A silicon piezoresistive pressure sensor for rigidly packaging a sensitive chip and a manufacturing process

Abstract

The application relates to the technical field of silicon-based MEMS sensor, in particular to a silicon piezoresistive pressure sensor with rigidly packaged sensitive chip and a manufacturing process, which comprises a stainless steel pipe seat, a metal pressure guide column suspended on the stainless steel pipe seat, a silicon piezoresistive pressure sensitive chip fixed at the top end of the metal pressure guide column and a metal wire, the silicon piezoresistive pressure sensitive chip is electrically connected with the stainless steel pipe seat, a pipe seat electrode pad is arranged on the stainless steel pipe seat, and the outer welding opening at the bottom end of the metal pressure guide column and the inner cavity bottom end welding opening of the stainless steel pipe seat are fusion welded into an alloy welding seam; the silicon piezoresistive pressure sensitive chip sequentially comprises a glass lining piece, a peak film pressure sensing diaphragm, a diffused silicon sensitive bridge resistor, a diffused silicon connecting wire, a diffused silicon homogenous pad, a metal film pad and a diffused silicon temperature sensing resistor from bottom to top. Through the cooperation of the above structure, the elastic characteristics of the silicon piezoresistive pressure sensitive chip, such as no hysteresis, high fatigue life and small static pressure influence, are continued, and the positive pressure overload capacity of the pressure sensor is also improved.

Description

Technical Field

[0001] This invention relates to the field of silicon-based MEMS sensor technology, and in particular to a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip and its manufacturing process. Background Technology

[0002] For silicon piezoresistive gauge pressure and differential pressure sensors, the pressure-sensitive chip packaged on the socket must airtightly isolate the pressure chamber being measured from the pressure reference chamber. The airtight isolation interface becomes part of the functional structure of the pressure-sensing chamber and is inevitably affected by the measured pressure and the environment. It needs to have ideal and matched mechanical properties and mechanical strength.

[0003] The airtight sealing structure formed by conventional liquid or adhesive bonding media inevitably has physical and chemical defects and limitations. Not only is it difficult to maintain the ideal elastic characteristics and performance stability of silicon-based pressure-sensitive chips, but it often becomes the main hidden danger for the structural reliability, robustness and long-term life degradation and failure of pressure sensors.

[0004] In view of this, in order to overcome the above-mentioned technical problems, the present invention proposes a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip and a manufacturing process, thereby solving the above-mentioned technical problems. Summary of the Invention

[0005] The main objective of this invention is to provide a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip and its manufacturing process. All pressure-sensing functional components of the silicon piezoresistive pressure sensor are sealed using a solid rigid hermetically tight seal that matches thermal stress. The Young's modulus or pressure resistance stiffness of the sealing interface is far superior to that of liquid or soft adhesives, eliminating the potential problems such as creep, hermetically tight deterioration, and stress mismatch caused by the latter as functional components of the pressure sensor. The sensor performance continues the ideal elastic characteristics of silicon piezoresistive pressure sensitive chips, such as no hysteresis, high fatigue life, and minimal static pressure influence, effectively solving the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip includes a stainless steel tube base, a metal pressure guiding column suspended on the stainless steel tube base, a silicon piezoresistive pressure sensitive chip fixed at the top of the metal pressure guiding column, and a metal wire. The silicon piezoresistive pressure sensitive chip is electrically connected to the stainless steel tube base. A tube base electrode pad is installed on the stainless steel tube base. The outer edge of the bottom end of the metal pressure guiding column is fused with the bottom end of the stainless steel tube base to form an alloy weld.

[0008] The metal pressure guiding column is provided with a pressure guiding column through hole along the central axis, and a pressure guiding column tail tube is provided at the bottom end of the pressure guiding column through hole;

[0009] The silicon piezoresistive pressure-sensitive chip, from bottom to top, includes a glass substrate, a peak-film pressure-sensitive diaphragm, a diffused silicon sensitive bridge resistor, a diffused silicon interconnect, a diffused silicon homogeneous pad, a metal film pad, a diffused silicon temperature-sensitive resistor, and a silicon dioxide layer.

[0010] The silicon piezoresistive pressure-sensitive chip, the glass substrate, and the top surface of the metal pressure-conducting pillar form a rigid hermetically sealed interface or a molten-sealed interface with a Young's modulus and compressive strength higher than that of brittle solids. The rigid hermetically sealed interface is made of insulating glass, and an electrostatic sealing interface is provided between the top surface of the metal pressure-conducting pillar and the glass substrate.

[0011] Preferably, the stainless steel tube base, metal pressure guiding column, silicon piezoresistive pressure sensitive chip, and metal wire are arranged from bottom to top.

[0012] Preferably, the cross-section of the single-crystal silicon on the glass substrate of the silicon piezoresistive pressure sensitive chip is shaped like an inverted mountain, with the inverted height of the central peak being flush with the inverted heights of the two side peaks. The side length of the tangent edge at the root of the side peak determines the planar dimensions of the peak film pressure-sensitive film, and the vertical distance between the root surface and the top surface of the silicon piezoresistive pressure sensitive chip determines the thickness of the peak film pressure-sensitive film. The center of the diagonal of the plane of the peak film pressure-sensitive film overlaps with the center of the diagonal of the flat surface of the silicon piezoresistive pressure sensitive chip.

[0013] Preferably, the planar shape, dimensions, and arrangement of the diffused silicon sensitive bridge resistor, diffused silicon connecting line, diffused silicon homogeneous pad, and metal film pad are centrally symmetrical about the central axis of the silicon piezoresistive pressure sensitive chip.

[0014] Preferably, the diffused silicon temperature-sensing resistors are arranged in planar arrays on the edge region of the silicon piezoresistive pressure-sensitive chip outside the peak-film pressure-sensing diaphragm, and their sheet resistance values ​​are the same as those of the diffused silicon sensitive bridge resistors.

[0015] Preferably, the coefficient of thermal expansion and contraction of the glass substrate is matched with that of monocrystalline silicon. A set of glass substrate grooves is located in the central region of the surface that is rigidly sealed to the substrate of the silicon piezoresistive pressure sensitive chip. The three-dimensional dimensions of the glass substrate grooves allow for elastic deformation of the flat surface of the peak film pressure-sensitive diaphragm under pressure, while also preventing excessive overload pressure deformation. The glass substrates of the gauge pressure and differential pressure silicon piezoresistive pressure sensitive chips have glass substrate through holes in their centers, while the glass substrates of the absolute pressure silicon piezoresistive pressure sensitive chips do not have glass substrate through holes in their centers.

[0016] A manufacturing process for a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip includes the following steps;

[0017] S1. Through the ionic bonding force formed by glass melting or the electrostatic attraction generated by anodic bonding, a rigid hermetically sealed interface is formed between the glass substrate of the silicon piezoresistive pressure sensitive chip and the metal pressure-conducting pillar. The silicon piezoresistive pressure sensitive chip is hermetically and rigidly fixed on the metal pressure-conducting pillar.

[0018] The ion bonding method involves adding insulating glass with a coefficient of thermal expansion between the glass substrate plane and the metal pressure-conducting pillar plane of the silicon piezoresistive pressure-sensitive chip. Through the ion bonding force generated during the melting and solidification process, the insulating glass simultaneously generates an airtight fusion sealing interface with the contact surfaces of the two substrates. The interface structure has greater stiffness and pressure resistance than the glass body.

[0019] Electrostatic attraction sealing is a method in which the polished surface of the metal pressure-conducting pillar and the polished surface of the glass substrate of the silicon piezoresistive pressure-sensitive chip are attracted by positive and negative charges under the combined action of an external electric field and a temperature field, generating a hermetically tight electrostatic sealing interface without a dielectric layer. Its Young's modulus and withstand pressure strength are greater than those of the substrate glass body.

[0020] S2. The bottom weld of the metal pressure guiding column and the bottom weld of the stainless steel tube seat are fused together to form an alloy weld. The silicon piezoresistive pressure sensitive chip, which is fixed on the metal pressure guiding column, is suspended in the inner cavity of the stainless steel tube seat. The structural rigidity and pressure resistance of the alloy weld are not lower than those of the body material, so as to achieve airtight rigid isolation between the pressure measurement cavity and the reference pressure cavity of the sensor.

[0021] S3. Lightly doped with P-type boron impurities and subjected to oxygen-free atmosphere heat treatment, shallow junction boron diffused silicon sensitive bridge resistor and diffused silicon temperature sensing resistor are fabricated.

[0022] After light doping and heat treatment, low-resistance interconnects for diffused silicon bridge resistors and temperature-sensing resistors and diffused silicon homogeneous pads are fabricated by doping with P-type boron impurities at solid solution concentration and performing heat treatment in an oxygen-free atmosphere.

[0023] Ohmic contact holes are sequentially etched, PVD-deposited metal films are deposited, and metal film pads are etched on silicon dioxide above each diffused silicon homogeneous pad.

[0024] S4. Peak-film pressure-sensitive diaphragms are fabricated by anisotropic wet chemical etching with chamfer compensation.

[0025] S5. Through the attraction generated by electrostatic bonding, the outer plane of the glass substrate groove, which has a glass substrate with or without a through-hole and whose coefficient of thermal expansion matches that of silicon, is hermetically and rigidly sealed to the side peak end face of the silicon piezoresistive pressure sensitive chip. The sensitive chip wafer and the glass substrate are stacked into a single wafer. Sensitive chips with a central through-hole are used to measure gauge pressure and differential pressure, while those without a central through-hole constitute absolute pressure sensitive chips.

[0026] S6. Divide the electrostatically bonded sensitive chip wafer into discrete pressure silicon piezoresistive pressure sensitive chips.

[0027] The beneficial effects of this invention are:

[0028] 1. The silicon piezoresistive pressure sensor with a rigid packaged sensitive chip and its manufacturing process described in this invention uses a solid rigid airtight seal with matching thermal stress to seal all pressure-sensing functional components of the silicon piezoresistive pressure sensor. The Young's modulus or pressure resistance stiffness of the sealing interface is far superior to that of the sealing interface of liquid or soft adhesive, eliminating the hidden dangers of creep, airtightness deterioration, stress mismatch and other problems caused by the latter as functional components of the pressure sensor. The sensor performance continues the ideal elastic characteristics of silicon piezoresistive pressure sensitive chip, such as no hysteresis, high fatigue life and small static pressure effect.

[0029] 2. The silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip and its manufacturing process described in this invention, wherein the sensitive chip is suspended in the inner cavity of the sensor socket without any direct contact with the socket, isolating it from the additional stress of external components such as the socket; the central groove of the glass substrate of the silicon piezoresistive pressure sensor can prevent excessive displacement of the chip peak film pressure-sensing diaphragm due to deflection, thereby improving the positive pressure overload capacity of the pressure sensor.

[0030] 3. The rigid-packaged silicon piezoresistive pressure sensor and its manufacturing process described in this invention have significant advantages over the classic flat piezoresistive diaphragm in terms of intrinsic piezoresistive sensitivity, linearity, output symmetry, and overload capacity. The diffused silicon temperature-sensing resistor on the silicon piezoresistive pressure sensor chip can not only provide the in-situ ambient temperature signal for real-time measurement of the sensitive bridge resistance, but also improve the thermal drift characteristics of the sensor sensitivity. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Figure 1 This is a top view of a silicon piezoresistive pressure sensor with a rigid packaged sensitive chip and its manufacturing process, according to the present invention.

[0033] Figure 2 This invention relates to a rigidly packaged silicon piezoresistive pressure sensor with a sensitive chip and its manufacturing process for a silicon piezoresistive gauge or differential pressure sensor. Figure 1 A cross-sectional view cut along the longitudinal dashed line.

[0034] Figure 3 This invention relates to a rigidly packaged silicon piezoresistive pressure sensor and its manufacturing process for a gauge pressure or differential pressure sensing chip. Figure 1 A cross-sectional view cut along the longitudinal dashed line.

[0035] Figure 4 This is a longitudinal cross-sectional view of a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip, and the manufacturing process of the present invention. The sensitive chip is rigidly and airtightly fixed on a metal pressure-conducting column by the glass fusion ion bonding force.

[0036] Figure 5 This is a longitudinal cross-sectional view of a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip and its manufacturing process, showing the sensitive chip being airtightly and rigidly fixed to a metal pressure-conducting column by electrostatic attraction.

[0037] In the diagram: 1. Silicon piezoresistive pressure-sensitive chip; 101. Diffused silicon sensitive bridge resistor; 102. Diffused silicon connecting wire; 103. Diffused silicon homogeneous pad; 104. Metal film pad; 105. Diffused silicon temperature-sensitive resistor; 106. Silicon dioxide layer; 107. Peak film pressure-sensitive diaphragm; 108. Glass backing; 109. Glass backing groove; 110. Glass backing through-hole; 2. Metal pressure-conducting pillar; 201. Pressure-conducting pillar through-hole; 202. Pressure-conducting pillar tail tube; 203. Insulating glass; 204. Fusion sealing interface; 205. Electrostatic sealing interface; 3. Stainless steel tube base; 301. Tube base electrode pad; 302. Alloy weld; 4. Metal wire. Detailed Implementation

[0038] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0039] like Figure 1-5 As shown, a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip includes a stainless steel tube base 3, a metal pressure-conducting column 2 suspended on the stainless steel tube base 3, a silicon piezoresistive pressure-sensitive chip 1 fixed to the top of the metal pressure-conducting column 2, and a metal wire 4. The silicon piezoresistive pressure-sensitive chip 1 is electrically connected to the stainless steel tube base 3. A tube base electrode pad 301 is mounted on the stainless steel tube base 3. The outer edge of the bottom end of the metal pressure-conducting column 2 is fused with the bottom end of the inner cavity of the stainless steel tube base 3 to form an alloy weld 302. The metal pressure-conducting column 2 has a pressure-conducting column through-hole 201 along its central axis, and a pressure-conducting column tail tube 202 is provided at the bottom end of the pressure-conducting column through-hole 201. The silicon piezoresistive pressure-sensitive chip 1 is electrically connected to the stainless steel tube base 3. The stainless steel tube base 3 has a tube base electrode pad 301 installed on the stainless steel tube base 3. The outer edge of the bottom end of the metal pressure-conducting column 2 is fused with the outer edge of the metal pressure-conducting column 2 to form an alloy weld 302. The metal pressure-conducting column 2 has a pressure-conducting column through-hole 201 along its central axis, and a pressure-conducting column tail tube 202 is provided at the bottom end of the pressure-conducting column through-hole 201. The silicon piezoresistive pressure-sensitive chip 1 is electrically connected to the stainless steel tube base 3. The outer edge of the bottom end of the metal pressure-conducting column 2 is fused with the outer edge of the metal pressure-conducting column 2 to form a silicon pressure-conducting column 1. The outer edge of the metal pressure-conducting column 2 is electrically connected to the stainless steel tube base The pressure-sensitive chip 1, from bottom to top, includes a glass substrate 108, a peak-film pressure-sensitive diaphragm 107, a diffused silicon sensitive bridge resistor 101, a diffused silicon connecting line 102, a diffused silicon homogeneous pad 103, a metal film pad 104, a diffused silicon temperature-sensitive resistor 105, and a silicon dioxide layer 106. A rigid hermetically sealed interface or fused sealing interface 204 with a Young's modulus and pressure resistance higher than that of brittle solids is formed between the top surfaces of the silicon piezoresistive pressure-sensitive chip 1, the glass substrate 108, and the metal pressure-conducting pillar 2. The rigid hermetically sealed interface is insulating glass 203, and an electrostatic sealing interface 205 is provided between the top surface of the metal pressure-conducting pillar 2 and the glass substrate 108.

[0040] In one embodiment of the present invention, the stainless steel tube base 3, the metal pressure-conducting column 2, the silicon piezoresistive pressure-sensitive chip 1, and the metal wire 4 are arranged from bottom to top; the cross-section of the single crystal silicon on the glass substrate of the silicon piezoresistive pressure-sensitive chip 1 is shaped like an inverted mountain, with the inverted height of the central peak being flush with the inverted heights of the two side peaks, the side length of the tangent edge at the root of the side peaks determining the planar dimensions of the peak film pressure-sensitive diaphragm 107, and the vertical distance between the root surface and the top surface of the silicon piezoresistive pressure-sensitive chip 1 determining the thickness of the peak film pressure-sensitive diaphragm 107. The center of the diagonal faces overlaps with the center of the flat diagonal faces of the silicon piezoresistive pressure sensitive chip 1; the planar shape, dimensions, and arrangement of the diffused silicon sensitive bridge resistor 101, diffused silicon connecting line 102, diffused silicon homogeneous pad 103, and metal film pad 104 are centrally symmetrical about the central axis of the silicon piezoresistive pressure sensitive chip 1; the diffused silicon temperature-sensing resistor 105 is arranged in a planar manner in the edge region of the silicon piezoresistive pressure sensitive chip 1 outside the peak film pressure-sensing diaphragm 107, and its sheet resistance value is the same as that of the diffused silicon sensitive bridge resistor 101.

[0041] In one embodiment of the present invention, the coefficient of thermal expansion and contraction of the glass substrate 108 is matched with that of single-crystal silicon. A set of glass substrate grooves 109 are provided in the central region of the surface that is rigidly sealed to the substrate of the silicon piezoresistive pressure sensitive chip 1. The three-dimensional dimensions of the glass substrate grooves 109 are designed to allow for elastic deformation of the flat surface of the peak film pressure-sensitive diaphragm under pressure, while also preventing excessive overload pressure deformation. The glass substrate 108 of the gauge pressure and differential pressure silicon piezoresistive pressure sensitive chip 1 has a glass substrate through hole 110 in the center, while the glass substrate 108 of the absolute pressure silicon piezoresistive pressure sensitive chip 1 does not have a glass substrate through hole 110 in the center.

[0042] A manufacturing process for a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip includes the following steps;

[0043] S1. Through the ionic bonding force formed by glass melting or the electrostatic attraction generated by anodic bonding, a rigid hermetically sealed interface is formed between the glass substrate 108 of the silicon piezoresistive pressure sensitive chip 1 and the metal pressure guiding post 2. The silicon piezoresistive pressure sensitive chip 1 is hermetically and rigidly fixed on the metal pressure guiding post 2.

[0044] The ion bonding method involves adding insulating glass 203 with a coefficient of thermal expansion between the glass substrate 108 plane and the metal pressure-conducting pillar 2 plane of the silicon piezoresistive pressure-sensitive chip 1. Through the ion bonding force generated during the melting and solidification process, the insulating glass 203 simultaneously generates an airtight fusion sealing interface 204 with the contact surfaces of the two surfaces. The interface structure has a stiffness and pressure resistance greater than that of the glass body.

[0045] The electrostatic attraction sealing method is achieved by the combined action of an external electric field and a temperature field. The polished surface of the metal pressure-conducting pillar 2 and the polished surface of the glass substrate 108 of the silicon piezoresistive pressure-sensitive chip 1 are attracted by positive and negative charges to generate a hermetic electrostatic sealing interface 205 without a dielectric layer. Its Young's modulus and withstand pressure strength are greater than those of the substrate glass body.

[0046] S2. The bottom weld of the metal pressure guiding column 2 and the bottom weld of the inner cavity of the stainless steel tube seat 3 are fused together to form an alloy weld 302. The silicon piezoresistive pressure sensitive chip 1, which is fixed on the metal pressure guiding column 2, is suspended in the inner cavity of the stainless steel tube seat 3. The structural rigidity and pressure resistance of the alloy weld 302 are not lower than those of the body material, so as to achieve airtight rigid isolation between the pressure measurement cavity and the reference pressure cavity of the sensor.

[0047] S3. Lightly doped with P-type boron impurities and subjected to oxygen-free atmosphere heat treatment, shallow junction boron diffused silicon sensitive bridge resistor 101 and diffused silicon temperature sensing resistor 105 are fabricated.

[0048] After light doping and heat treatment, the low-resistance connection line 102 of diffused silicon bridge resistor 101 and temperature sensing resistor 105 and diffused silicon homogeneous pad 103 are fabricated by doping with P-type boron impurity of solid solution concentration and heat treatment in oxygen-free atmosphere.

[0049] Ohmic contact holes, PVD-deposited metal films, and metal film pads 104 are sequentially etched on silicon dioxide buried pads 106 above each diffused silicon homogeneous pad 103.

[0050] S4. Peak film pressure-sensitive diaphragm 107 is fabricated by anisotropic chemical wet etching with chamfer compensation.

[0051] S5. Through the attraction generated by electrostatic bonding, the outer plane of the glass substrate groove 109 of the glass substrate 108 with glass substrate through hole 110 or without through hole and matching the thermal expansion coefficient of silicon is hermetically and rigidly sealed with the side peak end face of silicon piezoresistive pressure sensitive chip 1. The sensitive chip wafer and the glass substrate are stacked into a single wafer. Sensitive chips with central through hole measure gauge pressure and differential pressure, and sensitive chips without central through hole constitute absolute pressure type.

[0052] S6. Divide the electrostatically bonded sensitive chip wafer into discrete pressure silicon piezoresistive pressure sensitive chips 1.

[0053] It should be noted that this invention relates to a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip and its manufacturing process, as described below. Figure 1 Zhihe Figure 3As shown, a shallow junction boron diffused silicon sensitive bridge resistor 101 and a diffused silicon temperature-sensing resistor 105 are fabricated by lightly doping with P-type boron impurities and undergoing oxygen-free atmosphere heat treatment. After light doping and heat treatment, a low-resistance connection line 102 and a diffused silicon homogeneous pad 103 are fabricated by doping with P-type boron impurities at a solid solution concentration and undergoing oxygen-free atmosphere heat treatment. Ohmic contact holes, PVD-deposited metal films, and metal film pads 104 are sequentially etched on silicon dioxide buried 106 above each diffused silicon homogeneous pad 103. Anisotropy is compensated by chamfering. Chemical wet etching is used to fabricate a peak-film pressure-sensitive diaphragm 107. Through the attractive force generated by electrostatic bonding, the outer plane of the glass substrate groove 109 (either with a glass substrate through-hole 110 or without through-holes and matching the thermal expansion coefficient of silicon) is hermetically and rigidly sealed to the peak end face of the silicon piezoresistive pressure-sensitive chip 1. The sensitive chip wafer and the glass substrate are stacked into a single wafer. Sensitive chips with a central through-hole measure gauge pressure and differential pressure, while those without a central through-hole constitute absolute pressure sensitive chips. The electrostatically bonded sensitive chip wafer is then diced into discrete silicon piezoresistive pressure-sensitive chips 1.

[0054] Instructions attached Figure 5 The electrostatic bonding process of the hermetically sealed rigid package of the pressure silicon piezoresistive pressure sensitive chip 1 of the present invention includes at least the following specific steps: using CMP, the top surface of the metal pressure-conducting pillar 2, which matches the coefficient of thermal expansion of the glass substrate 108 of the sensitive chip, is optically mirror polished; through the attractive force generated by electrostatic bonding, the glass substrate 108 of the discrete silicon piezoresistive pressure sensitive chip 1 and the polished surface of the metal pressure-conducting pillar 2 are hermetically and rigidly sealed together, and the sensitive chip is fixed on the metal pressure-conducting pillar 2, as described in the attached diagram. Figure 2 As shown, an alloy weld 302 is formed by hot-melt welding of the outer diameter weld of the bottom end of the metal pressure guiding column 2 to the bottom end weld of the inner cavity of the stainless steel tube seat 3. The silicon piezoresistive pressure sensitive chip 1, which is fixed on the metal pressure guiding column 2, is suspended in the stainless steel tube seat 3; as described in the attached diagram. Figure 1 and attached Figure 2 As shown, the two ends of the metal wire 4 are bonded to the metal film pad 104 of the silicon piezoresistive pressure sensitive chip 1 and the tube electrode pad 301 of the stainless steel tube seat 3, respectively, to realize the electrical connection between the inside and outside of the sensor.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip, characterized in that, The device includes a stainless steel tube base (3), a metal pressure-conducting column (2) suspended on the stainless steel tube base (3), a silicon piezoresistive pressure-sensitive chip (1) fixed at the top of the metal pressure-conducting column (2), and a metal wire (4). The silicon piezoresistive pressure-sensitive chip (1) is electrically connected to the stainless steel tube base (3). The stainless steel tube base (3) is equipped with a tube base electrode pad (301). The outer edge of the bottom end of the metal pressure-conducting column (2) is fused with the bottom end of the inner cavity of the stainless steel tube base (3) to form an alloy weld (302). The metal pressure guiding column (2) is provided with a pressure guiding column through hole (201) along the central axis, and a pressure guiding column tail tube (202) is provided at the bottom end of the pressure guiding column through hole (201). The silicon piezoresistive pressure sensitive chip (1) includes, from bottom to top, a glass substrate (108), a peak film pressure-sensitive film (107), a diffused silicon sensitive bridge resistor (101), a diffused silicon connecting line (102), a diffused silicon homogeneous pad (103), a metal film pad (104), a diffused silicon temperature-sensitive resistor (105), and a silicon dioxide layer (106). A rigid hermetically sealed interface or fused sealing interface (204) with a Young's modulus and pressure resistance higher than that of brittle solids is formed between the top surface of the silicon piezoresistive pressure sensitive chip (1), the glass substrate (108) and the metal pressure guiding column (2). The rigid hermetically sealed interface is insulating glass (203). An electrostatic sealing interface (205) is provided between the top surface of the metal pressure guiding column (2) and the glass substrate (108). The stainless steel tube base (3), metal pressure guiding column (2), silicon piezoresistive pressure sensitive chip (1) and metal wire (4) are arranged from bottom to top; The single-crystal silicon cross-section on the glass substrate of the silicon piezoresistive pressure sensitive chip (1) is shaped like an inverted mountain. The inverted height of the middle peak is level with the inverted height of the two side peaks. The side length of the tangent edge at the root of the side peak determines the planar dimensions of the peak film pressure-sensitive film (107). The vertical distance between the root surface and the top surface of the silicon piezoresistive pressure sensitive chip (1) determines the thickness of the peak film pressure-sensitive film (107). The center of the diagonal of the plane of the peak film pressure-sensitive film (107) overlaps with the center of the diagonal of the flat surface of the silicon piezoresistive pressure sensitive chip (1). The planar shape, dimensions, and arrangement of the diffused silicon sensitive bridge resistor (101), diffused silicon connecting line (102), diffused silicon homogeneous pad (103), and metal film pad (104) are centrally symmetrical about the central axis of the silicon piezoresistive pressure sensitive chip (1). The diffused silicon temperature-sensitive resistor (105) is arranged in a planar manner on the edge region of the silicon piezoresistive pressure-sensitive chip (1) outside the peak film pressure-sensitive diaphragm (107), and its sheet resistance value is the same as that of the diffused silicon sensitive bridge resistor (101). The coefficient of thermal expansion and contraction of the glass substrate (108) is matched with that of single crystal silicon. There is a set of glass substrate grooves (109) in the central area of ​​the surface that is rigidly sealed to the substrate of the silicon piezoresistive pressure sensitive chip (1). The three-dimensional dimensions of the glass substrate grooves (109) allow the flat surface of the peak film pressure sensing diaphragm to be elastically deflected under pressure, and can also block excessive overload pressure deflection. The center of the glass substrate (108) of the gauge pressure and differential pressure silicon piezoresistive pressure sensitive chip (1) is provided with a glass substrate through hole (110), while the center of the glass substrate (108) of the absolute pressure silicon piezoresistive pressure sensitive chip (1) is not provided with a glass substrate through hole (110).

2. The manufacturing process of a silicon piezoresistive pressure sensor with a rigidly packaged sensitive chip according to claim 1, characterized in that: Includes the following steps; S1. Through the ionic bonding force formed by glass melting or the electrostatic attraction generated by anodic bonding, a rigid hermetically sealed interface is formed between the glass substrate (108) of the silicon piezoresistive pressure sensitive chip (1) and the metal pressure guiding column (2). The silicon piezoresistive pressure sensitive chip (1) is hermetically and rigidly fixed on the metal pressure guiding column (2). The ion bonding method involves adding insulating glass (203) with a coefficient of thermal expansion between the glass substrate (108) and the metal pressure-conducting pillar (2) of the silicon piezoresistive pressure-sensitive chip (1). Through the ion bonding force generated during the melting and solidification process, the insulating glass (203) simultaneously generates an airtight fusion sealing interface (204) with the contact surfaces of the two substrates. The interface structure has a stiffness and pressure resistance greater than that of the glass body. The electrostatic attraction sealing method is a gas-tight electrostatic sealing interface (205) without dielectric layer generated by the attraction of positive and negative charges between the polished surface of the metal pressure column (2) and the polished surface of the glass substrate (108) of the silicon piezoresistive pressure sensitive chip (1) under the combined action of external electric field and temperature field. Its Young's modulus and pressure resistance are greater than those of the substrate glass body. S2. The bottom weld of the metal pressure guide column (2) and the bottom weld of the stainless steel tube seat (3) are fused together to form an alloy weld (302). The silicon piezoresistive pressure sensitive chip (1) fixed on the metal pressure guide column (2) is suspended in the inner cavity of the stainless steel tube seat (3). The structural rigidity and pressure resistance of the alloy weld (302) are not lower than those of the body material, so as to realize the airtight rigid isolation between the pressure measurement cavity and the reference pressure cavity of the sensor. S3. Lightly doped with P-type boron impurities and subjected to oxygen-free atmosphere heat treatment, shallow junction boron diffused silicon sensitive bridge resistor (101) and diffused silicon temperature sensing resistor (105) are fabricated. After light doping and heat treatment, low-resistance interconnects (102) for diffused silicon bridge resistor (101) and temperature sensing resistor (105) and diffused silicon homogeneous pad (103) are fabricated by doping with P-type boron impurities at solid solution concentration and heat treatment in an oxygen-free atmosphere. Ohmic contact holes, PVD deposited metal films, and metal film pads (104) are sequentially etched on the silicon dioxide buried pad (106) above each diffused silicon homogeneous pad (103). S4. Peak film pressure-sensitive diaphragm (107) is fabricated by anisotropic chemical wet etching with chamfer compensation. S5. Through the attraction generated by electrostatic bonding, the outer plane of the glass substrate groove (109) of the glass substrate with glass substrate through hole (110) or without through hole and matching the thermal expansion coefficient of silicon is hermetically and rigidly sealed with the side peak end face of the silicon piezoresistive pressure sensitive chip (1). The sensitive chip wafer and the glass substrate are stacked into a single wafer. The sensitive chip with central through hole measures gauge pressure and differential pressure, and the sensitive chip without central through hole constitutes absolute pressure. S6. Divide the electrostatically bonded sensitive chip wafer into discrete pressure silicon piezoresistive pressure sensitive chips (1).

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