Bridge type suspended film infrared light source chip and preparation method thereof, infrared light source and assembly method thereof

Abstract

The invention discloses a bridge type suspended film infrared light source chip and a preparation method thereof, an infrared light source and an assembly method thereof, relates to the technical field of infrared light source design, and aims to solve the problem that the electrical property of a light source material of the infrared light source in the prior art is easy to change. A thick boron diffusion monocrystalline silicon layer and a first oxide layer are sequentially arranged on the substrate from bottom to top, and a polycrystalline silicon light-emitting film is arranged in the middle of the upper portion of the first oxide layer. The polycrystalline silicon light-emitting film is composed of a thick boron ion implantation polycrystalline silicon layer and an isolation silicon oxide layer which are sequentially arranged from bottom to top, and electrodes are arranged at the two ends of the isolation silicon oxide layer. A cavity structure is arranged in the middle of the substrate, and the polycrystalline silicon light-emitting thin film and the electrodes are suspended above the cavity structure to form a bridge type suspended film structure. The infrared light source has the advantages of high temperature resistance, oxidation resistance, high reliability, long service life, high photoelectric efficiency, high infrared radiation temperature, high emissivity, modulability and the like.

Description

Technical Field

[0001] The invention relates to a bridge-type suspended membrane infrared light source chip and a preparation method thereof, an infrared light source and an assembly method thereof, and belongs to the technical field of infrared light source design. Background Art

[0002] Infrared technology is widely used in optoelectronic devices, space monitoring and reconnaissance sensors, battlefield target friend-or-foe identification devices, infrared communication systems, industrial and mining production safety systems, missile warning systems, infrared medical treatment, pollution monitoring sensors, non-destructive testing of biological material phases, high-resolution imaging sensors, multispectral / space sensors, target guidance navigation and a large number of other commercial and military sensors. In these applications, infrared light source is one of the indispensable components of infrared technology.

[0003] Currently, the mainstream infrared light sources on the market are divided into infrared light-emitting diodes (LEDs), quantum cascade infrared lasers (QCLs), and thermal radiation infrared light sources. However, each of these sources has its drawbacks. Infrared light-emitting diodes typically emit wavelengths less than 5 μm and have extremely low radiant power. Quantum cascade lasers are complex to manufacture, expensive, and expensive. Thermal radiation infrared light sources are typically bulk radiation sources, requiring the addition of a mechanical chopper to achieve modulated output characteristics.

[0004] The infrared light source prepared using MEMS micro-nano processing technology is a thermal radiation infrared light source that uses an electric heating film structure with a thickness of microns to achieve electric heating. Compared with the above-mentioned traditional infrared light sources, it has a smaller volume, lower power consumption, simpler process, lower process cost, higher infrared emissivity, infrared radiation temperature and modulatable characteristics. Through silicon-based MEMS process preparation technology, large-scale quantitative production of infrared light source chips can be achieved.

[0005] Currently, MEMS infrared light sources typically use graphene, carbon nanotubes, platinum, diamond, or metal oxides as the electrothermal light-emitting layer. However, graphene and carbon nanotubes cannot withstand high heating temperatures, platinum easily oxidizes in air, and diamond and metal oxides have low luminous efficiency. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a bridge-type suspended membrane infrared light source chip and its preparation method, an infrared light source and its assembly method. The infrared light source has the advantages of high temperature resistance, oxidation resistance, high reliability, long life, high photoelectric efficiency, high infrared radiation temperature, high emissivity, and modulatability.

[0007] To achieve the above object, the present invention is implemented by adopting the following technical solutions: In a first aspect, the present invention provides a bridge-type suspended film infrared light source chip, comprising a substrate and a first oxide layer arranged in sequence from bottom to top, wherein a polycrystalline silicon light-emitting thin film is provided in the middle above the first oxide layer; The polysilicon light-emitting film comprises a concentrated boron ion-implanted polysilicon layer and an isolation silicon oxide layer arranged in sequence from bottom to top, with windows on both sides of the surface of the isolation silicon oxide layer, and electrodes are provided at the windows, and the electrodes are deposited in the windows to form ohmic contact with the concentrated boron ion-implanted polysilicon layer; Etched windows are provided on both sides of the polysilicon light-emitting film, and a cavity structure is provided in the middle of the substrate. The etched windows are connected to the cavity structure, so that the polysilicon light-emitting film and the electrode are suspended above the cavity structure to form a bridge-type suspended membrane structure.

[0008] Furthermore, the substrate adopts an SOI wafer, and the SOI wafer includes a silicon substrate, an SOI silicon dioxide mask layer and a concentrated boron diffused single crystal silicon layer arranged in sequence from bottom to top. The concentrated boron diffused single crystal silicon layer is obtained by diffusing concentrated boron into a single crystal silicon layer. The thickness of the silicon substrate is 400~500μm, the thickness of the SOI silicon dioxide mask layer is 1~2μm, and the thickness of the concentrated boron diffused single crystal silicon layer is 3~5μm.

[0009] Furthermore, at least one of the following conditions must be met: The thickness of the polysilicon light-emitting film is 3-7 μm; The thickness of the first oxide layer is 400-600 nm; The electrode is an aluminum electrode with a thickness of 0.5-2 μm; The heating resistance of the concentrated boron ion implanted polysilicon layer is 50-360Ω; The thickness of the isolation silicon oxide layer ranges from 70 to 150 nm, and is used to prevent the concentrated boron ion implanted polysilicon layer from being oxidized.

[0010] In a second aspect, the present invention further provides a method for preparing the bridge-type suspended membrane infrared light source chip according to any one of the first aspects, comprising: Performing concentrated boron diffusion on the single crystal silicon layer of the SOI wafer to obtain a concentrated boron diffused single crystal silicon layer; A first oxide layer is prepared by wet oxidation on the upper surface of the concentrated boron diffused single crystal silicon layer; A polysilicon light-emitting thin film layer is formed on the upper surface of the first oxide layer by low-pressure chemical vapor deposition, and concentrated boron ion implantation is performed on the polysilicon light-emitting thin film layer to obtain a concentrated boron ion implanted polysilicon layer; An isolation oxide layer is prepared on the upper surface of the polysilicon layer implanted with concentrated boron ions by thermal oxidation; Dry etching the concentrated boron ion implanted polysilicon layer and the isolation oxide layer to form quadrilateral convex shapes. The rectangular convex concentrated boron ion implanted polysilicon layer and the isolation oxide layer form a polysilicon light-emitting thin film. Spin-coating photoresist on the isolation oxide layer, and dry-etching windows on both sides of the isolation oxide layer surface; Aluminum electrodes are physically evaporated on top of the isolation oxide layer, and the excess aluminum electrode parts are peeled off by ultrasonic vibration and then alloyed and annealed. This allows the aluminum electrode to form an ohmic contact with the concentrated boron ion-implanted polysilicon layer through the window, thus achieving electrode connection. The first oxide layer, the concentrated boron diffused single crystal silicon layer and the SOI silicon dioxide mask layer on both sides of the polysilicon light emitting film are dry-etched from top to bottom to obtain an etching window; A cavity structure is etched in the middle of the lower surface of the SOI wafer using dry etching to obtain a bridge-type suspended membrane infrared light source chip; Laser scribing is used to split each small unit infrared light source chip. Compared with traditional blades splitting along the scribing groove, it can avoid the water jet causing the film to be cracked by cooling water and avoid excessive contact stress inside the wafer causing the film to collapse and break, greatly improving the yield of infrared light source chips.

[0011] Furthermore, the step of performing concentrated boron diffusion on the single crystal silicon layer of the SOI wafer to obtain a concentrated boron diffused single crystal silicon layer comprises: In a nitrogen atmosphere, the single crystal silicon layer of the SOI wafer is pre-deposited at 1000-1050°C; Cooling to 450-550°C, rinsing the single crystal silicon layer with a 5wt% hydrofluoric acid solution in a dark environment; The single crystal silicon layer is treated at 1000-1050°C in a nitrogen atmosphere and then subjected to dry oxygen oxidation treatment in an oxygen atmosphere; The borosilicate glass formed on the surface of the single crystal silicon layer is etched by using a BOE solution in a light-proof environment to obtain a concentrated boron diffused single crystal silicon layer.

[0012] Furthermore, the polysilicon light-emitting thin film layer is subjected to concentrated boron ion implantation to obtain concentrated boron ion implantation into the polysilicon layer. The conditions and parameters of the concentrated boron ion implantation include an implantation energy of 110-190 keV and an implantation dose of 2.4×10 15 ~ 5.0×10 15 / cm 2 ; And / or, the alloying annealing temperature is 450-500° C., and the time is 30-35 min.

[0013] In the third aspect, the present invention also provides an infrared light source, comprising a bridge-type suspended membrane infrared light source chip as described in any one of the first aspects, wherein the bridge-type suspended membrane infrared light source chip is embedded in the center of the lower surface of the base, a tube cap is connected above the base, a card slot is provided at the center of the upper surface of the tube cap, an infrared window is provided in the card slot, and three metal electrode pins are connected to the base, wherein two of the metal electrode pins are positive and negative pins, which pass through the base and are connected to the corresponding electrodes of the bridge-type suspended membrane infrared light source chip, and the remaining metal electrode pin is a ground pin.

[0014] Furthermore, the bridge-type suspended membrane infrared light source chip and the base are bonded together by epoxy resin, and the epoxy resin is used to prevent heat loss caused by direct contact between the base and the bridge-type suspended membrane infrared light source chip.

[0015] Furthermore, the base is a metal tube base or a ceramic tube base; and / or the infrared window is one of germanium, silicon, sapphire, barium fluoride, and zinc sulfide, and its thickness is 0.3 to 1 mm.

[0016] In a fourth aspect, the present invention further provides a method for assembling the infrared light source according to the third aspect, comprising: Apply glue to the center of the lower surface of the base, and the glue spot position corresponds to the azimuth angle of the bridge-type suspended membrane infrared light source chip; The bridge-type suspended membrane infrared light source chip is embedded in the center of the lower surface of the base with the front side facing upwards; Pass the positive and negative pins through the base and connect them to the corresponding electrodes of the bridge-type suspended film infrared light source chip; The pipe cap is placed on the base, and an inert gas is sealed between the base and the pipe cap to achieve fixation between the base and the pipe cap; An infrared window is arranged at the slot in the center of the upper surface of the tube cap to obtain an infrared light source.

[0017] Furthermore, the glue is epoxy resin; And / or, the step of sealing the space between the base and the cap with an inert gas comprises: First, the cavity formed by the base and the tube cap is evacuated, and then inert gas is injected into the cavity under vacuum or low pressure environment. Finally, the tube cap and the base are connected by resistance welding or laser welding.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The bridge-type suspended film infrared light source chip provided by the present invention uses concentrated boron ions to implant a polysilicon layer to achieve infrared luminescence, which can be regarded as a heating resistor and has a good infrared radiation temperature; a groove process is performed on the front side of the substrate and deep silicon etching is performed on the back side to form a bridge-type suspended polysilicon thin film structure, which can separate the contact between the polysilicon light-emitting film and the substrate, increase the heat dissipation capacity of the infrared light source, reduce heat loss in the ohmic heating process of the silicon filament, and improve the modulation capability, working efficiency and electro-optical conversion efficiency of the infrared light source.

[0019] The infrared light source provided by the present invention adopts TO coaxial packaging technology and inert gas sealing technology for the base and tube cap, which has the advantage of preventing the polysilicon light-emitting film from oxidizing and degenerating in the air. The electrodes at both ends of the infrared light source are bonded by gold wire using wire bonding technology to encapsulate it into an infrared light source. The infrared light source is equipped with an infrared window to achieve infrared light enhancement in a specific band, and the infrared light sources are arranged in an array to form a photoelectric identification device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a front view schematic diagram of a bridge-type suspended membrane infrared light source chip in one embodiment of the present invention; Figure 2 A cross-sectional schematic diagram of a bridge-type suspended membrane infrared light source chip in one embodiment of the present invention; Figure 3 This is a schematic structural diagram of a bridge-type suspended membrane infrared light source chip in one embodiment of the present invention; Figure 4 This is a schematic structural diagram of an infrared light source in an embodiment of the present invention; Figure 5 is a schematic cross-sectional view of an infrared light source in an embodiment of the present invention; Figure 6 This is a transverse cross-sectional SEM diagram of the bridge-type suspended membrane infrared light source chip in Example 2 of the present invention; Figure 7 Schematic diagram of a vertical cross-section SEM of a bridge-type suspended membrane infrared light source chip in Example 2 of the present invention; Figure 8 This is a radiation intensity diagram of a bridge-type suspended film infrared light source in one embodiment of the present invention; In the figure: 1-silicon substrate, 2-SOI silicon dioxide mask layer, 3-concentrated boron diffused single crystal silicon layer, 4-first oxide layer, 5-concentrated boron ion implanted polysilicon layer, 6-isolation silicon oxide layer, 7-electrode, 8-base, 9-bridge type suspended membrane infrared light source chip, 10-tube cap, 11-infrared window. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Example 1

[0022] like Figure 1 As shown, an embodiment of the present invention provides a bridge-type suspended membrane infrared light source chip 9, which includes a substrate 1. In this embodiment, the substrate 1 adopts an SOI wafer. The SOI wafer as a whole is a silicon-on-insulator structure, which includes a silicon substrate, an SOI silicon dioxide mask layer 2 and a single crystal silicon layer arranged in sequence from bottom to top. The single crystal silicon layer is converted into a concentrated boron diffused single crystal silicon layer 3 by concentrated boron diffusion. The thickness of the silicon substrate is 400~500μm, which is used to provide mechanical support. The thickness of the SOI silicon dioxide mask layer 2 is 1~2μm, which serves as an insulating isolation layer to reduce parasitic capacitance and leakage current. The thickness of the concentrated boron diffused single crystal silicon layer 3 is 3~5μm. The concentrated boron diffused single crystal silicon layer 3 serves as a self-heating layer in the infrared light source, which can absorb and store the heat radiated downward by the polycrystalline silicon light-emitting film above. When a certain amount of heat is stored, the layer will release the stored heat upward in the form of infrared radiation, and conduct the heat to the polycrystalline silicon light-emitting film on the upper layer, so that it reaches a higher infrared radiation temperature.

[0023] A first oxide layer 4 is provided above the concentrated boron diffused single crystal silicon layer 3. The thickness of the first oxide layer 4 is 400-600 nm, which can provide support for the rectangular suspended polysilicon light-emitting film.

[0024] A polysilicon light-emitting film is located above and in the center of the first oxide layer 4. The polysilicon light-emitting film consists of a concentrated boron ion-implanted polysilicon layer 5 and an isolation silicon oxide layer 6, arranged sequentially from bottom to top. The concentrated boron ion-implanted polysilicon layer 5 is produced using high-concentration boron ion implantation. By controlling the implantation dose and energy, it exhibits resistive heating characteristics, with a heating resistance of 50 to 360Ω. The isolation silicon oxide layer 6 is produced using thermal oxidation to prevent oxidation of the underlying concentrated boron ion-implanted polysilicon layer 5. It also serves as a mask for the implantation of the concentrated boron ion-implanted polysilicon layer 5 and prevents cracking in the polysilicon layer during post-implantation annealing.

[0025] Electrodes 7 are formed at both ends of the isolation silicon oxide layer 6 by physical thermal evaporation. In this embodiment, the electrodes 7 are aluminum electrodes. The electrodes 7 and the concentrated boron ion implanted polysilicon layer 5 have good ohmic contact.

[0026] Combine Figure 2The first oxide layer 4, the concentrated boron-diffused single-crystal silicon layer 3, and the SOI silicon dioxide mask layer 2 on both sides of the polysilicon light-emitting thin film are dry-etched to form etching windows. A cavity structure is provided in the middle of the backside of the substrate 1, formed by deep silicon etching. In this embodiment, the SOI silicon dioxide mask layer 2 also serves as a self-reaction stop layer for the deep silicon etching on the backside of the substrate 1 during the preparation process. This is because the etching rate slows down when the deep silicon etching reaches this layer, causing the deep silicon etching to stop adaptively, thus forming the cavity structure.

[0027] The polysilicon light-emitting film and the electrode 7 are suspended above by the cavity structure, forming a bridge-type suspended membrane structure, namely the bridge-type suspended membrane infrared light source chip 9 .

[0028] The rectangular windows on both sides of the polysilicon light-emitting film and the cavity structure on the back are connected to form a microbridge suspended membrane structure, which greatly reduces the heat conduction loss from the polysilicon light-emitting film to the bottom SOI substrate and improves the infrared radiation intensity. At the same time, this structure can directly realize convective heat exchange between the upper and lower surfaces of the infrared light source chip, reducing the heat capacity of the infrared light source chip so that it can achieve extremely fast heating and cooling rates, and improving its rapid modulation capability at higher frequencies.

[0029] The working principle of the bridge-type suspended film infrared light source chip 9 in this embodiment includes: Concentrated boron ions are implanted into the polycrystalline silicon layer 5 as an infrared light radiation layer. When voltage passes through the polycrystalline silicon light-emitting film, the carriers and lattice vibrations and expansion therein convert electrical energy into thermal energy to generate Joule heat. Its infrared radiation temperature is approximately 650K. The concentrated boron-diffused single-crystal silicon layer 3 below can absorb and store the infrared light radiated downward by the polycrystalline silicon light-emitting film and release it upward, further enhancing the infrared radiation temperature. At the same time, the radiation energy of silicon is mainly concentrated in the infrared band (wavelength is approximately 0.7 to 1000 microns). By changing the thickness of the polycrystalline silicon light-emitting film, the central wavelength of the infrared light can be controlled. Example 2

[0030] This embodiment provides a bridge-type suspended film infrared light source chip, and its specific parameters are as follows: Figure 6 The thickness of the polysilicon light-emitting film is 677.3nm, the thickness of the first oxide layer 4 is 479.8nm, the thickness of the concentrated boron diffused single crystal silicon layer 3 is 4.092μm, and the thickness of the SOI silicon dioxide mask layer is 903.1nm. Figure 7 The thickness of the aluminum electrode is 1.317μm, the thickness of the isolation silicon oxide layer 6 is 151.3nm, the thickness of the concentrated boron ion implanted polysilicon layer 5 is 498.4nm, and the thickness of the first oxide layer is 507.3nm (because each layer of the chip reaches the nanometer and micron level, current technology cannot achieve exactly the same thickness value every time it is measured).

[0031] Apply 5V voltage to the positive and negative pins of the infrared light source through a voltage source meter, and use an infrared spectroradiometer to test the radiation intensity of the infrared light source under 5V voltage, such as Figure 8 As shown, it can be seen that the radiation intensity of the infrared light source at 9.5μm is as high as 110 (W / cm 2 ), which effectively proves that the bridge-type suspended film infrared chip of this embodiment can be used as an infrared light source chip. Example 3

[0032] This embodiment provides a method for preparing the bridge-type suspended film infrared light source chip described in Example 1, which includes the following steps: Perform preparation work, specifically preparing the SOI wafer and cleaning it with standard cleaning methods.

[0033] The concentrated boron diffusion is performed on the single crystal silicon layer of the SOI wafer to obtain the concentrated boron diffused single crystal silicon layer 3. The specific operation is as follows: A single crystal silicon layer was pre-deposited at 1000-1050° C. in a nitrogen atmosphere with a flow rate of 1000 mL / min.

[0034] The temperature was lowered to 500° C., and the single crystal silicon layer was rinsed with a 5 wt % hydrofluoric acid solution in a light-proof environment.

[0035] The single crystal silicon layer was treated at 1000-1050° C. for 7 hours in a nitrogen atmosphere with a flow rate of 1000 mL / min, and then subjected to dry oxygen oxidation treatment for 0.5 hours in an oxygen atmosphere with a flow rate of 600 mL / min.

[0036] The borosilicate glass formed on the single crystal silicon layer is surface-etched using a BOE solution in a light-proof environment to obtain a concentrated boron-diffused single crystal silicon layer 3 .

[0037] A first oxide layer 4 with a thickness of 400-600 nm is prepared on the upper surface of the boron-diffused single crystal silicon layer 3 by wet oxidation.

[0038] A polysilicon light-emitting thin film layer with a thickness of 400 to 1000 nm is formed on the upper surface of the first oxide layer 4 by low pressure chemical vapor deposition (LPCVD), and concentrated boron ions are implanted into the polysilicon light-emitting thin film layer to obtain a concentrated boron ion implanted polysilicon layer 5. In this embodiment, the conditions for the concentrated boron ion implantation include an implantation energy of 110 to 190 keV and an implantation dose of 2.4×10 15 ~ 5.0×10 15 / cm 2 The resistance measured by the four-probe resistance method is approximately 50 Ω ~ 360 Ω.

[0039] An isolation oxide layer 6 is prepared on the upper surface of the polysilicon layer 5 implanted with concentrated boron ions by thermal oxidation, and the thickness of the isolation oxide layer 6 is 70-150 nm.

[0040] The concentrated boron ion implanted polysilicon layer 5 and the isolation oxide layer 6 are dry-etched to form rectangular protrusions. The etching stops at the first oxide layer. The rectangular protrusion-shaped concentrated boron ion implanted polysilicon layer 5 and the isolation oxide layer 6 form a polysilicon light-emitting thin film.

[0041] Photoresist is evenly coated on the isolation oxide layer 6, and rectangular windows are formed on both sides thereof by dry etching.

[0042] An electron beam coating machine is used to physically thermally evaporate an aluminum electrode on the isolation oxide layer 6. The thickness of the aluminum electrode is required to be 0.5~2μm. After the evaporation is completed, ultrasonic vibration is used to peel off the excess aluminum electrode part. Since photoresist is applied under the excess aluminum electrode part, the upper aluminum electrode can be peeled off by ultrasonic vibration in an organic solvent. However, the rectangular window cannot be peeled off because there is no photoresist. Finally, the aluminum electrode is alloyed and annealed at a temperature of 450~500℃ and an annealing time of 30~35min. Finally, an aluminum electrode is set in the rectangular window, so that the aluminum electrode forms an ohmic contact with the concentrated boron ion implanted polysilicon layer 5 through the rectangular window.

[0043] The first oxide layer 4, the concentrated boron diffused single crystal silicon layer 3 and the SOI silicon dioxide mask layer 2 on both sides of the polysilicon light emitting thin film are dry-etched in sequence from top to bottom to obtain etching windows.

[0044] Dry etching is performed on the middle part of the lower surface of the SOI wafer, using the SOI silicon dioxide mask layer 2 as an etching stop layer to obtain a cavity structure. In this embodiment, the size of the cavity structure is 2.8×2.8 mm, so that the polysilicon light-emitting film and the aluminum electrode are all suspended above the cavity structure, forming a bridge-type suspended membrane structure.

[0045] The bridge-type suspended membrane infrared light source chip is split by laser scribing to obtain small-unit bridge-type suspended membrane infrared light source chips 9 . Example 4

[0046] like Figure 4 As shown, on the basis of Example 1, this embodiment further provides an infrared light source, which includes the bridge-type suspended membrane infrared light source chip 9 described in Example 1. The bridge-type suspended membrane infrared light source chip 9 is embedded in the center of the lower surface of the base 8 with its front side facing upward, so that the air below the radiation area of ​​the bridge-type suspended membrane infrared light source chip 9 is connected to the outside world, avoiding the thermal stress vibration of the thin film in the bridge-type suspended membrane infrared light source chip caused by the thermal expansion and contraction of the air below the radiation area due to the flickering of the infrared light source, thereby improving the reliability and service life of the infrared light source.

[0047] In this embodiment, the base 8 is a metal tube base or a ceramic tube base, and the bridge-type suspended membrane infrared light source chip 9 is bonded to the base 8 by epoxy resin. The epoxy resin avoids direct contact between the base and the bridge-type suspended membrane infrared light source chip 9, reduces the heat loss caused by infrared heat conduction below, and reduces the power consumption of the infrared light source.

[0048] A tube cap 10 is sealed and connected above the base 8. A slot is provided at the center of the upper surface of the tube cap 10. An infrared window 11 is provided in the slot. In this embodiment, the infrared window 11 is made of one of germanium, silicon, sapphire, barium fluoride, and zinc sulfide, and has a thickness of 0.3 to 1 mm.

[0049] Combine Figure 5 There are three metal electrode pins connected to the bottom of the base 8, of which the two metal electrode pins are positive and negative pins, which pass through the base and are connected to the electrodes 7 of the bridge-type suspended membrane infrared light source chip 9 respectively, and the remaining metal electrode pin is the ground pin.

[0050] The working principle of the infrared light source of this embodiment is: Voltage is applied to the aluminum electrodes through the positive and negative pins, the bridge-type suspended film infrared light source chip 9 radiates infrared radiation, the infrared window 11 filters a specific infrared band, and can selectively enhance the infrared light emissivity of a certain band.

[0051] Since the present invention adopts inert gas packaging technology, the internal vacuum state is conducive to reducing the oxidation of the polysilicon light-emitting film of the bridge-type suspended membrane infrared light source chip 9, thereby increasing its service life. In addition, the bridge-type suspended membrane infrared light source chip 9 can radiate infrared radiation to a higher temperature in a vacuum. Example 5

[0052] This embodiment provides an assembly method of the infrared light source described in Embodiment 3, using a coaxial TO package, and includes the following steps: Glue is dispensed at four azimuth angles at the center of the lower surface of the base 8 using epoxy resin. The glue dispensing positions at the four azimuth angles correspond to the azimuth angles of the bridge-type suspended membrane infrared light source chip 9 .

[0053] The bridge type suspended membrane infrared light source chip 9 is embedded in the center of the lower surface of the base 8 by bonding with the front side facing upwards, and the positive and negative pins are passed through the base and bonded to the electrodes 7 of the bridge type suspended membrane infrared light source chip 9 accordingly.

[0054] The cap 10 is placed on the base 8, and the base 8 and the cap 10 are sealed with inert gas. The specific operation of the inert gas sealing is to first vacuum the cavity formed by the base 8 and the cap 10 (10 -3 ~ 10 -6Pa level) to exclude air and residual moisture, and then, in a vacuum or low-pressure environment, inject a high-purity inert gas (e.g., nitrogen with a purity of ≥99.999%) into the cavity. Finally, the cap 10 and the base 8 are sealed by resistance welding or laser welding. In this embodiment, the sealing performance of the package is also verified by the helium leakage rate to ensure that the polycrystalline silicon light-emitting film in the bridge-type suspended membrane infrared light source chip 9 will not be oxidized and denatured in the air.

[0055] An infrared window 11 is provided at the slot in the center of the upper surface of the tube cap 10 . In some embodiments, the infrared window 11 can be customized using different materials according to the application requirements such as the required infrared band, cost, and size.

[0056] In some embodiments, an optical surface can be introduced into the TO package to collimate and focus the infrared light radiated by the bridge-type suspended membrane infrared light source chip 9. The optical surface can be flexibly designed according to the optical path of the back-end application.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bridge-type suspended film infrared light source chip, characterized in that: It comprises a substrate and a first oxide layer arranged in sequence from bottom to top, wherein a polysilicon light-emitting thin film is provided in the middle portion above the first oxide layer; The polysilicon light-emitting film comprises a concentrated boron ion-implanted polysilicon layer and an isolation silicon oxide layer arranged in sequence from bottom to top, with windows on both sides of the surface of the isolation silicon oxide layer, and electrodes are provided at the windows, and the electrodes are deposited in the windows to form ohmic contact with the concentrated boron ion-implanted polysilicon layer; Etched windows are provided on both sides of the polysilicon light-emitting film, and a cavity structure is provided in the middle of the substrate. The etched windows are connected to the cavity structure, so that the polysilicon light-emitting film and the electrode are suspended above the cavity structure to form a bridge-type suspended membrane structure.

2. The bridge-type suspended membrane infrared light source chip according to claim 1, characterized in that: The substrate adopts an SOI wafer, which includes a silicon substrate, an SOI silicon dioxide mask layer and a concentrated boron diffused single crystal silicon layer arranged in sequence from bottom to top. The concentrated boron diffused single crystal silicon layer is obtained by diffusing concentrated boron into a single crystal silicon layer. The thickness of the silicon substrate is 400~500μm, the thickness of the SOI silicon dioxide mask layer is 1~2μm, and the thickness of the concentrated boron diffused single crystal silicon layer is 3~5μm.

3. The bridge-type suspended membrane infrared light source chip according to claim 1, characterized in that: At least one of the following conditions must be met: The thickness of the polysilicon light-emitting film is 3-7 μm; The thickness of the first oxide layer is 400-600 nm; The heating resistance of the concentrated boron ion implanted polysilicon layer is 50-360Ω; The electrode is an aluminum electrode with a thickness of 0.5-2 μm; The thickness of the isolation silicon oxide layer ranges from 70 to 150 nm, and is used to prevent the concentrated boron ion implanted polysilicon layer from being oxidized.

4. A method for preparing a bridge-type suspended membrane infrared light source chip according to any one of claims 1 to 3, characterized in that: include: Performing concentrated boron diffusion on the single crystal silicon layer of the SOI wafer to obtain a concentrated boron diffused single crystal silicon layer; A first oxide layer is prepared by wet oxidation on the upper surface of the concentrated boron diffused single crystal silicon layer; A polysilicon light-emitting thin film layer is formed on the upper surface of the first oxide layer by low-pressure chemical vapor deposition, and concentrated boron ion implantation is performed on the polysilicon light-emitting thin film layer to obtain a concentrated boron ion implanted polysilicon layer; An isolation oxide layer is prepared on the upper surface of the polysilicon layer implanted with concentrated boron ions by thermal oxidation; Dry etching the concentrated boron ion implanted polysilicon layer and the isolation oxide layer to form quadrilateral convex shapes. The rectangular convex concentrated boron ion implanted polysilicon layer and the isolation oxide layer form a polysilicon light-emitting thin film. Spin-coating photoresist on the isolation oxide layer, and dry-etching windows on both sides of the isolation oxide layer surface; Aluminum electrodes are physically evaporated on top of the isolation oxide layer, and the excess aluminum electrode parts are peeled off by ultrasonic vibration and then alloyed and annealed. This allows the aluminum electrode to form an ohmic contact with the concentrated boron ion-implanted polysilicon layer through the window, thus achieving electrode connection. The first oxide layer, the concentrated boron diffused single crystal silicon layer and the SOI silicon dioxide mask layer on both sides of the polysilicon light emitting film are dry-etched from top to bottom to obtain an etching window; A cavity structure is etched in the middle of the lower surface of the SOI wafer using dry etching to obtain a bridge-type suspended membrane infrared light source chip; Laser scribing is used to split the bridge-type suspended membrane infrared light source chip to obtain small-unit bridge-type suspended membrane infrared light source chips.

5. The method for preparing a bridge-type suspended membrane infrared light source chip according to claim 4, characterized in that: The method of performing concentrated boron diffusion on the single crystal silicon layer of the SOI wafer to obtain a concentrated boron diffused single crystal silicon layer comprises: In a nitrogen atmosphere, the single crystal silicon layer of the SOI wafer is pre-deposited at 1000-1050°C; Cooling to 450-550°C, rinsing the single crystal silicon layer with a 5wt% hydrofluoric acid solution in a dark environment; The single crystal silicon layer is treated at 1000-1050°C in a nitrogen atmosphere, and then subjected to dry oxygen oxidation treatment in an oxygen atmosphere; The borosilicate glass formed on the surface of the single crystal silicon layer is etched by using a BOE solution in a light-proof environment to obtain a concentrated boron diffused single crystal silicon layer.

6. The method for preparing a bridge-type suspended membrane infrared light source chip according to claim 4, characterized in that: The concentrated boron ion implantation is performed on the polycrystalline silicon light emitting thin film layer to implant the concentrated boron ions into the polycrystalline silicon layer. The conditions and parameters of the concentrated boron ion implantation include an implantation energy of 110-190 keV and an implantation dose of 2.4×10 15 ~ 5.0×10 15 / cm 2 ; And / or, the alloying annealing temperature is 450-500° C., and the time is 30-35 min.

7. An infrared light source, characterized in that: It comprises a bridge-type suspended membrane infrared light source chip as described in any one of claims 1 to 3, wherein the bridge-type suspended membrane infrared light source chip is embedded in the center of the lower surface of the base, a tube cap is connected above the base, a card slot is provided at the center of the upper surface of the tube cap, an infrared window is provided in the card slot, and three metal electrode pins are connected to the base, wherein two of the metal electrode pins are positive and negative pins, which pass through the base and are connected to the corresponding electrodes of the bridge-type suspended membrane infrared light source chip, and the remaining metal electrode pin is a ground pin.

8. The infrared light source according to claim 7, characterized in that The bridge-type suspended membrane infrared light source chip and the base are bonded together by epoxy resin, and the epoxy resin is used to prevent the base and the bridge-type suspended membrane infrared light source chip from direct contact and causing heat loss.

9. The infrared light source according to claim 7, characterized in that The base is a metal tube base or a ceramic tube base; and / or the infrared window is made of one of germanium, silicon, sapphire, barium fluoride, and zinc sulfide, and has a thickness of 0.3 to 1 mm.

10. A method for assembling an infrared light source as claimed in claim 8, characterized in that: include: Apply glue to the center of the lower surface of the base, and the glue spot position corresponds to the azimuth angle of the bridge-type suspended membrane infrared light source chip; Embed the bridge-type suspended membrane infrared light source chip with the front side facing upwards in the center of the lower surface of the base; Pass the positive and negative pins through the base and connect them to the corresponding electrodes of the bridge-type suspended film infrared light source chip; The pipe cap is placed on the base, and an inert gas is sealed between the base and the pipe cap to achieve fixation between the base and the pipe cap; An infrared window is arranged at the slot in the center of the upper surface of the tube cap to obtain an infrared light source.

11. The method for assembling an infrared light source according to claim 10, wherein: The glue is epoxy resin; And / or, the step of sealing the base and the cap with an inert gas comprises: First, the cavity formed by the base and the tube cap is evacuated, and then inert gas is injected into the cavity under vacuum or low pressure environment. Finally, the tube cap and the base are connected by resistance welding or laser welding.

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