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

Abstract

The application relates to the technical field of pressure sensor manufacturing, in particular to a high-sensitivity silicon-based piezoresistive pressure sensor and a manufacturing method. A double-throw wafer silicon chip is used as a substrate, and an insulating medium layer is grown on the top surface of the substrate; a polysilicon thin film is deposited on the insulating medium layer to form a polysilicon film layer; secondary oxidation is carried out on the polysilicon film layer to form a secondary oxidation layer with a preset thickness; ion implantation is carried out on the polysilicon film layer under vacuum conditions to form a piezoresistive sensitive device layer; the secondary oxidation layer and the polysilicon film layer are etched to form a sensitive device; annealing and rediffusion treatment are carried out on the sensitive device; a second insulating medium layer is deposited on the surface of the annealed and rediffused sensitive device; the second insulating medium layer is etched to form device connection wires; and a pad and a metal wire structure are formed on the top of the device connection wires and in the preset area outside the device connection wires through a photoetching, metal deposition and etching process, so that the problem of weak insulation performance of the silicon-based piezoresistive pressure sensor is solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of pressure sensor manufacturing, and particularly relates to a high-sensitivity silicon-based piezoresistive pressure sensor and a manufacturing method. BACKGROUND

[0002] The silicon-based pressure sensor plays a key role in the fields of automobile airbag state monitoring, tire pressure online system, wearable device physiological parameter detection, medical device blood pressure monitoring, and aerospace atmospheric data acquisition. The above application scenarios require the sensor to have high insulation performance to ensure signal stability, and the manufacturing cost needs to be controlled to meet the large-scale production demand.

[0003] To improve the insulation of the device, some schemes directly manufacture the piezoresistor using a single crystal silicon substrate, but it is difficult to form an insulating isolation layer at the bottom of the sensitive device. Some other schemes use a silicon-on-insulator (SOI) substrate material to realize bottom insulation by preparing a single crystal silicon device layer on the surface of the buried oxide layer.

[0004] The former scheme lacks a bottom insulation protection layer, which limits the electrical stability of the device. The latter scheme relies on expensive SOI substrate materials, which significantly increases the manufacturing cost. Therefore, there is an urgent need for a sensor preparation scheme that can realize high insulation performance on a silicon substrate and has controllable cost. SUMMARY

[0005] The application provides a high-sensitivity silicon-based piezoresistive pressure sensor and a manufacturing method to solve the problem of weak insulation performance of the silicon-based piezoresistive pressure sensor.

[0006] The first aspect of the application provides a manufacturing method of a high-sensitivity silicon-based piezoresistive pressure sensor, which comprises the following steps:

[0007] A cleaned double-etched wafer silicon chip is used as a substrate, and an insulating medium layer is grown on the top surface of the substrate;

[0008] A polysilicon thin film is deposited on the insulating medium layer to form a polysilicon film layer;

[0009] Secondary oxidation is performed on the polysilicon film layer to form a secondary oxidation layer with a preset thickness;

[0010] Ion implantation is performed on the polysilicon film layer under vacuum conditions to form a piezoresistive sensitive device layer;

[0011] The secondary oxidation layer and the polysilicon film layer are etched by a photolithography and etching process to form a sensitive device;

[0012] The sensitive device is subjected to annealing and re-diffusion treatment to obtain an annealed and re-diffused sensitive device;

[0013] Depositing a second insulating medium layer on the surface of the sensitive device after annealing and re-expanding, so as to serve as a top and side protective layer of the sensitive device;

[0014] Etching the second insulating medium layer by means of a photolithography and etching process, so as to form a device connecting wire;

[0015] Forming a pad and metal wire structure on the top and outer side of the device connecting wire by means of a photolithography, metal deposition and etching process.

[0016] The manufacturing method uses polycrystalline silicon as the sensitive device, improves the reaction sensitivity of the sensor by virtue of the good piezoresistive sensitivity of polycrystalline silicon, and forms an insulating isolation medium layer at the bottom of the sensitive device by means of thin film deposition, so as to improve the insulating performance of the whole device, which is similar to the SOI substrate structure. The insulating performance of the whole sensor and the anti-interference performance are enhanced by pre-preparing an insulating medium layer at the bottom of the device and depositing a second insulating medium layer on the top and side surface of the sensitive device, so as to solve the problem of weak insulating performance of the silicon-based piezoresistive pressure sensor.

[0017] Optionally, after the pad and metal wire structure is formed, the method further comprises:

[0018] Alloying the pad and metal wire structure, so as to stabilize the pad and metal wire structure;

[0019] Etching the bottom of the double-etched wafer silicon sheet by means of a photolithography and etching process, so as to form a silicon cup structure;

[0020] Sealing or bonding the etched double-etched wafer silicon sheet.

[0021] Alloying the pad and metal wire structure can improve the structural stability thereof. Etching the bottom of the double-etched wafer silicon sheet to form a silicon cup structure can help to optimize the mechanical performance of the sensor. Finally, sealing or bonding is used to complete the packaging, which can enhance the overall reliability of the sensor and improve its environmental adaptability.

[0022] Optionally, the step of growing an insulating medium layer on the top surface of the substrate comprises:

[0023] When a sacrificial oxide layer is selected, the oxide layer with a thickness of 0.05 microns to 15 microns is grown at a temperature ranging from 800 degrees Celsius to 1150 degrees Celsius under atmospheric pressure, 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;

[0024] When the thin film deposition method is selected to grow the insulating medium layer, the insulating medium layer is grown by using any one or a combination of the following methods:

[0025] If the silicon nitride film layer is used as the insulating medium layer, the silicon nitride film layer with a thickness of 80-150 nm is formed by chemical vapor deposition or plasma chemical vapor deposition under the conditions of a silicon dichloride flow rate of 10-50 sccm, an ammonia flow rate of 30-80 sccm, and a reaction temperature of 400-800 degrees Celsius.

[0026] If the silicon oxide film layer is used as the insulating medium layer, the silicon oxide film layer with a thickness of 80-150 nm is formed by chemical vapor deposition or plasma chemical vapor deposition under the conditions of a tetraethoxysilane flow rate of 20-100 sccm after vaporization, an oxygen flow rate of 20-100 sccm, and a reaction temperature of 400-1000 degrees Celsius.

[0027] By optimizing the growth process parameters of the insulating medium layer, the uniformity and density of the insulating medium layer can be improved, thereby enhancing the insulation performance of the sensor. At the same time, according to different requirements, the sacrificial oxide layer or the thin film deposition method can be selected to flexibly control the thickness and material properties of the medium layer, which helps to improve the stability and process adaptability of the sensor.

[0028] Optionally, the step of depositing a polysilicon film on the insulating medium layer includes:

[0029] The polysilicon film with a thickness of 100-5000 nm is deposited by chemical vapor deposition at a reaction temperature of 500-800 degrees Celsius and a silane flow rate of 20-800 sccm.

[0030] 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 appropriate thickness and uniformity, thereby helping to improve the electrical performance and structural stability of the piezoresistive sensitive layer, laying a foundation for subsequent formation of a high-sensitivity piezoresistive sensor layer.

[0031] Optionally, the step of performing secondary oxidation on the polysilicon film layer includes:

[0032] The secondary oxide layer with a thickness of 10-50 nm is grown at a temperature of 800-1050 degrees Celsius, a dry oxygen flow rate of 500-1500 sccm, and a trichloroethylene flow rate of 200-800 sccm.

[0033] By controlling the flow of dry oxygen and trichloroethylene in a certain temperature range for secondary oxidation, an oxidation layer with controllable thickness can be formed, thereby optimizing the surface characteristics of the polysilicon film layer, helping to improve the uniformity of the subsequent ion implantation process, and enhancing the interface stability and electrical properties of the piezoresistive sensitive layer.

[0034] Optionally, the step of ion implantation on the polysilicon film layer under vacuum conditions comprises:

[0035] In a vacuum environment, implanting trivalent or pentavalent doping elements into the polysilicon film layer with an implantation energy of 20-80 kiloelectron volts and an implantation dose of 3×10 14 ions / cm2 to 8×10 16 ions / cm2.

[0036] By controlling the ion implantation energy and dose in a vacuum environment, the distribution concentration and depth of the doping elements can be precisely regulated, thereby optimizing the carrier concentration and conductance characteristics of the polysilicon film layer, helping to improve the sensitivity and temperature stability of the piezoresistive sensitive layer.

[0037] Optionally, the structure of the sensitive device is a folded-back strip structure, and the top end of the folded-back strip structure is arc-shaped.

[0038] The use of a folded-back strip structure combined with top end arc shaping 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 the mechanical stability and may improve the performance of the sensor under dynamic stress conditions.

[0039] Optionally, the step of forming a pad and metal wire structure by photolithography, metal deposition, and etching processes on the top and outer side of the device connection wire in the predetermined area comprises:

[0040] Spin-coating a negative photoresist on the top and outer side of the device connection wire in the predetermined area at a speed of 1500-4000 rpm;

[0041] Pre-baking on a hot plate at 60-120°C for 20-140 seconds;

[0042] Exposing the top and outer side of the device connection wire in the predetermined area for 10-50 seconds and developing with a developing solution for 10-100 seconds;

[0043] Post-baking on a hot plate at 100-130°C for 20-120 seconds to form a pad pattern;

[0044] Depositing a metal layer or metal composite layer by magnetron sputtering or evaporation;

[0045] The metal layer or metal composite layer in the photoresist region is removed by wet etching or dry etching to form a pad and a metal wire structure.

[0046] The silicon wafer with the deposited metal layer is subjected to wet etching or dry etching to remove the metal film layer on the negative photoresist surface, and the remaining metal is used as a connecting wire between the sensitive device and the pad and as a pad for connection in the later packaging.

[0047] Optionally, the step of annealing and respraying the sensitive device comprises:

[0048] The annealing is performed at 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 inert gas is introduced as a protective gas;

[0049] The respraying is performed after the annealing, and the oxygen flow rate introduced in the respraying is 500 sccm to 2000 sccm, and the chlorine source flow rate is 300 sccm to 1500 sccm.

[0050] The annealing is performed at 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 inert gas is introduced as a protective gas;

[0051] The second aspect of the present application provides a high-sensitivity silicon-based piezoresistive pressure sensor, which is suitable for the manufacturing method of the high-sensitivity silicon-based piezoresistive pressure sensor described in the first aspect, and the silicon-based piezoresistive pressure sensor comprises:

[0052] A substrate formed by a double-polished wafer silicon wafer after cleaning;

[0053] A first insulating medium layer covering the top surface of the substrate;

[0054] A sensitive device formed by a polysilicon thin film deposited on the first insulating medium layer and subjected to ion implantation treatment under vacuum conditions, wherein the sensitive device is subjected to annealing and respraying after formation, and the shape and position of the sensitive device are formed by photolithography and etching processes on a second oxide layer covering the sensitive device and the polysilicon thin film;

[0055] A second oxide layer with a preset thickness and covering the sensitive device;

[0056] A second insulating medium layer as a top and side protective layer, covering the surface of the sensitive device and the second oxide layer, wherein the second insulating medium layer is a silicon nitride film layer or a silicon oxide film layer;

[0057] A device connecting wire is formed on the second insulating medium layer by a photoetching and etching process;

[0058] A pad and metal wire structure is formed on the top of the device connecting wire and the preset area outside the surface protection layer by a photoetching, metal deposition and etching process.

[0059] The high-sensitivity silicon-based piezoresistive pressure sensor has all the beneficial effects of the manufacturing method of the high-sensitivity silicon-based piezoresistive pressure sensor of any one of the first aspect, which will not be repeated here.

[0060] From the above technical solutions, the application provides a high-sensitivity silicon-based piezoresistive pressure sensor and a manufacturing method. A cleaned double-polished wafer silicon wafer is used as a substrate, and an insulating medium layer is grown on the top surface of the substrate. A polysilicon thin film is deposited on the insulating medium layer to form a polysilicon film layer. Secondary oxidation is performed on the polysilicon film layer to form a secondary oxidation layer with a preset thickness. Ion implantation is performed on the polysilicon film layer under vacuum conditions to form a piezoresistive sensor layer. The secondary oxidation layer and the polysilicon film layer are etched by a photoetching and etching process to form a sensitive device. The sensitive device is subjected to annealing and re-diffusion treatment. A second insulating medium layer is deposited on the surface of the annealed and re-diffused sensitive device as a top and side protection layer of the sensitive device. The second insulating medium layer is etched by a photoetching and etching process to form a device connecting wire. A pad and metal wire structure is formed on the top of the device connecting wire and the preset area outside the device connecting wire by a photoetching, metal deposition and etching process, thereby solving the problem of weak insulation performance of the silicon-based piezoresistive pressure sensor. BRIEF DESCRIPTION OF DRAWINGS

[0061] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings needed in the embodiments. Obviously, other drawings can also be obtained by those skilled in the art without creative labor.

[0062] Figure 1 The flowchart of the manufacturing method of the high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiments of the application is shown in the figure.

[0063] Figure 2 The structure diagram after the growth of the insulating medium layer in the manufacturing method of the high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiments of the application is shown in the figure.

[0064] Figure 3 The structure diagram after the formation of the polysilicon film layer in the manufacturing method of the high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiments of the application is shown in the figure.

[0065] Figure 4 Structure schematic diagram after forming secondary oxidation layer in the manufacturing method of high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiment of the present application;

[0066] Figure 5 Structure schematic diagram after forming piezoresistive sensitive device layer in the manufacturing method of high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiment of the present application;

[0067] Figure 6 Structure schematic diagram after forming sensitive device in the manufacturing method of high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiment of the present application;

[0068] Figure 7 Structure schematic diagram after annealing and re-diffusion treatment in the manufacturing method of high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiment of the present application;

[0069] Figure 8 Structure schematic diagram after depositing second insulating medium layer in the manufacturing method of high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiment of the present application;

[0070] Figure 9 Structure schematic diagram after forming device connecting wire in the manufacturing method of high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiment of the present application;

[0071] Figure 10 Structure schematic diagram after forming pad and metal wire structure in the manufacturing method of high-sensitivity silicon-based piezoresistive pressure sensor provided by the embodiment of the present application;

[0072] Illustration:

[0073] Wherein, 1-bi-throw wafer silicon chip; 2-insulating medium layer; 3-polysilicon film layer; 4-secondary oxidation layer; 5-piezoresistive sensitive device layer; 6-sensitive device; 7-sensitivedevice after annealing and re-diffusion; 8-second insulating medium layer; 9-device connecting wire; 10-pad and metal wire structure. DETAILED DESCRIPTION

[0074] The embodiments will be described in detail below with reference to the drawings. Unless otherwise indicated, the same numbers in different drawings indicate the same or similar elements. The embodiments described in the following description are not meant to be exhaustive or to be limited to the precise forms of the application. They are chosen and described to provide the best description of the system and methods consistent with the application.

[0075] Silicon-based piezoresistive pressure sensors play a key role in automotive airbag status monitoring, tire pressure online systems, wearable physiological parameter detection, medical device blood pressure monitoring, and aerospace atmospheric data acquisition. The above application scenarios require high insulation performance to ensure signal stability, while the manufacturing cost needs to be controlled to meet the demand of mass production.

[0076] In order to improve the insulation of the device, a single crystal silicon substrate is directly used to manufacture a piezoresistor in the related embodiments, but it is difficult to form an insulating isolation layer at the bottom of the sensitive device.

[0077] To solve the problem of weak insulation performance of silicon-based piezoresistive pressure sensors, see Figures 1-10 The present application provides a method for manufacturing a high-sensitivity silicon-based piezoresistive pressure sensor, which comprises:

[0078] S100: The cleaned double-etched wafer silicon chip 1 is used as a substrate, and an insulating medium layer 2 is grown on the top surface of the substrate.

[0079] It should be understood that the thickness of the insulating medium layer 2 is 0.05um to 15um.

[0080] In some embodiments, the step of growing an insulating medium layer 2 on the top surface of the substrate comprises:

[0081] When a sacrificial oxide layer is selected, the oxide layer with a thickness of 0.05 microns to 15 microns is grown at a temperature range of 800 degrees Celsius to 1150 degrees Celsius, with a dry oxygen flow rate of 1000sccm to 3000sccm, a wet oxygen flow rate of 1500sccm to 2500sccm, and a hydrogen flow rate of 2000sccm to 4000sccm under atmospheric pressure.

[0082] When the insulating medium layer 2 is grown in the form of thin film deposition, the insulating medium layer 2 is grown in the following manner:

[0083] If the silicon nitride film layer is used as the insulating medium layer 2, the silicon nitride film layer with a thickness of 80 nanometers to 150 nanometers is formed by low-pressure chemical vapor deposition or plasma chemical vapor deposition, with a dichlorodihydrogen silicon flow rate of 10sccm to 50sccm, an ammonia flow rate of 30sccm to 80sccm, and a reaction temperature of 400 degrees Celsius to 800 degrees Celsius.

[0084] If the silicon oxide film layer is used as the insulating medium layer 2, the silicon oxide film layer with a thickness of 80-150 nm is formed by low-pressure chemical vapor deposition or plasma chemical vapor deposition at a flow rate of 20-100 sccm for tetraethoxysilane vaporization, a flow rate of 20-100 sccm for oxygen, and a reaction temperature of 400-1000 degrees Celsius.

[0085] 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).

[0086] By optimizing the growth process parameters of the insulating medium layer 2, the uniformity and density of the insulating medium layer 2 can be improved, thereby enhancing the insulation performance of the sensor. At the same time, according to different requirements, the sacrificial oxide layer or thin film deposition method can be selected to flexibly control the thickness and material properties of the medium layer, which helps to improve the stability and process adaptability of the sensor.

[0087] S200: Depositing a polysilicon thin film on the insulating medium layer 2 to form a polysilicon film layer 3.

[0088] In some embodiments, the step of depositing a polysilicon thin film on the insulating medium layer 2 includes:

[0089] A polysilicon thin film with a thickness of 100-5000 nm is deposited by chemical vapor deposition at a reaction temperature of 500-800 degrees Celsius and a silane flow rate of 20-800 sccm.

[0090] By controlling the reaction temperature and silane flow rate of chemical vapor deposition, the deposition quality of the polysilicon thin film can be optimized to have appropriate thickness and uniformity, thereby helping to improve the electrical performance and structural stability of the piezoresistive sensitive layer, laying a foundation for subsequent formation of a high-sensitivity piezoresistive sensor layer 5.

[0091] S300: Performing secondary oxidation on the polysilicon film layer 3 to form a secondary oxide layer 4 with a preset thickness.

[0092] It should be understood that the preset thickness is 10-50 nm.

[0093] In some embodiments, the step of performing secondary oxidation on the polysilicon film layer 3 includes:

[0094] A second oxide layer 4 with a thickness of 10-50 nm is grown at a temperature range of 800-1050 °C with a dry oxygen flow of 500-1500 seem and a trichloroethylene flow of 200-800 seem.

[0095] By controlling the flow of dry oxygen and trichloroethylene in a specific temperature range for the secondary oxidation, an oxide layer with controllable thickness can be formed, thereby optimizing the surface properties of the polysilicon film layer 3, which helps to improve the uniformity of the subsequent ion implantation process, and at the same time enhances the interface stability and electrical properties of the piezoresistive sensitive layer.

[0096] S400: Ion implantation is performed on the polysilicon film layer 3 under vacuum conditions to form a piezoresistive sensor layer 5.

[0097] In some embodiments, the step of ion implantation on the polysilicon film layer 3 under vacuum conditions includes:

[0098] In a vacuum environment, the polysilicon film layer 3 is implanted with trivalent or pentavalent doping elements at an implantation energy of 20-80 keV and an implantation dose of 3x10 14 ions / cm2 to 8x10 16 ions / cm2.

[0099] 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 properties of the polysilicon film layer 3, which helps to improve the sensitivity and temperature stability of the piezoresistive sensitive layer.

[0100] S500: The second oxide layer 4 and the polysilicon film layer 3 are etched by lithography and etching processes to form a sensitive device 6.

[0101] It should be understood that the planar spin coating technique should be used first to coat the positive photoresist with a rotation speed of 1500-4000 rpm. Subsequently, a pre-baking treatment is performed on a hot plate with a time control of 20-140 seconds and a hot plate temperature setting of 60-120 °C. After the pre-baking step, a front exposure is performed with an exposure time of 10-50 seconds. Then, a developing process is executed with a soaking time of the developing solution of 10-100 seconds. Finally, a hot plate post-baking is performed with a time range of 20-120 seconds and a hot plate temperature setting of 100-130 °C to ensure the formation of clear sensitive device 6 and wire connection patterns on the surface.

[0102] Then, the second oxide layer 4 and the polysilicon film not covered by the photoresist pattern are removed by a wet etching technique. The thickness of the removed layer is in the range of 110 nm to 5050 nm. During the wet etching process, an etching solution of a mixture of hydrofluoric acid (49% concentration) and an aqueous solution of ammonium fluoride is used to remove the oxide layer. Subsequently, the photoresist is removed using a photoresist stripper. Finally, the polysilicon film layer 3 is removed using a silicon etching solution at a reaction temperature in the range of 30°C to 100°C. After the etching process, a thorough cleaning step is performed.

[0103] S600: annealing and resputtering the sensitive device 6 to obtain an annealed and resputtered sensitive device 7;

[0104] In some embodiments, the step of annealing and resputtering the sensitive device 6 comprises:

[0105] The annealing is performed at a pressure in the range of 740 torr to 760 torr, a process temperature in the range of 500°C to 1000°C, and a process time in the range of 30 minutes to 140 minutes, while an inert gas is introduced as a protective gas.

[0106] The resputtering is performed after the annealing, and the oxygen flow rate introduced during the resputtering is in the range of 500 sccm to 2000 sccm, and the chlorine source flow rate is in the range of 300 sccm to 1500 sccm.

[0107] It should be understood that the annealing process is performed at atmospheric pressure, and torr is a unit of pressure used to represent the pressure in a low-pressure or vacuum environment. The inert gas can be nitrogen, and the nitrogen flow rate is in the range of 1000 sccm to 3000 sccm.

[0108] By performing the annealing process at atmospheric pressure and in a temperature range, and using an inert gas for protection, the oxidation and contamination of the sensitive device 6 during high-temperature processing can be reduced. Controlling the flow rates of oxygen and chlorine source during the subsequent resputtering process helps to optimize the distribution and activation efficiency of the doping elements, thereby improving the electrical performance and long-term stability of the piezoresistive sensitive layer.

[0109] S700: depositing a second insulating medium layer 8 on the surface of the annealed and resputtered sensitive device 7 as a top and side protective layer of the sensitive device 6.

[0110] It should be understood that the second insulating medium layer 8 can be a silicon nitride film layer or a silicon oxide film layer.

[0111] In some embodiments, the step of depositing a second insulating medium layer 8 on the surface of the annealed and resputtered sensitive device 7 comprises growing the second insulating medium layer 8 in any one of the following ways or a combination of two ways:

[0112] If the silicon nitride film layer is used as the second insulating medium layer 8, the silicon nitride film layer is formed by low-pressure chemical vapor deposition or plasma chemical vapor deposition under the conditions that the flow rate of dichlorosilane is 10-50 sccm, the flow rate of ammonia is 30-80 sccm, and the reaction temperature is 400-800 °C, and the thickness of the silicon nitride film layer is 80-150 nm.

[0113] If the silicon oxide film layer is used as the second insulating medium layer 8, the silicon oxide film layer is formed by low-pressure chemical vapor deposition or plasma chemical vapor deposition under the conditions that the flow rate of tetraethoxysilane after vaporization is 20-100 sccm, the flow rate of oxygen is 20-100 sccm, and the reaction temperature is 400-1000 °C, and the thickness of the silicon oxide film layer is 80-150 nm.

[0114] The second insulating medium layer 8 of silicon nitride or silicon oxide is formed by chemical vapor deposition or plasma chemical vapor deposition under the conditions of optimized reaction gas flow rate and temperature, which can improve the compactness and uniformity of the surface protection of the sensitive device 6; the silicon nitride film layer can enhance the mechanical strength and chemical stability of the device, and the silicon oxide film layer can help improve the interface electrical properties, thereby improving the long-term reliability and environmental adaptability of the sensor.

[0115] S800: etching the second insulating medium layer 8 by photolithography and etching process to form the device connection wire 9.

[0116] The positive photoresist is coated by using a planar spin coating technique at a rotation speed of 1500-4000 rpm. Subsequently, the wafer is placed on a hot plate for pre-baking, and the time duration is 20-140 seconds, and the hot plate temperature is set to 60-120 °C. After the pre-baking step, the wafer front surface is exposed to light for 10-50 seconds. Then, the development process is performed, and the immersion time of the developing solution is 10-100 seconds. Subsequently, the hot plate post-baking is performed, and the time duration is 20-120 seconds, and the hot plate temperature is set to 100-130 °C, so as to ensure that a clear connection wire pattern is formed on the wafer surface. The subsequent steps include wire etching, which removes the silicon oxide or silicon nitride that is not covered by the photoresist by wet or dry process, and at the same time removes the residual photoresist.

[0117] S900: forming the pad and metal wire structure 10 on the top and outside of the device connection wire 9 by photolithography, metal deposition, and etching process.

[0118] It should be understood that the outside preset area is an area where the pad and metal wire are placed.

[0119] In some embodiments, the step of forming the pad and metal wire structure 10 on the top and outside of the device connecting wire 9 by photolithography, metal deposition and etching process includes:

[0120] Spin-coating a negative photoresist on the top and outside of the device connecting wire 9 at a rotation speed of 1500 rpm to 4000 rpm;

[0121] Pre-baking on a hot plate at 60 degrees Celsius to 120 degrees Celsius for 20 seconds to 140 seconds;

[0122] Exposing the top and outside of the device connecting wire 9 for 10 seconds to 50 seconds and developing with a developing solution for 10 seconds to 100 seconds;

[0123] Post-baking on a hot plate at 100 degrees Celsius to 130 degrees Celsius for 20 seconds to 120 seconds to form a pad pattern;

[0124] Depositing a metal layer or a metal composite layer by magnetron sputtering or evaporation;

[0125] Removing the metal layer or the metal composite layer in the photoresist area by wet etching or dry etching to form the pad and metal wire structure 10.

[0126] 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 for later packaging connection.

[0127] By optimizing the photolithography process parameters, including spin-coating rotation speed, pre-baking temperature and time, exposure time, developing time and post-baking conditions, the accuracy and consistency of the pad pattern can be improved; at the same time, the deposition of the metal layer by magnetron sputtering or evaporation, combined with the wet etching or dry etching process, helps to form a stable pad and metal wire structure, thereby improving the electrical connection reliability and signal transmission performance of the sensor.

[0128] The manufacturing method uses polycrystalline silicon as the sensitive device 6, which improves the reaction sensitivity of the sensor by taking advantage of its good piezoresistive sensitivity; polycrystalline silicon is easy to grow on different substrate surfaces by thin film deposition, which facilitates the formation of an insulating isolation medium layer at the bottom of the sensitive device 6, similar to an SOI substrate structure, thereby improving the overall insulation performance of the device; by pre-preparing an insulating medium layer 2 at the bottom of the device and depositing a second insulating medium layer 8 on the top and side surfaces of the sensitive device 6, the overall insulation and anti-interference performance of the sensor is enhanced, thereby solving the problem of weak insulation performance of silicon-based piezoresistive pressure sensors.

[0129] In some embodiments, after forming the pad and metal wire structure 10, the method further includes:

[0130] The pad and metal wire structure 10 is alloyed to stabilize the pad and metal wire structure 10.

[0131] Specifically, the alloying is performed at a high temperature of 450-700 degrees Celsius, and the baking process is protected by nitrogen gas as an inert gas, with a nitrogen flow of 1000-3000 sccm and a baking time of 10-45 minutes.

[0132] The bottom of the double-polished wafer silicon sheet 1 is etched by a photolithography and etching process to form a silicon cup structure.

[0133] It should be understood that a silicon cup structure can be formed by etching the silicon cup using a potassium hydroxide solution with a suitable concentration.

[0134] The etched double-polished wafer silicon sheet 1 is packaged by sealing or bonding.

[0135] The structure stability of the pad and metal wire structure 10 can be improved by alloying, the mechanical properties of the sensor can be optimized by etching the bottom of the double-polished wafer silicon sheet 1 to form a silicon cup structure, and the overall reliability of the sensor can be enhanced and its environmental adaptability can be improved by packaging using sealing or bonding.

[0136] In some embodiments, the sensitive device 6 has a folded strip structure, and the top end of the folded strip structure is arc-shaped.

[0137] The stress distribution of the sensitive device 6 can be optimized by using a folded strip structure and combining arc-shaped processing of the top end, thereby improving the response characteristics of the piezoresistive effect; at the same time, this structural design helps to enhance the mechanical stability and may improve the performance of the sensor under dynamic stress conditions.

[0138] Some embodiments of the present application provide a high-sensitivity silicon-based piezoresistive pressure sensor, which is suitable for the manufacturing method of the high-sensitivity silicon-based piezoresistive pressure sensor described above. The silicon-based piezoresistive pressure sensor comprises:

[0139] A substrate formed by a double-polished wafer silicon sheet 1 after cleaning;

[0140] An insulating medium layer 2 covering the top surface of the substrate;

[0141] A sensitive device 6 formed by a polysilicon thin film deposited on the insulating medium layer 2 and subjected to ion implantation treatment under vacuum conditions, the shape and position of the sensitive device 6 being formed by a photolithography and etching process on a second oxide layer 4 and the polysilicon thin film covering the sensitive device 6, and the sensitive device 6 being subjected to annealing and re-diffusion treatment after being formed;

[0142] A second oxide layer 4 with a predetermined thickness covering the sensitive device 6;

[0143] A second insulating medium layer 8 as a top and side protective layer covers the surface of the sensitive device 6 and the secondary oxidation layer 4, and the second insulating medium layer 8 is a silicon nitride film layer or a silicon oxide film layer;

[0144] A device connecting wire 9 is formed on the second insulating medium layer 8 through a photoetching and etching process;

[0145] A pad and metal wire structure 10 is formed through a photoetching, metal deposition and etching process, and the pad and metal wire structure 10 is arranged on the top of the hole of the device connecting wire 9 and in a preset area outside the surface protective layer.

[0146] The high-sensitivity silicon-based piezoresistive pressure sensor has all the beneficial effects of the manufacturing method of the high-sensitivity silicon-based piezoresistive pressure sensor described in the above embodiments, which will not be repeated here.

[0147] As can be seen from the above technical solutions, the embodiments of the present application provide a high-sensitivity silicon-based piezoresistive pressure sensor and a manufacturing method. A cleaned double-polished wafer silicon chip 1 is used as a substrate, and an insulating medium layer 2 is grown on the top surface of the substrate. A polysilicon thin film is deposited on the insulating medium layer 2 to form a polysilicon film layer 3. Secondary oxidation is performed on the polysilicon film layer 3 to form a secondary oxidation layer 4 with a preset thickness. Ion implantation is performed on the polysilicon film layer 3 under vacuum conditions to form a piezoresistive sensitive device layer 5. The secondary oxidation layer 4 and the polysilicon film layer 3 are etched through a photoetching and etching process to form a sensitive device 6. Annealing and re-diffusion treatment are performed on the sensitive device 6. A second insulating medium layer 8 is deposited on the surface of the annealed and re-diffused sensitive device 7 to serve as a top and side protective layer of the sensitive device 6. The second insulating medium layer 8 is etched through a photoetching and etching process to form a device connecting wire 9. A pad and metal wire structure 10 is formed on the top of the device connecting wire 9 and in a preset area outside the device connecting wire 9 through a photoetching, metal deposition and etching process, thereby solving the problem of weak insulation performance of the silicon-based piezoresistive pressure sensor.

[0148] The similar parts among the embodiments provided by the present application can be referred to each other, and the specific embodiments provided above are only a few examples under the general concept of the present application, and do not limit the protection scope of the present application. For those skilled in the art, any other embodiments extended according to the present application scheme without creative labor are within the protection scope of the present 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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