Pressure sensor chip capable of reducing output drift in situ and preparation method thereof

Abstract

The invention belongs to the technical field of MEMS piezoresistive pressure sensors, and particularly relates to a pressure sensor chip capable of reducing output drift in situ and a preparation method thereof, and the pressure sensor chip comprises a silicon substrate, first glass and second glass. The front surface of the silicon substrate comprises a plurality of sensitive resistors and calibration resistors, the sensitive resistors form a first Wheatstone bridge and are positioned in a stress concentration region of the sensitive structure, and the calibration resistors form a second Wheatstone bridge and are positioned in a stress-free region of the clamped structure; according to the pressure sensor chip, the sensitive resistor and the calibration resistor are prepared through a doping process, the difference value of the first Wheatstone bridge and the second Wheatstone bridge formed by the sensitive resistor and the calibration resistor is a pressure signal, and an offset signal caused by residual stress in the processing and packaging process of the pressure sensor chip is removed through the structure; the output drift amount is reduced in situ, and the performance of the pressure sensor is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of MEMS piezoresistive pressure sensors, and in particular relates to a pressure sensor chip for in-situ reduction of output drift and a preparation method thereof. Background Art

[0002] Pressure sensors are one of the most widely used sensors. They can be applied to the automotive industry, chemical industry, petroleum industry, aerospace, ships and submarines, consumer electronics and other fields, bringing convenience to people's lives and production. With the development of MEMS (micro-electromechanical system) technology, MEMS pressure sensors based on the piezoresistive effect have many significant advantages such as small size, low cost, integration, high linearity, and high sensitivity. They are increasingly used in pressure sensors.

[0003] Under ideal conditions, the output of MEMS piezoresistive pressure sensors is constant at the same pressure. In actual use, the output of MEMS piezoresistive pressure sensors at the same pressure will drift over time. The above phenomenon is caused by residual stress caused by the manufacturing and packaging process of the pressure sensor chip.

[0004] The manufacturing process of MEMS piezoresistive pressure sensor chips includes photolithography, etching, coating, thinning, polishing and bonding. Each process step in the chip processing may bring stress to the chip, such as residual stress from thin film manufacturing, residual stress from thinning and polishing, and residual stress from bonding. During the packaging process of MEMS piezoresistive pressure sensor chips, the chip needs to be fixed on the substrate through silicone. The mismatch between the thermal expansion coefficients of the substrate and the chip material causes thermal residual stress and residual stress caused by the glue. In some application fields, the pressure sensor chip needs to directly contact the pressure source for measurement, and needs to accurately provide the two parameters of pressure and temperature of the pressure source.

[0005] In summary, existing pressure sensor chips are affected by residual stress, resulting in reduced performance and inability to accurately provide the two parameters of pressure and temperature of the pressure source. Summary of the invention

[0006] In order to solve the above-mentioned problems in the prior art, the present invention, on the one hand, adopts a pressure sensor chip for in-situ reduction of output drift, including a silicon substrate 3, wherein a pressure-sensitive silicon film is provided in the silicon substrate 3, wherein the area corresponding to the pressure-sensitive silicon film is a stress concentration area of ​​the sensitive structure, and the remaining area of ​​the silicon substrate is a stress-free area of ​​the fixed support structure; a heavily doped wire 7 and a plurality of sensitive resistors 6 are prepared on the front side of the silicon substrate, wherein the plurality of sensitive resistors 6 are connected through the heavily doped wire 7 to form a first Wheatstone bridge, and are located in the stress concentration area of ​​the sensitive structure; the pressure sensor chip also includes: a first glass 9 and a second glass 1; the front side of the silicon substrate 3 is bonded to the first glass 9, and the back side of the silicon substrate 3 is bonded to the second glass 1; the front side of the silicon substrate 3 also includes a plurality of calibration resistors 5, wherein the plurality of calibration resistors 5 are connected through the heavily doped wire 7 to form a second Wheatstone bridge, and are located in the stress-free area of ​​the fixed support structure.

[0007] The first glass 9 is provided with a blind hole 10 and a through hole. One side of the blind hole 10 of the first glass 9 and the silicon substrate 3 form an absolute pressure vacuum cavity structure. A platinum resistor 11 is provided on the other side of the first glass 9. The second glass 1 is provided with a through hole 2 for introducing a pressure signal.

[0008] The silicon substrate 3 is of N-type and has a thickness of 400 μm.

[0009] The thickness of the first glass 9 is 400-500 μm, and the thickness of the second glass 9 is 800-1000 μm.

[0010] The front side of the silicon substrate 3 further includes a metal PAD 8 , which is connected to the heavily-doped wire 7 .

[0011] The number of sensitive resistors 6 and calibration resistors 5 are both four, and they correspond one to one; the four sensitive resistors 6 are symmetrically distributed at the center positions of the four sides of the stress concentration area of ​​the sensitive structure, among which the placement directions of two sensitive resistors 6 are parallel to the sides corresponding to their positions, and the placement directions of the remaining two sensitive resistors 6 are perpendicular to the sides corresponding to their positions; the four calibration resistors 5 are respectively located outside the corresponding sensitive resistors 6 and are placed in the same direction as the corresponding sensitive resistors 6, and the four calibration resistors 5 are at the same distance from the corresponding sensitive resistors 6 and are on the same axis.

[0012] On the other hand, a method for preparing a pressure sensor chip for in-situ reducing output drift includes:

[0013] S1: Obtain an N-type single-throw silicon wafer and perform standard cleaning on the N-type single-throw silicon wafer;

[0014] S2: preparing a sensitive resistor, a calibration resistor and a heavily doped conductor on the front side of the product obtained in step S1 by a doping process;

[0015] S3: preparing a metal PAD on the front side of the product obtained in step S2;

[0016] S4: preparing a pressure-sensitive silicon film and a cavity thereunder on the product obtained in step S3;

[0017] S5: Photolithography of bonding conduction area and metal PAD area on the front side of the product obtained in step S4;

[0018] S6: etching the bonding conduction area and the metal PAD area of ​​the product obtained in step S5 to obtain a prepared silicon substrate;

[0019] S7: Obtain a first glass and a second glass, and bond the front side of the prepared silicon substrate to the first glass, and the back side to the second glass.

[0020] Preparing a sensitive resistor, a calibration resistor and a heavily doped conductor on the front side of the product obtained in step S1 includes:

[0021] S21: growing a thin layer of silicon dioxide on both sides of the product obtained in step S1 by thermal oxidation, and photolithography out regions of a sensitive resistor and a calibration resistor on the silicon dioxide thin layer on the front side of the product obtained in step S1 by using a photoresist;

[0022] S22: lightly doping the product obtained in step S21 with boron by ion implantation and then removing the photoresist;

[0023] S23: using photoresist to photolithographically form a heavily doped conductive line region on the front side of the product obtained in step S22;

[0024] S24: heavily doping the product obtained in step S23 with boron by ion implantation and then removing the photoresist;

[0025] S25: performing high temperature annealing on the product obtained in step S24 to form sensitive resistors, calibration resistors and heavily doped conductors.

[0026] Preparing a metal PAD on the front side of the product obtained in step S2 includes:

[0027] S31: manufacturing an insulating isolation layer on the front side of the product obtained in step S2;

[0028] S32: photolithographically etching a contact hole on the front side of the product obtained in step S31, wherein the contact hole is located above the heavily doped conductive line;

[0029] S33: sputtering the metal layer on the front side of the product obtained in step S32, and photolithography of a metal pattern on the front side of the product after the sputtering of the metal layer using a photoresist;

[0030] S34, etching the product obtained in step S33, removing the photoresist after forming the metal pattern, and then performing alloying treatment to form a metal PAD.

[0031] Preparing a pressure-sensitive silicon film and a cavity thereunder on the product obtained in step S3 includes:

[0032] S41: manufacturing an insulating isolation layer on the front side of the product obtained in step S3;

[0033] S42: protecting the front side of the product obtained in step S41, and thinning and polishing the back side;

[0034] S43: manufacturing a corrosion protection layer on the back side of the product obtained in step S43;

[0035] S44: using photoresist to etch the pressure-sensitive silicon film on the back side of the product obtained in step S43;

[0036] S45: Etching the back side of the product obtained in step S44 to form a pressure-sensitive silicon film and a cavity thereunder.

[0037] Beneficial effects:

[0038] 1. The chip of the present invention adopts a sandwich structure of first glass-silicon substrate-second glass. A blind hole is opened on the first glass, and one side of the blind hole is bonded to the silicon substrate to form an absolute pressure vacuum cavity structure, thereby protecting the front piezoresistive area, so that the corrosiveness of some gases or liquids will not have a bad effect on the front piezoresistive and metal; the present invention transmits pressure through the second glass pressure-conducting hole, so that the pressure directly contacts the pressure-sensitive silicon film of the silicon substrate, ensuring the directness and accuracy of pressure measurement;

[0039] 2. The present invention prepares four P-type sensitive resistors and four P-type calibration resistors through a doping process. The four P-type resistors are located in the stress concentration area of ​​the sensitive structure of the pressure sensor chip and form a first Wheatstone full bridge. The four P-type calibration resistors are located in the stress-free area of ​​the fixed support structure and form a second Wheatstone full bridge. When the pressure signal is applied to the pressure-sensitive diaphragm, the four sensitive resistors in the stress concentration area will produce a change in resistance under the piezoresistive effect, so that the first Wheatstone bridge outputs a first signal, the value of which is composed of the pressure signal and the offset signal caused by the residual stress. The second Wheatstone bridge composed of the four calibration resistors in the stress-free area of ​​the fixed support structure will output a second signal, the value of which is the offset signal caused by the residual stress. During use, the difference between the first signal and the second signal is the pressure signal. This method removes the offset signal caused by the residual stress of the pressure sensor chip during processing and packaging, reduces the output drift in situ, ensures the performance of the pressure sensor, and does not increase the chip size.

[0040] 3. On the basis of measuring the pressure signal, the pressure sensor chip of the present invention adds a temperature measurement function. The platinum resistor placed above the first glass realizes the temperature measurement function, ensuring the accuracy of temperature measurement and the precision of temperature compensation of the pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A three-dimensional schematic diagram of a pressure sensor chip structure for in-situ reduction of output drift provided by an embodiment of the present invention;

[0042] Figure 2 A schematic cross-sectional view of a pressure sensor chip structure for in-situ reduction of output drift provided by an embodiment of the present invention;

[0043] Figure 3 A flow chart of a method for manufacturing a pressure sensor chip for in-situ reduction of output drift provided by an embodiment of the present invention;

[0044] Figure 4 A structural diagram corresponding to a method for manufacturing a pressure sensor chip for in-situ reducing output drift provided by an embodiment of the present invention;

[0045] Figure 5 A schematic diagram of a pressure sensor chip for wet etching of the cavity below the pressure-sensitive silicon membrane provided by an embodiment of the present invention;

[0046] Fig. 6A A schematic diagram of a combination of dry-etching a cavity below a pressure-sensitive silicon film, dry-etching a blind hole, and dry-etching a pressure-conducting hole provided in an embodiment of the present invention;

[0047] Figure 6B A schematic diagram of a combination of wet etching of a cavity below a pressure-sensitive silicon film, dry etching of a blind hole, and dry etching of a pressure-conducting hole provided in an embodiment of the present invention;

[0048] Figure 6C A schematic diagram of a combination of dry etching of a cavity below a pressure-sensitive silicon film, wet etching of a blind hole, and dry etching of a pressure-conducting hole provided in an embodiment of the present invention;

[0049] Fig.6D A schematic diagram of a combination of wet etching of a cavity below a pressure-sensitive silicon film, wet etching of a blind hole, and dry etching of a pressure-conducting hole provided in an embodiment of the present invention;

[0050] In the above drawings, 1 is the second glass, 2 is the pressure-conducting hole, 3 is the silicon substrate, 4 is the cavity under the pressure-sensitive silicon film, 5 is the calibration resistor, 6 is the sensitive resistor, 7 is the heavily doped wire, 8 is the metal PAD, 9 is the first glass, 10 is the blind hole of the first glass, and 11 is the platinum resistor; Layer 1 is the second glass, Layer 2 is the silicon substrate, Layer 3 is a thin layer of dioxide film, Layer 4 is the first insulating isolation layer, Layer 5 is the metal layer, Layer 6 is the second insulating isolation layer, Layer 7 is the first glass, and Layer 8 is the platinum resistor. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] like Figure 1 , Figure 2 As shown, a pressure sensor chip for reducing output drift in situ comprises: a first glass 9, a silicon substrate 3 and a second glass 1; the front side of the silicon substrate 3 is bonded to the first glass 9, and the back side of the silicon substrate 3 is bonded to the second glass 1; the silicon substrate 3 has at least one pressure-sensitive silicon film, the corresponding area of ​​the pressure-sensitive silicon film is a stress concentration area of ​​the sensitive structure, and the remaining area of ​​the silicon substrate 3 is a stress-free area of ​​the fixed support structure; the front side of the silicon substrate 3 is prepared with a heavily doped wire (7), four P-type sensitive resistors 6 and four P-type calibration resistors 5, the four P-type sensitive resistors 6 are connected by the heavily doped wire 7 to form a first Wheatstone full bridge, and are located in the stress concentration area of ​​the sensitive structure, and the four P-type calibration resistors 5 are connected by the heavily doped wire 7 to form a second Wheatstone full bridge, and are located in the stress-free area of ​​the fixed support structure.

[0053] The bonding interface between the first glass and the silicon substrate needs to be free of metal, so the present invention uses a heavily doped resistor as a conductor.

[0054] The silicon substrate 3 is of N-type and generally has a thickness of 400 μm.

[0055] The thickness of the first glass 9 is 400-500 μm, the thickness of the second glass 1 is 800-1000 μm, and the first glass 9, the second glass 1 and the silicon substrate 3 are all bonded by an anodic bonding process.

[0056] A blind hole 10 and a through hole are formed on the first glass 9. One side of the blind hole 10 of the first glass 9 and the silicon substrate 3 form an absolute pressure vacuum cavity structure. A platinum resistor 11 formed of platinum metal is provided on the other side of the first glass 9. A through hole (i.e., a pressure conducting hole 2) is formed on the second glass 1 for introducing a pressure signal.

[0057] The shape of the through hole of the first glass 9 can be triangular, circular, square, rectangular, polygonal or rhombus, etc.; the pressure-sensitive diaphragm is displayed as a flat film type, and can also be an E-type film or a beam-island-membrane structure, etc.; the shape of the sensitive resistor 6 and the calibration resistor 5 is not limited to a straight-line type, and can also be a serpentine type and a folded type, etc.

[0058] The sensitive resistor 6 and the calibration resistor 5 are prepared in the same layout, and the length and width of the two are consistent. They are implemented by ion implantation doping process, and the junction depth, square resistance, ion concentration and resistance value of the two are the same.

[0059] The four P-type sensitive resistors 6 correspond to the four P-type calibration resistors 5 one by one; the four P-type sensitive resistors 6 are symmetrically distributed at the center positions of the four sides of the stress concentration area of ​​the sensitive structure, wherein the placement directions of two P-type sensitive resistors 6 are parallel to the sides corresponding to their positions, and the placement directions of the remaining two P-type sensitive resistors 6 are perpendicular to the sides corresponding to their positions; the four P-type calibration resistors 5 are respectively located outside the corresponding sensitive resistors 6 and are placed in the same direction as the corresponding sensitive resistors 6, and the four P-type calibration resistors 5 are at the same distance from the corresponding sensitive resistors 6 and are on the same axis.

[0060] The front side of the silicon substrate 3 further includes: a metal PAD 8; and a heavily doped conductor 7 that is electrically connected to the metal PAD 8.

[0061] Working principle: When the pressure source is applied to the pressure-sensitive diaphragm through the pressure-conducting hole 2 on the second glass 1, the four sensitive resistors 6 in the stress concentration area will produce a change in resistance under the piezoresistive effect, so that the first Wheatstone bridge outputs a first signal, the value of which is composed of the pressure signal and the offset signal caused by the residual stress; the second Wheatstone bridge composed of the four calibration resistors 5 in the stress-free area of ​​the fixed support structure will output a second signal, the value of which is the offset signal caused by the residual stress. In use, the difference between the first signal and the second signal is the pressure signal. This method removes the offset signal caused by the residual stress of the chip during processing and packaging, reduces the output drift in situ, ensures the performance of the pressure sensor, and does not increase the chip size. At the same time, the platinum resistor 11 above the first glass 9 completes the temperature measurement function, ensuring the accuracy of temperature measurement and the accuracy of temperature compensation of the pressure sensor.

[0062] like Figure 3 , Figure 4 As shown, a method for preparing a pressure sensor chip for in-situ reducing output drift includes:

[0063] S1: Obtain N-type single-throw silicon wafer Layer 2 and perform standard cleaning on the N-type single-throw silicon wafer;

[0064] S2: growing a thin silicon dioxide layer Layer 3 on both sides of the product obtained in step S1 by thermal oxidation, and using photoresist to photoetch out the regions of the sensitive resistor 6 and the calibration resistor 5 on the silicon dioxide layer Layer 3 on the front side of the product obtained in step S1; the photoresist is used as an ion implantation barrier layer, and the silicon dioxide layer will make the ion implantation evenly distributed;

[0065] S3: lightly doping the product obtained in step S2 with boron by ion implantation and then removing the photoresist;

[0066] S4: using photoresist to photolithographically form a heavily doped conductive line region on the front side of the product obtained in step S3;

[0067] S5: heavily doping the product obtained in step S4 with boron by ion implantation and then removing the photoresist; performing high-temperature annealing on the product after the photoresist is removed to form a sensitive resistor 6, a calibration resistor 5 and a heavily doped conductor 7, ensuring the uniformity of impurity ions in the lightly doped region and the heavily doped region, forming a fixed junction depth and square resistance, and forming interconnection lines between resistors of the same type in the heavily doped region;

[0068] S6: manufacturing a first insulating isolation layer Layer 4 on the front side of the product obtained in step S5, wherein the insulating isolation layer comprises silicon dioxide or silicon nitride or a composite film layer of the two;

[0069] S7: Photolithography is performed to form a contact hole on the front side of the product obtained in step S6. The contact hole is above the heavily doped wire and is smaller in size than the heavily doped wire.

[0070] S8: magnetron sputtering or evaporation metal layer Layer 5 of the product obtained in step S7, photolithography metal pattern on the front side of the product after sputtering or evaporation of the metal layer using photoresist; etching the product with the metal pattern, removing the photoresist after forming the required metal pattern, and then performing alloying treatment to form metal PAD8;

[0071] S9: manufacturing a second insulating isolation layer Layer 6 on the front side of the product obtained in step S8, wherein the insulating isolation layer comprises silicon dioxide or silicon nitride or a composite film layer of the two;

[0072] S10: protecting the front side of the product obtained in step S9, and thinning and polishing the back side;

[0073] S11: manufacturing a corrosion protection layer on the back of the product obtained in step S10, wherein the corrosion protection layer comprises silicon dioxide or silicon nitride or a composite film layer of the two;

[0074] S12: using photoresist to photoetch the pressure-sensitive silicon film etching area on the back side of the product obtained in step S11, and dry-etching the pressure-sensitive silicon film and the cavity thereunder;

[0075] S13: photolithography a bonding conductive area and a metal PAD area on the front side of the product obtained in step S12, and after removing the insulating isolation layer on the surface of the bonding conductive area and the metal PAD area by dry or wet method, bonding the front side of the obtained product to the first glass layer 7;

[0076] S14: After removing the back corrosion protection layer of the product obtained in step S13 by dry or wet method, the back side of the obtained product is bonded to the second glass Layer 1.

[0077] The through holes on the first glass are manufactured by sandblasting or laser engraving, and the through holes are used for wire bonding in the metal PAD area; the blind holes are manufactured by sandblasting to form an absolute pressure chamber with the pressure-sensitive silicon film on the silicon substrate; the platinum resistor is used for temperature measurement, which is prepared by sputtering or evaporation, and then the metal pattern is defined by photolithography and etching.

[0078] The through holes on the second glass are prepared by sandblasting or laser engraving for conducting pressure.

[0079] In one embodiment, if Figure 5 As shown, in Figure 4 Based on the manufacturing process, step S12 uses wet etching to etch the cavity below the pressure-sensitive silicon film. Before wet etching, the front side of the silicon substrate needs to be protected.

[0080] In one embodiment, as shown in FIG6 , Figure 4 On the basis of the manufacturing process, the first glass and the second glass are replaced with silicon material, and the anodic bonding in the process is changed to silicon-silicon bonding. Fig. 6A It is a combination of dry etching of the cavity below the pressure-sensitive silicon film, dry etching of the blind hole, and dry etching of the pressure-conducting hole; Figure 6B It is a combination of wet etching of the cavity below the pressure-sensitive silicon film, dry etching of the blind hole, and dry etching of the pressure-conducting hole; Figure 6C It is a combination of dry etching of the cavity below the pressure-sensitive silicon film, wet etching of the blind hole, and dry etching of the pressure-conducting hole; Fig.6D It is a combination of wet etching of the cavity below the pressure-sensitive silicon film, wet etching of the blind hole, and dry etching of the pressure-conducting hole.

[0081] The above embodiments further illustrate the purpose, technical solutions and advantages of the present invention in detail. It should be understood that the above embodiments are only preferred implementation modes of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pressure sensor chip for reducing output drift in situ, comprising a silicon substrate (3), a pressure-sensitive silicon film in the silicon substrate (3), a region corresponding to the pressure-sensitive silicon film being a stress concentration region of a sensitive structure, and the remaining region of the silicon substrate being a stress-free region of a fixed support structure; a heavily doped wire (7) and a plurality of sensitive resistors (6) are prepared on the front side of the silicon substrate, the plurality of sensitive resistors (6) are connected by the heavily doped wire (7) to form a first Wheatstone bridge, and are located in the stress concentration region of the sensitive structure, characterized in that: The pressure sensor chip further comprises: a first glass (9) and a second glass (1); the front side of the silicon substrate (3) is bonded to the first glass (9), and the back side of the silicon substrate (3) is bonded to the second glass (1); the front side of the silicon substrate (3) further comprises a plurality of calibration resistors (5), the plurality of calibration resistors (5) are connected via heavily doped wires (7) to form a second Wheatstone bridge, and are located in a stress-free area of ​​the fixed support structure.

2. The pressure sensor chip for reducing output drift in situ according to claim 1, characterized in that: The first glass (9) is provided with a blind hole (10), one side of the blind hole (10) of the first glass (9) and the silicon substrate (3) form an absolute pressure vacuum cavity structure, and the other side of the first glass (9) is provided with a platinum resistor (11); the second glass (1) is provided with a pressure conducting hole (2) for introducing a pressure signal.

3. The pressure sensor chip for reducing output drift in situ according to claim 1, characterized in that: The silicon substrate (3) is of N type and has a thickness of 400 μm.

4. The pressure sensor chip for in-situ reducing output drift according to claim 1, characterized in that: The thickness of the first glass (9) is 400-500 μm, and the thickness of the second glass (9) is 800-1000 μm.

5. The pressure sensor chip for reducing output drift in situ according to claim 1, characterized in that: The front side of the silicon substrate (3) further comprises: a metal PAD (8), and the metal PAD (8) is connected to the heavily doped wire (7).

6. The pressure sensor chip for reducing output drift in situ according to claim 1, characterized in that: The number of the sensitive resistors (6) and the calibration resistors (5) are both four, and they correspond one to one; the four sensitive resistors (6) are symmetrically distributed at the center positions of the four sides of the stress concentration area of ​​the sensitive structure, wherein the placement directions of two of the sensitive resistors (6) are parallel to the sides corresponding to the positions, and the placement directions of the remaining two sensitive resistors (6) are perpendicular to the sides corresponding to the positions; the four calibration resistors (5) are respectively located outside the corresponding sensitive resistors (6) and are placed in the same direction as the corresponding sensitive resistors (6); the four calibration resistors (5) are at the same distance from the corresponding sensitive resistors (6) and are on the same axis.

7. A method for preparing a pressure sensor chip for in-situ reducing output drift according to any one of claims 1 to 6, characterized in that: include: S1: Obtain an N-type single-throw silicon wafer and perform standard cleaning on the N-type single-throw silicon wafer; S2: preparing a sensitive resistor, a calibration resistor and a heavily doped conductor on the front side of the product obtained in step S1 by a doping process; S3: preparing a metal PAD on the front side of the product obtained in step S2; S4: preparing a pressure-sensitive silicon film and a cavity thereunder on the product obtained in step S3; S5: Photolithography of bonding conduction area and metal PAD area on the front side of the product obtained in step S4; S6: etching the bonding conduction area and the metal PAD area of ​​the product obtained in step S5 to obtain a prepared silicon substrate; S7: Obtain a first glass and a second glass, and bond the front side of the prepared silicon substrate to the first glass, and the back side to the second glass.

8. The method for preparing a pressure sensor chip for in-situ reducing output drift according to claim 7, characterized in that: Preparing a sensitive resistor, a calibration resistor and a heavily doped conductor on the front side of the product obtained in step S1 includes: S21: growing a thin layer of silicon dioxide on both sides of the product obtained in step S1 by thermal oxidation, and photolithography out regions of a sensitive resistor and a calibration resistor on the silicon dioxide thin layer on the front side of the product obtained in step S1 by using a photoresist; S22: lightly doping the product obtained in step S21 with boron by ion implantation and then removing the photoresist; S23: using photoresist to photolithographically form a heavily doped conductive line region on the front side of the product obtained in step S22; S24: heavily doping the product obtained in step S23 with boron by ion implantation and then removing the photoresist; S25: performing high temperature annealing on the product obtained in step S24 to form sensitive resistors, calibration resistors and heavily doped conductors.

9. The method for preparing a pressure sensor chip for in-situ reducing output drift according to claim 8, characterized in that: Preparing a metal PAD on the front side of the product obtained in step S2 includes: S31: manufacturing an insulating isolation layer on the front side of the product obtained in step S2; S32: photolithographically etching a contact hole on the front side of the product obtained in step S31, wherein the contact hole is located above the heavily doped conductive line; S33: sputtering the metal layer on the front side of the product obtained in step S32, and photolithography of a metal pattern on the front side of the product after the sputtering of the metal layer using a photoresist; S34, etching the product obtained in step S33, removing the photoresist after forming the metal pattern, and then performing alloying treatment to form a metal PAD.

10. The method for preparing a pressure sensor chip for in-situ reducing output drift according to claim 9, characterized in that: Preparing a pressure-sensitive silicon film and a cavity thereunder on the product obtained in step S3 includes: S41: manufacturing an insulating isolation layer on the front side of the product obtained in step S3; S42: protecting the front side of the product obtained in step S41, and thinning and polishing the back side; S43: manufacturing a corrosion protection layer on the back side of the product obtained in step S43; S44: using photoresist to etch the pressure-sensitive silicon film on the back side of the product obtained in step S43; S45: Etching the back side of the product obtained in step S44 to form a pressure-sensitive silicon film and a cavity thereunder.

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