MEMS infrared light source with double-sided structure, preparation method and packaging device

Abstract

The present invention discloses a MEMS infrared light source with a double-sided structure, a preparation method and a packaging device, the infrared light source includes a silicon substrate, a support layer, a heating electrode, an isolation layer, a planar electrode, and an infrared radiation material layer; a substrate cavity that runs through from top to bottom is provided in the silicon substrate, the support layer covers the upper end face and the lower end face of the silicon substrate, and the isolation layer covers the outer side face of the support layer; the support layer and the isolation layer at both ends of the substrate cavity are suspended to form two suspended islands respectively; the outer side wall of the suspended island extends outward to form a cantilever beam connected to the side wall of the substrate cavity; the outer side face of the suspended island is provided with an infrared radiation material layer; the isolation layer in the suspended island is embedded with a heating electrode, and the heating electrode is arranged close to the support layer. The above-mentioned infrared light source symmetrically arranges two suspended islands with infrared radiation material layers at both ends of the substrate cavity, and the radiation intensity of the light source is improved through the double-sided structure, the degree of integration of the infrared light source is enhanced, and the volume of the device is reduced.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a MEMS infrared light source with a double-sided structure, a preparation method and a packaging device. Background Art

[0002] In recent years, infrared technology has been widely used in gas detection, industrial process monitoring and medical diagnosis. In the field of infrared detection technology, the performance of the core component infrared light source is very important. Generally speaking, the greater the infrared radiation power, the higher the detection accuracy. Traditional tungsten lamps, SiC ceramic rods and metal foil (wire) infrared light sources have been gradually replaced by MEMS (Micro-Electro-Mechanical System) infrared light sources due to their disadvantages such as low efficiency, large size and low modulation. Generally, MEMS infrared light sources are composed of a semiconductor film support layer and a metal film heating layer on a single end of a silicon substrate. Their radiation power is relatively small, which limits their wide application.

[0003] The core component MEMS infrared light source has the advantages of small size, easy integration, high modulation, and low cost, and has been extensively researched, developed, and manufactured. Currently, most MEMS infrared light sources have low radiation power due to their thin film structure limitations, making it difficult to meet some high-precision detection application scenarios. Therefore, it is particularly necessary to develop a new structure MEMS infrared light source to increase the radiation intensity.

[0004] Generally, MEMS infrared light sources are made by processing a support layer and a heating electrode film on the surface of a silicon-based substrate. The heating electrode is energized to generate Joule heat, which then emits infrared radiation energy. During the operation of the MEMS infrared light source, the maximum temperature of the membrane surface is usually around 400~650℃. Although excessively high temperatures can increase the radiation power, high temperature environments can easily cause the heating electrode to rupture and fail, greatly shortening the life of the light source device. In addition, the cavity size and heating area of ​​the MEMS infrared light source are relatively small, making the total emitted radiation power very limited. Although an array structure can be set up, it will cause a significant increase in the cost of the detection equipment and an increase in the volume of the structure, which is not conducive to the integration and miniaturization of micro-nano devices.

[0005] Similar solutions: CN220604613U discloses an infrared light source with a laminated structure, which includes multiple infrared light-emitting components, which are stacked and graphene is used as the light-emitting layer. The infrared light power density per unit area is increased by stacking the components. CN111115565A invented a back-emitting infrared light source. After a support layer is set on one side of a single-crystal silicon wafer, a MEMS process is etched on the other side to form a hollow structure with a silicon-based edge and a through-hole in the middle area. At the same time, an infrared thermal radiator, an isolation layer and a reflective layer are sequentially set on the support layer to obtain a back-emitting infrared light source, thereby improving the infrared emission efficiency. CN105004694A provides an array infrared light source device based on MEMS technology and a preparation method thereof. The infrared light source device includes an infrared light-emitting part and a focusing cover part. The metal heating area and the high-emissivity material together form a number of infrared radiation sources, which effectively solve the problems of high packaging cost and large device size.

[0006] The above improvements and optimizations all have certain limitations. For example, the graphene light-emitting layer is easily oxidized and decomposed to fail. At the same time, the processing of the light source device cannot be achieved through the standard MEMS process, and it is difficult to promote and use it on a large scale and at low cost. The back-emitting MEMS infrared light source is based on single-sided radiation, and the improvement in radiation power is very limited. Setting up an array structure will increase the cost and volume, which will greatly limit its wide application. Therefore, it is difficult for the existing technical methods to solve the problem of low radiation power of MEMS infrared light sources. Summary of the invention

[0007] The embodiments of the present invention provide a MEMS infrared light source with a double-sided structure, a preparation method and a packaging device, aiming to solve the problem of low radiation power of the MEMS infrared light source in the prior art method.

[0008] In a first aspect, an embodiment of the present application provides a MEMS infrared light source with a double-sided structure, wherein the infrared light source includes a silicon substrate, a support layer, a heating electrode, an isolation layer, a planar electrode, and an infrared radiation material layer;

[0009] The silicon substrate is provided with a substrate cavity which passes through from top to bottom, the support layer is covered and arranged on the upper end surface and the lower end surface of the silicon substrate, and the isolation layer is covered and arranged on the outer side surface of the support layer;

[0010] The support layer and the isolation layer at both ends of the substrate cavity are suspended to form two suspension islands respectively; the outer side walls of the suspension islands extend outward to form cantilever beams connected to the side walls of the substrate cavity; the support layer and the isolation layer outside the substrate cavity are suspended to form an outer frame; the outer sides of the suspension islands are provided with infrared radiation material layers;

[0011] A heating electrode is embedded in the isolation layer in the floating island, and the heating electrode is arranged close to the supporting layer; the heating electrode passes through the cantilever beam and extends to the outer frame; two planar electrodes electrically connected to the heating electrode in the outer frame are arranged on both sides of the outer frame.

[0012] In a second aspect, an embodiment of the present application further provides a method for manufacturing a MEMS infrared light source with a double-sided structure, wherein the manufacturing method is used to manufacture the MEMS infrared light source with a double-sided structure as described in the first aspect above, wherein the manufacturing method comprises:

[0013] The silicon substrate is cleaned with a cleaning solution, and then a film is coated on the upper and lower surfaces of the silicon substrate to deposit a support layer;

[0014] Using metal magnetron sputtering and stripping processing technology to process heating electrodes on the support layers on the upper and lower sides of the silicon substrate respectively, and performing annealing heat treatment;

[0015] Using a CVD coating process to process the heating electrodes on the upper and lower sides of the silicon substrate to obtain an isolation layer;

[0016] The isolation layers on the upper and lower sides of the silicon substrate are etched and opened by plasma dry etching or wet etching, and then subjected to film coating to obtain a planar electrode;

[0017] Infrared radiation material layers are processed in the suspended island regions formed on the upper and lower sides of the silicon substrate respectively;

[0018] Etching windows in the peripheral areas of the suspended islands on the upper and lower sides of the silicon substrate;

[0019] The central area of ​​the silicon substrate is wet anisotropically etched through an etching window to form a substrate cavity.

[0020] In a third aspect, an embodiment of the present application further provides a packaging device, wherein the packaging device includes the MEMS infrared light source with a double-sided structure as described in the first aspect above, and the packaging device also includes a base, a gold-plated pad, and a metal wire;

[0021] The gold-plated pads are provided on the lower side of each vertex in the infrared light source, and the gold-plated pads are assembled on the upper end surface of the base. The planar electrodes on the upper end surface of the silicon substrate are electrically connected to at least one of the metal wires, and each of the gold-plated pads is electrically connected to at least one of the metal wires.

[0022] The embodiment of the present invention provides a MEMS infrared light source with a double-sided structure, a preparation method and a packaging device, the infrared light source includes a silicon substrate, a support layer, a heating electrode, an isolation layer, a planar electrode, and an infrared radiation material layer; a substrate cavity that runs through from top to bottom is provided in the silicon substrate, the support layer is covered and arranged on the upper end face and the lower end face of the silicon substrate, and the isolation layer is covered and arranged on the outer side face of the support layer; the support layer and the isolation layer at both ends of the substrate cavity are suspended to form two suspended islands respectively; the outer side wall of the suspended island extends outward to form a cantilever beam connected to the side wall of the substrate cavity; the outer side face of the suspended island is provided with an infrared radiation material layer; the isolation layer in the suspended island is embedded with a heating electrode, and the heating electrode is arranged close to the support layer. The above infrared light source is symmetrically arranged on the horizontal plane in the middle of the silicon substrate, two suspended islands are arranged at both ends of the substrate cavity respectively, and an infrared radiation material layer is arranged on the outer side face of the suspended island, the radiation intensity of the light source is improved through the double-sided structure, the integration degree of the infrared light source is enhanced, and the device volume is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0024] Figure 1 The overall structure diagram of the MEMS infrared light source with a double-sided structure provided by an embodiment of the present invention;

[0025] Figure 2 A cross-sectional structural diagram of a MEMS infrared light source with a double-sided structure provided by an embodiment of the present invention;

[0026] Figure 3 A cross-sectional structural diagram of a MEMS infrared light source with a double-sided structure in a first processing state provided by an embodiment of the present invention;

[0027] Figure 4 A cross-sectional structural diagram of a MEMS infrared light source with a double-sided structure in a second processing state provided by an embodiment of the present invention;

[0028] Figure 5 A cross-sectional structural diagram of a MEMS infrared light source with a double-sided structure in a third processing state provided by an embodiment of the present invention;

[0029] Figure 6 A cross-sectional structural diagram of a MEMS infrared light source with a double-sided structure in a fourth processing state provided by an embodiment of the present invention;

[0030] Figure 7A cross-sectional structural diagram of a MEMS infrared light source with a double-sided structure in a fifth processing state provided by an embodiment of the present invention;

[0031] Figure 8 A cross-sectional structural diagram of a MEMS infrared light source with a double-sided structure in a sixth processing state provided by an embodiment of the present invention;

[0032] Fig. 9 A flow chart of a method for preparing a MEMS infrared light source with a double-sided structure provided by an embodiment of the present invention;

[0033] Fig.10 A structural diagram of a packaging device provided in an embodiment of the present invention.

[0034] Figure numerals: 1, silicon substrate; 2, supporting layer; 3, heating electrode; 4, isolation layer; 5, planar electrode; 6, infrared radiation material layer; 7, base; 8, gold-plated pad; 9, metal wire; 201, first film layer; 202, second film layer; 102, substrate cavity; 101, window; 103, cantilever beam. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0037] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0038] See also Figure 1 to Figure 2As shown in the figure, a MEMS infrared light source with a double-sided structure, wherein the infrared light source includes a silicon substrate 1, a support layer 2, a heating electrode 3, an isolation layer 4, a planar electrode 5, and an infrared radiation material layer 6; the silicon substrate 1 is provided with a substrate cavity 102 that passes through from top to bottom, the support layer 2 is covered and arranged on the upper end surface and the lower end surface of the silicon substrate 1, and the isolation layer 4 is covered and arranged on the outer side surface of the support layer 2; the support layer 2 and the isolation layer 4 located at both ends of the substrate cavity 102 are suspended to form two suspended islands respectively; the outer side walls of the suspended islands extend outward The cantilever beam 103 is extended to form a cantilever beam 103 connected to the side wall of the substrate cavity 102; the support layer 2 and the isolation layer 4 located outside the substrate cavity 102 are suspended to form an outer frame; the outer side surfaces of the suspended islands are provided with an infrared radiation material layer 6; the isolation layer 4 in the suspended islands is embedded with a heating electrode 3, and the heating electrode 3 is arranged close to the support layer 2; the heating electrode 3 passes through the cantilever beam 103 and extends to the outer frame; two planar electrodes 5 electrically connected to the heating electrode 3 in the outer frame are arranged on both sides of the outer frame.

[0039] like Figure 1 As shown, the silicon substrate 1 is symmetrically arranged with a horizontal plane in the middle part, two floating islands are arranged at both ends of the substrate cavity 102, and an infrared radiation material layer 6 is arranged on the outer side of the floating island. The floating island and the infrared radiation material layer 6 arranged on its outer surface are combined into an infrared radiation emitting component, and an infrared radiation emitting component is arranged on both the upper and lower surfaces of the silicon substrate 1, thereby forming a double-sided structure MEMS infrared light source device, which greatly improves the infrared radiation power. In one embodiment of the present application, each floating island extends outward to form four cantilever beams 103. In other embodiments, more than four cantilever beams 103, or three cantilever beams 103, two cantilever beams 103, or one cantilever beam 103 can be arranged. The length and width of the cantilever beam 103 can be designed and processed according to actual needs, and are not specifically limited in the present invention. Generally speaking, the more cantilever beams 103 there are, the more heat conduction paths there are, the power consumption of the device increases, the response time increases, and the modulation frequency and depth decrease; however, the increase in the number of cantilever beams 103 has a positive effect on improving the stability of the light source device. In the preferred embodiment, four cantilever beams 103 can be provided to balance the device characteristics and stability. The heating electrode area and pattern can be set according to the product application scenario, and no examples are given here. The larger the heating area, the increased risk of high-temperature failure of the device during operation, and the shorter the service life. Typically, the silicon substrate 1 can be set to be rectangular, and its size is 1.5×1.5mm to 3.6×3.6mm, and the surface area of ​​the suspended island is 0.49 to 4.41mm 2 For example, if the floating island is set to be rectangular, the size of the floating island can be set to 0.7×0.7 mm to 2.1×2.1 mm.

[0040] like Figure 2 As shown, the infrared light source includes a silicon substrate 1, a support layer 2, a heating electrode 3, an isolation layer 4, a planar electrode 5, and an infrared radiation material layer 6; a substrate cavity 102 is provided in the silicon substrate 1, the support layer 2 is covered and arranged on the upper end surface and the lower end surface of the silicon substrate 1, and the isolation layer 4 is covered and arranged on the outer side surface of the support layer 2. The support layer 2 can be set as a multi-layer film, for example, the support layer 2 can be set to be composed of a first film layer 201 and a second film layer 202, wherein the first film layer 201 is a SiO2 layer, and the second film layer 202 is a SiN x .

[0041] The support layer 2 and the isolation layer 4 at both ends of the substrate cavity 102 are suspended to form two suspension islands respectively; the outer side walls of the suspension islands extend outward to form cantilever beams 103 connected to the side walls of the substrate cavity 102; the support layer 2 and the isolation layer 4 located outside the substrate cavity 102 are suspended to form an outer peripheral frame; the outer side surfaces of the suspension islands are provided with infrared radiation material layers 6; the isolation layer 4 in the suspension islands is embedded with a heating electrode 3, and the heating electrode 3 is arranged close to the support layer 2; the heating electrode 3 penetrates the cantilever beam 103 and extends to the outer peripheral frame; two planar electrodes 5 electrically connected to the heating electrode 3 in the outer peripheral frame are arranged on both sides of the outer peripheral frame. The planar electrode 5 is connected to the heating electrode 3 through the etched holes on the isolation layer 4. Two infrared radiation emitting components are formed on the upper and lower surfaces of the silicon substrate 1 respectively. The upper and lower surfaces of the silicon substrate 1 are etched to form windows 101, and the substrate cavity 102 is further obtained by front wet anisotropic etching, forming a MEMS infrared light source with a double-sided structure design, which greatly improves the infrared radiation power.

[0042] In a more specific embodiment, the suspension island is a circular, rectangular or triangular suspension island; the number of the cantilever beams 103 is one or more; the substrate cavity 102 is a vertically symmetrical inverted trapezoidal structure; the size of the two ends of the substrate cavity 102 is larger than the size of the middle section of the substrate cavity 102. Specifically, the heating electrode 3 is embedded in each of the suspension islands, and the heating electrode 3 is formed by winding a spiral heating wire, or the heating electrode 3 is a planar film electrode.

[0043] The floating island can be set as a circular floating island, so as to improve the uniformity of heating of the infrared radiation emitting component corresponding to the floating island. Furthermore, the heating electrodes 3 embedded in the floating island can be spiral heating wires, so that the outer structure of the spiral heating wires matches the circular floating island, and the heating electrodes 3 can be evenly laid in the circular floating island, thereby further improving the uniformity of heating of the infrared radiation emitting component corresponding to the floating island, thereby improving the uniformity of infrared radiation of the device and the application effect. In a more specific embodiment, the silicon substrate is a single crystal silicon substrate or a silicon wafer on insulator substrate. Wherein, the supporting layer is a single layer of SiO2, a single layer of Si3N4 or a single layer of SiN x , or the supporting layer is SiO2, Si3N4 and SiN x A composite film layer composed of at least two layers.

[0044] Specifically, the silicon substrate 1 may be a single crystal silicon substrate or a silicon wafer on insulator (SOI silicon wafer) substrate, and the support layer 2 may be a single layer of SiO2, a single layer of Si3N4 or a single layer of SiN x , or the supporting layer is SiO2, Si3N4 and SiN x In one specific embodiment of the present application, the support layer 2 is provided with a composite film layer composed of a first film layer 201 and a second film layer 202, wherein the first film layer 201 is a SiO2 layer, and the second film layer 202 is a SiN x The first film layer 201 is arranged closely to the surface of the silicon substrate 1 .

[0045] In a more specific embodiment, the heating electrode 3 is a metal composite film layer composed of one or more of Pt, Au, W, Al, TiN, NiCr alloy, MoSi2, or the heating electrode 3 is a doped polysilicon film. Specifically, the isolation layer 4 is a single layer of SiO2, a single layer of Si3N4 or a single layer of SiN x , or the isolation layer 4 is SiO2, Si3N4 and SiN x A composite film layer composed of at least two layers.

[0046] The heating electrode 3 can be a metal composite film layer composed of one or more of Pt, Au, W, Al, TiN, NiCr alloy, MoSi2, or a doped polysilicon film. The isolation layer can be a single layer of SiO2, a single layer of Si3N4, or a single layer of SiN x , or set the isolation layer 4 to SiO2, Si3N4 and SiN x A composite film layer composed of at least two layers.

[0047] In a more specific embodiment, the planar electrode 5 is a Pt metal film layer, an Au metal film layer or an Al metal film layer. The infrared radiation material layer 6 is one of nano-platinum black, nano-black silicon, carbon nanotubes, graphene, amorphous carbon film doped with metal elements, or Au / Al2O3 / Au super surface material, or ZnNiP chemical plating layer.

[0048] Among them, the planar electrode 5 can be set to a Pt metal film layer, an Au metal film layer or an Al metal film layer, and the infrared radiation material layer 6 can be set to be one of nano-platinum black, nano-black silicon, carbon nanotubes, graphene, amorphous carbon film doped with metal elements, or Au / Al2O3 / Au super surface material, or ZnNiP chemical plating layer.

[0049] The embodiment of the present invention further provides a method for preparing a MEMS infrared light source with a double-sided structure, and the method can be used to manufacture the MEMS infrared light source with a double-sided structure described in the above embodiment, such as Fig. 9 As shown, the preparation method includes steps S1-S7.

[0050] S1. Cleaning the silicon substrate with a cleaning solution, and then coating the upper and lower surfaces of the silicon substrate to deposit a support layer.

[0051] like Figure 3 As shown, first prepare a silicon substrate 1, which can be a single crystal silicon substrate or an SOI silicon wafer substrate. Before coating, the silicon substrate needs to be cleaned with ammonia / hydrogen peroxide, hydrochloric acid / hydrogen peroxide, acetone, deionized water and other cleaning solutions. After cleaning the silicon substrate 1, a support layer 2 can be deposited on the silicon substrate 1. The support layer 2 is a single layer of SiO2, a single layer of Si3N4 or a single layer of SiN x , or the support layer 2 is SiO2, Si3N4 and SiN x A composite film layer composed of at least two layers of. Generally, SiO2 has tensile stress and low thermal conductivity, Si3N4 or SiN x The present invention adopts SiO2 and SiN x The two-layer composite film structure is stress-adaptive, high thermal stability and low heat loss. The total thickness of the two-layer composite film structure is controlled at 1.1-3.6μm. The 600-2000nm SiO2 film is processed on the upper and lower surfaces of the silicon substrate 1 using a thermal oxygen coating process, the oxygen flow rate is controlled at 3-5L / min, and the reaction temperature is about 1100℃. Then, the LPCVD coating process is used to coat the upper and lower surfaces of the silicon substrate 1 with 500-1600nm SiN xFilm processing, the volume flow ratio of the reaction gases SiH2Cl2 and NH3 is 1:3-1:4, the reaction temperature is about 800℃, the chamber pressure is 300mTorr, SiN x The film forming rate is 3~6nm / min.

[0052] S2. Using metal magnetron sputtering and stripping processing technology to process heating electrodes on the support layers on the upper and lower sides of the silicon substrate respectively, and perform annealing heat treatment.

[0053] like Figure 4 As shown, the heating electrode 3 is processed on the support layer 2 on the upper and lower surfaces of the silicon substrate 1, respectively. The heating electrode 3 can be one or more metal composite film layers of Pt, Au, W, Al, TiN, nickel-chromium alloy, MoSi, or a doped polycrystalline silicon (Poly-Si) film. The present invention uses metal magnetron sputtering and lift-off technology to process the Pt film as the heating electrode 3. First, the silicon substrate 1 with the support layer 2 is cleaned, and the adhesion promoter hexamethyldisilazane (HDMS) is sprayed to increase the adhesion between the photoresist and the semiconductor film. A negative photoresist with a thickness of 1-3μm is spin-coated, and the processes of pre-baking, exposure, development and post-baking are performed. Then, the Pt film is processed, and a layer of Ti, Cr or Ni metal film with a thickness of 10-50nm is sputtered first to increase the bonding force between the heating electrode 3 and the support layer 2, and then a 200-500nm Pt film is processed. The metal magnetron sputtering power is 100-200W, the chamber pressure is about 3.0mTorr, the Ar gas flow rate is 50-100sccm, and the Pt film formation rate is 5-10nm / min. Acetone solution and alcohol are used for stripping and ultrasonic cleaning. In order to improve the stability of the heating electrode 3, a rapid annealing heat treatment at 400-600℃ is required, and the annealing time is 2-10min.

[0054] S3. Using a CVD (chemical vapor deposition) coating process to obtain an isolation layer on the heating electrodes on the upper and lower sides of the silicon substrate.

[0055] like Figure 5 As shown, an isolation layer 4 is processed on the upper and lower surfaces of the silicon substrate 1 on the heating electrode 3, and the isolation layer 4 is a single layer of SiO2, a single layer of Si3N4 or a single layer of SiN x , or the isolation layer 4 is SiO2, Si3N4 and SiN xThe present invention adopts PECVD coating process to process SiO2 isolation layer 4 with thickness of 400-800nm, with 5% SiH4 / N2 flow rate of 100-200sccm, N2O flow rate of 600-800sccm, chamber pressure of 800-900mTorr, reaction temperature of 250-350℃, radio frequency (RF) power of 15-25W, and deposition rate of SiO2 isolation layer 4 of 50-70nm / min.

[0056] S4. Use plasma dry etching or wet etching to etch holes in the isolation layers on the upper and lower sides of the silicon substrate, and perform coating processing to obtain a planar electrode.

[0057] like Figure 6 As shown, the isolation layer 4 film layer on the upper and lower surfaces of the silicon substrate 1 is etched to open holes and then plated to obtain a planar electrode 5 (Pad electrode). The etching opening can be performed by plasma dry etching or by a mixed solution wet etching process of HF and H2O2. The planar electrode 5 can be an electrode composed of a Pt metal film layer, an Au metal film layer or an Al metal film layer, and the Pt metal film layer, the Au metal film layer or the Al metal film layer is prepared by metal magnetron sputtering and lift-off process. The present invention adopts plasma dry etching process to etch holes on SiO2 isolation layer 4, uses 1-5μm photoresist as dry etching mask, the flow rates of CF4 and CHF3 in etching gas are 10-20sccm and 30-40sccm respectively, the Ar flow rate is 200-300sccm, the chamber pressure is 200-300mTorr, the RF power is 400-500W, and the etching rate of SiO2 isolation layer 4 is 400-800nm / min. Then the above sample is subjected to re-coating, photolithography and development and other processing steps, and then a metal magnetron coating process is used to process a 400-800nm ​​thick Pt metal film layer, thereby obtaining a planar electrode 5; in order to increase the bonding force between the planar electrode 5 and the bottom heating electrode 3, an ultra-thin 10-50nm thick Ti film layer, Cr film layer or Ni film layer can be introduced between the planar electrode 5 and the heating electrode 3 as an intermediate film layer. Finally, a stripping and debonding operation is performed, and the processing steps are similar to the above-mentioned steps for processing the heating electrode 3, which will not be repeated here.

[0058] S5. Processing infrared radiation material layers in the floating island regions formed on the upper and lower sides of the silicon substrate respectively.

[0059] like Figure 7As shown, an infrared radiation material layer 6 is processed on the isolation layer 4 corresponding to the upper and lower surfaces of the silicon substrate 1 and the floating island area. The infrared radiation material layer 6 has a special micro-nano structure and a high infrared radiation rate. It can be one of nano-platinum black, nano-black silicon, carbon nanotubes, graphene, amorphous carbon film doped with metal elements, or Au / Al2O3 / Au super surface material, or ZnNiP chemical plating. The present invention uses an in-situ growth strategy and a photolithography process to prepare vertical carbon nanotubes as the infrared radiation material layer 6. First, a photoresist is used as a mask, and then a magnetron sputtering device is used to process a 10 nm Ti layer and a 50 nm TiN layer, and a 5-10 nm Fe metal film in sequence. Among them, the Ti layer and the TiN layer prevent Fe from migrating and diffusing at high temperature, and Fe nanoparticles are the key catalyst for the growth of vertical carbon nanotube materials. In an acetone solution, a stripping and degumming operation is performed, and the processing steps are similar to the above method steps, which will not be repeated here. Then, 500-1000sccm of H2 and 30-80sccm of C2H2 are introduced into the reaction chamber, the pressure is 50-100mbr, the temperature is 500-700℃, and the growth time is 8-10min. After the reaction is completed, it is cooled in N2 atmosphere to obtain 10-120μm thick vertical carbon nanotubes as infrared radiation material layer 6.

[0060] S6. Etching to form windows in the peripheral areas of the suspended islands on the upper and lower sides of the silicon substrate.

[0061] like Figure 8 As shown, the isolation layer 4 and the support layer 2 located in the peripheral area of ​​the suspended island on the upper and lower surfaces of the silicon substrate 1 are etched to form a window 101. The present invention adopts a plasma dry etching process to ensure that the side walls of the etched window 101 are highly flat. In order to protect the structure of other non-etched areas from being damaged, a 5-10μm thick photoresist is used as a mask. The etching process of the SiO2 film layer in the isolation layer 4 and the support layer 2 is consistent with the above method, but the etching time is adjusted. The SiN in the support layer 2 x The membrane layer is also etched by plasma dry etching, with the etching gas SF6 and CHF3 flow rates of 20-40sccm and 5-10sccm respectively, He flow rate of 50-200sccm, chamber pressure of 300-500mTorr, RF power of 300-500W, SiN x The etching rate is 100-200nm / min.

[0062] S7. Perform wet anisotropic etching on the central area of ​​the silicon substrate through the etching window to form a substrate cavity.

[0063] Wet anisotropic etching is performed in the central area of ​​the silicon substrate 1 through the etching window, and both sides of the silicon substrate can be etched at the same time, so as to form two symmetrical trapezoidal cavities in the upper and lower parts, which are combined into a substrate cavity 102. A suspended island supported by a cantilever beam is formed on the upper and lower surfaces of the silicon substrate 1, respectively. The planar electrode 5 is located in the non-suspended area (peripheral frame), which is convenient for the subsequent wire bonding and welding operations of the light source. The present invention uses a TMAH solution to perform anisotropic etching on the silicon substrate 1 to form the substrate cavity 102. Silicon-based wet etching solutions such as KOH or EDP can also be used. A TMAH solution with a concentration of 25% is selected for etching, and a condensation reflux device is installed to prevent the corrosive solution from volatilizing. The heating temperature is 80-90°C, the etching rate is 0.5-1.0μm / min, and the etching is washed with clean water to obtain the following Figure 1 and Figure 2 The infrared light source shown has completed the processing operation of the infrared light source.

[0064] The above-mentioned preparation method is based on a double-sided wet anisotropic etching process, and the processed MEMS infrared light source can improve the integration degree of the device, reduce the volume, and reduce the processing and manufacturing cost.

[0065] An embodiment of the present application also discloses a packaging device, wherein the packaging device includes a MEMS infrared light source with a double-sided structure as described in the above embodiment, and the packaging device also includes a base, a gold-plated pad, and a metal wire; the gold-plated pad is provided on the lower side of each vertex in the infrared light source, and the gold-plated pad is assembled on the upper end surface of the base, each planar electrode on the upper end surface of the silicon substrate is electrically connected to at least one of the metal wires, and each of the gold-plated pads is electrically connected to at least one of the metal wires.

[0066] Specifically, Fig.10 As shown, the packaged device includes four gold-plated pads 8 formed by gold plating on the surface, and the thickness of the gold-plated pads 8 is 100-300μm. The four corners of the infrared light source chip are supported by the four gold-plated pads 8 and fixed on the base 7. The plane electrode 5 in the infrared radiation emitting component on the lower surface of the silicon substrate 1 is in contact with and fixed to the gold-plated pads, and then the gold-plated pads are connected using metal wires 9 and the metal wires 9 are welded to the pins on the base 7 to form a path. The plane electrode 5 in the infrared radiation emitting component on the upper surface of the silicon substrate 1 is directly welded to the pins on the base 7 using one or more metal wires 9 to form a path.

[0067] The above-mentioned MEMS infrared light source with a double-sided structure design has infrared radiation emitting components arranged on the upper and lower surfaces of the silicon substrate 1, which greatly improves the radiation power of the infrared light source and meets the requirements of some high-precision infrared detection applications. At the same time, a suspended island structure supported by cantilever beams is arranged on the upper and lower surfaces of the silicon substrate 1, which greatly reduces the power consumption of the entire heating film, speeds up the response of the light source, and improves the modulation frequency and modulation depth of the light source. Each suspended island is supported by one or more cantilever beams to ensure that the light source chip can work reliably for a long time.

[0068] The embodiment of the present invention provides a MEMS infrared light source with a double-sided structure, a preparation method and a packaging device, the infrared light source includes a silicon substrate, a support layer, a heating electrode, an isolation layer, a planar electrode, and an infrared radiation material layer; a substrate cavity that runs through from top to bottom is provided in the silicon substrate, the support layer is covered and arranged on the upper end face and the lower end face of the silicon substrate, and the isolation layer is covered and arranged on the outer side face of the support layer; the support layer and the isolation layer at both ends of the substrate cavity are suspended to form two suspended islands respectively; the outer side wall of the suspended island extends outward to form a cantilever beam connected to the side wall of the substrate cavity; the outer side face of the suspended island is provided with an infrared radiation material layer; the isolation layer in the suspended island is embedded with a heating electrode, and the heating electrode is arranged close to the support layer. The above infrared light source is symmetrically arranged on the horizontal plane in the middle of the silicon substrate, two suspended islands are arranged at both ends of the substrate cavity respectively, and an infrared radiation material layer is arranged on the outer side face of the suspended island, the radiation intensity of the light source is improved through the double-sided structure, the integration degree of the infrared light source is enhanced, and the device volume is reduced.

[0069] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A MEMS infrared light source with a double-sided structure, characterized in that: The infrared light source comprises a silicon substrate, a supporting layer, a heating electrode, an isolation layer, a planar electrode, and an infrared radiation material layer; The silicon substrate is provided with a substrate cavity which passes through from top to bottom, the support layer is covered on the upper end surface and the lower end surface of the silicon substrate, and the isolation layer is covered on the outer side surface of the support layer; the infrared light source is symmetrically arranged on the middle horizontal plane of the silicon substrate; The support layer and the isolation layer at both ends of the substrate cavity are suspended to form two suspension islands respectively; the outer side walls of the suspension islands extend outward to form cantilever beams connected to the side walls of the substrate cavity; the support layer and the isolation layer outside the substrate cavity are suspended to form an outer frame; the outer sides of the suspension islands are provided with infrared radiation material layers; A heating electrode is embedded in the isolation layer in the floating island, and the heating electrode is arranged close to the supporting layer; the heating electrode passes through the cantilever beam and extends to the outer frame; two planar electrodes electrically connected to the heating electrode in the outer frame are arranged on both sides of the outer frame.

2. The MEMS infrared light source with a double-sided structure according to claim 1, characterized in that: The suspension island is circular, rectangular or triangular; the number of the cantilever beams is one or more; the dimensions of the two ends of the substrate cavity are larger than the dimensions of the middle section of the substrate cavity, and the substrate cavity presents an inverted trapezoidal structure that is symmetrical up and down.

3. The MEMS infrared light source with a double-sided structure according to claim 2, characterized in that: Heating electrodes are embedded in the suspended islands.

4. The MEMS infrared light source with a double-sided structure according to any one of claims 1 to 3, characterized in that: The silicon substrate is a single crystal silicon substrate or a silicon-on-insulator substrate.

5. The MEMS infrared light source with a double-sided structure according to any one of claims 1 to 3, characterized in that: The support layer is a single layer of SiO2, a single layer of Si3N4 or a single layer of SiNx, or the support layer is a composite film layer composed of at least two layers of SiO2, Si3N4 and SiNx; The isolation layer is a single layer of SiO2, a single layer of Si3N4 or a single layer of SiNx, or the isolation layer is a composite film layer composed of at least two layers of SiO2, Si3N4 and SiNx.

6. The MEMS infrared light source with a double-sided structure according to any one of claims 1 to 3, characterized in that: The heating electrode is a metal composite film layer composed of one or more of Pt, Au, W, Al, TiN, nickel-chromium alloy, and MoSi2, or the heating electrode is a doped polycrystalline silicon film.

7. The MEMS infrared light source with a double-sided structure according to any one of claims 1 to 3, characterized in that: The planar electrode is a Pt metal film layer, an Au metal film layer or an Al metal film layer.

8. The MEMS infrared light source with a double-sided structure according to any one of claims 1 to 3, characterized in that: The infrared radiation material layer is one of nano-platinum black, nano-black silicon, carbon nanotubes, graphene, amorphous carbon film doped with metal elements, or Au / Al2O3 / Au super surface material, or ZnNiP chemical plating layer.

9. A method for manufacturing a MEMS infrared light source with a double-sided structure, the method being used to manufacture the MEMS infrared light source with a double-sided structure as claimed in any one of claims 1 to 8, characterized in that: The manufacturing method comprises: The silicon substrate is cleaned with a cleaning solution, and then a film is coated on the upper and lower surfaces of the silicon substrate to deposit a support layer; Using metal magnetron sputtering and stripping processing technology to process heating electrodes on the support layers on the upper and lower sides of the silicon substrate respectively, and performing annealing heat treatment; Using a CVD coating process to process the heating electrodes on the upper and lower sides of the silicon substrate to obtain an isolation layer; The isolation layers on the upper and lower sides of the silicon substrate are etched and opened by plasma dry etching or wet etching, and then subjected to film coating to obtain a planar electrode; Infrared radiation material layers are processed in the suspended island regions formed on the upper and lower sides of the silicon substrate respectively; Etching windows in the peripheral areas of the suspended islands on the upper and lower sides of the silicon substrate; The central area of ​​the silicon substrate is wet anisotropically etched through an etching window to form a substrate cavity.

10. A packaging device, characterized in that: The packaged device comprises the MEMS infrared light source with a double-sided structure as claimed in any one of claims 1 to 8, and the packaged device further comprises a base, a gold-plated pad, and a metal wire; The gold-plated pads are provided on the lower side of each vertex in the infrared light source, and the gold-plated pads are assembled on the upper end surface of the base. The planar electrodes on the upper end surface of the silicon substrate are electrically connected to at least one of the metal wires, and each of the gold-plated pads is electrically connected to at least one of the metal wires.

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