A manufacturing process of SDB type silicon MEMS high temperature pressure sensor

Abstract

The application discloses a manufacturing process of an SDB type silicon MEMS high-temperature pressure sensor and relates to the technical field of pressure detection devices of micro electro mechanical systems, and comprises the following steps: step S1, preparation of SOI material based on a silicon substrate; step S2, photoetching of a resistance area and ion implantation; step S3, photoetching of a protection area; step S4, wet etching; step S5, manufacturing of a lead hole and a metal lead; step S6, metallization and passivation; and step S7, photoetching of a back etching area. The SDB type silicon MEMS high-temperature pressure sensor manufacturing process has no damage to a pressure sensitive resistance surface and is good in uniformity and consistency.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure detection devices of micro-electromechanical systems, and in particular to a manufacturing process of an SDB-type silicon MEMS high-temperature pressure sensor. Background Art

[0002] MEMS, or micro-electromechanical systems, is an emerging, interdisciplinary, high-tech research field. Piezoresistive pressure sensors manufactured based on MEMS technology have gained widespread application in the modern market due to their exceptional accuracy, reliability, and relatively low manufacturing costs. Silicon MEMS high-temperature pressure sensors are a common type of pressure sensor. Due to their ability to operate normally at high temperatures, they are widely used for pressure measurement in aviation, aerospace engine testing, and the weapons industry. Almost all ignition process testing and research requires the participation of silicon MEMS high-temperature pressure sensors.

[0003] Currently, silicon MEMS high-temperature pressure sensors are manufactured primarily through bulk silicon processing and surface processing. Both techniques rely on certain etching or material additions, which imposes limitations. With the rapid advancement of micromachining technology, SDB (Solid-Band-Derived Bonding) has emerged as a key technology for high-performance sensors due to its superior temperature performance. SDB involves chemically and physically bonding two materials together to form a reliable physical connection. This technique is crucial for fabricating complex and reliable silicon structures.

[0004] In the typical production process for silicon MEMS high-temperature pressure sensors, the four resistors that comprise the sensor's Wheatstone bridge are photolithographically fabricated with identical mechanical dimensions and aspect ratios. Dry etching is then used to remove the single-crystal silicon device layer outside the resistor regions. This leaves four piezoresistors with a highly sensitive piezoresistive effect, with opposite piezoresistance variations in their vertical and horizontal arrangement. Furthermore, the uniform dry etching ensures a relatively low zero-point output, or offset voltage, for the four-resistor Wheatstone bridge. Typically, at a 5V supply voltage, the offset voltage can be kept below 10 millivolts, facilitating signal processing in subsequent circuits. However, this process also presents certain challenges. First, dry etching equipment is relatively expensive, resulting in low efficiency during deep etching. Second, the plasma used in the dry etching process bombards the silicon device surface, causing lattice damage and stress. This is a significant disadvantage in the production of high-performance, high-precision, and high-stability pressure sensors.

[0005] To address these issues, the current common practice is to use a wet etching process instead of a dry etching process. However, a significant drawback of the traditional wet etching process is its low uniformity. This is primarily due to the difficulty in controlling the wet etching endpoint. The concentration of the etching liquid changes with corrosion consumption, the etching endpoint is difficult to detect, and the duration of the etching endpoint is difficult to determine. This can lead to lateral corrosion of the resistor area by the wet etching process. This, in turn, causes uneven corrosion progress. Ultimately, this leads to inconsistent resistance uniformity across the four arms of the Wheatstone bridge, resulting in a higher voltage output value (offset voltage) of the Wheatstone bridge.

[0006] It can be seen that the development of an SDB-type silicon MEMS high-temperature pressure sensor manufacturing process with no damage to the pressure sensitive resistor surface and good uniformity and consistency meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the MEMS field. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a SDB type silicon MEMS high temperature pressure sensor manufacturing process with no damage to the surface of the pressure sensitive resistor and good uniformity and consistency.

[0008] To achieve the above object, the present invention adopts a technical solution: a SDB type silicon MEMS high temperature pressure sensor manufacturing process, comprising the following steps:

[0009] Step S1, preparation of SOI material based on silicon substrate: select two double-polished silicon wafers, use high-temperature oxidation method to oxidize the front side of the silicon wafers to form a silicon dioxide insulating layer, then bond the silicon dioxide insulating layers of the two silicon wafers together in an ethylene glycol solution of bis(trihydroxymethylaminopropane), take them out and heat them on a flat and smooth iron plate electric furnace, then bake them in an oven, use nitrogen protection to complete pre-bonding, and then perform annealing under nitrogen protection; finally, thin the top silicon wafer to obtain SOI material based on silicon substrate;

[0010] Step S2, photolithography resistor area, ion implantation: Using the silicon substrate-based SOI material produced in step S1 as a substrate, photolithography is used to define a resistor area on the front side of the substrate, and ion implantation is performed to form the resistor area. The implanted ions are then activated by high-temperature thermal annealing.

[0011] Step S3, photolithography corrosion protection zone: defining the corrosion protection zone on the front side of the substrate by photolithography;

[0012] Step S4, wet etching: manufacturing the varistor by wet etching;

[0013] Step S5, making lead holes and metal leads: making lead holes and metal leads on the front side of the substrate;

[0014] Step S6, metallization and passivation: sputtering a metal layer for connecting the piezoresistive resistor on the varistor produced in step S4 to form a Wheatstone bridge, and depositing a passivation layer on the upper surface of the device by chemical vapor deposition to protect the device;

[0015] Step S7, photolithography of the backside corrosion area: performing photolithography on the backside corrosion area.

[0016] Preferably, the temperature of the high-temperature oxidation in step S1 is 930-1230° C., the oxygen flow rate is controlled at 0.7-1.3 cm / s, and the thickness of the silicon dioxide insulating layer is ≤300 nm.

[0017] Preferably, the mass percentage concentration of the ethylene glycol solution of bis(trihydroxymethylaminopropane) in step S1 is 3-8wt%.

[0018] Preferably, the heating temperature in step S1 is 185-195° C. and the heating time is 2-4 hours.

[0019] Preferably, the baking temperature in step S1 is 290-330° C. and the baking time is 3-5 hours.

[0020] Preferably, the annealing treatment in step S1 is performed at a temperature of 1090-1120° C. for 1-2 hours.

[0021] Preferably, the thinning process in step S1 is performed by mechanical grinding and polishing.

[0022] Preferably, the ion implanted in step S1 is boron ions or ions of other Group III elements, and the ion implantation dose is 1×10 19 ~1×10 21 atoms / square centimeter.

[0023] Preferably, the high temperature thermal annealing in step S2 is performed at a temperature of 1120-1180° C., for a time of 14-25 minutes, under nitrogen atmosphere.

[0024] Preferably, the corrosion protection zone in step S2 is located at the outer edge of the resistance zone, and the resistance zone is included in the corrosion protection zone.

[0025] Preferably, the wet etching in step S4 is isotropic etching, and the etching solution used includes the following components in weight percentage: acetic acid 20-25wt%, hydrofluoric acid 8-10wt%, tea polyphenols 1-3wt%, tris(hydroxymethyl)methylglycine 1-3wt%, H2O28-10wt%, and the balance is deionized water.

[0026] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0027] (1) The SDB-type silicon MEMS high-temperature pressure sensor manufacturing process disclosed in the present invention has low process difficulty, high reliability, is easy to obtain a high yield, has low dependence on equipment, is suitable for continuous large-scale production, and has high promotion and application value.

[0028] (2) The SDB type silicon MEMS high temperature pressure sensor manufacturing process disclosed in the present invention adopts SOI material based on silicon substrate as the substrate, so that the final pressure sensor has high measurement sensitivity and precision, better temperature performance and ultra-high stability; outside the photolithographic pressure sensitive resistor area, the secondary photolithographic etching protection area is carried out, and then wet etching is performed, so that the lateral corrosion of the wet etching will not affect the resistance value of the bridge arm resistance of the Wheatstone bridge, thereby reducing the offset voltage; the four pressure sensitive resistors of the Wheatstone bridge can be manufactured without surface damage, and the uniformity and consistency of the four pressure sensitive resistors of the Wheatstone bridge can be guaranteed, so that the final offset voltage reaches the same level as or even higher than that of dry etching.

[0029] (3) The present invention discloses a manufacturing process for an SDB-type silicon MEMS high-temperature pressure sensor, wherein the wet etching is isotropic etching, and the etching solution used comprises the following components in weight percentage: acetic acid 20-25wt%, hydrofluoric acid 8-10wt%, tea polyphenols 1-3wt%, tris(hydroxymethyl)methylglycine 1-3wt%, H2O2 8-10wt%, and the balance is deionized water. By rationally selecting the composition formula of the etching solution, the components can better interact with each other, thereby effectively improving the etching effect and efficiency. By rationally selecting the process parameters, the process steps can be simplified, the process reliability and the device yield can be improved, the device can be guaranteed to operate normally in a high-temperature environment, and the application range of the sensor can be broadened. In the preparation process of SOI material based on silicon substrate, the bonding in ethylene glycol solution of ditrihydroxymethylaminopropane can effectively improve the bonding strength and stability. DETAILED DESCRIPTION

[0030] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0031] Example 1, a process for manufacturing an SDB-type silicon MEMS high-temperature pressure sensor, comprising the following steps:

[0032] Step S1, preparation of SOI material based on silicon substrate: select two double-polished silicon wafers, use high-temperature oxidation method to oxidize the front side of the silicon wafers to form a silicon dioxide insulating layer, then bond the silicon dioxide insulating layers of the two silicon wafers together in an ethylene glycol solution of bis(trihydroxymethylaminopropane), take them out and heat them on a flat and smooth iron plate electric furnace, then bake them in an oven, use nitrogen protection to complete pre-bonding, and then perform annealing under nitrogen protection; finally, thin the top silicon wafer to obtain SOI material based on silicon substrate;

[0033] Step S2, photolithography resistor area, ion implantation: Using the silicon substrate-based SOI material produced in step S1 as a substrate, photolithography is used to define a resistor area on the front side of the substrate, and ion implantation is performed to form the resistor area. The implanted ions are then activated by high-temperature thermal annealing.

[0034] Step S3, photolithography corrosion protection zone: defining the corrosion protection zone on the front side of the substrate by photolithography;

[0035] Step S4, wet etching: manufacturing the varistor by wet etching;

[0036] Step S5, making lead holes and metal leads: making lead holes and metal leads on the front side of the substrate;

[0037] Step S6, metallization and passivation: sputtering a metal layer for connecting the piezoresistive resistor on the varistor produced in step S4 to form a Wheatstone bridge, and depositing a passivation layer on the upper surface of the device by chemical vapor deposition to protect the device;

[0038] Step S7, photolithography of the backside corrosion area: performing photolithography on the backside corrosion area.

[0039] The temperature of the high-temperature oxidation in step S1 is 930°C, the oxygen flow rate is controlled at 0.7 cm / s, and the thickness of the silicon dioxide insulating layer is ≤300 nm; the mass percentage concentration of the ethylene glycol solution of bis(trihydroxymethylaminopropane) in step S1 is 3 wt %; the temperature of the heating in step S1 is 185°C and the time is 2 h; the temperature of the baking in step S1 is 290°C and the time is 3 h; the temperature of the annealing in step S1 is 1090°C and the time is 1 h; the thinning treatment in step S1 is performed by mechanical grinding and polishing; the ion implanted substance in step S1 is boron ions or ions of other Group III elements, and the ion implantation dose is 1×10 19 atoms / square centimeter.

[0040] The high temperature thermal annealing in step S2 is performed at a temperature of 1120° C. for 14 minutes under nitrogen atmosphere. The corrosion protection zone in step S2 is located at the outer edge of the resistance zone, and the resistance zone is included in the corrosion protection zone.

[0041] The wet etching in step S4 is isotropic etching, and the etching solution used includes the following components in weight percentage: acetic acid 20wt%, hydrofluoric acid 8wt%, tea polyphenol 1wt%, tris(hydroxymethyl)methylglycine 1wt%, H2O28wt%, and the balance is deionized water.

[0042] Example 2, a process for manufacturing an SDB-type silicon MEMS high-temperature pressure sensor, comprising the following steps:

[0043] Step S1, preparation of SOI material based on silicon substrate: select two double-polished silicon wafers, use high-temperature oxidation method to oxidize the front side of the silicon wafers to form a silicon dioxide insulating layer, then bond the silicon dioxide insulating layers of the two silicon wafers together in an ethylene glycol solution of bis(trihydroxymethylaminopropane), take them out and heat them on a flat and smooth iron plate electric furnace, then bake them in an oven, use nitrogen protection to complete pre-bonding, and then perform annealing under nitrogen protection; finally, thin the top silicon wafer to obtain SOI material based on silicon substrate;

[0044] Step S2, photolithography resistor area, ion implantation: Using the silicon substrate-based SOI material produced in step S1 as a substrate, photolithography is used to define a resistor area on the front side of the substrate, and ion implantation is performed to form the resistor area. The implanted ions are then activated by high-temperature thermal annealing.

[0045] Step S3, photolithography corrosion protection zone: defining the corrosion protection zone on the front side of the substrate by photolithography;

[0046] Step S4, wet etching: manufacturing the varistor by wet etching;

[0047] Step S5, making lead holes and metal leads: making lead holes and metal leads on the front side of the substrate;

[0048] Step S6, metallization and passivation: sputtering a metal layer for connecting the piezoresistive resistor on the varistor produced in step S4 to form a Wheatstone bridge, and depositing a passivation layer on the upper surface of the device by chemical vapor deposition to protect the device;

[0049] Step S7, photolithography of the backside corrosion area: performing photolithography on the backside corrosion area.

[0050] The temperature of the high-temperature oxidation in step S1 is 1030°C, the oxygen flow rate is controlled at 0.8 cm / s, and the thickness of the silicon dioxide insulating layer is ≤300 nm; the mass percentage concentration of the ethylene glycol solution of bis(trihydroxymethylaminopropane) in step S1 is 4 wt %; the temperature of the heating in step S1 is 187°C and the time is 2.5 h; the temperature of the baking in step S1 is 300°C and the time is 3.5 h; the temperature of the annealing in step S1 is 1100°C and the time is 1.2 h; the thinning treatment in step S1 is performed by mechanical grinding and polishing; the ion implanted substance in step S1 is boron ions or ions of other Group III elements, and the ion implantation dose is 6×10 19 atoms / square centimeter.

[0051] The high temperature thermal annealing in step S2 is performed at a temperature of 1140° C. for 17 minutes under nitrogen atmosphere. The corrosion protection zone in step S2 is located at the outer edge of the resistance zone, and the resistance zone is included in the corrosion protection zone.

[0052] The wet etching in step S4 is isotropic etching, and the etching solution used includes the following components in weight percentage: acetic acid 22wt%, hydrofluoric acid 8.5wt%, tea polyphenols 1.5wt%, tris(hydroxymethyl)methylglycine 1.5wt%, H2O28.5wt%, and the balance is deionized water.

[0053] Example 3, a process for manufacturing an SDB-type silicon MEMS high-temperature pressure sensor, comprising the following steps:

[0054] Step S1, preparation of SOI material based on silicon substrate: select two double-polished silicon wafers, use high-temperature oxidation method to oxidize the front side of the silicon wafers to form a silicon dioxide insulating layer, then bond the silicon dioxide insulating layers of the two silicon wafers together in an ethylene glycol solution of bis(trihydroxymethylaminopropane), take them out and heat them on a flat and smooth iron plate electric furnace, then bake them in an oven, use nitrogen protection to complete pre-bonding, and then perform annealing under nitrogen protection; finally, thin the top silicon wafer to obtain SOI material based on silicon substrate;

[0055] Step S2, photolithography resistor area, ion implantation: Using the silicon substrate-based SOI material produced in step S1 as a substrate, photolithography is used to define a resistor area on the front side of the substrate, and ion implantation is performed to form the resistor area. The implanted ions are then activated by high-temperature thermal annealing.

[0056] Step S3, photolithography corrosion protection zone: defining the corrosion protection zone on the front side of the substrate by photolithography;

[0057] Step S4, wet etching: manufacturing the varistor by wet etching;

[0058] Step S5, making lead holes and metal leads: making lead holes and metal leads on the front side of the substrate;

[0059] Step S6, metallization and passivation: sputtering a metal layer for connecting the piezoresistive resistor on the varistor produced in step S4 to form a Wheatstone bridge, and depositing a passivation layer on the upper surface of the device by chemical vapor deposition to protect the device;

[0060] Step S7, photolithography of the backside corrosion area: performing photolithography on the backside corrosion area.

[0061] The temperature of the high-temperature oxidation in step S1 is 1100°C, the oxygen flow rate is controlled at 1 cm / s, and the thickness of the silicon dioxide insulating layer is ≤300nm; the mass percentage concentration of the ethylene glycol solution of bis(trihydroxymethylaminopropane) in step S1 is 6wt%; the temperature of the heating in step S1 is 190°C and the time is 3h; the temperature of the baking in step S1 is 310°C and the time is 4h; the temperature of the annealing treatment in step S1 is 1105°C and the time is 1.5h; the thinning treatment in step S1 is performed by mechanical grinding and polishing; the ion implanted substance in step S1 is boron ions or ions of other Group III elements, and the ion implantation dose is 1×10 20 atoms / square centimeter.

[0062] The high-temperature thermal annealing in step S2 is performed at a temperature of 1150° C. for 20 minutes under nitrogen atmosphere. The corrosion protection zone in step S2 is located at the outer edge of the resistance zone, and the resistance zone is contained within the corrosion protection zone. The wet etching in step S4 is isotropic etching, and the etching solution used includes the following components in weight percentage: acetic acid 23wt%, hydrofluoric acid 9wt%, tea polyphenols 2wt%, trihydroxymethyl methylglycine 2wt%, H2O29wt%, and the balance is deionized water.

[0063] Example 4, a process for manufacturing an SDB-type silicon MEMS high-temperature pressure sensor, comprising the following steps:

[0064] Step S1, preparation of SOI material based on silicon substrate: select two double-polished silicon wafers, use high-temperature oxidation method to oxidize the front side of the silicon wafers to form a silicon dioxide insulating layer, then bond the silicon dioxide insulating layers of the two silicon wafers together in an ethylene glycol solution of bis(trihydroxymethylaminopropane), take them out and heat them on a flat and smooth iron plate electric furnace, then bake them in an oven, use nitrogen protection to complete pre-bonding, and then perform annealing under nitrogen protection; finally, thin the top silicon wafer to obtain SOI material based on silicon substrate;

[0065] Step S2, photolithography resistor area, ion implantation: Using the silicon substrate-based SOI material produced in step S1 as a substrate, photolithography is used to define a resistor area on the front side of the substrate, and ion implantation is performed to form the resistor area. The implanted ions are then activated by high-temperature thermal annealing.

[0066] Step S3, photolithography corrosion protection zone: defining the corrosion protection zone on the front side of the substrate by photolithography;

[0067] Step S4, wet etching: manufacturing the varistor by wet etching;

[0068] Step S5, making lead holes and metal leads: making lead holes and metal leads on the front side of the substrate;

[0069] Step S6, metallization and passivation: sputtering a metal layer for connecting the piezoresistive resistor on the varistor produced in step S4 to form a Wheatstone bridge, and depositing a passivation layer on the upper surface of the device by chemical vapor deposition to protect the device;

[0070] Step S7, photolithography of the backside corrosion area: performing photolithography on the backside corrosion area.

[0071] The temperature of the high-temperature oxidation in step S1 is 1200°C, the oxygen flow rate is controlled at 1.2 cm / s, and the thickness of the silicon dioxide insulating layer is ≤300 nm; the mass percentage concentration of the ethylene glycol solution of bis(trihydroxymethylaminopropane) in step S1 is 7 wt %; the temperature of the heating in step S1 is 193°C and the time is 3.5 h; the temperature of the baking in step S1 is 320°C and the time is 4.5 h; the temperature of the annealing in step S1 is 1110°C and the time is 1.8 h; the thinning treatment in step S1 is performed by mechanical grinding and polishing; the ion implanted substance in step S1 is boron ions or ions of other Group III elements, and the ion implantation dose is 5×10 20 atoms / square centimeter.

[0072] The high temperature thermal annealing in step S2 is performed at a temperature of 1170° C. for 23 minutes under nitrogen atmosphere. The corrosion protection zone in step S2 is located at the outer edge of the resistance zone, and the resistance zone is included in the corrosion protection zone.

[0073] The wet etching in step S4 is isotropic etching, and the etching solution used includes the following components in weight percentage: acetic acid 24wt%, hydrofluoric acid 9.5wt%, tea polyphenols 2.5wt%, tris(hydroxymethyl)methylglycine 2.5wt%, H2O29.5wt%, and the balance is deionized water.

[0074] Example 5, a process for manufacturing an SDB-type silicon MEMS high-temperature pressure sensor, comprising the following steps:

[0075] Step S1, preparation of SOI material based on silicon substrate: select two double-polished silicon wafers, use high-temperature oxidation method to oxidize the front side of the silicon wafers to form a silicon dioxide insulating layer, then bond the silicon dioxide insulating layers of the two silicon wafers together in an ethylene glycol solution of bis(trihydroxymethylaminopropane), take them out and heat them on a flat and smooth iron plate electric furnace, then bake them in an oven, use nitrogen protection to complete pre-bonding, and then perform annealing under nitrogen protection; finally, thin the top silicon wafer to obtain SOI material based on silicon substrate;

[0076] Step S2, photolithography resistor area, ion implantation: Using the silicon substrate-based SOI material produced in step S1 as a substrate, photolithography is used to define a resistor area on the front side of the substrate, and ion implantation is performed to form the resistor area. The implanted ions are then activated by high-temperature thermal annealing.

[0077] Step S3, photolithography corrosion protection zone: defining the corrosion protection zone on the front side of the substrate by photolithography;

[0078] Step S4, wet etching: manufacturing the varistor by wet etching;

[0079] Step S5, making lead holes and metal leads: making lead holes and metal leads on the front side of the substrate;

[0080] Step S6, metallization and passivation: sputtering a metal layer for connecting the piezoresistive resistor on the varistor produced in step S4 to form a Wheatstone bridge, and depositing a passivation layer on the upper surface of the device by chemical vapor deposition to protect the device;

[0081] Step S7, photolithography of the backside corrosion area: performing photolithography on the backside corrosion area.

[0082] The temperature of the high-temperature oxidation in step S1 is 1230°C, the oxygen flow rate is controlled at 1.3 cm / s, and the thickness of the silicon dioxide insulating layer is ≤300 nm; the mass percentage concentration of the ethylene glycol solution of bis(trihydroxymethylaminopropane) in step S1 is 8 wt %; the temperature of the heating in step S1 is 195°C and the time is 4 h; the temperature of the baking in step S1 is 330°C and the time is 5 h; the temperature of the annealing in step S1 is 1120°C and the time is 2 h; the thinning treatment in step S1 is performed by mechanical grinding and polishing; the ion implanted substance in step S1 is boron ions or ions of other Group III elements, and the ion implantation dose is 1×10 21 atoms / square centimeter.

[0083] The high temperature thermal annealing in step S2 is performed at a temperature of 1180° C. for 25 minutes under nitrogen atmosphere. The corrosion protection zone in step S2 is located at the outer edge of the resistance zone, and the resistance zone is included in the corrosion protection zone.

[0084] The wet etching in step S4 is isotropic etching, and the etching solution used includes the following components in weight percentage: acetic acid 25wt%, hydrofluoric acid 10wt%, tea polyphenols 3wt%, tris(hydroxymethyl)methylglycine 3wt%, H2O2 10wt%, and the balance is deionized water.

[0085] Comparative Example

[0086] A manufacturing process for an SDB-type silicon MEMS high-temperature pressure sensor is substantially the same as that of Example 1, except that tea polyphenols and tris(hydroxymethyl)methylglycine are not added to the etching solution, and there is no step of photolithographically etching the protection zone.

[0087] In order to further illustrate the beneficial technical effects of the SDB-type silicon MEMS high-temperature pressure sensor manufacturing process involved in each embodiment of the present invention, relevant performance tests were conducted on the sensors manufactured by the SDB-type silicon MEMS high-temperature pressure sensor manufacturing process involved in Examples 1-5 and the comparative example. The test results show that the pressure sensitive resistors of the sensors manufactured in Examples 1-5 have no damage on the surface and good uniformity and consistency; the pressure sensitive resistors of the sensors of the comparative example products have obvious damage on the surface and poor uniformity and consistency.

[0088] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A manufacturing process for an SDB type silicon MEMS high temperature pressure sensor, characterized in that: The steps include: Step S1, preparation of SOI material based on silicon substrate: select two double-polished silicon wafers, use high-temperature oxidation method to oxidize the front side of the silicon wafers to form a silicon dioxide insulating layer, then bond the silicon dioxide insulating layers of the two silicon wafers together in an ethylene glycol solution of bis(trihydroxymethylaminopropane), take them out and heat them on a flat and smooth iron plate electric furnace, then bake them in an oven, use nitrogen protection to complete pre-bonding, and then perform annealing under nitrogen protection; finally, thin the top silicon wafer to obtain SOI material based on silicon substrate; Step S2, photolithography resistor area, ion implantation: Using the silicon substrate-based SOI material produced in step S1 as a substrate, photolithography is used to define a resistor area on the front side of the substrate, and ion implantation is performed to form the resistor area. The implanted ions are then activated by high-temperature thermal annealing. Step S3, photolithographic corrosion protection zone: defining the corrosion protection zone on the front side of the substrate by photolithography; the corrosion protection zone is located outside the resistance zone, and the resistance zone is included in the corrosion protection zone; Step S4, wet etching: manufacturing the varistor by wet etching; the etching solution used in the wet etching comprises the following components: acetic acid, hydrofluoric acid, tea polyphenols, tris(hydroxymethyl)methylglycine, H2O2 and deionized water; Step S5, making lead holes and metal leads: making lead holes and metal leads on the front side of the substrate; Step S6, metallization and passivation: sputtering a metal layer for connecting the piezoresistive resistor on the varistor produced in step S4 to form a Wheatstone bridge, and depositing a passivation layer on the upper surface of the device by chemical vapor deposition to protect the device; Step S7, photolithography of the backside corrosion area: performing photolithography on the backside corrosion area.

2. The SDB type silicon MEMS high temperature pressure sensor manufacturing process according to claim 1, characterized in that: The temperature of the high-temperature oxidation in step S1 is 930-1230° C., the oxygen flow rate is controlled at 0.7-1.3 cm / s, and the thickness of the silicon dioxide insulating layer is ≤300 nm.

3. The SDB type silicon MEMS high temperature pressure sensor manufacturing process according to claim 1, characterized in that: The mass percentage concentration of the ethylene glycol solution of bis(trihydroxymethylaminopropane) in step S1 is 3-8wt%.

4. The SDB type silicon MEMS high temperature pressure sensor manufacturing process according to claim 1, characterized in that: The heating temperature in step S1 is 185-195° C. and the time is 2-4 hours; the baking temperature in step S1 is 290-330° C. and the time is 3-5 hours.

5. The SDB type silicon MEMS high temperature pressure sensor manufacturing process according to claim 1, characterized in that: The temperature of the annealing treatment in step S1 is 1090-1120° C., and the time is 1-2 hours; the thinning treatment in step S1 is performed by mechanical grinding and polishing.

6. The SDB type silicon MEMS high temperature pressure sensor manufacturing process according to claim 1, characterized in that: The material of the ion implantation in step S1 is boron ions or ions of other Group III elements, and the ion implantation dose is 1×10 19 ~1×10 21 atoms / square centimeter.

7. The SDB type silicon MEMS high temperature pressure sensor manufacturing process according to claim 1, characterized in that: The high temperature thermal annealing in step S2 is performed at a temperature of 1120-1180° C. for 14-25 minutes under a nitrogen atmosphere.

8. The SDB type silicon MEMS high temperature pressure sensor manufacturing process according to claim 1, characterized in that: The wet etching in step S4 is isotropic etching, and the etching solution used includes the following components in weight percentage: acetic acid 20-25wt%, hydrofluoric acid 8-10wt%, tea polyphenols 1-3wt%, tris(hydroxymethyl)methylglycine 1-3wt%, H2O2 8-10wt%, and the balance is deionized water.