MEMS infrared light source and manufacturing method thereof

Abstract

The present invention provides a MEMS infrared light source and a manufacturing method thereof. The MEMS infrared light source includes: a substrate, a support layer, an adjustable emission structure, a heating structure, and an electrode structure. The adjustable emission structure includes: a first metal layer, a dielectric layer, and a second metal layer. The first metal layer is attached below the dielectric layer, the second metal layer is attached above the dielectric layer, and the first metal layer is connected to the support layer. The heating structure is attached above the dielectric layer, with a gap between the heating structure and the second metal layer, and the heating structure is electrically connected to the electrode structure. The support layer is connected to the substrate and is used to fix the adjustable emission structure to the substrate. The present invention can improve the modulation characteristics of the MEMS infrared light source.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared light sources, and in particular to a MEMS infrared light source and a manufacturing method thereof. Background Art

[0002] With the development of the Internet of Things, real-time monitoring systems are becoming increasingly important. Gas sensors are increasingly widely used to measure inorganic gases like carbon dioxide and sulfur hexafluoride, as well as organic gases like methane and ethanol. They can be found in homes, industry, and even the military.

[0003] In infrared detection systems, the performance of the infrared light source largely determines the accuracy of gas detection. Current MEMS (Micro-Electro-Mechanical System) infrared light sources primarily utilize a layer of micro-nanostructures, primarily metamaterials, attached to the light source surface. However, traditional metamaterials require an additional dielectric layer to isolate the heating resistor, increasing the weight and volume of the suspended membrane structure and thus reducing the light source's modulation characteristics. Summary of the Invention

[0004] To solve the above problems, the MEMS infrared light source and its manufacturing method provided by the present invention eliminate the isolation layer by gap-fitting the heating structure and the second metal layer on the dielectric layer, thereby reducing the weight and volume of the MEMS infrared light source and improving the modulation characteristics of the light source.

[0005] In a first aspect, the present invention provides a MEMS infrared light source, comprising: a substrate, a support layer, an emission adjustment structure, a heating structure, and an electrode structure;

[0006] The emission adjustment structure includes: a first metal layer, a dielectric layer, and a second metal layer;

[0007] The first metal layer is attached to the bottom of the dielectric layer, the second metal layer is attached to the top of the dielectric layer, and the first metal layer is connected to the support layer;

[0008] The heating structure is attached to the dielectric layer, the heating structure is gap-matched with the second metal layer, and the heating structure is electrically connected to the electrode structure;

[0009] The support layer is connected to the substrate, and is used to fix the emission adjustment structure on the substrate.

[0010] Optionally, the first metal layer and the second metal layer are made of the same material;

[0011] The material of the first metal layer includes: gold, silver or copper;

[0012] The material of the dielectric layer includes: aluminum oxide or silicon dioxide;

[0013] The material of the second metal layer includes: gold, silver or copper;

[0014] The material of the electrode structure is carbon or polysilicon;

[0015] The material of the heating structure is carbon or polysilicon;

[0016] The material of the support layer is silicon nitride or silicon dioxide.

[0017] Optionally, the thickness of the first metal layer is 50-100 nm, the thickness of the dielectric layer is 80-200 nm, and the thickness of the second metal layer is 80-120 nm;

[0018] The thickness of the heating structure is 80-120 nm.

[0019] Optionally, the second metal layer includes: a plurality of emission subunits;

[0020] A plurality of emission subunits are arranged at intervals on the surface of the dielectric layer.

[0021] Optionally, the length of the emission subunit is 400-600 nm, and the width of the emission subunit is 50-100 nm;

[0022] The center distance between two adjacent emission subunits is 1900-2100nm;

[0023] The transmitting subunit has a cross structure.

[0024] Optionally, the heating structure includes: a plurality of resistance wires;

[0025] A plurality of resistance wires are connected in parallel, and the plurality of resistance wires are electrically connected to the electrode structure;

[0026] With respect to the direction in which the plurality of resistance wires are arranged in the dielectric layer, the width of the resistance wires close to the edge of the dielectric layer is greater than the width of the resistance wires close to the geometric center of the dielectric layer.

[0027] Optionally, the resistance wire is provided with a plurality of avoidance holes;

[0028] The transmitting subunit through which the resistance wire passes is located in the avoidance hole.

[0029] Optionally, the electrode structure includes: a first electrode and a second electrode;

[0030] The first electrode and the second electrode are respectively located on two opposite sides of the plurality of resistance wires;

[0031] One end of the resistance wire is electrically connected to the first electrode, and the other end of the resistance wire is electrically connected to the second electrode;

[0032] The resistance wire is in the shape of a snake.

[0033] Optionally, the support layer includes: a connecting portion and a supporting portion;

[0034] One end of the connecting portion is connected to the substrate, the other end of the connecting portion is connected to the supporting portion, and the emission adjustment structure is located on the supporting portion;

[0035] The connecting portion is used to make the supporting portion suspended relative to the substrate;

[0036] The length of the support portion is 1000-1500 μm, the width of the support portion is 1000-1500 μm, and the thickness of the support portion is 300-500 nm;

[0037] The width of the connecting portion is 80-120 μm, and the thickness of the connecting portion is 300-500 nm.

[0038] In a second aspect, the present invention provides a method for manufacturing a MEMS infrared light source, for manufacturing the MEMS infrared light source as described in any one of the above items, the method comprising:

[0039] providing a substrate;

[0040] forming a support layer on a surface of the substrate;

[0041] forming a first metal layer, a dielectric layer, and a second metal layer in sequence on the surface of the support layer;

[0042] A heating structure and an electrode structure are formed on a surface of the dielectric layer facing away from the first metal layer.

[0043] The MEMS infrared light source and its manufacturing method provided in the embodiment of the present invention, by arranging the heating structure on the side of the regulating emission structure away from the supporting layer, and making the heating structure and the second metal layer gap-fitted on the side of the dielectric layer away from the supporting layer, not only eliminates the isolation layer between the heating structure and the regulating emission structure, but also reduces the weight and volume of the MEMS infrared light source, thereby improving the modulation characteristics of the light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1-Figure 7 This is a schematic diagram illustrating the steps of manufacturing a MEMS infrared light source from a cross-sectional perspective according to one embodiment of the present application;

[0045] Figures 8 to 13 This is a schematic diagram illustrating the steps of manufacturing a MEMS infrared light source from a top view according to an embodiment of the present application.

[0046] Reference numerals

[0047] 1. Substrate; 11. Suspended cavity; 2. Support layer; 21. Connecting part; 22. Support part; 3. Adjustable emission structure; 31. First metal layer; 32. Dielectric layer; 33. Second metal layer; 331. Emission subunit; 4. Heating structure; 41. Avoidance hole; 5. Electrode structure. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only 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 making creative efforts shall fall within the scope of protection of the present invention.

[0049] It should be noted that, in the present invention, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0050] In the first aspect, this embodiment provides a MEMS infrared light source, see Figure 7 and Figure 13 The MEMS infrared light source includes: a substrate 1, a support layer 2, an emission adjustment structure 3, a heating structure 4 and an electrode structure 5.

[0051] The surface of the substrate 1 is provided with a suspended cavity 11; the support layer 2 is used to suspend the emission adjustment structure 3 and the heating structure 4 on the substrate 1. The suspended cavity 11 can be a through-hole structure extending through the upper and lower surfaces of the substrate 1, or a blind hole structure with only the top end open; the support layer 2 can be disposed below or above the upper surface of the substrate 1.

[0052] In this embodiment, the suspended cavity 11 is a through-hole structure penetrating the upper and lower surfaces of the substrate 1; Figure 8 , the support layer 2 is arranged above the upper surface of the substrate 1.

[0053] Specifically, the material of the support layer 2 is silicon nitride or silicon dioxide. The support layer 2 includes: a connecting portion 21 and a supporting portion 22. One end of the connecting portion 21 is connected to the substrate 1, and the other end of the connecting portion 21 is connected to the supporting portion 22. The adjustable emission structure 3 is located on the supporting portion 22. The connecting portion 21 is used to make the supporting portion 22 suspended relative to the substrate 1. The length of the supporting portion 22 is 1000-1500μm, the width of the supporting portion 22 is 1000-1500μm, and the thickness of the supporting portion 22 is 300-500nm; the width of the connecting portion 21 is 80-120μm, and the thickness of the connecting portion 21 is 300-500nm.

[0054] In this embodiment, the support portion 22 is a rectangular structure, and the support portion 22 is located directly above the suspended cavity 11; the number of the connecting portions 21 is four, and the four connecting portions 21 respectively fix the four corners of the support portion 22 to the substrate 1; the length and width of the support portion 22 are both 1200μm, and the thickness of the support portion 22 is 400nm; the width of the connecting portion 21 is 80-120μm, and the thickness of the connecting portion 21 is 400nm. This embodiment does not specifically limit the length of the connecting portion 21; the materials of the connecting portion 21 and the supporting portion 22 are both silicon nitride with high mechanical strength.

[0055] The emission adjustment structure 3 includes: a first metal layer 31, a dielectric layer 32, and a second metal layer 33. The material of the first metal layer 31 includes: gold, silver, or copper; the material of the dielectric layer 32 includes: aluminum oxide or silicon dioxide; the material of the second metal layer 33 includes: gold, silver, or copper. The thickness of the first metal layer 31 is 50-100nm, the thickness of the dielectric layer 32 is 80-200nm, and the thickness of the second metal layer 33 is 80-120nm; the thickness of the heating structure 4 is 80-120nm. In this embodiment, the materials of the first metal layer 31 and the second metal layer 33 are the same, and the materials of the first metal layer 31 and the second metal layer 33 are both gold; the material of the dielectric layer 32 is aluminum oxide.

[0056] The first metal layer 31 is attached to the upper surface of the support portion 22; the first metal layer 31 is attached to the lower surface of the dielectric layer 32; and the second metal layer 33 is attached to the upper surface of the dielectric layer 32. The heating structure 4 is attached to the upper surface of the dielectric layer 32. The heating structure 4 and the second metal layer 33 are loosely coupled. The heating structure 4 is electrically connected to the electrode structure 5. The electrode structure 5 is made of carbon or polysilicon; the heating structure 4 is made of carbon or polysilicon.

[0057] The lower surface of the second metal layer 33 and the lower surface of the heating structure 4 may be on the same horizontal plane or on different horizontal planes. In this embodiment, the lower surface of the second metal layer 33 and the lower surface of the heating structure 4 are on the same horizontal plane and flush with the heating structure 4. The electrode structure 5 is flush with the heating structure 4, and both the electrode structure 5 and the heating structure 4 are made of carbon.

[0058] Furthermore, the second metal layer 33 includes a plurality of emitting subunits 331. The emitting subunits 331 are arranged at equal intervals on the upper surface of the dielectric layer 32. Each emitting subunit 331 is 400-600 nm long and 50-100 nm wide, and the center-to-center distance between two adjacent emitting subunits 331 is 1900-2100 nm.

[0059] In this embodiment, each emitting subunit 331 is a cross structure, has a length of 500 nm, a width of 80 nm, and a center distance of 2000 nm between two adjacent emitting subunits 331 .

[0060] The heating structure 4 includes: a plurality of resistance wires. The plurality of resistance wires are connected in parallel; the plurality of resistance wires are electrically connected to the electrode structure 5. The plurality of resistance wires can be arranged in a concentric circle on the upper surface of the dielectric layer 32, or can be arranged along a fixed direction on the upper surface of the dielectric layer 32. In this embodiment, the resistance wires are serpentine-shaped; the plurality of resistance wires are arranged along the left-right direction on the upper surface of the dielectric layer 32. The width of the resistance wires near the edge of the dielectric layer 32 is greater than the width of the resistance wires near the geometric center of the dielectric layer 32. That is, the width gradually increases from one or two resistance wires located in the middle to the resistance wires on opposite sides.

[0061] For example, there are five resistance wires. The widths of the five groups of resistance wires, from left to right, are: 25-35μm, 20-30μm, 15-25μm, 20-30μm, and 25-35μm. By limiting the width of the resistance wires, the resistance wires closer to the substrate 1 can generate heat more efficiently, thereby compensating for the loss of heat directed to the substrate 1 through the connection portion 21. This allows the temperature at each position of the heating structure 4 to remain consistent, ensuring the uniformity of the light source.

[0062] The electrode structure 5 includes a first electrode and a second electrode. The first electrode and the second electrode are located on the front and rear sides of a plurality of resistance wires, respectively. One end of each resistance wire is electrically connected to the first electrode, and the other end of each resistance wire is electrically connected to the second electrode. The first and second electrodes are each led to the substrate 1 via corresponding connecting portions 21, so that the first and second electrodes are electrically connected to the power supply through the connection terminals within the substrate 1.

[0063] Furthermore, the resistance wire is provided with a plurality of avoidance holes 41. The emission subunit 331 through which the resistance wire passes is located within the avoidance holes 41. The radius of the avoidance holes 41 is 300-400 nm. In this embodiment, the radius of the avoidance holes 41 is 350 nm. By providing the avoidance holes 41, a clearance fit between the heating structure 4 and the second metal layer 33 can be achieved, thereby ensuring that the MEMS infrared light source has a stable light source resistance and stable emission power, thereby further ensuring the uniformity of the light source.

[0064] The MEMS infrared light source provided in this embodiment has a simple structure and is easy to process. Electrical response is achieved through the nanostructured resistance wire, while magnetic response is achieved through the shape of the resistance wire and the design of the metal-dielectric-metal adjustable emission structure 3. When these two responses are in the same frequency band, they cause electromagnetic waves in that frequency band to resonate, and the resonant electromagnetic waves are absorbed or emitted. Due to this resonant characteristic, the adjustable emission structure 3 can ensure a high emissivity. Using a cross structure on the top layer of the adjustable emission structure 3 significantly shortens the response frequency band, achieving the narrowband characteristics of the light source. Using a heating structure 4 overlying the adjustable emission structure 3 requires that the material of the heating structure 4 have very little obstruction to electromagnetic waves in the corresponding frequency band, and carbon precisely meets this characteristic. In particular, when each emission subunit 331 has a length of 545 nm and a width of 85 nm, the overall emissivity of the MEMS infrared light source in the 4 μm frequency band can reach as high as 99%. This allows the MEMS infrared light source to improve the emissivity of the light source and reduce the bandwidth of the emission spectrum while minimizing the impact of increased volume and mass on the light source's modulation characteristics.

[0065] In the second aspect, this embodiment provides a method for manufacturing a MEMS infrared light source, which is used to manufacture the MEMS infrared light source as described above. Figures 1 to 13 , among which, in Figures 5 to 7 and Figures 11 to 13 The transmitting subunit 331 in the figure is in an amplified state. The relative size and number of the specific transmitting subunit 331 can be determined according to the actual situation. The figure only shows the position and arrangement of the transmitting subunit 331. Figures 6 and 7 and Figures 12 to 13The resistance wires in the figure are in an amplified state. The relative size and number of the specific resistance wires can be determined according to the actual situation. The figure only shows the position and arrangement of the resistance wires. The method includes steps S101 to S104:

[0066] Step S101: providing a substrate 1, wherein the substrate 1 is a silicon substrate 1.

[0067] Step S102 : forming a support layer 2 on a surface of the substrate 1 .

[0068] The step S102 includes: using LPCVD (Low Pressure Chemical Vapor Deposition) process to deposit a layer of low-stress silicon nitride or silicon dioxide with a thickness of 300-500nm on the substrate 1, and using a dry etching process to pattern the support layer 2; using a dry etching process to etch away the silicon nitride or silicon dioxide on the back of the substrate 1.

[0069] Step S103 : forming a first metal layer 31 , a dielectric layer 32 and a second metal layer 33 in sequence on the surface of the support layer 2 .

[0070] The step S103 includes: sputtering a layer of gold, silver or copper with a thickness of 50-100 nm on the supporting film layer; patterning the first metal layer 31 using a lift-off process; magnetron sputtering a layer of aluminum oxide with a thickness of 80-200 nm on the first metal layer 31 or depositing a layer of silicon dioxide with a thickness of 80-200 nm using PECVD; patterning the dielectric layer 32 using an etching process; sputtering a layer of metal with a thickness of 50-100 nm that is the same as the material of the first metal layer 31 on the dielectric layer 32; and patterning a cross structure with a length of 400-600 nm and a width of 50-100 nm using a lift-off process, i.e., the second metal layer 33.

[0071] Step S104 : forming a heating structure 4 and an electrode structure 5 in the dielectric layer 32 on a surface facing away from the first metal layer 31 .

[0072] The step S104 includes: spraying a layer of carbon with a thickness of 80-200 nm on the dielectric layer 32; and patterning the heating structure 4 and the electrode structure 5 extending to the substrate 1 by lift-off.

[0073] After step S104, the method further includes: etching from the back side of substrate 1 using dry etching or wet etching until the silicon nitride layer, i.e., support layer 2, is etched, thereby forming a suspended cavity in substrate 1. In this way, support layer 2 and emission adjustment structure 3 and heating structure 4 on support layer 2 form a suspended membrane structure.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A MEMS infrared light source, characterized in that: include: Substrate, support layer, emission adjustment structure, heating structure and electrode structure; The emission adjustment structure includes: a first metal layer, a dielectric layer, and a second metal layer; The first metal layer is attached to the bottom of the dielectric layer, the second metal layer is attached to the top of the dielectric layer, and the first metal layer is connected to the support layer; The heating structure is attached to the dielectric layer, the heating structure is gap-matched with the second metal layer, and the heating structure is electrically connected to the electrode structure; The support layer is connected to the substrate, and is used to fix the emission adjustment structure on the substrate.

2. The MEMS infrared light source according to claim 1, characterized in that: The first metal layer and the second metal layer are made of the same material; The material of the first metal layer includes: gold, silver or copper; The material of the dielectric layer includes: aluminum oxide or silicon dioxide; The material of the second metal layer includes: gold, silver or copper; The material of the electrode structure is carbon or polysilicon; The material of the heating structure is carbon or polysilicon; The material of the support layer is silicon nitride or silicon dioxide.

3. The MEMS infrared light source according to claim 1, characterized in that: The thickness of the first metal layer is 50-100 nm, the thickness of the dielectric layer is 80-200 nm, and the thickness of the second metal layer is 80-120 nm; The thickness of the heating structure is 80-120 nm.

4. The MEMS infrared light source according to claim 1, characterized in that: The second metal layer includes: a plurality of emission subunits; A plurality of emission subunits are arranged at intervals on the surface of the dielectric layer.

5. The MEMS infrared light source according to claim 4, characterized in that: The length of the emission subunit is 400-600 nm, and the width of the emission subunit is 50-100 nm; The center distance between two adjacent emission subunits is 1900-2100nm; The transmitting subunit has a cross structure.

6. The MEMS infrared light source according to claim 4, characterized in that: The heating structure includes: a plurality of resistance wires; A plurality of resistance wires are connected in parallel, and the plurality of resistance wires are electrically connected to the electrode structure; With respect to the direction in which the plurality of resistance wires are arranged in the dielectric layer, the width of the resistance wires close to the edge of the dielectric layer is greater than the width of the resistance wires close to the geometric center of the dielectric layer.

7. The MEMS infrared light source according to claim 6, characterized in that: The resistance wire is provided with a plurality of avoidance holes; The transmitting subunit through which the resistance wire passes is located in the avoidance hole.

8. The MEMS infrared light source according to claim 6, characterized in that: The electrode structure includes: a first electrode and a second electrode; The first electrode and the second electrode are respectively located on two opposite sides of the plurality of resistance wires; One end of the resistance wire is electrically connected to the first electrode, and the other end of the resistance wire is electrically connected to the second electrode; The resistance wire is in the shape of a snake.

9. The MEMS infrared light source according to claim 1, characterized in that: The support layer includes: a connecting portion and a supporting portion; One end of the connecting portion is connected to the substrate, the other end of the connecting portion is connected to the supporting portion, and the emission adjustment structure is located on the supporting portion; The connecting portion is used to make the supporting portion suspended relative to the substrate; The length of the support portion is 1000-1500 μm, the width of the support portion is 1000-1500 μm, and the thickness of the support portion is 300-500 nm; The width of the connecting portion is 80-120 μm, and the thickness of the connecting portion is 300-500 nm.

10. A method for manufacturing a MEMS infrared light source, characterized in that: For manufacturing the MEMS infrared light source according to any one of claims 1 to 9, the method comprises: providing a substrate; forming a support layer on a surface of the substrate; forming a first metal layer, a dielectric layer, and a second metal layer in sequence on the surface of the support layer; A heating structure and an electrode structure are formed on a surface of the dielectric layer facing away from the first metal layer.

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