CN210559358U

CN210559358U - Pressure sensor

Info

Publication number: CN210559358U
Application number: CN201920279828.3U
Authority: CN
Inventors: 李刚; 刘迪; 胡维; 吕萍
Original assignee: Memsensing Microsystems Suzhou China Co Ltd
Current assignee: Memsensing Microsystems Suzhou China Co Ltd
Priority date: 2019-03-06
Filing date: 2019-03-06
Publication date: 2020-05-19
Anticipated expiration: 2029-03-06

Abstract

The utility model relates to a pressure sensor, this pressure sensor includes: a semiconductor substrate; the first vacuum cavity is formed by combining a plurality of first grooves which are arranged at intervals through first heat treatment; the groove is positioned in the semiconductor substrate, penetrates through part of the semiconductor substrate until the groove is communicated with the first vacuum cavity, and the groove and the first vacuum cavity are encircled to form an induction body. The pressure sensing film of the pressure sensor has high flatness and small thickness, and can be as thin as 1 micron.

Description

Pressure sensor

Technical Field

The utility model relates to a micro-electromechanical system field especially relates to a pressure sensor.

Background

With the continuous development of the micro-electromechanical system technology, the cost of the pressure sensor is gradually reduced, and the application of the pressure sensor also enters a plurality of fields such as medical treatment, automobiles, meteorological detection, height measurement, consumer electronics and the like. The commonly used pressure sensors include capacitance type, piezoelectric type and piezoresistive type, wherein the piezoresistive pressure sensor has a simpler process, is suitable for batch production and is the mainstream direction of pressure sensor development.

The pressure-sensitive film of the piezoresistive pressure sensor is the most critical structure, and the following methods are commonly used for preparing the piezoresistive pressure-sensitive film at present. One method is a method for anisotropically etching the back surface of a silicon wafer by using an alkaline solution, and the method can obtain a pressure-sensitive film with a certain thickness while obtaining a back cavity by time control, but the uniformity of etching of the whole wafer cannot be ensured by using the method, so that the pressure-sensitive film with high flatness is difficult to obtain. The second is electrochemical corrosion, which requires an expensive potentiostat and is expensive to produce. The third is: adopting a C-SOI process, firstly etching a groove in the shape of a pressure cavity on the front surface of a Si wafer (called as a wafer 1); then, silicon oxide is deposited on the other Si wafer (called wafer 2) on both sides, and Si-SiO is carried out on the front side of the wafer 1 and any side of the wafer 2₂Bonding; thinning the wafer 2 to a certain thickness to obtain a suspended film and a closed pressure cavity; if the method is used for preparing the gauge pressure sensor, the back of the wafer 1 is etched in a deep reactive ion etching mode, so that the pressure cavity is communicated with the outside. The film obtained by the method has larger thickness and higher production cost when being used for preparing the small-range pressure sensor.

Therefore, how to obtain a pressure-sensitive film with low manufacturing cost, thinner thickness and higher flatness is a technical problem to be solved in the field.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that reduce pressure sensor's pressure sensing film's manufacturing cost, improve pressure sensing film's roughness, reduce pressure sensing film's thickness.

In order to solve the above problem, the utility model provides a pressure sensor, it includes: a semiconductor substrate; the first vacuum cavity is formed by combining a plurality of first grooves which are arranged at intervals through first heat treatment; the groove is positioned in the semiconductor substrate, penetrates through part of the semiconductor substrate until the groove is communicated with the first vacuum cavity, and the groove and the first vacuum cavity are encircled to form an induction body.

Optionally, the semiconductor substrate includes a substrate and a device layer located on the substrate, and the device layer is an epitaxial layer.

Optionally, a second vacuum chamber suspended in the device layer is provided, and the second vacuum chamber is located in the induction body and formed by combining a plurality of second grooves arranged at intervals through a second heat treatment.

Optionally, the second vacuum container is located directly above the first vacuum container.

Optionally, the second heat treatment is rapid thermal annealing.

Optionally, the groove is annular with a gap; the number of the grooves is two, the grooves are a first groove and a second groove respectively, the first groove surrounds the outer side of the second groove, and the gap of the first groove and the gap of the second groove are arranged at an interval of 180 degrees.

Optionally, the first heat treatment is rapid thermal annealing.

The utility model discloses a pressure sensor's first vacuum cavity, first vacuum cavity is formed through the combination of first heat treatment by a plurality of interval arrangements's first groove for part between the first groove is tied and is formed the pressure sensing film together (also becomes unsettled film), can simplify the manufacturing process of pressure sensing film. Meanwhile, the pressure sensing film of the pressure sensor has high flatness and small thickness, and can be as thin as 1 micron. Moreover, the side wall of the first vacuum cavity formed by the heat treatment process is smooth, and corners are all round corners, so that the pressure-sensitive film basically has no stress.

Drawings

Fig. 1-15 are cross-sectional views of a pressure sensor at various stages of manufacture in an embodiment of the invention;

fig. 16 is a plan view of a pressure sensor in an embodiment of the invention.

Detailed Description

The following description will first explain in detail a specific embodiment of the pressure sensor and the manufacturing method thereof provided by the present invention with reference to the accompanying drawings.

As shown in fig. 1, a substrate 1 is provided, the substrate 1 comprising an upper surface 11 and a lower surface 12. In the present embodiment, the substrate 1 is a single crystal silicon substrate. Of course, in other embodiments, other suitable semiconductor materials may be used for the substrate 1.

As shown in fig. 2, a protective layer 13 having a plurality of patterns 14 (i.e., windows) is formed on the upper surface of the substrate 1. The manufacturing method of the protective layer 13 includes: after a protective material layer (not shown) is formed on the upper surface of the substrate 1 by using processes such as low pressure chemical vapor deposition, plasma chemical vapor deposition, thermal oxidation, etc., a portion of the protective material layer is removed by using photolithography and wet etching processes, or photolithography and dry etching processes, to form the protective layer 13 having the pattern 14. In this embodiment, the material of the protection layer 13 is silicon oxide, and in other embodiments of the present invention, the material of the protection layer 13 may also be a dielectric material such as silicon nitride, silicon carbide, or silicon oxynitride, and may be a single-layer or multi-layer composite structure.

As shown in fig. 3, the substrate 1 is etched using the protective layer 13 as a mask, and a plurality of first holes 15 are formed in the substrate 1. Since the first hole 15 is located on the surface of the substrate 1, it may also be referred to as a first groove. In this embodiment, the substrate 1 is etched to form a plurality of first holes 15 by using an anisotropic etching process, such as a deep reactive ion silicon etching (DRIE) process, and a portion between two adjacent first holes 15 is defined as a pattern 15 a. In this embodiment, the first holes 15 are arranged in an array, the first holes 15 are round holes, the depth of the round holes is several micrometers, the diameter of the round holes is about 0.5 micrometers to 1.5 micrometers, for example, the diameter of the round holes may be 1 micrometer, and the interval between the round holes is about 0.5 micrometer. Of course, in other embodiments, the first holes 15 may be provided as holes with other shapes, the holes may be rectangular, circular, pentagonal, hexagonal or other polygonal shapes, and the size and the interval of the first holes may be adjusted according to the lithography capability of the lithography machine.

As shown in fig. 4, the protective layer 13 is removed. In a specific embodiment, the protective layer 13 is removed using a dry etching or wet etching process, such as buffered hydrofluoric acid (BOE).

As shown in fig. 5, the substrate 1 is subjected to a first thermal process such that a plurality of first holes 15 (refer to fig. 4) are merged into a floating first vacuum chamber 16, which means that the first vacuum chamber 16 is located inside the substrate 1 with a certain interval from the upper surface 11 of the substrate 1. The portion of the substrate 1 between the upper surface 11 and the first vacuum chamber 16 is defined as a first flying film 17.

As shown in fig. 4 to 5, under the action of the first heat treatment, the first holes 15 are expanded in the horizontal direction, so that the first holes 15 are communicated with each other, and thus are combined into a complete large hole, i.e., the first vacuum chamber 16. Meanwhile, under the effect of the first heat treatment, the energy of the upper surface of the substrate 1 is reduced, so that the upper surface of the substrate 1 is migrated, and the ends of the patterns 15a are integrated with each other, thereby forming a first suspended thin film 17 above the first vacuum chamber 16. The first suspended film 17 formed by the first heat treatment process is flat and thin, and can be as thin as 1 micron. In a particular embodiment, the first vacuum chamber 16 is located centrally above the interior of the substrate 1. Moreover, the sidewalls of the first vacuum chamber 16 formed by the first thermal treatment process are smooth, and as shown in fig. 5, the corners of the first vacuum chamber 16 are rounded, so that the first suspended thin film 17 has substantially no stress. Because the vacuum cavity and the suspended film are formed by utilizing a heat treatment process, a series of adverse effects caused by traditional bulk silicon etching, sacrificial layer etching and wafer bonding are avoided.

Specifically, the first heat treatment is performed in an oxygen-free, low-pressure (sub-atmospheric) environment to prevent the substrate 1 from being oxidized. In one embodiment, the oxygen-free environment is a pure hydrogen environment. Of course, in other embodiments, the oxygen-free environment may be an inert gas environment. The ambient pressure of the first thermal treatment may be less than 1 atmosphere, so that the pressure inside the first vacuum chamber 16 is formed to be less than 1 atmosphere.

In this embodiment, the temperature of the first heat treatment is 1100 degrees celsius. Of course, in other embodiments, the temperature of the first heat treatment may be higher than 1100 degrees celsius. Further, in this embodiment, the first heat treatment is rapid thermal annealing.

As shown in fig. 6, a device layer 18 covering the substrate 1 is formed by an epitaxial process. Since the epitaxial process is adopted, the material of the device layer 18 is the same as that of the substrate 1, and in this embodiment, the material of the device layer 18 is single crystal silicon.

As shown in fig. 7, a protective layer 19 having a plurality of patterns 20 (i.e., windows) is formed on the device layer 18. The manufacturing method of the protective layer 19 includes: after forming a protective material layer (not shown) on the upper surface of the device layer 18 by using processes such as low pressure chemical vapor deposition, plasma chemical vapor deposition, or thermal oxidation, the protective material layer is partially removed by using photolithography and wet etching processes, or photolithography and dry etching processes, so as to form the protective layer 19 having the pattern 20. In this embodiment, the material of the protection layer 19 is silicon oxide, and in other embodiments of the present invention, the material of the protection layer 19 may also be a dielectric material such as silicon nitride, silicon carbide, or silicon oxynitride, and may be a single-layer or multi-layer composite structure.

As shown in fig. 8, the substrate 1 having the device layer 18 is etched using the protective layer 19 as a mask, and a plurality of second holes 21 are formed in the substrate 1. Since the second hole 21 is located at the surface of the device layer 18, the second hole 21 may also be referred to as a second groove. In this embodiment, the substrate 1 is etched to form a plurality of second holes 21 by using an anisotropic etching process, such as a deep reactive ion silicon etching (DRIE) process, and a portion between two adjacent second holes 21 is defined as a pattern 21 a. In this embodiment, the plurality of second holes 21 are arranged in an array, the second holes 21 are round holes, the depth of the round holes is several micrometers, the diameter of the round holes may be 0.5 micrometers to 1.5 micrometers, for example, the diameter of the round holes may be 1 micrometer, and the interval between the round holes is about 0.5 micrometer. Of course, in other embodiments, the second hole 21 may be provided as a hole with other shapes, and the hole may be a rectangle, a circle, a pentagon, a hexagon or other polygons. Further, in the present embodiment, the plurality of second holes 21 are located right above the first vacuum chamber 16.

As shown in fig. 9, the protective layer 19 is removed. In a particular embodiment, a dry etch or wet etch process, such as buffered hydrofluoric acid (BOE), is used to remove the protective layer 19.

As shown in fig. 10, the substrate 1 is subjected to a first heat treatment so that a plurality of second holes 21 (refer to fig. 9) are merged into the second vacuum chamber 7 which is suspended, that is, the second vacuum chamber 7 is located inside the substrate 1 having the device layer 18 and is spaced apart from the upper surface of the device layer 18. The portion between the upper surface 11 of the device layer 18 and the second vacuum chamber 7 is defined as a second flying film 8 (also referred to as a pressure sensitive film). In the present embodiment, the second vacuum chamber 7 is located directly above the first vacuum chamber 16, and the width (horizontal dimension) of the second vacuum chamber 7 is smaller than the width of the first vacuum chamber 16.

As shown in fig. 9 to 10, under the second heat treatment, the second holes 21 are expanded in the horizontal direction, so that the second holes 21 are communicated with each other, and thus are combined into a complete large hole, i.e., the second vacuum chamber 7. Meanwhile, under the action of the second heat treatment, the energy of the upper surface of the device layer 18 is reduced, so that the upper surface of the device layer 18 is migrated, and the end portions of the patterns 21a are combined into a whole, thereby forming the second suspended thin film 8 above the second vacuum chamber 7. The second suspended film 8 formed by the second heat treatment process is very flat and thin, and can be as thin as 1 micron. Moreover, the side walls of the second vacuum chamber 7 formed by the first heat treatment process are smooth, and as shown in fig. 10, the corners of the second vacuum chamber 7 are rounded, and the second suspended film 8 has substantially no stress.

Specifically, the second heat treatment is performed in an oxygen-free, low-pressure (sub-atmospheric pressure) environment to prevent the substrate 1 from being oxidized. In one embodiment, the oxygen-free environment is a pure hydrogen environment. Of course, in other embodiments, the oxygen-free environment may be an inert gas environment. The ambient pressure of the second heat treatment may be less than 1 atmosphere, so that the pressure inside the second vacuum chamber 7 is formed to be less than 1 atmosphere.

In this embodiment, the temperature of the second heat treatment is 1100 degrees celsius. Of course, in other embodiments, the temperature of the second heat treatment may be higher than 1100 degrees celsius. Further, in this embodiment, the second heat treatment is rapid thermal annealing.

As shown in fig. 11, a first dielectric layer 23 is formed on the device layer 18, and serves as a barrier layer, the material of the first dielectric layer may be silicon oxide, silicon nitride, silicon oxynitride, or the like, and the forming process may be low pressure chemical vapor deposition, plasma chemical vapor deposition, thermal oxidation, or the like.

With continued reference to FIG. 11, a number of piezoresistors 10 are formed, the piezoresistors 10 being located directly above the second vacuum chamber 7. In the present embodiment, the piezoresistive 10 is formed by ion implantation, i.e. by ion implantation of a specific region of the surface layer of the device layer 18 to obtain the piezoresistive 10.

With continued reference to fig. 11, a second dielectric layer 22 is formed overlying the first dielectric layer 23. The material of the second dielectric layer 22 may be silicon oxide, silicon nitride, silicon oxynitride, etc., and the forming process may be low-pressure chemical vapor deposition, plasma chemical vapor deposition, thermal oxidation, etc.

As shown in fig. 12, portions of the second dielectric layer 22 and the first dielectric layer 23 are removed to form a plurality of windows 24, each window 24 exposing a corresponding portion of the piezoresistive 10. The window 24 is formed by photolithography followed by reactive ion etching.

As shown in fig. 13, several metal electrodes 9 are formed on the second dielectric layer 22, and a portion of the metal electrodes 9 fills the window 24 and forms ohmic contact with the piezoresistors 10. In the present embodiment, the method for forming the metal electrode 9 includes: forming a metal material layer covering the second dielectric layer 22, wherein a part of the metal material layer is filled into the window 24 and forms ohmic contact with the piezoresistor 10 below; the metal material layer can be formed by deposition or electroplating; and forming a patterned mask layer above the metal material layer, and etching the metal material layer by using the patterned mask layer as a mask to form a metal electrode 9, wherein the etching process can be dry etching or wet etching, and the patterned mask layer can be a photoresist layer.

As shown in fig. 14, a passivation layer 26 having a pattern 27 is formed on the metal electrode 9, the passivation layer 26 covers the second dielectric layer 22, and the pattern 27 is located on the periphery of the metal electrode 9.

The manufacturing method of the protective layer 26 includes: after forming a protective material layer (not shown) on the upper surfaces of the second dielectric layer 22 and the metal electrode 9 by using processes such as low pressure chemical vapor deposition, plasma chemical vapor deposition, thermal oxidation, etc., a part of the protective material layer is removed by using photolithography and wet etching processes, or photolithography and dry etching processes, so as to form the protective layer 26 having the pattern 27. In this embodiment, the material of the protection layer 26 is silicon oxide, and in other embodiments of the present invention, the material of the protection layer 26 may also be a dielectric material such as silicon nitride, silicon carbide, or silicon oxynitride, and may be a single-layer or multi-layer composite structure.

As shown in fig. 15, the second dielectric layer 22 and the first dielectric layer 23 are etched to the substrate 1 by using the passivation layer 26 as a mask, so as to form a trench 25 and the sensing body 6 surrounded by the trench 25, wherein the trench 25 is communicated with the first vacuum chamber 16 to form a receiving chamber (not shown). In this embodiment, the etching process is a dry etching process, specifically, a deep reactive ion silicon etching (DRIE) process.

In particular, the second vacuum chamber 7 is located within the sensing body 6, and the piezoresistor 10 and the metal electrode 9 are both located within the sensing body 6. The sensing body 6 is enclosed by the trench 25 and the first vacuum chamber 16, and can move in a direction perpendicular to the substrate 1 to be deformed when being subjected to an external force so as to detect pressure according to a change in resistance value of the piezoresistor 10.

Referring to fig. 15 and 16, in the present embodiment, the grooves 25 are ring-shaped with notches (not labeled), and the number of the grooves 25 is two, namely, an outer groove and an inner groove, wherein the notches of the outer groove and the notches of the inner groove are arranged at an interval of 180 degrees. More specifically, the groove 25 is rectangular, with a notch provided on one side. The part of the substrate 1 between the outer side groove and the inner side groove forms a support beam 5, the part of the substrate 1 in the gap of the groove 25 also forms another support beam, and the two support beams are both connected with the sensing body 6, so that the sensing body 6 can be suspended.

It should be noted that, referring to fig. 15, in the embodiment of the present invention, the number of the grooves 25 is not limited to two, and the number thereof may be arbitrarily set, for example, only one groove 25 may be provided. The number of notches of each groove 25 may be arbitrarily set, and may be, for example, two. The shape of the groove 25 is not limited to a rectangle, and may be a polygon such as a circle, a pentagon, or a hexagon.

In addition, the number of the first vacuum containers 16 is not limited to one, and may be two, two first vacuum containers 16 are arranged at intervals in the horizontal direction, the second vacuum container 7 is located between the two first vacuum containers 16, and each first vacuum container is communicated with the vertically extending groove, in which case, all the first vacuum containers and all the grooves enclose the sensing body.

In addition, in the modified example of the embodiment, after the first vacuum chamber 16 is formed, the steps of forming the device layer and the second vacuum chamber may be omitted, and the steps of forming the piezoresistance, the metal electrode and the trench may be directly performed, the sensing body formed according to the modified method has no second suspended film therein, and the first suspended film formed according to the first heat treatment step is the pressure sensitive film.

The following describes in detail a specific embodiment of the pressure sensor according to the present invention with reference to the accompanying drawings.

As shown in fig. 15, the pressure sensor includes a substrate 1. In the present embodiment, the substrate 1 is a single crystal silicon substrate. Of course, in other embodiments, other suitable semiconductor materials may be used for the substrate 1.

A first vacuum chamber 16 is formed in the substrate 1 in a floating manner, in which the first vacuum chamber 16 is located inside the substrate 1 and spaced apart from an upper surface (not shown) of the substrate 1 by a predetermined distance. The first vacuum chamber 16 is formed by combining a plurality of first grooves arranged at intervals, which are positioned on the surface of the substrate 1, through a first heat treatment. In other words, the first vacuum chambers 16 are formed by forming a plurality of first grooves spaced apart from each other on the surface of the substrate 1 and then performing the first heat treatment.

Under the action of the first heat treatment, the first grooves are expanded in the horizontal direction, so that the first grooves are communicated with each other, and are combined into a complete large hole, namely the first vacuum chamber 16. Meanwhile, under the effect of the first heat treatment, the energy of the upper surface of the substrate 1 is reduced, so that the upper surface of the substrate 1 is migrated, and the ends of the portions between the first grooves are integrated with each other, thereby forming a first suspended thin film (not shown) above the first vacuum chamber 16. The first suspended film formed by the first heat treatment process is very flat and thin, and can be as thin as 1 micron. In a particular embodiment, the first vacuum chamber 16 is located centrally above the interior of the substrate 1.

In this embodiment, a device layer 18 is formed on a substrate 1, the device layer 18 is formed by epitaxial growth, i.e. an epitaxial layer, and has the same material as the substrate 1, and the substrate 1 and the device layer 18 constitute a semiconductor substrate (not shown).

The device layer 18 is formed with a first dielectric layer 23, which serves as a barrier layer, made of silicon oxide, silicon nitride, silicon oxynitride, or the like, and formed by a process such as low pressure chemical vapor deposition, plasma chemical vapor deposition, or thermal oxidation.

A second dielectric layer 22 is formed on the first dielectric layer 23. The material of the second dielectric layer 22 may be silicon oxide, silicon nitride, silicon oxynitride, etc., and the forming process may be low-pressure chemical vapor deposition, plasma chemical vapor deposition, thermal oxidation, etc.

A trench 25 passes through the semiconductor substrate above the first vacuum chamber 16, the first dielectric layer 23, and the second dielectric layer 22, and communicates with the first vacuum chamber 16. The channel 25 and the first vacuum chamber 16 enclose the sensing body 6.

In the present embodiment, the second vacuum chamber 7 is formed in the device layer 18 in a floating manner, and the floating means that the second vacuum chamber 7 is located inside the device layer 18 and is spaced from the upper surface (not labeled) of the device layer 18. The second vacuum container 7 is located within the sensing body 6 and directly above the first vacuum container 16.

The second vacuum chamber 7 is formed by combining a plurality of second grooves which are arranged at intervals and are positioned on the surface of the device layer 18 through second heat treatment. In other words, the second vacuum chambers 7 may be combined by forming a plurality of second grooves arranged at intervals on the surface of the device layer 18 and performing the second heat treatment.

Under the action of the second heat treatment, the second grooves are expanded along the horizontal direction, so that the second grooves are communicated with each other, and are combined into a complete large hole, namely the second vacuum cavity 7. Meanwhile, under the action of the second heat treatment, the energy of the upper surface of the device layer 18 is reduced, so that the upper surface of the device layer 18 is migrated, and the end portions of the portions between the second grooves are combined into a whole, thereby forming a second suspended film (not shown) above the second vacuum chamber 7. The second suspended film formed by the second heat treatment process is very flat and thin, and can be as thin as 1 micron. In a particular embodiment, the second vacuum chamber 7 is located centrally above the interior of the device layer 18.

Specifically, the second heat treatment is performed in an oxygen-free, low-pressure (sub-atmospheric pressure) environment to prevent the device layer 18 and the substrate 1 from being oxidized. In one embodiment, the oxygen-free environment is a pure hydrogen environment. Of course, in other embodiments, the oxygen-free environment may be an inert gas environment. The ambient pressure of the second heat treatment may be less than 1 atmosphere, so that the pressure inside the second vacuum chamber 7 is formed to be less than 1 atmosphere.

It should be noted that the number of the first vacuum containers 16 is not limited to one, and may be two, two first vacuum containers 16 are arranged at intervals along the horizontal direction, the second vacuum container 7 is located between the two first vacuum containers 16, and each first vacuum container is communicated with the vertically extending groove, in which case, all the first vacuum containers and all the grooves enclose the sensing body.

In the modified example of the present invention, the pressure sensor has no second vacuum chamber and no device layer 18 (so that the semiconductor substrate is constituted by a simple substrate), the first dielectric layer 23 directly covers the surface of the substrate 1, and the piezoresistor 10 is directly formed on the surface of the substrate 1.

The surface of the device layer 18 is formed with a plurality of piezoresistors 10, the piezoresistors 10 being located directly above the second vacuum chamber 7. In the present embodiment, the piezoresistive 10 is formed by ion implantation, i.e. by ion implantation of a specific region of the surface layer of the device layer 18 to obtain the piezoresistive 10. The metal electrode 9 is located above the second dielectric layer 22, and one end of the metal electrode passes through the second dielectric layer 22 and the first dielectric layer 23 to form ohmic contact with the lower piezoresistor 10.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A pressure sensor, comprising:

a semiconductor substrate;

the first vacuum cavity is formed by combining a plurality of first grooves which are arranged at intervals through first heat treatment;

the groove is positioned in the semiconductor substrate, penetrates through part of the semiconductor substrate until the groove is communicated with the first vacuum cavity, and the groove and the first vacuum cavity are encircled to form an induction body.

2. The pressure sensor of claim 1, wherein the semiconductor substrate comprises a substrate and a device layer on the substrate, the device layer being an epitaxial layer.

3. The pressure sensor of claim 2, wherein the device layer has a second vacuum chamber suspended therein, the second vacuum chamber being located in the sensing body and formed by combining a plurality of second grooves arranged at intervals by a second heat treatment.

4. A pressure sensor as claimed in claim 3, wherein the second vacuum chamber is located directly above the first vacuum chamber.

5. A pressure sensor according to claim 3, wherein the second thermal treatment is rapid thermal annealing.

6. The pressure sensor according to any one of claims 1 to 5, wherein the groove is annular with a notch;

the number of the grooves is two, the grooves are a first groove and a second groove respectively, the first groove surrounds the outer side of the second groove, and the gap of the first groove and the gap of the second groove are arranged at an interval of 180 degrees.

7. A pressure sensor according to any of claims 1 to 5, wherein the first thermal treatment is rapid thermal annealing.