High-sensitivity silicon-based piezoresistive pressure sensor and manufacturing method thereof

Abstract

The invention relates to the technical field of pressure sensor manufacturing, in particular to a high-sensitivity silicon-based piezoresistive pressure sensor and a manufacturing method thereof.The manufacturing method includes the steps that firstly, a double-polished-wafer silicon wafer serves as a substrate, and an insulating dielectric layer grows on the top face of the substrate; depositing a polycrystalline silicon thin film on the insulating dielectric layer to form a polycrystalline silicon film layer; performing secondary oxidation on the polycrystalline silicon film layer to form a secondary oxide layer with a preset thickness; performing ion implantation on the polycrystalline silicon film layer under a vacuum condition to form a piezoresistive sensitive device layer; etching the secondary oxide layer and the polycrystalline silicon film layer to form a sensitive device; carrying out annealing and re-diffusion treatment on the sensitive device; depositing a second insulating dielectric layer on the surface of the sensitive device after annealing and re-expanding; etching the second insulating dielectric layer to form a device connecting wire; through photoetching, metal deposition and etching processes, a bonding pad and a metal wire structure are formed in preset areas on the top and the outer side of a device connecting wire, and the problem that the insulation performance of a silicon-based piezoresistive pressure sensor is poor is solved.

Description

Technical Field

[0001] The present application relates to the technical field of pressure sensor manufacturing, and in particular to a high-sensitivity silicon-based piezoresistive pressure sensor and a manufacturing method thereof. Background Art

[0002] Silicon-based pressure sensors play a key role in automotive airbag status monitoring, online tire pressure systems, wearable device physiological parameter detection, medical device blood pressure monitoring, and aerospace atmospheric data acquisition. These applications require sensors with high insulation performance to ensure signal stability while also keeping manufacturing costs low to accommodate large-scale production.

[0003] To improve the insulation performance of the device, some solutions use single-crystal silicon substrates to directly make varistors, but this structure makes it difficult to form an insulating isolation layer at the bottom of the sensitive device; other solutions use silicon-on-insulator (SOI) substrate materials and achieve bottom insulation by preparing a single-crystal silicon device layer on the surface of the buried oxide layer.

[0004] The former approach lacks a bottom insulating protective layer, limiting the device's electrical stability; the latter relies on expensive SOI substrate materials, significantly increasing manufacturing costs. Therefore, a cost-effective sensor fabrication method that achieves high insulation performance on a silicon substrate is urgently needed. Summary of the Invention

[0005] The present application provides a highly sensitive silicon-based piezoresistive pressure sensor and a manufacturing method thereof, in order to solve the problem of weak insulation performance of silicon-based piezoresistive pressure sensors.

[0006] A first aspect of the present application provides a method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor, the method comprising: Using the cleaned double-polished silicon wafer as a substrate, and growing an insulating dielectric layer on the top surface of the substrate; depositing a polysilicon thin film on the insulating dielectric layer to form a polysilicon film layer; Performing secondary oxidation on the polysilicon film layer to form a secondary oxidation layer of a preset thickness; Performing ion implantation on the polysilicon film layer under vacuum conditions to form a piezoresistive sensitive device layer; Etching the secondary oxide layer and the polysilicon film layer by photolithography and etching processes to form a sensitive device; Performing annealing and re-diffusion processing on the sensitive device to obtain an annealed and re-diffused sensitive device; Depositing a second insulating dielectric layer on the surface of the sensitive device after annealing and then expansion to serve as a top and side protection layer of the sensitive device; Etching the second insulating dielectric layer by photolithography and etching processes to form device connecting wires; Through photolithography, metal deposition and etching processes, pads and metal wire structures are formed on the top and outside of the device connecting wires.

[0007] The manufacturing method adopts polycrystalline silicon as a sensitive device and utilizes its good piezoresistive sensitivity to improve the response sensitivity of the sensor; polycrystalline silicon can be easily grown on the surfaces of different substrates through thin film deposition, which facilitates the formation of an insulating isolation dielectric layer at the bottom of the sensitive device, similar to the SOI substrate structure, thereby improving the overall insulation performance of the device; by pre-preparing an insulating dielectric layer at the bottom of the device and depositing a second insulating dielectric layer on the upper surface and side of the sensitive device, the overall insulation and anti-interference properties of the sensor are enhanced, thereby solving the problem of weak insulation performance of silicon-based piezoresistive pressure sensors.

[0008] Optionally, after forming the pad and the metal wire structure, the method further includes: Performing alloy treatment on the pad and the metal wire structure to stabilize the pad and the metal wire structure; Etching the bottom of the double-polished silicon wafer by photolithography and etching processes to form a silicon cup structure; The etched double-polished silicon wafer is packaged by sealing or bonding.

[0009] By alloying the pads and metal wire structures, their structural stability can be improved; by etching the bottom of the double-polished silicon wafer to form a silicon cup structure, it helps to optimize the mechanical properties of the sensor; finally, the packaging is completed by sealing or bonding, which can enhance the overall reliability of the sensor and improve its environmental adaptability.

[0010] Optionally, the step of growing an insulating dielectric layer on the top surface of the substrate includes: When a sacrificial oxide layer is grown, a thickness of 0.05 μm to 15 μm is grown at atmospheric pressure at a temperature range of 800°C to 1150°C with a dry oxygen flow rate of 1000 sccm to 3000 sccm, a wet oxygen flow rate of 1500 sccm to 2500 sccm, and a hydrogen flow rate of 2000 sccm to 4000 sccm. When thin film deposition is selected to grow the insulating dielectric layer, the insulating dielectric layer is grown using any one or a combination of the following methods: If a silicon nitride film layer is used as an insulating dielectric layer, a silicon nitride film layer with a thickness of 80 nanometers to 150 nanometers is formed by chemical vapor deposition or plasma chemical vapor deposition under the conditions of a silicon dichloride flow rate of 10 sccm to 50 sccm, an ammonia flow rate of 30 sccm to 80 sccm, and a reaction temperature of 400 degrees Celsius to 800 degrees Celsius; If a silicon oxide film layer is used as an insulating dielectric layer, a silicon oxide film layer with a thickness of 80 nanometers to 150 nanometers is formed by chemical vapor deposition or plasma chemical vapor deposition under the conditions of tetraethoxysilane vaporization with a flow rate of 20 sccm to 100 sccm, an oxygen flow rate of 20 sccm to 100 sccm, and a reaction temperature of 400 degrees Celsius to 1000 degrees Celsius.

[0011] By optimizing the growth process parameters of the insulating dielectric layer, the uniformity and density of the insulating dielectric layer can be improved, thereby enhancing the insulation performance of the sensor. At the same time, by selecting a sacrificial oxide layer or thin film deposition method according to different needs, the thickness and material properties of the dielectric layer can be flexibly controlled, which helps to improve the stability and process adaptability of the sensor.

[0012] Optionally, the step of depositing a polysilicon thin film on the insulating dielectric layer includes: A polysilicon film with a thickness of 100 nanometers to 5000 nanometers is deposited by chemical vapor deposition at a reaction temperature of 500 degrees Celsius to 800 degrees Celsius and a silane flow rate of 20 sccm to 800 sccm.

[0013] By controlling the reaction temperature and silane flow rate of chemical vapor deposition, the deposition quality of the polysilicon film can be optimized to give it an appropriate thickness and uniformity, thereby helping to improve the electrical properties and structural stability of the piezoresistive sensitive layer, laying the foundation for the subsequent formation of a highly sensitive piezoresistive sensitive device layer.

[0014] Optionally, the step of performing secondary oxidation on the polysilicon film layer includes: A secondary oxide layer with a thickness of 10 nanometers to 50 nanometers is grown in a temperature range of 800 degrees Celsius to 1050 degrees Celsius with a dry oxygen flow rate of 500 sccm to 1500 sccm and a trichloroethylene flow rate of 200 sccm to 800 sccm.

[0015] By controlling the flow rates of dry oxygen and trichloroethylene within a specific temperature range for secondary oxidation, an oxide layer with controllable thickness can be formed, thereby optimizing the surface properties of the polysilicon film layer, helping to improve the uniformity of subsequent ion implantation processes, and enhancing the interface stability and electrical properties of the piezoresistive sensitive layer.

[0016] Optionally, the step of performing ion implantation on the polysilicon film layer under vacuum conditions includes: In vacuum conditions, the implantation energy ranged from 20 keV to 80 keV and the injection pressure was 3×10 14 Ion number / cm² to 8×10 16 The implantation dose is 100 ions / square centimeter, and trivalent or pentavalent doping elements are implanted into the polysilicon film layer.

[0017] By controlling the ion implantation energy and dosage in a vacuum environment, the distribution concentration and depth of the doping elements can be precisely controlled, thereby optimizing the carrier concentration and conductivity characteristics of the polysilicon film layer, which helps to improve the sensitivity and temperature stability of the piezoresistive sensitive layer.

[0018] Optionally, the structure of the sensitive device is a folded strip structure, and the top of the folded strip structure is curved.

[0019] The use of a folded strip structure combined with a curved top treatment can optimize the stress distribution of the sensitive device, thereby improving the response characteristics of the piezoresistive effect; at the same time, this structural design helps to enhance mechanical stability and may improve the performance of the sensor under dynamic stress conditions.

[0020] Optionally, the steps of forming a pad and a metal wire structure on the top and outer preset areas of the device connecting wires by photolithography, metal deposition and etching processes include: Spin coating negative photoresist on the top of the device connecting wire and the outer preset area at a speed of 1500 rpm to 4000 rpm; Bake on a hot plate at 60 to 120 degrees Celsius for 20 to 140 seconds; Expose the top and outer preset areas of the device connecting wires for 10 to 50 seconds, and then soak them in a developer for 10 to 100 seconds for development; Post-baking on a hot plate at 100 to 130 degrees Celsius for 20 to 120 seconds to form a pad pattern; Depositing a metal layer or a metal composite layer by magnetron sputtering or evaporation; The metal layer or metal composite layer in the photoresist area is removed by wet or dry etching to form a bonding pad and metal wire structure.

[0021] The silicon wafer with the metal layer deposited above is wet or dry etched to remove the metal film layer on the negative resist surface. Part of the retained metal is used as the connecting wire between the sensitive device and the pad, and part is used as the pad for the subsequent packaging connection.

[0022] Optionally, the step of performing annealing and re-diffusion treatment on the sensitive device includes: Annealing is performed under the conditions of a pressure of 740 torr to 760 torr, a process temperature of 500 degrees Celsius to 1000 degrees Celsius, and a process time of 30 minutes to 140 minutes, while introducing an inert gas as a protective gas; After annealing, a re-diffusion process is performed, wherein the flow rate of the oxygen gas introduced during the re-diffusion process is 500 sccm to 2000 sccm, and the flow rate of the chlorine source is 300 sccm to 1500 sccm.

[0023] By performing annealing treatment at normal pressure and temperature range and using inert gas protection, the oxidation and contamination of sensitive devices during high-temperature treatment can be reduced; controlling the flow rate of oxygen and chlorine sources in the subsequent diffusion treatment helps to optimize the distribution and activation efficiency of the doping elements, thereby improving the electrical properties and long-term stability of the piezoresistive sensitive layer.

[0024] A second aspect of the present application provides a high-sensitivity silicon-based piezoresistive pressure sensor, which is applicable to the method for manufacturing the high-sensitivity silicon-based piezoresistive pressure sensor described in the first aspect. The silicon-based piezoresistive pressure sensor comprises: A substrate consisting of cleaned double-polished silicon wafers; a first insulating dielectric layer covering the top surface of the substrate; A sensitive device composed of a polysilicon thin film deposited on the first insulating dielectric layer and subjected to ion implantation under vacuum conditions, the sensitive device undergoing annealing and rediffusion after formation, and its shape and position being determined by photolithography and etching of the secondary oxide layer and the polysilicon thin film covering it; a secondary oxide layer having a preset thickness and covering the sensitive device; A second insulating dielectric layer as a top and side protection layer, covering the surface of the sensitive device and the secondary oxide layer, wherein the second insulating dielectric layer is a silicon nitride film layer or a silicon oxide film layer; forming device connection wires on the second insulating dielectric layer by photolithography and etching processes; The pad and metal wire structure are formed by photolithography, metal deposition and etching processes, and are arranged on the top of the device connection wire hole and in a preset area outside the surface protection layer.

[0025] Since the high-sensitivity silicon-based piezoresistive pressure sensor has all the beneficial effects of the method for manufacturing the high-sensitivity silicon-based piezoresistive pressure sensor described in any one of the first aspects above, they will not be described in detail here.

[0026] It can be seen from the above technical solution that the present application provides a highly sensitive silicon-based piezoresistive pressure sensor and a manufacturing method, which first uses a cleaned double-polished silicon wafer as a substrate, and grows an insulating dielectric layer on the top surface of the substrate; deposits a polycrystalline silicon thin film on the insulating dielectric layer to form a polycrystalline silicon film layer; performs secondary oxidation on the polycrystalline silicon film layer to form a secondary oxide layer of a preset thickness; ion implants the polycrystalline silicon film layer under vacuum conditions to form a piezoresistive sensitive device layer; etches the secondary oxide layer and the polycrystalline silicon film layer by photolithography and etching processes to form a sensitive device; anneals and re-diffusions the sensitive device; deposits a second insulating dielectric layer on the surface of the annealed and re-expanded sensitive device as a top and side protective layer of the sensitive device; etches the second insulating dielectric layer by photolithography and etching processes to form device connecting wires; forms a pad and a metal wire structure in a preset area on the top and outside of the device connecting wires by photolithography, metal deposition and etching processes to solve the problem of weak insulation performance of silicon-based piezoresistive pressure sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 A schematic flow chart of a method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor according to an embodiment of the present application; Figure 2 This is a schematic structural diagram of the method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor provided in an embodiment of the present application after growing an insulating dielectric layer; Figure 3 This is a schematic structural diagram of the method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor provided in an embodiment of the present application after a polysilicon film layer is formed; Figure 4 This is a schematic diagram of the structure after forming a secondary oxide layer in the method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor provided in an embodiment of the present application; Figure 5 This is a schematic structural diagram of the method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor provided in an embodiment of the present application after forming a piezoresistive sensitive device layer; Figure 6 This is a schematic structural diagram of the highly sensitive silicon-based piezoresistive pressure sensor provided in an embodiment of the present application after forming a sensitive device in the manufacturing method; Figure 7 This is a schematic diagram of the structure of the high-sensitivity silicon-based piezoresistive pressure sensor after annealing and re-diffusion treatment in the manufacturing method of the embodiment of the present application; Figure 8 This is a schematic structural diagram of the method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor provided in an embodiment of the present application after depositing a second insulating dielectric layer; Figure 9 This is a schematic diagram of the structure after forming device connection wires in the manufacturing method of the high-sensitivity silicon-based piezoresistive pressure sensor provided in an embodiment of the present application; Figure 10 This is a schematic structural diagram of the highly sensitive silicon-based piezoresistive pressure sensor provided in an embodiment of the present application after forming a bonding pad and a metal wire structure; Illustration: Among them, 1-double-polished silicon wafer; 2-insulating dielectric layer; 3-polysilicon film layer; 4-secondary oxide layer; 5-piezoresistive sensitive device layer; 6-sensitive device; 7-sensitive device after annealing and expansion; 8-second insulating dielectric layer; 9-device connecting wire; 10-pad and metal wire structure. DETAILED DESCRIPTION

[0029] The following embodiments are described in detail, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following embodiments are not intended to represent all possible implementations consistent with the present application. They are merely examples of systems and methods consistent with certain aspects of the present application.

[0030] Silicon-based piezoresistive pressure sensors play a key role in applications such as automotive airbag status monitoring, online tire pressure systems, physiological parameter detection in wearable devices, blood pressure monitoring in medical devices, and atmospheric data acquisition in aerospace. These applications require sensors with high insulation performance to ensure signal stability while also keeping manufacturing costs low to accommodate large-scale production.

[0031] In order to improve the insulation performance of the device, a single crystal silicon substrate is used in the related embodiments to directly manufacture the varistor, but this structure makes it difficult to form an insulating isolation layer at the bottom of the sensitive device.

[0032] To solve the problem of weak insulation performance of silicon-based piezoresistive pressure sensors, see Figures 1-10 Some embodiments of the present application provide a method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor, the method comprising: S100: Using the cleaned double-polished silicon wafer 1 as a substrate, growing an insulating dielectric layer 2 on the top surface of the substrate.

[0033] It should be understood that the thickness of the insulating dielectric layer 2 is 0.05 um to 15 um.

[0034] In some embodiments, the step of growing the insulating dielectric layer 2 on the top surface of the substrate includes: When a sacrificial oxide layer is grown, a thickness of 0.05 μm to 15 μm is grown at atmospheric pressure at a temperature range of 800°C to 1150°C with a dry oxygen flow rate of 1000 sccm to 3000 sccm, a wet oxygen flow rate of 1500 sccm to 2500 sccm, and a hydrogen flow rate of 2000 sccm to 4000 sccm. When thin film deposition is selected to grow the insulating dielectric layer 2, the insulating dielectric layer 2 is grown using any one or a combination of the following methods: If a silicon nitride film layer is used as the insulating dielectric layer 2, a silicon nitride film layer with a thickness of 80 nm to 150 nm is formed by low pressure chemical vapor deposition or plasma chemical vapor deposition under the conditions of a silicon dichloride flow rate of 10 sccm to 50 sccm, an ammonia flow rate of 30 sccm to 80 sccm, and a reaction temperature of 400°C to 800°C. If a silicon oxide film layer is used as the insulating dielectric layer 2, a silicon oxide film layer with a thickness of 80 nanometers to 150 nanometers is formed by low-pressure chemical vapor deposition or plasma chemical vapor deposition under the conditions of tetraethoxysilane vaporization with a flow rate of 20 sccm to 100 sccm, an oxygen flow rate of 20 sccm to 100 sccm, and a reaction temperature of 400 degrees Celsius to 1000 degrees Celsius.

[0035] It should be understood that sccm (Standard Cubic Centimeter per minute) represents the volume of gas (in cubic centimeters) introduced into the reaction chamber per minute under standard conditions (0 degrees Celsius, 1 atmosphere).

[0036] By optimizing the growth process parameters of the insulating dielectric layer 2, the uniformity and density of the insulating dielectric layer 2 can be improved, thereby enhancing the insulation performance of the sensor. At the same time, by selecting a sacrificial oxide layer or a thin film deposition method according to different needs, the thickness and material properties of the dielectric layer can be flexibly controlled, which helps to improve the stability and process adaptability of the sensor.

[0037] S200 : depositing a polysilicon thin film on the insulating dielectric layer 2 to form a polysilicon film layer 3 .

[0038] In some embodiments, the step of depositing a polysilicon thin film on the insulating dielectric layer 2 includes: A polysilicon film with a thickness of 100 nanometers to 5000 nanometers is deposited by chemical vapor deposition at a reaction temperature of 500 degrees Celsius to 800 degrees Celsius and a silane flow rate of 20 sccm to 800 sccm.

[0039] By controlling the reaction temperature and silane flow rate of chemical vapor deposition, the deposition quality of the polysilicon film can be optimized to have an appropriate thickness and uniformity, thereby helping to improve the electrical performance and structural stability of the piezoresistive sensitive layer, laying the foundation for the subsequent formation of a highly sensitive piezoresistive sensitive device layer 5.

[0040] S300 : performing secondary oxidation on the polysilicon film layer 3 to form a secondary oxidation layer 4 of a preset thickness.

[0041] It should be understood that the preset thickness is 10 nanometers to 50 nanometers.

[0042] In some embodiments, the step of performing secondary oxidation on the polysilicon film layer 3 includes: A secondary oxide layer 4 with a thickness of 10 nm to 50 nm is grown in a temperature range of 800°C to 1050°C with a dry oxygen flow rate of 500 sccm to 1500 sccm and a trichloroethylene flow rate of 200 sccm to 800 sccm.

[0043] By controlling the flow rates of dry oxygen and trichloroethylene within a specific temperature range for secondary oxidation, an oxide layer with controllable thickness can be formed, thereby optimizing the surface properties of the polysilicon film layer 3, helping to improve the uniformity of subsequent ion implantation processes, and enhancing the interface stability and electrical properties of the piezoresistive sensitive layer.

[0044] S400 : performing ion implantation on the polysilicon film layer 3 under vacuum conditions to form a piezoresistive sensitive device layer 5 .

[0045] In some embodiments, the step of performing ion implantation on the polysilicon film layer 3 under vacuum conditions includes: In vacuum conditions, the implantation energy ranged from 20 keV to 80 keV and the injection pressure was 3×10 14 Ion number / cm² to 8×10 16 The trivalent or pentavalent doping element is implanted into the polysilicon film layer 3 with an implantation dose of ions per square centimeter.

[0046] By controlling the ion implantation energy and dose in a vacuum environment, the distribution concentration and depth of the doping elements can be precisely controlled, thereby optimizing the carrier concentration and conductivity characteristics of the polysilicon film layer 3, which helps to improve the sensitivity and temperature stability of the piezoresistive sensitive layer.

[0047] S500 : etching the secondary oxide layer 4 and the polysilicon film layer 3 by photolithography and etching processes to form a sensitive device 6 .

[0048] It should be understood that, first, a planar spin coating technique should be adopted to coat the positive photoresist at a speed of 1500 rpm to 4000 rpm. Subsequently, a pre-baking process is performed on a hot plate, with the time controlled between 20 seconds and 140 seconds, and the hot plate temperature being set at 60 degrees Celsius to 120 degrees Celsius. After the pre-baking step is completed, a front exposure is performed, with the exposure time being between 10 seconds and 50 seconds. Then, a development process is performed, with the immersion time in the developer being 10 seconds to 100 seconds. Finally, a hot plate post-baking process is performed, with the time range being 20 seconds to 120 seconds, and the hot plate temperature being set at 100 degrees Celsius to 130 degrees Celsius, to ensure that a clear sensitive device 6 and wire connection pattern are formed on the surface.

[0049] Wet etching is then used to remove the secondary oxide layer 4 and the polysilicon film not covered by the photolithographic pattern. The thickness removed ranges from 110 nanometers to 5050 nanometers. During the wet etching process, a mixture of hydrofluoric acid (49% concentration) and an aqueous solution of ammonium fluoride is used to remove the oxide layer. Subsequently, a photoresist stripping solution is used to remove the photoresist. Finally, a silicon etching solution is used to remove the polysilicon film layer 3, with the reaction temperature controlled between 30°C and 100°C. After the etching process is complete, a thorough cleaning step is performed.

[0050] S600: performing annealing and re-diffusion processing on the sensitive device 6 to obtain an annealed and re-diffused sensitive device 7; In some embodiments, the steps of annealing and re-diffusion processing the sensitive device 6 include: Annealing is performed under the conditions of a pressure of 740 torr to 760 torr, a process temperature of 500 degrees Celsius to 1000 degrees Celsius, and a process time of 30 minutes to 140 minutes, while introducing an inert gas as a protective gas; After annealing, a re-diffusion process is performed, wherein the flow rate of the oxygen gas introduced during the re-diffusion process is 500 sccm to 2000 sccm, and the flow rate of the chlorine source is 300 sccm to 1500 sccm.

[0051] It should be understood that the annealing process is performed at normal pressure. Torr is a unit of pressure used to represent the pressure in a low pressure or vacuum environment. The inert gas can be nitrogen, with a nitrogen flow rate of 1000 sccm to 3000 sccm.

[0052] By performing annealing treatment at normal pressure and temperature range and using inert gas protection, oxidation and contamination of the sensitive device 6 during high-temperature treatment can be reduced; controlling the flow rate of oxygen and chlorine sources in the subsequent diffusion treatment helps to optimize the distribution and activation efficiency of the doping elements, thereby improving the electrical properties and long-term stability of the piezoresistive sensitive layer.

[0053] S700 : depositing a second insulating dielectric layer 8 on the surface of the annealed and then expanded sensitive device 7 to serve as a top and side protection layer of the sensitive device 6 .

[0054] It should be understood that the second insulating dielectric layer 8 may be a silicon nitride film layer or a silicon oxide film layer.

[0055] In some embodiments, the step of depositing the second insulating dielectric layer 8 on the surface of the annealed and then expanded sensitive device 7 includes growing the second insulating dielectric layer 8 in any one of the following ways or a combination of two ways: If a silicon nitride film layer is used as the second insulating dielectric layer 8, a silicon nitride film layer with a thickness of 80 nm to 150 nm is formed by low pressure chemical vapor deposition or plasma chemical vapor deposition under the conditions of a silicon dichloride flow rate of 10 sccm to 50 sccm, an ammonia flow rate of 30 sccm to 80 sccm, and a reaction temperature of 400°C to 800°C. If a silicon oxide film layer is used as the second insulating dielectric layer 8, a silicon oxide film layer with a thickness of 80 nanometers to 150 nanometers is formed by low-pressure chemical vapor deposition or plasma chemical vapor deposition under the conditions of tetraethoxysilane vaporization with a flow rate of 20 sccm to 100 sccm, an oxygen flow rate of 20 sccm to 100 sccm, and a reaction temperature of 400 degrees Celsius to 1000 degrees Celsius.

[0056] By forming a second insulating dielectric layer 8 of silicon nitride or silicon oxide through chemical vapor deposition or plasma chemical vapor deposition processes under conditions of optimized reaction gas flow and temperature, the density and uniformity of the surface protection of the sensitive device 6 can be improved; the silicon nitride film layer can enhance the mechanical strength and chemical stability of the device, and the silicon oxide film layer helps to improve the interface electrical properties, thereby jointly improving the long-term reliability and environmental adaptability of the sensor.

[0057] S800: Etching the second insulating dielectric layer 8 by photolithography and etching processes to form device connecting wires 9.

[0058] The positive photoresist is coated using a planar spin coating technique at a speed of 1500 to 4000 rpm. Subsequently, the wafer is placed on a hot plate for pre-baking, which lasts for 20 to 140 seconds, with the hot plate temperature set between 60 degrees Celsius and 120 degrees Celsius. After the pre-baking step is completed, the front side of the wafer is exposed for a time of 10 to 50 seconds. The development process is then performed, with the immersion time in the developer being 10 to 100 seconds. This is followed by a hot plate post-baking, which lasts for 20 to 120 seconds, with the hot plate temperature set between 100 and 130 degrees Celsius, to ensure a clear connection wire pattern is formed on the wafer surface. Subsequent steps include wire etching, which removes silicon oxide or silicon nitride not covered by the photoresist through a wet or dry process, and simultaneously removes the residual photoresist.

[0059] S900: forming a pad and a metal wire structure 10 on the top and outside of the device connecting wire 9 by photolithography, metal deposition and etching processes.

[0060] It should be understood that the outer preset area is a pre-planned area for placing pads and metal wires.

[0061] In some embodiments, the steps of forming the pad and metal wire structure 10 on the top and outer predetermined areas of the device connecting wire 9 by photolithography, metal deposition and etching processes include: Spin-coat a negative photoresist on the top and outer preset area of ​​the device connecting wire 9 at a speed of 1500 rpm to 4000 rpm; Bake on a hot plate at 60 to 120 degrees Celsius for 20 to 140 seconds; Expose the top and outer preset areas of the device connecting wire 9 for 10 to 50 seconds, and then soak them in a developer for 10 to 100 seconds for development; Post-baking on a hot plate at 100 to 130 degrees Celsius for 20 to 120 seconds to form a pad pattern; Depositing a metal layer or a metal composite layer by magnetron sputtering or evaporation; The metal layer or metal composite layer in the photoresist area is removed by wet or dry etching to form a bonding pad and a metal wire structure 10 .

[0062] It should be understood that the metal layer can be an aluminum layer or an aluminum composite layer. The metal wire serves as a connecting wire between the sensitive device 6 and the pad, and the pad is used for subsequent packaging connection.

[0063] By optimizing the photolithography process parameters, including spin coating speed, pre-baking temperature and time, exposure time, development time, and post-baking conditions, the accuracy and consistency of the pad pattern can be improved. At the same time, depositing the metal layer by magnetron sputtering or evaporation, combined with wet or dry etching processes, helps to form structurally stable pads and metal wires, thereby improving the electrical connection reliability and signal transmission performance of the sensor.

[0064] The manufacturing method adopts polycrystalline silicon as the sensitive device 6 and utilizes its good piezoresistive sensitivity to improve the response sensitivity of the sensor; polycrystalline silicon can be easily grown on different substrate surfaces by thin film deposition, which facilitates the formation of an insulating isolation dielectric layer at the bottom of the sensitive device 6, similar to the SOI substrate structure, thereby improving the overall insulation performance of the device; by pre-preparing an insulating dielectric layer 2 at the bottom of the device and depositing a second insulating dielectric layer 8 on the upper surface and side of the sensitive device 6, the overall insulation and anti-interference properties of the sensor are enhanced, thereby solving the problem of weak insulation performance of silicon-based piezoresistive pressure sensors.

[0065] In some embodiments, after forming the pad and metal conductor structure 10, the method further includes: The pad and the metal wire structure 10 are alloyed to stabilize the pad and the metal wire structure 10 .

[0066] Specifically, the alloy is baked at a high temperature of 450 degrees Celsius to 700 degrees Celsius. Nitrogen is filled during the baking process as an inert protection. The nitrogen flow rate is 1000 sccm to 3000 sccm, and the baking time is 10 minutes to 45 minutes.

[0067] The bottom of the double-polished silicon wafer 1 is etched by photolithography and etching processes to form a silicon cup structure.

[0068] It should be understood that a potassium hydroxide solution of appropriate concentration may be used to perform silicon cup etching to form a silicon cup structure.

[0069] The etched double-polished silicon wafer 1 is packaged by sealing or bonding.

[0070] By alloying the pad and the metal wire structure 10, its structural stability can be improved; by etching the bottom of the double-polished silicon wafer 1 to form a silicon cup structure, it helps to optimize the mechanical properties of the sensor; finally, the packaging is completed by sealing or bonding, which can enhance the overall reliability of the sensor and improve its environmental adaptability.

[0071] In some embodiments, the structure of the sensor device 6 is a folded strip structure, and the top of the folded strip structure is curved.

[0072] The use of a folded strip structure combined with a top arc treatment can optimize the stress distribution of the sensitive device 6, thereby improving the response characteristics of the piezoresistive effect; at the same time, this structural design helps to enhance mechanical stability and may improve the performance of the sensor under dynamic stress conditions.

[0073] Some embodiments of the present application provide a high-sensitivity silicon-based piezoresistive pressure sensor, which is applicable to the method for manufacturing the high-sensitivity silicon-based piezoresistive pressure sensor described in the above embodiments. The silicon-based piezoresistive pressure sensor includes: A substrate consisting of a cleaned double-polished silicon wafer 1; an insulating dielectric layer 2 covering the top surface of the substrate; A sensitive device 6 composed of a polysilicon thin film deposited on the insulating dielectric layer 2 and subjected to ion implantation under vacuum conditions, wherein the sensitive device 6 is subjected to annealing and re-diffusion after formation, and its shape and position are determined by photolithography and etching of the secondary oxide layer 4 and the polysilicon thin film covering it; A secondary oxide layer 4 having a preset thickness and covering the sensitive device 6; A second insulating dielectric layer 8 as a top and side protection layer, covering the surface of the sensitive device 6 and the secondary oxide layer 4, wherein the second insulating dielectric layer 8 is a silicon nitride film layer or a silicon oxide film layer; Device connecting wires 9 formed on the second insulating dielectric layer 8 by photolithography and etching processes; The pad and metal wire structure 10 are formed by photolithography, metal deposition and etching processes, and are arranged on the top of the hole of the device connecting wire 9 and the preset area outside the surface protection layer.

[0074] Since the high-sensitivity silicon-based piezoresistive pressure sensor has all the beneficial effects of the method for manufacturing the high-sensitivity silicon-based piezoresistive pressure sensor described in the above embodiment, they will not be described in detail here.

[0075] As can be seen from the above technical solution, the embodiment of the present application provides a highly sensitive silicon-based piezoresistive pressure sensor and a manufacturing method thereof, wherein a cleaned double-polished silicon wafer 1 is first used as a substrate, and an insulating dielectric layer 2 is grown on the top surface of the substrate; a polycrystalline silicon thin film is deposited on the insulating dielectric layer 2 to form a polycrystalline silicon film layer 3; a secondary oxidation is performed on the polycrystalline silicon film layer 3 to form a secondary oxidation layer 4 of a preset thickness; ion implantation is performed on the polycrystalline silicon film layer 3 under vacuum conditions to form a piezoresistive sensitive device layer 5; the secondary oxide is etched by photolithography and etching processes. The invention relates to a method for fabricating a silicon-based piezoresistive pressure sensor. The method comprises the following steps: forming a silicon-based piezoresistive pressure sensor 7 and forming a silicon-based piezoresistive pressure sensor 7; ...; forming a silicon-based piezoresistive pressure sensor; forming a silicon-based piezoresistive pressure sensor; forming a silicon-based piezoresistive pressure sensor; forming a silicon-based piezoresistive pressure sensor; forming a silicon-based piezoresistive pressure sensor; forming a silicon-based piezoresistive pressure sensor; forming a silicon-based piezoresistive pressure sensor; forming a

[0076] Similar parts between the embodiments provided in this application can be referenced to each other. The specific implementation methods provided above are only a few examples under the overall concept of this application and do not constitute a limitation on the scope of protection of this application. For those skilled in the art, any other implementation methods expanded based on the scheme of this application without expending creative work shall fall within the scope of protection of this application.

Claims

1. A method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor, characterized in that: The method comprises: Using the cleaned double-polished silicon wafer as a substrate, and growing an insulating dielectric layer on the top surface of the substrate; depositing a polysilicon thin film on the insulating dielectric layer to form a polysilicon film layer; Performing secondary oxidation on the polysilicon film layer to form a secondary oxidation layer of a preset thickness; Performing ion implantation on the polysilicon film layer under vacuum conditions to form a piezoresistive sensitive device layer; Etching the secondary oxide layer and the polysilicon film layer by photolithography and etching processes to form a sensitive device; Performing annealing and re-diffusion processing on the sensitive device to obtain an annealed and re-diffused sensitive device; Depositing a second insulating dielectric layer on the surface of the sensitive device after annealing and then expansion to serve as a top and side protection layer of the sensitive device; Etching the second insulating dielectric layer by photolithography and etching processes to form device connecting wires; Through photolithography, metal deposition and etching processes, pads and metal wire structures are formed on the top and outside of the device connecting wires.

2. The method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor according to claim 1, wherein: After forming the pad and the metal conductor structure, the method further includes: Performing alloy treatment on the pad and the metal wire structure to stabilize the pad and the metal wire structure; Etching the bottom of the double-polished silicon wafer by photolithography and etching processes to form a silicon cup structure; The etched double-polished silicon wafer is packaged by sealing or bonding.

3. The method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor according to claim 1, wherein: The step of growing an insulating dielectric layer on the top surface of the substrate comprises: When a sacrificial oxide layer is grown, a thickness of 0.05 μm to 15 μm is grown at atmospheric pressure at a temperature range of 800°C to 1150°C with a dry oxygen flow rate of 1000 sccm to 3000 sccm, a wet oxygen flow rate of 1500 sccm to 2500 sccm, and a hydrogen flow rate of 2000 sccm to 4000 sccm. When thin film deposition is selected to grow the insulating dielectric layer, the insulating dielectric layer is grown using any one or a combination of the following methods: If a silicon nitride film layer is used as an insulating dielectric layer, a silicon nitride film layer with a thickness of 80 nanometers to 150 nanometers is formed by chemical vapor deposition or plasma chemical vapor deposition under the conditions of a silicon dichloride flow rate of 10 sccm to 50 sccm, an ammonia flow rate of 30 sccm to 80 sccm, and a reaction temperature of 400 degrees Celsius to 800 degrees Celsius; If a silicon oxide film layer is used as an insulating dielectric layer, a silicon oxide film layer with a thickness of 80 nanometers to 150 nanometers is formed by chemical vapor deposition or plasma chemical vapor deposition under the conditions of tetraethoxysilane vaporization with a flow rate of 20 sccm to 100 sccm, an oxygen flow rate of 20 sccm to 100 sccm, and a reaction temperature of 400 degrees Celsius to 1000 degrees Celsius.

4. The method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor according to claim 1, wherein: The step of depositing a polysilicon thin film on the insulating dielectric layer comprises: A polysilicon film with a thickness of 100 nanometers to 5000 nanometers is deposited by chemical vapor deposition at a reaction temperature of 500 degrees Celsius to 800 degrees Celsius and a silane flow rate of 20 sccm to 800 sccm.

5. The method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor according to claim 1, wherein: The step of performing secondary oxidation on the polysilicon film layer comprises: A secondary oxide layer with a thickness of 10 nanometers to 50 nanometers is grown in a temperature range of 800 degrees Celsius to 1050 degrees Celsius with a dry oxygen flow rate of 500 sccm to 1500 sccm and a trichloroethylene flow rate of 200 sccm to 800 sccm.

6. The method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor according to claim 1, wherein: The step of performing ion implantation on the polysilicon film layer under vacuum conditions comprises: In vacuum conditions, the implantation energy ranged from 20 keV to 80 keV and the injection pressure was 3×10 14 Ion number / cm² to 8×10 16 The implantation dose is 100 ions / square centimeter, and trivalent or pentavalent doping elements are implanted into the polysilicon film layer.

7. The method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor according to claim 1, wherein: The structure of the sensitive device is a folded strip structure, and the top of the folded strip structure is arc-shaped.

8. The method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor according to claim 1, wherein: The steps of forming pads and metal conductor structures on the top and outside of the device connecting conductors by photolithography, metal deposition and etching processes include: Spin coating negative photoresist on the top of the device connecting wire and the outer preset area at a speed of 1500 rpm to 4000 rpm; Bake on a hot plate at 60 to 120 degrees Celsius for 20 to 140 seconds; Expose the top and outer preset areas of the device connecting wires for 10 to 50 seconds, and then soak them in a developer for 10 to 100 seconds for development; Post-baking on a hot plate at 100 to 130 degrees Celsius for 20 to 120 seconds to form a pad pattern; Depositing a metal layer or a metal composite layer by magnetron sputtering or evaporation; The metal layer or metal composite layer in the photoresist area is removed by wet or dry etching to form a bonding pad and metal wire structure.

9. The method for manufacturing a highly sensitive silicon-based piezoresistive pressure sensor according to claim 1, wherein: The steps of annealing and re-diffusion treating the sensitive device include: Annealing is performed under the conditions of a pressure of 740 torr to 760 torr, a process temperature of 500 degrees Celsius to 1000 degrees Celsius, and a process time of 30 minutes to 140 minutes, while introducing an inert gas as a protective gas; After annealing, a re-diffusion process is performed, wherein the flow rate of the oxygen gas introduced during the re-diffusion process is 500 sccm to 2000 sccm, and the flow rate of the chlorine source is 300 sccm to 1500 sccm.

10. A high-sensitivity silicon-based piezoresistive pressure sensor, characterized in that: A method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor applicable to any one of claims 1 to 9, wherein the silicon-based piezoresistive pressure sensor comprises: A substrate consisting of cleaned double-polished silicon wafers; a first insulating dielectric layer covering the top surface of the substrate; A sensitive device composed of a polysilicon thin film deposited on the first insulating dielectric layer and subjected to ion implantation under vacuum conditions, the sensitive device undergoing annealing and rediffusion after formation, and its shape and position being determined by photolithography and etching of the secondary oxide layer and the polysilicon thin film covering it; a secondary oxide layer having a preset thickness and covering the sensitive device; A second insulating dielectric layer as a top and side protection layer, covering the surface of the sensitive device and the secondary oxide layer, wherein the second insulating dielectric layer is a silicon nitride film layer or a silicon oxide film layer; forming device connection wires on the second insulating dielectric layer by photolithography and etching processes; The pad and metal wire structure are formed by photolithography, metal deposition and etching processes, and are arranged on the top of the device connection wire hole and in a preset area outside the surface protection layer.

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