A MEMS pressure sensor and a method of manufacturing the same
By employing thermopile and lens structures in a MEMS pressure sensor, the parasitic problem of traditional MEMS pressure sensors is solved, achieving high-precision air pressure and three-dimensional mechanical detection, with fast response and miniaturization characteristics.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUXI WEIGAN SEMICON CO LTD
- Filing Date
- 2022-09-19
- Publication Date
- 2026-07-21
AI Technical Summary
Traditional MEMS pressure sensors suffer from parasitic problems, which affect measurement sensitivity.
It adopts a thermopile structure and lens structure to replace the traditional piezoresistive and capacitive MEMS pressure sensors, and integrates a transparent layer, a reflective layer and a lens structure to use infrared light for measurement.
It improves measurement sensitivity, achieves high-precision air pressure and three-dimensional mechanical detection, has a fast response time, a simple and easy-to-implement structure, is suitable for wafer-level packaging, and enables the sensor to be miniaturized and highly reliable.
Smart Images
Figure CN115420408B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, and in particular to a MEMS pressure sensor and its fabrication method. Background Technology
[0002] MEMS devices are microelectromechanical devices fabricated using microfabrication processes, developed based on microelectronics technology. They are widely used as sensors and actuators. For example, MEMS devices can be pressure sensors, accelerometers, gyroscopes, and silicon capacitor microphones.
[0003] Traditional MEMS pressure sensors are typically piezoresistive MEMS pressure sensors and capacitive MEMS pressure sensors. Piezoresistive MEMS pressure sensors and capacitive MEMS pressure sensors often suffer from parasitic problems during the measurement process, which affect the measurement sensitivity. Summary of the Invention
[0004] In view of the above problems, the purpose of this invention is to provide a MEMS pressure sensor and its fabrication method, which adopts a thermopile structure and a lens structure to replace the traditional piezoresistive MEMS pressure sensor and capacitive MEMS pressure sensor, thereby reducing parasitics and improving sensitivity.
[0005] The first aspect of the present invention provides a MEMS pressure sensor, comprising: Substrate; A thermopile structure is located on the substrate; A bonding layer is located on the substrate and surrounds the thermopile structure; A transparent layer is located on the surface of the bonding layer away from the substrate. A groove is formed on the surface of the transparent layer near the substrate, and a lens structure is formed within the groove. A reflective layer is located on the surface of the transparent layer away from the bonding layer, and the reflective layer has a through-hole penetrating the reflective layer; The position of the through hole corresponds to the position of the convex lens. The through hole is used to receive infrared light, so that the infrared light irradiates the transparent layer and then irradiates the thermopile structure through the lens structure.
[0006] In some embodiments, the substrate has a back cavity that extends through the substrate.
[0007] In some embodiments, a dielectric layer is included, the dielectric layer being located on the substrate, and the thermopile structure is embedded within the dielectric layer.
[0008] In some embodiments, the dielectric layer includes a first dielectric layer and a second dielectric layer stacked together, wherein the first dielectric layer is located on a first surface of the substrate and the second dielectric layer is located on the surface of the first dielectric layer.
[0009] In some embodiments, a contact metal is included, which extends from a second surface of the substrate toward the second dielectric layer, penetrates the substrate and the first dielectric layer, and terminates inside the second dielectric layer.
[0010] In some embodiments, the thermopile structure includes multiple thermocouples and multiple metal connecting wires, which connect multiple separate thermocouples end to end in sequence, so that the multiple thermocouples are connected in series to form a thermopile structure.
[0011] In some embodiments, the two ends of the thermocouples connected in series are connected to the corresponding contact metals via the metal connecting wires.
[0012] In some embodiments, a pad is included, the pad being located on a second surface of the substrate, the pad being electrically connected to a corresponding contact metal.
[0013] In some embodiments, the first dielectric layer is a silicon oxide layer, and the second dielectric layer is a silicon nitride layer.
[0014] In some embodiments, the bonding layer is hollow, and the inner surface of the bonding layer, the inner surface of the groove of the transparent layer, and the surface of the dielectric layer define a sealed cavity, and the lens structure is located within the cavity.
[0015] A second aspect of the present invention provides a method for fabricating a MEMS pressure sensor, comprising: A thermopile structure is formed on the substrate; A first bonding layer is formed on the surface of the substrate; A reflective layer with through holes is formed on the second surface of the transparent layer; A second bonding layer is formed on the first surface of the transparent layer; A groove is formed on the first surface of the transparent layer, and a lens structure is located within the groove; The first bonding layer and the second bonding layer are bonded together to form the bonding layer; The position of the through hole corresponds to the position of the convex lens. The through hole is used to receive infrared light, so that the infrared light irradiates the transparent layer and then irradiates the thermopile structure through the lens structure.
[0016] In some embodiments, prior to forming the thermopile structure, a dielectric layer is formed on a first surface of the substrate, and the thermopile structure is embedded within the dielectric layer.
[0017] In some embodiments, the method of forming the dielectric layer includes: A first dielectric layer is formed on the substrate; and A first dielectric layer and a second dielectric layer are formed on the first dielectric layer.
[0018] In some embodiments, this includes forming a contact metal after forming the first and second dielectric layers.
[0019] In some embodiments, the step of forming the contact metal includes: A first contact hole is formed penetrating the substrate, the first dielectric layer, and the first and second dielectric layers; and The first contact hole is filled with metal material to form a contact metal.
[0020] In some embodiments, a method for forming the thermopile structure includes: Multiple thermocouples are formed on the surfaces of the first and second dielectric layers; A second dielectric layer with a second contact hole is formed; Forming a plurality of metal interconnects, each metal interconnect located on the surface of the second dielectric layer and filling a corresponding second contact hole; and A third second dielectric layer is formed, which covers the metal interconnect. The metal connecting wires connect multiple separate thermocouples end to end in sequence, so that the multiple thermocouples are connected in series to form a thermopile structure.
[0021] In some embodiments, the two ends of the thermocouples connected in series are connected to the corresponding contact metals via the metal connecting wires.
[0022] In some embodiments, while forming the first bonding layer, a pad is formed on the second surface of the substrate, the pad being electrically connected to a corresponding contact metal.
[0023] In some embodiments, the first dielectric layer is a silicon oxide layer, and the first second dielectric layer, the second second dielectric layer, and the third second dielectric layer are silicon nitride layers.
[0024] In some embodiments, the bonding layer is hollow, and the inner surface of the bonding layer, the inner surface of the groove of the transparent layer, and the surface of the dielectric layer define a sealed cavity, and the lens structure is located within the cavity.
[0025] The MEMS pressure sensor provided by this invention integrates core components: a transparent layer, a reflective layer, a lens structure, and an infrared thermopile structure. It can be applied to traditional air pressure detection or more complex three-dimensional mechanical detection, and has high measurement accuracy and fast response time.
[0026] Furthermore, the core components of this embodiment of the invention only include a transparent layer, a reflective layer, a lens structure, and an infrared thermopile structure, which are simple in structure, easy to implement, and adopt wafer-level packaging, which can realize the miniaturization of the sensor size.
[0027] Furthermore, in this embodiment of the invention, the core components of the MEMS pressure sensor, the lens structure and the infrared thermopile structure, are integrated into a sealed cavity, which is not prone to air leakage and has high reliability.
[0028] Furthermore, in this embodiment of the invention, the MEMS pressure sensor is formed by growing silicon oxide, polycrystalline silicon, silicon nitride, and metal processes. Its fabrication process is compatible with integrated circuit processes, providing a feasible basis for realizing monolithic integration of MEMS pressure sensors and processing circuits, while reducing the complexity of the process and lowering costs. Attached Figure Description
[0029] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which: Figure 1 A cross-sectional view of a MEMS pressure sensor according to an embodiment of the present invention is shown; Figure 2 This diagram shows a top view of the MEMS pressure sensor according to an embodiment of the present invention, excluding the reflective layer and the transparent layer. Figures 3a to 16a Cross-sectional views of various stages in the fabrication process of the MEMS pressure sensor according to an embodiment of the present invention are shown. Figures 3b to 16b A top view is shown of each stage in the fabrication process of the MEMS pressure sensor according to an embodiment of the present invention. Detailed Implementation
[0030] The invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. Furthermore, some well-known parts may not be shown.
[0031] This invention can be presented in various forms, some of which will be described below.
[0032] Figure 1 A cross-sectional view of a MEMS pressure sensor according to an embodiment of the present invention is shown. Figure 2This diagram shows a top view of the MEMS pressure sensor according to an embodiment of the present invention, excluding the reflective and transparent layers. Figure 2 The portion shown by the dashed line is embedded inside the dielectric layer; as... Figure 1 and Figure 2 As shown, the MEMS pressure sensor 10 includes a substrate 110, a first dielectric layer 120, a second dielectric layer 140, multiple thermopile structures 150, a contact metal 130, a bonding layer 170, a reflective layer 180, a lens structure 191, and a transparent layer 190.
[0033] The first dielectric layer 120 is located on a first surface of the substrate 110, and the second dielectric layer 140 is located on the surface of the first dielectric layer 120 away from the substrate 110. The substrate 110 has a back cavity 101 that penetrates the substrate 110 and exposes the surface of the first dielectric layer 120. In this embodiment, the substrate 110 is, for example, an N-type single-crystal silicon substrate, and the crystal orientation of the N-type single-crystal silicon substrate is, for example, (100). The first dielectric layer 120 is, for example, a silicon oxide layer, and the second dielectric layer 140 is, for example, a silicon nitride layer.
[0034] Multiple thermopile structures 150 are embedded within the second dielectric layer 140. Each thermopile structure 150 includes multiple thermocouples 151 and multiple metal connecting wires 152. The metal connecting wires 152 connect multiple separate thermocouples 151 end-to-end in sequence, so that the multiple thermocouples are connected in series to form a thermopile structure 150. The thermocouples 151 are made of, for example, polycrystalline silicon, and the metal connecting wires 152 are made of, for example, aluminum.
[0035] In one specific embodiment, the substrate 110, the first dielectric layer 120 and the second dielectric layer 140 are all rectangular, and the MEMS pressure sensor 10 includes four sets of thermopile structures 150, each set of thermopile structures 150 being located on one side of the second dielectric layer 140.
[0036] The contact metal 130 extends from the second surface of the substrate 110 (where the first and second surfaces of the substrate 110 are opposite each other) toward the second dielectric layer 140, penetrates the substrate 110 and the first dielectric layer 120, and terminates inside the second dielectric layer 140. The contact metal 130 is used to achieve conductive connection between the thermopile structure 150 and the outside world. The two ends of the thermocouple 151 of each set of thermopile structures 150 are connected to the contact metal 130 via metal connecting wires 152, thus electrically connecting to the outside world via the contact metal 130. Further, the contact metal 130 exposed on the second surface of the substrate 110 is respectively connected to pads 130a.
[0037] The bonding layer 170 is located on the surface of the second dielectric layer 140, and the transparent layer 190 is located on the surface of the bonding layer 170 away from the second dielectric layer 140. The first surface of the transparent layer 190 has a groove extending from the first surface of the transparent layer 190 away from the bonding layer 170, and a lens structure 191 is located in the central region of the groove. The bonding layer 170 is hollow, and the inner surface of the bonding layer 170 and the inner surface of the groove of the transparent layer 190 define a cavity 102, within which the lens structure 191 is located. In this embodiment, the lens structure 191 is, for example, a convex lens structure.
[0038] The reflective layer 180 is located on the second surface of the transparent layer 190. The reflective layer 180 has a through-hole 181 located in the central region of the transparent layer 190, corresponding to the position of the lens structure 191. The through-hole 181 penetrates the reflective layer 180, exposing the second surface of the transparent layer 190. In this embodiment, the bonding layer 170 and the reflective layer 180 are made of the same material, for example, both are gold layers. The transparent layer 190 is, for example, a glass layer. The transparent layer 190 is used to sense external pressure.
[0039] The MEMS pressure sensor of this embodiment integrates core components: a transparent layer 190, a lens structure 191, a reflective layer 180, and an infrared thermopile structure 150. It can be applied to traditional air pressure detection or more complex three-dimensional mechanical detection. Specifically, infrared light emitted from an infrared light source 20 located outside the MEMS pressure sensor illuminates a portion of the reflective layer 180, is reflected out of the MEMS pressure sensor by the reflective layer 180, illuminates a portion of the through-hole 181, and then illuminates the transparent layer 190 through the through-hole 181. Further illumination occurs through the transparent layer 190... The infrared light is irradiated onto the lens structure 191 and refracted through the lens structure 191 to the thermopile structure 150. When the transparent layer 190 is deformed by an external force, the lens structure 191 deforms along with the transparent layer 190, and the optical path of the infrared light received by the thermopile structure 150 changes. Therefore, by measuring the output voltage of the infrared thermopile structure 150, air pressure or three-dimensional vector mechanical parameters can be sensed. Compared with traditional piezoresistive pressure sensors or capacitive pressure sensors, the pressure sensor of this application has higher measurement accuracy and faster response time.
[0040] Furthermore, the core components of this embodiment of the invention only include a transparent layer, a reflective layer, a lens structure, and an infrared thermopile structure, which are simple in structure, easy to implement, and adopt wafer-level packaging, which can realize the miniaturization of the sensor size.
[0041] Furthermore, in this embodiment of the invention, the core components of the MEMS pressure sensor, the lens structure 191 and the infrared thermopile structure, are integrated into a sealed cavity, which is not prone to air leakage and has high reliability.
[0042] Furthermore, in this embodiment of the invention, the fabrication process of the MEMS pressure sensor is compatible with the integrated circuit process, providing a feasible basis for realizing the monolithic integration of the MEMS pressure sensor and the processing circuit, while reducing the complexity of the process and lowering the cost.
[0043] Figures 3a to 16a Cross-sectional views of various stages in the fabrication process of the MEMS pressure sensor according to an embodiment of the present invention are shown. Figures 3b to 16b The diagram shows a top view of each stage in the fabrication process of the MEMS pressure sensor according to an embodiment of the present invention, wherein... Figures 3a to 15a for Figures 3b to 15b Cross-sectional view along the AA direction. The following will combine... Figures 3a to 15a as well as Figures 3b to 15b The fabrication process of the MEMS pressure sensor according to an embodiment of the present invention will be described.
[0044] like Figure 3a and Figure 3b As shown, a substrate 110 is provided, and a first dielectric layer 120 and a first second dielectric layer 141 are sequentially formed on a first surface of the substrate 110.
[0045] In this embodiment, the substrate 110 is, for example, an N-type single-crystal silicon substrate, and the crystal orientation of the N-type single-crystal silicon substrate is, for example, (100). The first dielectric layer 120 is, for example, a silicon oxide layer, and the first and second dielectric layers 141 are, for example, silicon nitride layers.
[0046] like Figure 4a and Figure 4b As shown, the first layer, the second dielectric layer 141, the first dielectric layer 120, and the substrate 110 are etched to form a first contact hole 110a in the first layer, the second dielectric layer 141, the first dielectric layer 120, and the substrate 110.
[0047] In this step, for example, a photoresist layer is formed on the surface of the first second dielectric layer 141, the photoresist layer is patterned using a photolithography process to form a photoresist mask, and the first second dielectric layer 141, the first dielectric layer 120, and the substrate 110 are etched through the photoresist mask to form the first contact hole 110a. The first contact hole 110a penetrates the first second dielectric layer 141, the first dielectric layer 120, and the substrate 110.
[0048] like Figure 5a and Figure 5b As shown, conductive material is filled into the first contact hole 110a to form contact metal 130.
[0049] In this step, for example, a deposition process is used to fill the interior of the first contact hole 110a with conductive material, and a polishing process is used to polish the conductive material outside the first contact hole 110a, so that the conductive material only fills the interior of the first contact hole 110a, thereby forming the contact metal 130. The contact metal 130 is exposed on the second surface of the substrate 110 (the first surface and the second surface of the substrate 110 are opposite each other) and the surface of the first layer and the second dielectric layer 141.
[0050] like Figure 6a and Figure 6b As shown, a thermocouple 151 is formed on the surface of the first layer and the second dielectric layer 141.
[0051] In this step, for example, a polysilicon layer is formed on the surface of the first second dielectric layer 141 and the surface of the contact metal 131 using a deposition process. Then, for example, a photolithography and etching process is used to pattern the polysilicon layer to form a thermocouple 151. This includes multiple thermocouples 151, which are separated from each other, and each thermocouple 151 does not contact the exposed contact metal 130 on the surface of the first second dielectric layer 141.
[0052] like Figure 7a and Figure 7b As shown, a second dielectric layer 142 with a second contact hole 142a is formed.
[0053] In this step, for example, a second dielectric layer 142 is formed on the surface of the first dielectric layer 141 using a deposition process. The second dielectric layer 142 covers the surface of the first dielectric layer 141, the surface of the contact metal 131, and the surface and sidewalls of the thermocouples 151. Next, for example, the second dielectric layer 142 is patterned using a photolithography process to form a second contact hole 142a. The second contact hole 142a penetrates the second dielectric layer 142, exposing the surface of the contact metal 130 and portions of the surfaces of the multiple thermocouples 151. The second contact hole 142a is located at the beginning and end of each thermocouple. In this embodiment, the second dielectric layer 142 is, for example, a silicon nitride layer.
[0054] like Figure 8a and Figure 8b As shown, a metal connecting line 152 is formed.
[0055] In this step, for example, a conductive metal material is formed on the surface of the second dielectric layer 142 using a deposition process. The conductive metal material covers the surface of the second dielectric layer 142 and fills the second contact hole 142a. Then, for example, a photolithography process and an etching process are used to pattern the conductive metal layer to form a metal connection line 152. Each metal connection line 152 connects one end of a thermocouple 151 to one end of another thermocouple 151, so that the metal connection line 152 connects multiple separate thermocouples 151 in series, and connects the two ends of the series thermocouples 151 to the corresponding contact metal 130. The metal connection line 152 and the thermocouples 151 constitute a thermopile structure 150.
[0056] In this embodiment, four thermopile structures 150 are included. The substrate 110 is rectangular, and the four thermopile structures 150 are respectively arranged on the four sides of the substrate 110.
[0057] like Figure 9a and Figure 9b As shown, a third second dielectric layer 143 is formed.
[0058] In this step, a third second dielectric layer 143 is formed on the surface of the second second dielectric layer 142, and the third second dielectric layer 143 covers the surface of the second second dielectric layer 142 and the metal interconnect 152. The third second dielectric layer 143 is, for example, a silicon nitride layer. The first second dielectric layer 141, the second second dielectric layer 142, and the third second dielectric layer 143 constitute the second dielectric layer 140.
[0059] like Figure 10a and Figure 10b As shown, a first bonding layer 171 is formed on the surface of the third second dielectric layer 143 and a pad 130a is formed on the surface of the substrate 110 away from the dielectric layer 120.
[0060] In this step, for example, a deposition process is used to form a metal material layer on the surface of the third second dielectric layer 143 and on the surface of the substrate 110 away from the dielectric layer 120. Then, for example, photolithography and etching processes are used to pattern the metal material layer to form a first bonding layer 171 on the surface of the first dielectric layer 124, and to form a plurality of mutually separated pads 130a on the surface of the substrate 110 away from the dielectric layer 20. The first bonding layer 171 is located at the edge of the dielectric layer 140, surrounding the thermopile structure 150 and the infrared light source 160. The plurality of pads 130a correspondingly contact the contact metal 130 exposed on the surface of the substrate 110. In this embodiment, the material of the pads 130a and the first bonding layer 171 is, for example, gold.
[0061] like Figure 11a , Figure 11b , Figure 12a and Figure 12b As shown, a transparent layer 190 is provided, and a reflective layer 180 with through holes 181 is formed on the second surface of the transparent layer 190.
[0062] In this step, for example, a deposition process is used to form the reflective layer 180 on the second surface of the transparent layer 190. Then, photolithography and etching processes are used to form the via 181 in the reflective layer 180. The via 181 is located in the central region of the reflective layer 180 and penetrates the reflective layer 180, exposing the transparent layer 190. In this embodiment, the material of the transparent layer 190 is, for example, a glass layer, and the reflective layer 180 is, for example, a gold material layer.
[0063] like Figure 13a and Figure 13b As shown, a second bonding layer 172 is formed on the first surface of the transparent layer 190.
[0064] In this step, for example, a metal material layer is formed on the first surface of the transparent layer 190 using a sputtering process. Then, for example, the metal material layer is thickened using an electroplating process, and the metal material layer is etched using photolithography and etching processes to form the second bonding layer 172. The second bonding layer 172 is located at the edge of the first surface of the transparent layer 190, corresponding to the position of the first bonding layer 171.
[0065] like Figure 14a and Figure 14b As shown, the first surface of the transparent layer 190 is etched to form a groove on the first surface of the transparent layer 190, and a lens structure 191 is formed in the central region of the groove. The lens structure 191 corresponds to the position of the through hole 181.
[0066] like Figure 15a and Figure 15b As shown, the first bonding layer 171 and the second bonding layer 172 are bonded together. The first bonding layer 171 and the second bonding layer 172 together form a bonding layer 170. The inner surface of the bonding layer 170 and the inner surface of the groove in the transparent layer 190 define a sealed cavity 102, within which the lens structure 191 is located. In this embodiment, the lens structure 191 is, for example, a convex lens structure.
[0067] like Figure 16a and Figure 16b As shown, a dorsal cavity 101 is formed.
[0068] In this step, a resist layer is formed on the second surface of the substrate 110, the resist layer is patterned using photolithography to form a resist mask, and the substrate 110 is etched through the resist mask to form the back cavity 101, thereby releasing the thermopile structure 150. The back cavity 101 penetrates the substrate 110, exposing the surface of the first dielectric layer 120. The MEMS pressure sensor provided by this invention integrates core components: a transparent layer, a reflective layer, a lens structure, and an infrared thermopile structure. It can be applied to traditional air pressure detection or more complex three-dimensional mechanical detection, and has high measurement accuracy and fast response time.
[0069] Furthermore, the core components of this embodiment of the invention only include a transparent layer, a reflective layer, a lens structure, and an infrared thermopile structure, which are simple in structure, easy to implement, and adopt wafer-level packaging, which can realize the miniaturization of the sensor size.
[0070] Furthermore, in this embodiment of the invention, the core components of the MEMS pressure sensor, the lens structure and the infrared thermopile structure, are integrated into a sealed cavity, which is not prone to air leakage and has high reliability.
[0071] Furthermore, in this embodiment of the invention, the MEMS pressure sensor is formed by growing silicon oxide, polycrystalline silicon, silicon nitride, and metal processes. Its fabrication process is compatible with integrated circuit processes, providing a feasible basis for realizing monolithic integration of MEMS pressure sensors and processing circuits, while reducing the complexity of the process and lowering costs.
[0072] As described above, these embodiments of the present invention do not exhaustively cover all details, nor do they limit the invention to the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The invention is limited only by the claims and their full scope and equivalents.
Claims
1. A MEMS pressure sensor, comprising: Substrate; A dielectric layer is located on the substrate. The dielectric layer includes a first dielectric layer and a second dielectric layer stacked together. The first dielectric layer is located on a first surface of the substrate, and the second dielectric layer is located on the surface of the first dielectric layer. The first dielectric layer is a silicon oxide layer, and the second dielectric layer is a silicon nitride layer. A thermopile structure is embedded inside the dielectric layer; A bonding layer, located on the second dielectric layer, surrounds the thermopile structure; A transparent layer is located on the surface of the bonding layer away from the substrate. A groove is formed on the surface of the transparent layer near the substrate, and a lens structure is formed within the groove. A reflective layer is located on the surface of the transparent layer away from the bonding layer, and the reflective layer has a through-hole penetrating the reflective layer; The position of the through hole corresponds to the position of the lens structure. The through hole is used to receive infrared light, so that the infrared light irradiates the transparent layer and then irradiates the thermopile structure through the lens structure. The bonding layer is hollow inside, and the inner surface of the bonding layer, the inner surface of the groove of the transparent layer, and the surface of the second dielectric layer define a sealed cavity, and the lens structure is located inside the cavity.
2. The MEMS pressure sensor according to claim 1, wherein, The substrate has a back cavity that extends through the substrate.
3. The MEMS pressure sensor according to claim 1, wherein, It includes a contact metal that extends from the second surface of the substrate toward the second dielectric layer, penetrates the substrate and the first dielectric layer, and terminates inside the second dielectric layer.
4. The MEMS pressure sensor according to claim 3, wherein, The thermopile structure includes multiple thermocouples and multiple metal connecting wires. The metal connecting wires connect multiple separate thermocouples end to end in sequence, so that the multiple thermocouples are connected in series to form a thermopile structure.
5. The MEMS pressure sensor according to claim 4, wherein, The two ends of the series thermocouples are connected to the corresponding contact metals via the metal connecting wires.
6. The MEMS pressure sensor according to claim 3, wherein, Includes pads located on a second surface of the substrate, the pads being electrically connected to corresponding contact metals.
7. A method for fabricating a MEMS pressure sensor, comprising: A second dielectric layer is formed on the substrate; A thermopile structure is formed inside the second dielectric layer, and the thermopile is embedded in the second dielectric layer; A first bonding layer is formed on the surface of the second dielectric layer; A reflective layer with through holes is formed on the second surface of the transparent layer; A second bonding layer is formed on the first surface of the transparent layer; A groove is formed on the first surface of the transparent layer, and a lens structure is located within the groove; The first bonding layer and the second bonding layer are bonded together to form the bonding layer. The bonding layer is hollow inside. The inner surface of the bonding layer, the inner surface of the groove of the transparent layer, and the surface of the second dielectric layer define a sealed cavity. The lens structure is located inside the cavity. The position of the through hole corresponds to the position of the lens structure. The through hole is used to receive infrared light, so that the infrared light irradiates the transparent layer and then irradiates the thermopile structure through the lens structure.
8. The method according to claim 7, wherein, The process includes forming a first dielectric layer on the substrate prior to forming the second dielectric layer, wherein the second dielectric layer is located on the first dielectric layer.
9. The method according to claim 8, wherein, include: A first and a second dielectric layer are formed, and then a contact metal is formed.
10. The method according to claim 9, wherein, The steps for forming the contact metal include: A first contact hole is formed penetrating the substrate, the first dielectric layer, and the first and second dielectric layers; and The first contact hole is filled with metal material to form a contact metal.
11. The method according to claim 10, wherein, The method of forming the thermopile structure includes: Multiple thermocouples are formed on the surfaces of the first and second dielectric layers; A second dielectric layer with a second contact hole is formed; Forming a plurality of metal interconnects, each metal interconnect located on the surface of the second dielectric layer and filling a corresponding second contact hole; and A third second dielectric layer is formed, which covers the metal interconnect. The metal connecting wires connect multiple separate thermocouples end to end in sequence, so that the multiple thermocouples are connected in series to form a thermopile structure.
12. The method according to claim 11, wherein, The two ends of the series thermocouples are connected to the corresponding contact metals via the metal connecting wires.
13. The method according to claim 7, wherein, While forming the first bonding layer, a pad is formed on the second surface of the substrate, and the pad is electrically connected to a corresponding contact metal.
14. The method according to claim 11, wherein, The first dielectric layer is a silicon oxide layer, and the first second dielectric layer, the second second dielectric layer, and the third second dielectric layer are silicon nitride layers.