A MEMS infrared light source based on a heat-insulating vacuum cavity and a preparation method thereof

Abstract

The application discloses a kind of MEMS infrared light source based on heat insulation vacuum cavity and preparation method thereof, and infrared light source includes infrared light source main body and silicon cap bonded above it, and infrared light source main body includes silicon substrate, mask layer, resistance layer and insulating dielectric layer sequentially arranged from bottom to top;Resistance layer is formed by metal stripping process Graphical resistance structure;Insulating dielectric layer is annular;Resistance layer pad area is deposited with electrode layer;The upper surface of silicon substrate is etched out heat insulation groove;Silicon cap is bonded above insulating dielectric layer, and vacuum cavity is formed between silicon cap and infrared light source main body, and the inner surface of silicon cap is deposited with anti-reflection film.The infrared light source and preparation method disclosed in the application can solve the heat transfer problem of MEMS infrared light source, can effectively reduce the heat loss caused by heat convection between light source and air, improve the electro-optical conversion efficiency and thermal radiation of light source, reduce the power consumption of light source, and improve the stability in actual working environment.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic device technology, and in particular to a MEMS infrared light source based on a heat-insulating vacuum cavity and its fabrication method. Background Technology

[0002] MEMS infrared light sources utilize the Planck radiator's electro-thermal effect to induce the emission of infrared light from the radiating layer. Their working principle involves the infrared light source generating Joule heat under an external driving voltage, causing its temperature to rise and thus producing infrared radiation. A MEMS infrared light source basically consists of a substrate, a mask layer, and a resistive layer. The substrate supports the mask layer and resistive layer. The resistive layer is made of conductive metal and converts electricity into heat energy by applying a certain voltage.

[0003] Currently, MEMS infrared light sources are fabricated using semiconductor processes, starting with a silicon wafer substrate. A supporting thin-film structure is then deposited on the wafer, followed by the fabrication of resistive layers and other structures on the thin film. However, existing light sources suffer from low radiation efficiency and significant heat loss during operation, resulting in insufficient temperature rise and inability to meet application requirements. The heat loss primarily manifests as solid-state heat transfer and convective heat transfer with the air, significantly increasing the power consumption of the light source. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a MEMS infrared light source based on a thermally insulated vacuum cavity and its fabrication method. This aims to reduce the power consumption of the MEMS infrared light source, increase its operating temperature, solve the heat transfer problem, effectively reduce heat loss caused by thermal convection between the light source and the air, improve the electro-optical conversion efficiency and thermal radiation of the light source, reduce power consumption, and enhance stability in practical working environments.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A MEMS infrared light source based on a thermally insulated vacuum cavity includes an infrared light source body and a silicon cap bonded to it. The infrared light source body includes a silicon substrate, a mask layer, a resistive layer, and an insulating dielectric layer arranged sequentially from bottom to top. The resistive layer is formed into a patterned resistive structure through a metal lift-off process. The central region of the resistive structure is spiral-shaped and serves as a heating region. The side regions are rectangular and serve as pad regions. The heating region and the pad regions are connected by connecting resistors. The insulating dielectric layer is annular and distributed on the mask layer between the heating region and the pad region, with a portion located on the connecting resistors. An electrode layer is deposited on the pad region of the resistive layer. The mask layer located around the heating region is etched to form four etching windows. Thermal insulation grooves are etched into the upper surface of the silicon substrate through the etching windows. The silicon cap is bonded to the top of the insulating dielectric layer, and a vacuum cavity is formed between the silicon cap and the infrared light source body. An antireflection film is deposited on the inner surface of the silicon cap.

[0007] In the above scheme, an antireflection film is deposited on the outer surface of the silicon cap.

[0008] In the above scheme, the mask layer is one or more of silicon oxynitride, silicon dioxide, or silicon nitride.

[0009] In the above scheme, the resistive layer is made of platinum.

[0010] In the above scheme, the insulating dielectric layer is silicon dioxide.

[0011] In the above scheme, the electrode layer is gold.

[0012] In the above scheme, the antireflective membrane is magnesium fluoride, silicon dioxide, or titanium dioxide.

[0013] A method for fabricating a MEMS infrared light source based on a thermally insulated vacuum cavity includes the following steps:

[0014] S1. A mask layer is grown on a silicon wafer using thin film growth technology;

[0015] S2. Deposit a resistor layer on the mask layer and form a resistor structure through a metal stripping process. The central region of the resistor structure is spiral-shaped and serves as a heating region, while the side regions are rectangular and serve as pad regions. Connection resistors are reserved between the heating region and the pad regions.

[0016] S3. Deposit an electrode layer on the pad area and form a rectangular electrode area through a metal stripping process;

[0017] S4. An insulating dielectric layer is grown on the mask layer between the electrode region and the heating region using thin film growth technology;

[0018] S5. An etching window is formed around the heating area of ​​the resistive layer by etching a mask layer. The silicon substrate is etched through the etching window to form a heat insulation groove, thus obtaining the infrared light source body.

[0019] S6. Finally, the silicon cap with the antireflection coating is bonded to the insulating dielectric layer of the infrared light source body using a wafer bonding process, forming a vacuum cavity between the silicon cap and the infrared light source body.

[0020] In the above scheme, in steps S1 and S4, the thin film growth technology is the LPCVD method; in steps S2 and S3, the resistive layer and the electrode layer are deposited using electron beam evaporation or sputtering processes.

[0021] In the above scheme, the silicon cap is prepared by the following method: a layer of photoresist is spin-coated on a silicon wafer, and then an etched area is formed after photolithography exposure. Finally, the silicon cap is formed by ICP etching, and an antireflection film is deposited by PECVD.

[0022] Through the above technical solution, the MEMS infrared light source based on a heat-insulating vacuum cavity and its fabrication method provided by the present invention have the following beneficial effects:

[0023] The MEMS infrared light source disclosed in this invention consists of four etched windows forming heat insulation grooves, which in turn form a four-beam structure for support. These grooves are bonded to a silicon cap to form a vacuum cavity. When the MEMS infrared light source is working, it can solve the heat transfer problem of the MEMS infrared light source, effectively reduce the heat loss caused by thermal convection between the light source and the air, reduce heat loss, improve the electro-optical conversion efficiency and thermal radiation of the light source, reduce the power consumption of the light source, and thus improve the stability in the actual working environment. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0025] Figure 1 This is a front cross-sectional view of a MEMS infrared light source based on a heat-insulating vacuum cavity disclosed in an embodiment of the present invention.

[0026] Figure 2 This is a top view of a MEMS infrared light source main structure based on a heat-insulating vacuum cavity, as disclosed in an embodiment of the present invention.

[0027] Figure 3 This is a process flow diagram of a method for fabricating a MEMS infrared light source based on a thermally insulated vacuum cavity, as disclosed in an embodiment of the present invention.

[0028] Figure 4 This is a top view of the resistive layer of a MEMS infrared light source based on a thermally insulated vacuum cavity, as disclosed in an embodiment of the present invention.

[0029] Figure 5 This is a process flow diagram of a silicon cap in a MEMS infrared light source based on a thermally insulated vacuum cavity, as disclosed in an embodiment of the present invention.

[0030] In the figure, 1. Silicon substrate; 2. Mask layer; 3. Resistor layer; 4. Electrode layer; 5. Insulating dielectric layer; 6. Silicon cap; 7. Antireflection film; 8. Vacuum cavity; 9. Heat insulation groove; 10. Etching window; 11. Heating area; 12. Pad area; 13. Connection resistor. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] This invention provides a MEMS infrared light source based on a heat-insulated vacuum cavity 8, such as... Figure 1 As shown, it includes an infrared light source body and a silicon cap 6 bonded to it.

[0033] The infrared light source body comprises, from bottom to top, a silicon substrate 1, a mask layer 2, a resistive layer 3, and an insulating dielectric layer 5; the resistive layer 3 is formed into a patterned resistive structure through a metal lift-off process, such as... Figure 2 As shown, the central region of the resistor structure is spiral-shaped and serves as the heating region 11; the side regions are rectangular and serve as the pad regions 12. The heating region 11 and the pad regions 12 are connected by a connecting resistor 13. The insulating dielectric layer 5 is annular and distributed on the mask layer 2 between the heating region 11 and the pad regions 12, with a portion located on the connecting resistor 13. The pad regions 12 of the resistor layer 3 have electrode layers 4 deposited on them. The mask layer 2 located around the heating region 11 forms four etching windows 10 through etching, and the upper surface of the silicon substrate 1 is etched with heat insulation grooves 9 through the etching windows 10.

[0034] The silicon cap 6 is bonded to the top of the insulating dielectric layer 5, forming a vacuum cavity 8 between the silicon cap 6 and the infrared light source body. An antireflection film 7 is deposited on the inner surface of the silicon cap 6, which can greatly increase the transmittance of infrared light. In this embodiment, an antireflection film 7 is also deposited on the outer surface of the silicon cap 6, which can further improve the transmittance of infrared light.

[0035] Specifically, the mask layer 2 is one or more of silicon oxynitride, silicon dioxide, or silicon nitride.

[0036] In this embodiment, the resistive layer 3 is made of platinum, the insulating dielectric layer 5 is made of silicon dioxide, and the electrode layer 4 is made of gold.

[0037] Specifically, the antireflective membrane 7 is made of magnesium fluoride, silicon dioxide, or titanium dioxide.

[0038] A method for fabricating a MEMS infrared light source based on a thermally insulated vacuum cavity 8, such as... Figure 3 As shown, it includes the following steps:

[0039] S1. A mask layer 2 is grown on a silicon wafer using the LPCVD method;

[0040] S2. Deposit a resistor layer 3 on the mask layer 2 using electron beam evaporation or sputtering, and form a resistor structure through a metal lift-off process, such as... Figure 4 As shown, the central region of the resistor structure is spiral-shaped and serves as the heating region 11, while the side regions are rectangular and serve as the pad regions 12. The heating region 11 and the pad regions 12 are reserved for connection resistors 13.

[0041] S3. Electron beam evaporation or sputtering is used to deposit electrode layer 4 in pad area 12, and a rectangular electrode area is formed by metal stripping process.

[0042] S4. An insulating dielectric layer 5 is grown on the mask layer 2 between the electrode region and the heating region 11 using the LPCVD method.

[0043] S5. The mask layer 2 is etched around the heating area 11 of the resistive layer 3 to form an etching window 10. The silicon substrate 1 is then etched with KOH through the etching window 10 to form a heat insulation groove 9, forming a four-beam fixed support structure, thus obtaining the infrared light source body.

[0044] S6. Finally, the silicon cap 6 with the antireflection coating 7 is bonded to the insulating dielectric layer 5 of the infrared light source body using a wafer bonding process, forming a vacuum cavity 8 between the silicon cap 6 and the infrared light source body. The wafer bonding process is a direct bonding process between silicon and silicon dioxide.

[0045] Specifically, such as Figure 5 As shown, the silicon cap 6 is prepared as follows: a layer of photoresist is spin-coated on a silicon wafer, and then an etched area is formed after photolithography exposure. Finally, the silicon cap 6 is formed by ICP etching, and an antireflection film 7 is deposited by PECVD.

[0046] The MEMS infrared light source of this invention is based on the principle of thermal radiation and features small size, low power consumption, high modulation frequency, wide wavelength range, and long lifespan. With the integration of nanotechnology and nanostructures with sensors becoming increasingly important, this invention innovatively fabricates a MEMS infrared light source based on a vacuum cavity structure. When the MEMS infrared light source is operating, it can solve the heat transfer problem, effectively reducing heat loss due to thermal convection between the light source and the air, thus reducing heat loss, improving the electro-optical conversion efficiency and thermal radiation of the light source, lowering power consumption, and enhancing stability in practical working environments.

[0047] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A MEMS infrared light source based on a heat-insulated vacuum cavity, characterized in that, The system includes an infrared light source body and a silicon cap bonded to it. The infrared light source body comprises, from bottom to top, a silicon substrate, a mask layer, a resistive layer, and an insulating dielectric layer. The resistive layer is formed into a patterned resistive structure through a metal lift-off process. The central region of the resistive structure is spiral-shaped, serving as a heating region; the side regions are rectangular, serving as pad regions. The heating region and the pad regions are connected by connecting resistors. The insulating dielectric layer is annular and distributed on the mask layer between the heating region and the pad regions, with a portion located on the connecting resistors. The pads of the resistive layer... An electrode layer is deposited in the region; a mask layer located around the heating region is etched to form four etching windows, and a heat insulation groove is etched into the upper surface of the silicon substrate through the etching windows; the silicon cap is bonded to the top of the insulating dielectric layer, and a vacuum cavity is formed between the silicon cap and the infrared light source body; an antireflection film is deposited on the inner surface of the silicon cap, and an antireflection film is deposited on the outer surface of the silicon cap; the silicon cap is prepared as follows: a layer of photoresist is spin-coated on a silicon wafer, and then an etched region is formed after photolithography exposure; finally, the silicon cap is formed by ICP etching, and an antireflection film is deposited by PECVD.

2. The MEMS infrared light source based on a heat-insulating vacuum cavity according to claim 1, characterized in that, The mask layer is one or more of silicon oxynitride, silicon dioxide, or silicon nitride.

3. The MEMS infrared light source based on a heat-insulating vacuum cavity according to claim 1, characterized in that, The resistive layer is made of platinum.

4. A MEMS infrared light source based on a heat-insulating vacuum cavity according to claim 1, characterized in that, The insulating dielectric layer is silicon dioxide.

5. A MEMS infrared light source based on a heat-insulating vacuum cavity according to claim 1, characterized in that, The electrode layer is made of gold.

6. A MEMS infrared light source based on a heat-insulating vacuum cavity according to claim 1, characterized in that, The antireflective membrane is made of magnesium fluoride, silicon dioxide, or titanium dioxide.

7. A method for fabricating a MEMS infrared light source based on a thermally insulated vacuum cavity as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. A mask layer is grown on a silicon wafer using thin film growth technology; S2. Deposit a resistor layer on the mask layer and form a resistor structure through a metal stripping process. The central region of the resistor structure is spiral-shaped and serves as a heating region, while the side regions are rectangular and serve as pad regions. Connection resistors are reserved between the heating region and the pad regions. S3. Deposit an electrode layer on the pad area and form a rectangular electrode area through a metal stripping process; S4. An insulating dielectric layer is grown on the mask layer between the electrode region and the heating region using thin film growth technology; S5. An etching window is formed around the heating area of ​​the resistive layer by etching a mask layer. The silicon substrate is etched through the etching window to form a heat insulation groove, thus obtaining the infrared light source body. S6. Finally, the silicon cap with the antireflection coating is bonded to the insulating dielectric layer of the infrared light source body using a wafer bonding process, forming a vacuum cavity between the silicon cap and the infrared light source body.

8. The preparation method according to claim 7, characterized in that, In steps S1 and S4, the thin film growth technique is LPCVD; in steps S2 and S3, the resistive layer and electrode layer are deposited using electron beam evaporation or sputtering processes.

9. The preparation method according to claim 7, characterized in that, The silicon cap is prepared as follows: a layer of photoresist is spin-coated on a silicon wafer, and then an etched area is formed after photolithography exposure. Finally, the silicon cap is formed by ICP etching, and an antireflection film is deposited by PECVD.

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