semiconductor detector based on external photoelectric effect and a semiconductor detector based on internal photoelectric effect according to different principles. For example, a vacuum photodiode is one of the photoelectric emission ultraviolet detectors based on external photoelectric effect, and a silicon-based photodiode is one of the semiconductor detectors based on internal photoelectric effect.

[0003] At present, the commercialized ultraviolet detector is a vacuum photomultiplier and a silicon-based photodiode. The vacuum photomultiplier works by using the principle of external photoelectric effect, and the silicon-based photodiode works by using the internal photoelectric effect of semiconductor materials. Among them, different light-sensitive materials of the vacuum photomultiplier have different sensitivities to different wavelengths of light, and the photomultiplier has only one photocathode, so the selected light-sensitive material must have a certain sensitivity in the full wave band. Therefore, the sensitivity of the photomultiplier to light is limited. Generally, the sensitivity of the I-Cs cathode decreases sharply when the wavelength is greater than 200 nanometers, and the sensitivity of the Te-Cs cathode decreases sharply when the wavelength is greater than 320 nm. In addition, the window material limits the MgF2 crystal that can transmit vacuum ultraviolet light above 115 nm; the short-wave cutoff wavelength of sapphire is 150 nm; synthetic quartz can transmit ultraviolet light above 160 nm; the short-wave cutoff wavelength of ultraviolet glass is 185 nm; the above several materials can be used as window materials for ultraviolet detection of the vacuum photomultiplier; but the window material limits the response cutoff wavelength of the photomultiplier in the short-wave region of the spectrum. The transmittance of the window material affects the spectral response sensitivity of the photomultiplier in the short-wave region. The vacuum photomultiplier will be disturbed by high temperature and electromagnetic radiation when working, and generally needs to work under high voltage.

[0004] Silicon-based photodiode is a radiation detector with semiconductor material as a detection medium. The most common semiconductor materials are germanium and silicon. The principle of semiconductor detector is internal photoelectric effect, which is divided into photoconductive effect and photovoltaic effect. In photoconductive effect, after the semiconductor absorbs photons with sufficient energy, some of the electrons or holes are activated from the original bound state to the free state, resulting in an increase in the electrical conductivity of the semiconductor and a decrease in the resistance of the circuit. In photovoltaic effect, photo-generated charges produce a small potential difference across the junction in the semiconductor. The generated photovoltage is amplified by the photovoltaic device and can be directly measured. The devices made according to the photoconductive effect and the photovoltaic effect are called semiconductor photoconductive detectors and semiconductor photovoltaic detectors, respectively. The photovoltaic and photoconductive types can be divided into silicon-based and non-silicon-based (mostly wide-bandgap materials) according to the materials. The band gap of Si is relatively narrow, about 1.12eV, and the corresponding cutoff wavelength is about 1.1μm. Because an expensive filter is needed to eliminate the influence of visible light and infrared light when preparing an ultraviolet detector, it is difficult to have a high ultraviolet / visible rejection ratio. Wide-bandgap materials refer to semiconductor materials with a band gap of 2.3eV or more, such as silicon carbide (SiC), gallium nitride (GaN), diamond, and gallium oxide (Ga2O3). For example, the band gap of diamond is 5.5eV, so ultraviolet light with a wavelength shorter than 225nm can respond to it.

[0005] However, the preparation of wide-bandgap materials is relatively lagging behind, and the preparation process is difficult, requiring special growth conditions such as high temperature and high pressure. For example, high-quality diamond thin films are difficult to prepare by epitaxy and physical processing, and the yield is low and the cost is very high. The preparation technology of large-size single crystal substrates is still immature. For example, 8-inch SiC single crystal samples have been developed, but compared with advanced silicon semiconductor devices, the size of the single crystal substrate is still small and the defect level is still high. It cannot be truly mass-produced and cannot guarantee the yield.

[0006] Therefore, the existing ultraviolet detector preparation process is complex, the stability is poor, and the sensitivity for effectively detecting ultraviolet signals is poor, and the detection range of the ultraviolet band is small. SUMMARY

[0007] The purpose of the present application is to provide a MEMS thermoelectric pile ultraviolet detector and a preparation method thereof, to solve the problems of the existing ultraviolet detector preparation process being complex, the stability being poor, and the sensitivity for effectively detecting ultraviolet signals being poor, and the detection range of the ultraviolet band being small.

[0008] In a first aspect, the present application provides a MEMS thermoelectric pile ultraviolet detector, comprising:

[0009] The MEMS thermoelectric pile ultraviolet detection unit, the nano forest unit and the metal particle unit arranged on the surface around the nano forest unit are arranged above the MEMS thermoelectric pile ultraviolet detection unit; and the metal particle unit is used for increasing the ultraviolet radiation absorption rate.

[0010] In the technical solution, the MEMS thermoelectric pile ultraviolet detector comprises a MEMS thermoelectric pile ultraviolet detection unit, a nano forest unit and a metal particle unit arranged on the surface around the nano forest unit, the nano forest unit is arranged above the MEMS thermoelectric pile ultraviolet detection unit, and the metal particle unit is used for increasing the ultraviolet radiation absorption rate, so that high-sensitivity detection of ultraviolet radiation in the 10-400 nm wave band is realized, the detection sensitivity is improved, and the detection range is also expanded.

[0011] In a possible implementation, the MEMS thermoelectric pile ultraviolet detection unit comprises a silicon substrate, a dielectric layer, metal wires, a thermocouple and an ultraviolet absorption layer arranged in sequence on the silicon substrate, and the nano forest unit is arranged on the upper surface of the ultraviolet absorption layer.

[0012] In a possible implementation, the metal particle unit is composed of any one of silver, aluminum or gold.

[0013] In a possible implementation, the nano structure in the nano forest unit has any one of a shape of a conical shape, a table shape, a column shape or a planar combination thereof.

[0014] In a possible implementation, the material of the ultraviolet absorption layer comprises zinc oxide, silicon carbide, gallium nitride, gallium oxide or titanium dioxide.

[0015] In a second aspect, the application further provides a preparation method of a MEMS thermoelectric pile ultraviolet detector, which is used for preparing the MEMS thermoelectric pile ultraviolet detector in any one of the first aspect, and the method comprises the following steps.

[0016] Preparation of a MEMS thermoelectric pile ultraviolet detection unit;

[0017] Preparation of a nano forest unit above the MEMS thermoelectric pile ultraviolet detection unit by dry etching;

[0018] Formation of a metal particle unit on the surface around the nano forest unit by a sputtering process;

[0019] The metal particle unit is used for increasing the ultraviolet radiation absorption rate.

[0020] In a possible implementation, the preparation of the MEMS thermoelectric pile ultraviolet detection unit comprises the following steps.

[0021] providing a silicon substrate;

[0022] forming a medium layer on the silicon substrate by disposing a silicon dioxide, silicon dioxide-silicon nitride or silicon dioxide-silicon nitride-silicon dioxide film layer;

[0023] depositing a thermocouple strip on the medium layer and patterning to form a thermocouple;

[0024] depositing a metal wire around the thermocouple;

[0025] depositing zinc oxide, silicon carbide, gallium nitride, gallium oxide or titanium dioxide with high ultraviolet absorption rate to form an ultraviolet absorption layer;

[0026] back cavity etching the silicon substrate.

[0027] In a possible implementation, a nano forest unit is prepared above the MEMS thermoelectric stack ultraviolet detection unit by dry etching, comprising:

[0028] forming the nano forest unit by sequentially coating a polymer and patterning treatment, and plasma bombardment on the ultraviolet absorption layer.

[0029] In a possible implementation, the metal particle unit is composed of any one of silver, aluminum or gold.

[0030] In a possible implementation, the shape of the nano structure in the nano forest unit includes any one of a conical shape, a table shape, a column shape or a planar combination thereof.

[0031] The preparation method of the MEMS thermoelectric stack ultraviolet detector provided in the second aspect has the same beneficial effects as the MEMS thermoelectric stack ultraviolet detector described in the first aspect or any possible implementation of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0032] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0033] Figure 1 a structure schematic diagram of a MEMS thermoelectric stack ultraviolet detector provided by an embodiment of the present application is shown;

[0034] Figure 2 a structure schematic diagram of another MEMS thermoelectric stack ultraviolet detector provided by an embodiment of the present application is shown;

[0035] Figure 3A schematic diagram showing the output comparison of a thermoelectric detector with integrated and non-integrated nano-forest units and metal particle units arranged on the surface around the nano-forest units in the 400nm waveband is shown;

[0036] Figure 4 A schematic diagram showing the output comparison of a thermoelectric detector with integrated and non-integrated nano-forest units and metal particle units arranged on the surface around the nano-forest units in the 300nm waveband is shown;

[0037] Figure 5 A schematic diagram showing the output comparison of a thermoelectric detector with integrated and non-integrated nano-forest units and metal particle units arranged on the surface around the nano-forest units in the 260nm waveband is shown;

[0038] Figure 6 A schematic diagram showing the output comparison of a thermoelectric detector with integrated and non-integrated nano-forest units and metal particle units arranged on the surface around the nano-forest units in the 250nm waveband is shown;

[0039] Figure 7 A schematic diagram showing the output comparison of a thermoelectric detector with integrated and non-integrated nano-forest units and metal particle units arranged on the surface around the nano-forest units in the 240nm waveband is shown;

[0040] Figure 8 A schematic diagram showing the output comparison of a thermoelectric detector with integrated and non-integrated nano-forest units and metal particle units arranged on the surface around the nano-forest units in the 230nm waveband is shown;

[0041] Figure 9 A schematic diagram showing the output comparison of a thermoelectric detector with integrated and non-integrated nano-forest units and metal particle units arranged on the surface around the nano-forest units in the 220nm waveband is shown;

[0042] Figure 10 A flowchart showing a preparation method of a MEMS thermoelectric detector ultraviolet detector provided by an embodiment of the application is shown;

[0043] Figure 11 A flowchart showing another preparation method of a MEMS thermoelectric detector ultraviolet detector provided by an embodiment of the application is shown.

[0044] Reference signs:

[0045] 10-MEMS thermoelectric pile ultraviolet detection unit; 201-nanometer forest unit; 202-metal particle unit; 101-silicon substrate; 102-dielectric layer; 103-metal wire; 104-thermocouple; 105-ultraviolet absorption layer. DETAILED DESCRIPTION

[0046] In order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the terms "first", "second", etc. are used to distinguish the same or similar items with basically the same function and role. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and do not limit the order. Those skilled in the art can understand that the terms "first", "second", etc. do not limit the number and execution order, and the terms "first", "second", etc. also do not mean that they are necessarily different.

[0047] It should be noted that in the present application, the words "exemplary" or "for example" are used to indicate an example, illustration or description. Any embodiment or design scheme described as "exemplary" or "for example" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the use of "exemplary" or "for example" is intended to present the relevant concept in a specific manner.

[0048] In the present application, "at least one" means one or more, and "multiple" means two or more. The association relationship of the associated objects is described, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following cases: A exists alone, A and B exist together, B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it. "At least one of the following" or similar expressions means any combination of these items, including any combination of single item or multiple items. For example, at least one of a, b or c, can represent: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b and c can be single or multiple.

[0049] Figure 1 A structure diagram of a MEMS thermoelectric pile ultraviolet detector provided by an embodiment of the present application is shown, as shown in Figure 1 The MEMS thermoelectric pile ultraviolet detector includes:

[0050] The MEMS thermoelectric pile ultraviolet detection unit 10, the nanometer forest unit 201 and the metal particle unit 202 arranged on the four surrounding surfaces of the nanometer forest unit 201, the nanometer forest unit 201 is arranged above the MEMS thermoelectric pile ultraviolet detection unit 10.

[0051] The metal particle unit 202 is used to increase the absorption rate of ultraviolet radiation.

[0052] The working principle of the MEMS thermoelectric detector is based on the Seebeck effect. In general, it can form a temperature difference between the cold and hot ends of the device by sensing the infrared electromagnetic waves radiated by an object, thereby converting it into a measurable electrical signal, and further achieving the purpose of detecting the infrared radiation signal. The application uses a nano forest unit and a metal particle unit arranged on the surface around the nano forest unit. The nano forest unit is arranged above the MEMS thermoelectric detector ultraviolet detection unit. The metal particle unit is used to increase the absorption rate of ultraviolet radiation. The nano forest unit and the metal particle unit arranged on the surface around the nano forest unit are integrated on the MEMS thermoelectric detector ultraviolet detection unit, realizing high-sensitivity detection of ultraviolet radiation in the 10-400 nanometer wave band.

[0053] In summary, the MEMS thermoelectric detector provided by the embodiments of the application includes a MEMS thermoelectric detector ultraviolet detection unit, a nano forest unit, and a metal particle unit arranged on the surface around the nano forest unit. The nano forest unit is arranged above the MEMS thermoelectric detector ultraviolet detection unit. The metal particle unit is used to increase the absorption rate of ultraviolet radiation, thereby improving the high-sensitivity detection of ultraviolet radiation in the 10-400 nanometer wave band. The detection range is also expanded while the detection sensitivity is improved.

[0054] Figure 2 Another structure diagram of the MEMS thermoelectric detector provided by the embodiments of the application is shown. As shown in Figure 2 The MEMS thermoelectric detector ultraviolet detection unit 10 includes a silicon substrate 101, a dielectric layer 102, a metal wire 103, a thermocouple 104, and an ultraviolet absorption layer 105 arranged in sequence on the silicon substrate 101. The nano forest unit 201 is arranged on the upper surface of the ultraviolet absorption layer 105.

[0055] The material of the ultraviolet absorption layer includes zinc oxide, silicon carbide, gallium nitride, gallium oxide, or titanium dioxide. The above-mentioned ultraviolet material is a wide bandgap material. However, unlike the wide bandgap photodetector, the thermoelectric detector only uses the material as an absorption layer or integrates the nano forest unit, but not as a substrate. Therefore, the process difficulty is greatly reduced.

[0056] Optionally, the composition of the metal particle unit includes any one of silver, aluminum, or gold, which is not specifically limited in the embodiments of the application.

[0057] Optionally, the shape of the nano structure in the nano forest unit includes any one of a conical shape, a table shape, a column shape, or a planar combination thereof, which is not specifically limited in the embodiments of the application.

[0058] Figure 3 A schematic diagram of the output of a thermopile detector integrating and not integrating a nanoforest unit and metal particle units arranged on the surface of the four sides of the nanoforest unit at a 400 nm wavelength band is shown in FIG. 6. As shown in FIG. 6, the horizontal axis represents time (Time) in seconds (S), and the vertical axis represents output voltage (Output voltage) in millivolts (mV). The output voltage corresponding to the MEMS thermopile ultraviolet detector F1 shown in the present application is greater than the output voltage corresponding to the thermopile detector F2 of the conventional non-integrated nanoforest unit and the metal particle units arranged on the surface of the four sides of the nanoforest unit. Figure 3

[0059] Figure 4 A schematic diagram of the output of a thermopile detector integrating and not integrating a nanoforest unit and metal particle units arranged on the surface of the four sides of the nanoforest unit at a 300 nm wavelength band is shown in FIG. 7. As shown in FIG. 7, the horizontal axis represents time (Time) in seconds (S), and the vertical axis represents output voltage (Output voltage) in millivolts (mV). The output voltage corresponding to the MEMS thermopile ultraviolet detector F1 shown in the present application is greater than the output voltage corresponding to the thermopile detector F2 of the conventional non-integrated nanoforest unit and the metal particle units arranged on the surface of the four sides of the nanoforest unit. Figure 4

[0060] Figure 5 A schematic diagram of the output of a thermopile detector integrating and not integrating a nanoforest unit and metal particle units arranged on the surface of the four sides of the nanoforest unit at a 260 nm wavelength band is shown in FIG. 8. As shown in FIG. 8, the horizontal axis represents time (Time) in seconds (S), and the vertical axis represents output voltage (Output voltage) in millivolts (mV). The output voltage corresponding to the MEMS thermopile ultraviolet detector F1 shown in the present application is greater than the output voltage corresponding to the thermopile detector F2 of the conventional non-integrated nanoforest unit and the metal particle units arranged on the surface of the four sides of the nanoforest unit after 10 seconds. Figure 5

[0061] Figure 6 A schematic diagram of the output of a thermopile detector integrating and not integrating a nanoforest unit and metal particle units arranged on the surface of the four sides of the nanoforest unit at a 250 nm wavelength band is shown in FIG. 9. As shown in FIG. 9, the horizontal axis represents time (Time) in seconds (S), and the vertical axis represents output voltage (Output voltage) in millivolts (mV). The output voltage corresponding to the MEMS thermopile ultraviolet detector F1 shown in the present application is greater than the output voltage corresponding to the thermopile detector F2 of the conventional non-integrated nanoforest unit and the metal particle units arranged on the surface of the four sides of the nanoforest unit after 10 seconds. Figure 6 ​​​As shown in the figure, the horizontal axis represents time (Time) in seconds (S), and the vertical axis represents output voltage (Output voltage) in millivolts (mV). The output voltage corresponding to the MEMS thermoelectric pile ultraviolet detector F1 shown in the present application is greater than the output voltage corresponding to the thermoelectric pile detector F2 of the conventional non-integrated nanoforest unit and the metal particle unit arranged on the four surrounding surfaces of the nanoforest unit within 15-50 seconds.

[0062] Figure 7 The output comparison diagram of the thermoelectric pile detector integrated with the non-integrated nanoforest unit and the metal particle unit arranged on the four surrounding surfaces of the nanoforest unit at the 240 nm wave band is shown in the figure, as Figure 7 As shown in the figure, the horizontal axis represents time (Time) in seconds (S), and the vertical axis represents output voltage (Output voltage) in millivolts (mV). The output voltage corresponding to the MEMS thermoelectric pile ultraviolet detector F1 shown in the present application is less than the output voltage corresponding to the thermoelectric pile detector F2 of the conventional non-integrated nanoforest unit and the metal particle unit arranged on the four surrounding surfaces of the nanoforest unit.

[0063] Figure 8 The output comparison diagram of the thermoelectric pile detector integrated with the non-integrated nanoforest unit and the metal particle unit arranged on the four surrounding surfaces of the nanoforest unit at the 230 nm wave band is shown in the figure, as Figure 8 As shown in the figure, the horizontal axis represents time (Time) in seconds (S), and the vertical axis represents output voltage (Output voltage) in millivolts (mV). The output voltage corresponding to the MEMS thermoelectric pile ultraviolet detector F1 shown in the present application is less than the output voltage corresponding to the thermoelectric pile detector F2 of the conventional non-integrated nanoforest unit and the metal particle unit arranged on the four surrounding surfaces of the nanoforest unit.

[0064] Figure 9 The output comparison diagram of the thermoelectric pile detector integrated with the non-integrated nanoforest unit and the metal particle unit arranged on the four surrounding surfaces of the nanoforest unit at the 220 nm wave band is shown in the figure, as Figure 9 As shown in the figure, the horizontal axis represents time (Time) in seconds (S), and the vertical axis represents output voltage (Output voltage) in millivolts (mV). The output voltage corresponding to the MEMS thermoelectric pile ultraviolet detector F1 shown in the present application is substantially less than the output voltage corresponding to the thermoelectric pile detector F2 of the conventional non-integrated nanoforest unit and the metal particle unit arranged on the four surrounding surfaces of the nanoforest unit.

[0065] In the present application, the thermoelectric device is based on the detection principle of light-heat-electric conversion, and its working range can cover the ultraviolet band, and can detect ultraviolet radiation at room temperature. By selecting a suitable ultraviolet absorption layer, a very significant wide-spectrum absorption rate (10-400 nm) can be achieved. Moreover, the thermoelectric device can work at zero voltage or zero current, which can reduce the shot noise caused by the bias voltage and the additional thermal noise generated by the Joule heat. Furthermore, the preparation process of the thermoelectric device is simple, compatible with the CMOS process, and can be mass-produced at a very low cost.

[0066] Further, on the basis of the thermoelectric device, the thermoelectric device for ultraviolet detection integrated with the nano-forest unit can improve the absorption rate of the ultraviolet radiation by the thermoelectric absorption layer by integrating the nano-forest unit and the metal particle unit of the material with high ultraviolet absorption, and can improve the detection range and resolution of the thermoelectric device for ultraviolet detection in the ultraviolet band, and realize wide-spectrum detection.

[0067] Specifically, after the nano-forest unit is integrated, the metal sputtered on the nano-forest unit can enhance the absorption of the ultraviolet band by the absorption layer, and thus improve the output. Moreover, the thermoelectric device for ultraviolet detection integrated with the nano-forest unit is compatible with the CMOS process, and has a simple preparation process, and can be mass-produced at a low cost.

[0068] In summary, the MEMS thermoelectric device for ultraviolet detection provided by the embodiments of the present application includes a MEMS thermoelectric device for ultraviolet detection, a nano-forest unit and a metal particle unit arranged on the surface of the nano-forest unit, the nano-forest unit is arranged above the MEMS thermoelectric device for ultraviolet detection, and the metal particle unit is used to increase the ultraviolet radiation absorption rate, thereby improving the high-sensitivity detection of the 10-400 nm ultraviolet radiation, and expanding the detection range while improving the detection sensitivity.

[0069] Figure 10 A flowchart of a preparation method of a MEMS thermoelectric device for ultraviolet detection provided by the embodiments of the present application is shown in FIG. 1. Figure 10 As shown in FIG. 1, the method is used for preparing any of the MEMS thermoelectric devices for ultraviolet detection. Figures 1-2 The method includes the following steps.

[0070] Step 301: preparing a MEMS thermoelectric device for ultraviolet detection.

[0071] In the present application, a MEMS thermopile UV detector can be prepared by providing a silicon substrate; forming a medium layer on the silicon substrate by setting a silicon dioxide, silicon dioxide-silicon nitride or silicon dioxide-silicon nitride-silicon dioxide film layer; depositing a thermocouple strip on the medium layer and patterning to form a thermocouple; depositing a metal wire around the thermocouple; depositing zinc oxide, silicon carbide, gallium nitride, gallium oxide or titanium dioxide with high UV absorption rate to form a UV absorption layer; and performing back cavity etching on the silicon substrate.

[0072] Step 302: preparing a nano forest unit above the MEMS thermopile UV detector by dry etching.

[0073] In the present application, the nano forest unit is formed by sequentially rotating and polymerizing a polymer and performing a patterning process and plasma bombardment on the UV absorption layer.

[0074] Step 303: forming a metal particle unit around the surface of the nano forest unit by sputtering process.

[0075] The metal particle unit is used to increase the UV radiation absorption rate.

[0076] Figure 11 A flowchart of another preparation method of a MEMS thermopile UV detector provided by an embodiment of the present application is shown in FIG. 3. Figure 11 As shown in FIG. 3, the preparation method includes the following steps: (a) providing a silicon substrate; (b) forming a medium layer on the silicon substrate by setting a silicon dioxide, silicon dioxide-silicon nitride or silicon dioxide-silicon nitride-silicon dioxide film layer; (c) depositing a thermocouple strip on the medium layer and patterning to form a thermocouple; (d) depositing a metal wire; (e) depositing zinc oxide, silicon carbide, gallium nitride, gallium oxide or titanium dioxide with high UV absorption rate to form a UV absorption layer; (f) performing back cavity etching on the silicon substrate; (g) rotating and polymerizing a polymer; (h) etching to form a nano forest unit; and (i) sputtering a metal to form a metal particle unit.

[0077] In the present application, a medium layer can be formed on the silicon substrate by thermal oxidation or CVD method.

[0078] In the present application, the polymer can include polyimide, PR or PMMA, which is not limited in the embodiments of the present application.

[0079] In the present application, the metal particle unit is composed of any one of silver, aluminum or gold; and the shape of the nano structure in the nano forest unit includes any one of a conical shape, a table shape, a column shape or a planar combination thereof.

[0080] In summary, the preparation method of the MEMS thermoelectric pile ultraviolet detector provided by the embodiments of the present application is as follows: a MEMS thermoelectric pile ultraviolet detection unit is prepared; a nano forest unit is prepared above the MEMS thermoelectric pile ultraviolet detection unit through dry etching; and a metal particle unit is formed on the surface of the four sides of the nano forest unit through a sputtering process. The metal particle unit is used to increase the ultraviolet radiation absorption rate, thereby improving the high-sensitivity detection of ultraviolet radiation in the 10-400 nm wave band. The detection sensitivity is improved, and the detection range is also expanded. The preparation method is simpler than most ultraviolet detectors, the morphology gap is controllable, and the method is compatible with the CMOS process, and is suitable for mass production.

[0081] The preparation method of the MEMS thermoelectric pile ultraviolet detector provided by the embodiments of the present application can prepare the MEMS thermoelectric pile ultraviolet detector as shown in any of Figures 1-2 Any of the MEMS thermoelectric pile ultraviolet detectors provided by the embodiments of the present application are not repeated here.

[0082] Although the present application is described herein in conjunction with various embodiments, other variations of the disclosed embodiments can be understood and implemented by those skilled in the art with reference to the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "one" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. Some measures are described in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0083] Although the present application is described herein in conjunction with specific features and embodiments thereof, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of the present application. Accordingly, the present specification and drawings are merely illustrative of the exemplary embodiments of the present application, and are considered to cover any and all modifications, variations, combinations or equivalents that fall within the scope of the present application. Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include these modifications and variations.

Claims

1. A MEMS thermopile ultraviolet detector, characterized in that, include: The MEMS thermopile ultraviolet detection unit comprises a nanoforest unit and metal particle units disposed around the surface of the nanoforest unit, with the nanoforest unit positioned above the MEMS thermopile ultraviolet detection unit. The metal particle units are used to increase the ultraviolet radiation absorption rate. The MEMS thermopile ultraviolet detection unit includes a silicon substrate, and a dielectric layer, metal interconnects, a thermocouple, and an ultraviolet absorption layer sequentially disposed on the silicon substrate. The nanoforest unit is disposed on the upper surface of the ultraviolet absorption layer. The material of the ultraviolet absorption layer includes zinc oxide, silicon carbide, gallium nitride, gallium oxide, or titanium dioxide.

2. The MEMS thermopile ultraviolet detector according to claim 1, characterized in that, The composition of the metal particle unit includes any one of silver, aluminum, or gold.

3. The MEMS thermopile ultraviolet detector according to claim 1, characterized in that, The shape of the nanostructures in the nanoforest unit includes any one of cone-shaped, truncated, or columnar shapes.

4. A method for fabricating a MEMS thermopile ultraviolet detector, characterized in that, The method for fabricating the MEMS thermopile ultraviolet detector according to any one of claims 1-3 includes: Fabrication of a MEMS thermopile ultraviolet detection unit; Nanoforest units were prepared on top of the ultraviolet detection unit of the MEMS thermopile by dry etching. Metal particle units are formed on the surface around the nanoforest unit using a sputtering process. The metal particle unit is used to increase the ultraviolet radiation absorption rate.

5. The method for fabricating a MEMS thermopile ultraviolet detector according to claim 4, characterized in that, The fabrication of the MEMS thermopile ultraviolet detection unit includes: Provide silicon substrates; A dielectric layer is formed on the silicon substrate by depositing a silicon dioxide, silicon dioxide-silicon nitride, or silicon dioxide-silicon nitride-silicon dioxide film layer. Thermocouple strips are deposited and patterned on the dielectric layer to form thermocouples; Deposit metal interconnects around the thermocouple; Deposition forms an ultraviolet-absorbing layer using zinc oxide, silicon carbide, gallium nitride, gallium oxide, or titanium dioxide, which have high ultraviolet absorption rates. The silicon substrate is subjected to back cavity etching.

6. The method for fabricating a MEMS thermopile ultraviolet detector according to claim 5, characterized in that, Nanoforest units are fabricated on top of the MEMS thermopile ultraviolet detection unit by dry etching, including: The nanoforest units are formed by sequentially spin-coating a polymer onto the ultraviolet absorption layer and patterning it, followed by plasma bombardment.

7. The method for fabricating a MEMS thermopile ultraviolet detector according to claim 4, characterized in that, The composition of the metal particle unit includes any one of silver, aluminum, or gold.

8. The method for fabricating a MEMS thermopile ultraviolet detector according to claim 4, characterized in that, The shape of the nanostructures in the nanoforest unit includes any one of cone-shaped, truncated, or columnar shapes.

Images