阅读说明：本技术 一种线性渐变梁结构的mems压阻式压力传感器及其制备方法 (MEMS piezoresistive pressure sensor with linear gradient beam structure and preparation method thereof ) 是由 武斌 许克宇 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种线性渐变梁结构的MEMS压阻式压力传感器及其制备方法,其中,压力传感器包括具有线性渐变梁膜结构的硅应变膜、压敏电阻、重掺杂接触区域、金属引线和玻璃底座,硅应变膜为硅衬底的正面经过光刻刻蚀和背面经过背腔刻蚀工艺后形成的具有线性渐变梁膜结构的硅膜,压敏电阻位于线性渐变梁膜结构的端部,金属引线和重掺杂接触区在硅应变梁膜的正面形成欧姆接触,玻璃底座位于硅应变膜的背面且与硅应变膜键合。通过采用本发明的压阻式压力传感器,不仅实现了通过调节渐变梁结构的线性变化比例,达到提高压力传感器线性度和降低后期调试补偿难度的目的,而且还实现了通过调整压敏电阻与渐变梁结构之间的尺寸大小,实现提高灵敏度的目的。(The invention discloses an MEMS piezoresistive pressure sensor with a linear gradient beam structure and a preparation method thereof, wherein the pressure sensor comprises a silicon strain film with the linear gradient beam film structure, a piezoresistor, a heavily doped contact region, a metal lead and a glass base, the silicon strain film is a silicon film with the linear gradient beam film structure, which is formed after the front surface of a silicon substrate is subjected to photoetching and etching and the back surface is subjected to back cavity etching, the piezoresistor is positioned at the end part of the linear gradient beam film structure, the metal lead and the heavily doped contact region form ohmic contact on the front surface of the silicon strain beam film, and the glass base is positioned on the back surface of the silicon strain film and is bonded with the silicon strain film. By adopting the piezoresistive pressure sensor, the purposes of improving the linearity of the pressure sensor and reducing the later debugging compensation difficulty are achieved by adjusting the linear change proportion of the gradual change beam structure, and the purpose of improving the sensitivity is also achieved by adjusting the size between the piezoresistor and the gradual change beam structure.)

1. The MEMS piezoresistive pressure sensor with the linear gradient beam structure is characterized by comprising a silicon strain film with the linear gradient beam film structure, a piezoresistor, a heavily doped contact region, a metal lead and a glass base, wherein the silicon strain film is a silicon film with the linear gradient beam film structure, the front surface of a silicon substrate is subjected to photoetching and etching, the back surface of the silicon substrate is subjected to a back cavity etching process, the piezoresistor is located at the end part of the linear gradient beam film structure, the metal lead and the heavily doped contact region form ohmic contact on the front surface of the silicon strain beam film, and the glass base is located at the back surface of the silicon strain film and is bonded with the silicon strain film.

2. The MEMS piezoresistive pressure sensor with a linearly graded beam structure according to claim 1, wherein the silicon substrate is an N-type <100> crystal plane silicon wafer or an N-type <100> crystal plane SOI silicon wafer.

3. The MEMS piezoresistive pressure sensor according to claim 2, wherein the linearly graded beam film structure is a linearly graded cross and is located in the central region of the silicon strained film.

4. The MEMS piezoresistive pressure sensor of claim 3, wherein the linearly graded beam structure comprises a linearly graded cross beam, and the beam membrane structure is composed of the linearly graded cross beam and a circular boss or a square boss.

5. The MEMS piezoresistive pressure sensor with the linearly graded beam structure according to claim 4, wherein the piezoresistors are symmetrically arranged at the ends of the linearly graded beam film structure in at least four groups.

6. The MEMS piezoresistive pressure sensor with the linearly graded beam structure according to claim 5, wherein each group of piezoresistors comprises a plurality of piezoresistor strips.

7. A method for manufacturing a MEMS piezoresistive pressure sensor with a linearly graded beam structure according to any of the claims 1 to 6, characterized in that it comprises the following steps:

s1, manufacturing a piezoresistor and a heavily doped contact area which are mutually connected on the front surface of the silicon substrate;

s2, manufacturing a lead hole and a metal lead on the front surface of the silicon substrate;

s3, manufacturing a linear gradient beam film structure on the front surface of the silicon substrate through photoetching;

s4, performing back cavity etching on the back of the silicon substrate until the back cavity etching is stopped at a proper thickness to prepare a silicon strain film with a linear gradient beam film structure;

and S5, bonding the silicon strain film with the linear gradient beam film structure obtained in the step S4 with a glass base, and scribing to obtain the MEMS piezoresistive pressure sensor with the linear gradient beam film structure.

8. The method of claim 7, wherein in step S2, the piezoresistor and the heavily doped contact region are formed by ion implantation.

9. The method as claimed in claim 7, wherein in S2, the metal lead is selected from at least one of Al, Cr/Au, and Ti/Au.

10. The method for manufacturing the MEMS piezoresistive pressure sensor with the linearly graded beam structure according to claim 7, wherein the specific method of S3 is as follows: and defining the shape of a cross beam on the front surface of the silicon substrate by photoetching, and etching to manufacture a cross beam structure to obtain the silicon strain film with the linear gradient beam film structure.

Technical Field

The invention belongs to the technical field of sensors of micro-electro-mechanical systems, and particularly relates to an MEMS piezoresistive pressure sensor with a linear gradient beam structure and a preparation method thereof.

Background

The MEMS piezoresistive pressure sensor converts the external pressure change into corresponding electric signals based on the monocrystalline silicon piezoresistive effect, and the external pressure is measured by a Wheatstone bridge formed by four equivalent resistors. The MEMS piezoresistive pressure sensor is mainly applied to the relevant fields of industrial control, automotive electronics, consumer electronics, medical electronics, aerospace and the like. The MEMS piezoresistive pressure sensor is designed and developed by adopting MEMS technology, and is internally composed of a silicon diaphragm obtained by adopting a silicon wafer as a force sensitive element, four pairs of equivalent resistors manufactured by MEMS technologies such as doping, etching and the like, interconnecting wires with low resistance, metal leads subjected to evaporation deposition and the like, and a plurality of functional layers integrated by various materials.

In addition, the MEMS beam film piezoresistive pressure sensor has excellent linearity, but deep silicon etching is involved in the manufacturing process of the flow sheet, and the radial depth error of the large-size deep silicon etching is larger (+/-10 percent) at present, so that the thickness uniformity of a flat film layer after the front beam film etching is not guaranteed, and the risk of breaking a strain film of the sensor is increased; for the piezoresistive pressure sensor, the thickness of the strain diaphragm is the most critical, the performance difference of the same sensor is larger due to the uneven thickness, the difficulty of subsequent debugging and compensation is increased, and the manufacturing cost is increased.

Disclosure of Invention

In order to solve the above problems, an object of the present invention is to provide a MEMS piezoresistive pressure sensor with a linearly graded beam structure, which solves the problems of poor linearity, poor sensitivity, easy chipping, large performance difference caused by non-uniform thickness of a silicon strain film, and large difficulty in post-debugging and compensation in the MEMS piezoresistive pressure sensor in the prior art.

The invention also aims to provide a preparation method of the MEMS piezoresistive pressure sensor with the linear gradient beam structure.

In order to achieve the purpose, the technical scheme of the invention is realized as follows: the MEMS piezoresistive pressure sensor with the linear gradient beam structure comprises a silicon strain film with the linear gradient beam film structure, a piezoresistor, a heavily doped contact region, a metal lead and a glass base, wherein the silicon strain film is a silicon film with the linear gradient beam film structure, the front surface of a silicon substrate is subjected to photoetching and etching, the back surface of the silicon substrate is subjected to back cavity etching, the piezoresistor is located at the end part of the linear gradient beam film structure, the metal lead and the heavily doped contact region form ohmic contact on the front surface of the silicon strain beam film, and the glass base is located at the back surface of the silicon strain film and is bonded with the silicon strain film.

Preferably, the silicon substrate is an N-type <100> crystal plane silicon wafer or an N-type <100> crystal plane SOI silicon wafer.

Preferably, the linear graded beam film structure is in a shape of a linear graded cross and is located in a central area of the silicon strained film.

Preferably, the linear gradually-changing beam film structure comprises a linear gradually-changing cross beam, and the beam film structure is composed of the linear gradually-changing cross beam and a circular boss or a square boss.

Preferably, the piezoresistors are at least provided with four groups and symmetrically arranged at the end parts of the linear gradient beam film structure.

Preferably, each set of said piezoresistors comprises a number of varistor strips.

The second technical scheme of the invention is realized as follows: a preparation method of the MEMS piezoresistive pressure sensor with the linear gradient beam structure specifically comprises the following steps:

s1, manufacturing a piezoresistor and a heavily doped contact area which are mutually connected on the front surface of the silicon substrate;

s2, manufacturing a lead hole and a metal lead on the front surface of the silicon substrate;

s3, manufacturing a linear gradient beam film structure on the front surface of the silicon substrate through photoetching;

s4, performing back cavity etching on the back of the silicon substrate until the back cavity etching is stopped at a proper thickness to prepare a silicon strain film with a linear gradient beam film structure;

and S5, bonding the silicon strain film with the linear gradient beam film structure obtained in the step S4 with a glass base, and scribing to obtain the MEMS piezoresistive pressure sensor with the linear gradient beam film structure.

Preferably, in S2, the piezoresistor and the heavily doped contact region are formed by ion implantation.

Preferably, in S2, the metal wire is selected from at least one of Al, Cr/Au, and Ti/Au materials.

Preferably, the specific method of S3 is: and defining the shape of a cross beam on the front surface of the silicon substrate by photoetching, and etching to manufacture a cross beam structure to obtain the silicon strain film with the linear gradient beam film structure.

Compared with the prior art, the piezoresistive pressure sensor is formed by arranging the beam film structure with linear gradual change, the piezoresistor, the heavily doped contact area and the metal lead on the front surface of the silicon substrate and arranging the cavity on the back surface of the silicon substrate and bonding the glass base, so that the aims of improving the linearity of the pressure sensor and reducing the difficulty of later-stage debugging compensation are fulfilled by adjusting the linear change proportion of the gradual change beam structure, and the aim of improving the sensitivity is fulfilled by adjusting the size between the piezoresistor and the gradual change beam structure; in addition, the piezoresistive pressure sensor has good practicability and high cost performance, and is worthy of being widely popularized and used.

In addition, the manufacturing method of the invention adopts the steps of firstly photoetching and etching the front surface of the silicon substrate to manufacture the linear gradient beam film structure, manufacturing the piezoresistor, the heavily doped contact area, the lead hole and the metal lead which are connected with each other, then etching the back surface of the silicon substrate to form the cavity, and bonding the cavity with the glass base, thereby not only effectively reducing the risk of breaking the strain diaphragm caused by larger radial depth error of large-size deep silicon etching, but also reducing the manufacturing cost.

Drawings

Fig. 1 is a schematic perspective view of a MEMS piezoresistive pressure sensor with a linear graded beam structure obtained by a first manufacturing process in an embodiment of the present invention;

FIG. 2 is a first cross-sectional view of a MEMS piezoresistive pressure sensor with a linear graded beam structure obtained by a first fabrication process according to an embodiment of the present invention;

FIG. 3 is a second cross-sectional view of a MEMS piezoresistive pressure sensor with a linear graded beam structure obtained by a first manufacturing process in an embodiment of the present invention;

FIG. 4 is a front view of a MEMS piezoresistive pressure sensor with a linear graded beam structure obtained by a first fabrication process in an embodiment of the present invention;

fig. 5 is a schematic flow chart of a first manufacturing process of a MEMS piezoresistive pressure sensor with a linearly graded beam structure according to an embodiment of the present invention, where:

FIG. 5a is a schematic view of a thinning process of a prepared wafer;

FIG. 5b is a schematic diagram of a varistor fabrication;

FIG. 5c is a schematic view of a heavily doped contact region;

FIG. 5d is a schematic view of electrode hole fabrication;

FIG. 5e is a schematic view of a metal lead fabrication;

FIG. 5f is a schematic view of a linear graded beam film structure;

FIG. 5g is a back cavity etch map;

FIG. 5h is a first schematic view of silicon-glass bonding;

FIG. 5i is a second schematic view of silicon-glass bonding;

FIG. 6 is a schematic perspective view of a MEMS piezoresistive pressure sensor with a linear graded beam structure obtained by a first manufacturing process according to an embodiment of the present invention;

FIG. 7 is a first cross-sectional view of a MEMS piezoresistive pressure sensor with a linear graded beam structure obtained by a first fabrication process in an embodiment of the present invention;

FIG. 8 is a second cross-sectional view of a MEMS piezoresistive pressure sensor with a linear graded beam structure obtained by a first fabrication process in an embodiment of the present invention;

FIG. 9 is a front view of a MEMS piezoresistive pressure sensor with a linearly graded beam structure obtained by a first fabrication process in an embodiment of the present invention;

fig. 10 is a schematic flow chart of a second manufacturing process of the MEMS piezoresistive pressure sensor with the linearly graded beam structure according to the embodiment of the present invention, in which:

FIG. 10a is a schematic view of a thinning process of a prepared wafer;

FIG. 10b is a schematic diagram of a varistor fabrication;

FIG. 10c is a schematic view of a heavily doped contact region;

FIG. 10d is a schematic view of electrode hole fabrication;

FIG. 10e is a schematic view of metal lead fabrication;

FIG. 10f is a schematic view of a linear graded beam film structure;

FIG. 10g is a back cavity etch map;

FIG. 10h is the first schematic view of silicon-glass bonding;

FIG. 10i is a second schematic view of silicon-glass bonding;

fig. 11 is a schematic diagram of beam film structures in different forms in a manufacturing method of a MEMS piezoresistive pressure sensor with a linearly graded beam structure according to an embodiment of the present invention, where:

FIG. 11a is a schematic view of a first form of beam membrane structure;

FIG. 11b is a schematic view of a second form of beam membrane structure;

fig. 11c is a schematic view of a third form of beam film structure.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the description of the present invention, it is to be understood that the terms "vertical", "lateral", "longitudinal", "front", "rear", "left", "right", "upper", "lower", "horizontal", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description of the present invention, and do not mean that the device or member to which the present invention is directed must have a specific orientation or position, and thus, cannot be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1

The MEMS piezoresistive pressure sensor with a linear graded beam structure provided in embodiment 1 of the present invention is specifically shown in fig. 1-4 and 6-9, and includes a silicon strain film with a linear graded beam film structure, a piezoresistor, a heavily doped contact region, a metal lead and a glass base, where the silicon strain film is a silicon film with a linear graded beam film structure formed by performing photolithography etching on a front surface of a silicon substrate and performing back cavity etching on a back surface of the silicon substrate, the piezoresistor is located at an end of the linear graded beam film structure, the metal lead and the heavily doped contact region form ohmic contact on the front surface of the silicon strain beam film, and the glass base is located on the back surface of the silicon strain film and is bonded to the silicon strain film.

After the scheme is adopted, the beam film structure with linear gradual change, the piezoresistor, the heavily doped contact area and the metal lead are arranged on the front surface of the silicon substrate, the cavity is arranged on the back surface of the silicon substrate and the piezoresistive pressure sensor is formed by bonding the glass base, so that the aims of improving the linearity of the pressure sensor and reducing the later debugging compensation difficulty are fulfilled by adjusting the linear change proportion of the gradual change beam structure, and the aim of improving the sensitivity is fulfilled by adjusting the size between the piezoresistor and the gradual change beam structure.

Further, the silicon substrate is an N-type <100> crystal plane silicon wafer or an N-type <100> crystal plane SOI silicon wafer.

Furthermore, the linear gradient beam film structure is in a linear gradient cross shape and is positioned in the central area of the silicon strain film.

Further, the linear gradually-changed beam film structure comprises a linear gradually-changed cross beam, and the beam film structure is composed of the linear gradually-changed cross beam and a circular boss or a square boss.

Further, the piezoresistors are at least provided with four groups and are symmetrically arranged at the end parts of the linear gradient beam film structure.

Further, each group of piezoresistors comprises a plurality of piezoresistor strips.

Example 2

Embodiment 2 of the present invention provides a method for manufacturing an MEMS piezoresistive pressure sensor having a linear graded beam structure described in embodiment 1, which specifically includes the following steps:

s1, manufacturing a piezoresistor and a heavily doped contact area which are mutually connected on the front surface of the silicon substrate;

s2, manufacturing a lead hole and a metal lead on the front surface of the silicon substrate;

s3, manufacturing a linear gradient beam film structure on the front surface of the silicon substrate through photoetching;

s4, performing back cavity etching on the back of the silicon substrate until the back cavity etching is stopped at a proper thickness to prepare a silicon strain film with a linear gradient beam film structure;

and S5, bonding the silicon strain film with the linear gradient beam film structure obtained in the step S4 with a glass base, and scribing to obtain the MEMS piezoresistive pressure sensor with the linear gradient beam film structure.

After the scheme is adopted, the linear gradient beam film structure is manufactured by photoetching and etching the front surface of the silicon substrate, the piezoresistor, the heavily doped contact area, the lead hole and the metal lead which are connected with each other are manufactured, the cavity is formed by etching the back surface of the silicon substrate, and the glass base is bonded, so that the risk of breaking the strain diaphragm caused by large-size deep silicon etching radial depth error is effectively reduced, and the manufacturing cost is also reduced.

Further, in S2, the piezoresistor and the heavily doped contact region are formed by ion implantation.

Further, in S2, the metal wire is selected from at least one of Al, Cr/Au, and Ti/Au materials.

Further, the specific method of S3 is as follows: and defining the shape of a cross beam on the front surface of the silicon substrate by photoetching, and etching to manufacture a cross beam structure to obtain the silicon strain film with the linear gradient beam film structure.

The preparation method described in embodiment 2 of the present invention is explained in detail below, and the MEMS piezoresistive pressure sensor with a linearly graded beam structure described in embodiment 1 can be obtained by the following two methods:

the first method (the method mainly adopts an N-type <100> crystal face silicon wafer as a silicon substrate to manufacture the MEMS piezoresistive pressure sensor with the linear gradient beam film structure):

a) preparing a sheet, thinning: thinning the N-type <100> crystal plane silicon wafer 1 to a proper thickness, as shown in FIG. 5 a;

b) photoetching the piezoresistor 2: photoetching a piezoresistor pattern in the front area of the silicon wafer, implanting ions into the piezoresistor pattern, and annealing to obtain the piezoresistor, as shown in FIG. 5B;

c) photoetching the heavily doped contact region 3: photoetching a heavily doped contact region pattern in the front surface area of the silicon wafer, implanting ions into the B +, and annealing to obtain a heavily doped contact region as shown in FIG. 5 c;

d) opening the electrode hole 4: photoetching to obtain an electrode hole as shown in FIG. 5 d;

e) manufacturing a metal lead 5, and connecting ohm: depositing a metal layer by adopting the processes of evaporation, sputtering and the like, etching to obtain a metal lead, and annealing and alloying to form ohmic contact as shown in figure 5 e;

f) manufacturing a gradient beam film structure 6: the front side is lithographically defined to be in the shape of a linear gradually-changed cross beam, and a shallow etching mode is adopted to obtain a cross beam structure, as shown in figure 5 f;

g) back cavity etching 7: wet etching the cavity window to the size required by the flat film, as shown in fig. 5 g;

h) anodic bonding and scribing: anodic bonding combines the silicon chip 1 and Pyrex 7740 glass 8 under vacuum to form a vacuum sealed cavity, and a differential pressure or absolute pressure sensor is manufactured according to the condition that no hole is formed on the bonded glass, as shown in figures 5h and 5 i.

Wherein the Pyrex 7740 glass 8 may be perforated (as shown in FIG. 2) or non-perforated (as shown in FIG. 3), when perforated, such sensors are differential pressure sensors; when non-perforated is selected, such sensors are absolute pressure sensors.

The second method (the method mainly adopts an N-type <100> crystal face SOI silicon chip as a silicon substrate to manufacture the MEMS piezoresistive pressure sensor with the linear gradual change beam film structure):

a) preparing a wafer, etching a marking layer: to N type<100>Aligning a 1' zero layer of a crystal face SOI (Silicon-On-Insulator) Silicon wafer with an etching mark, and carrying out thermal oxidation On the surface of the Silicon waferSilicon dioxide 11', as shown in fig. 10 a;

b) photo-etching piezoresistor 2': photoetching a piezoresistor pattern in the device layer region of the SOI silicon chip, implanting ions into B +, and annealing to obtain the piezoresistor, as shown in FIG. 10B;

c) photoetching heavily-doped contact region 3': photoetching a heavily doped contact region pattern in the device layer region of the SOI silicon wafer, implanting ions into the B +, and annealing to obtain a heavily doped contact region as shown in FIG. 10 c;

d) opening electrode hole 4': obtaining a SiO2 layer or a SiN layer by adopting an LPCVD process, and obtaining an electrode hole by photoetching, as shown in figure 10 d;

e) making metal leads 5', ohmic connection: depositing a metal layer by adopting the processes of evaporation, sputtering and the like, etching to obtain a metal lead, and annealing and alloying to form ohmic contact as shown in figure 10 e;

f) manufacturing a gradient beam film structure 6': photoetching and defining the shape of the gradually-changed cross beam on the front surface, and obtaining a structure of the gradually-changed cross beam by adopting a shallow layer etching mode, wherein the structure is shown in FIG. 10 f;

g) back cavity 7' etching: the front and back sides are etched with deep silicon etch back cavities until encountering the buried oxide layer, as shown in fig. 10 g;

h) silicon glass bonding and scribing: and bonding the silicon strain membrane with the glass/perforated glass anode, and scribing to obtain an absolute pressure sensor or a differential pressure sensor, as shown in fig. 10h and fig. 10 i.

Wherein, when the glass base 8' may be perforated (as shown in FIG. 7) or non-perforated (as shown in FIG. 8), when perforated is used, such sensors are differential pressure sensors; when non-perforated is selected, such sensors are absolute pressure sensors.

In addition, in a specific implementation process, the shape of the linear gradient beam film structure is not limited to the conventional cross beam structure, and can be changed into other structures, as shown in fig. 11a to 11 c; the gradient beam film structure is also suitable for a pressure sensor with an inverted structure.

The piezoresistive pressure sensor with the linear gradient beam film structure is characterized in that the piezoresistive pressure sensor with the linear gradient beam film structure is provided for the first time, and the piezoresistor is positioned at the end part of the linear gradient beam film structure, so that the linearity of the pressure sensor is ensured, and the high sensitivity of the pressure sensor is improved.

The following table 1 is a comparison of the performance of the actual test of the MEMS piezoresistive pressure sensor obtained by the method of the present invention and the performance of the actual test of the conventional piezoresistive pressure sensor.

Table 1 comparison of actual performance data of MEMS piezoresistive pressure sensors obtained according to the invention with conventional piezoresistive pressure sensors

As can be seen from the data in Table 1, the MEMS piezoresistive pressure sensor obtained by the invention has higher sensitivity and linearity.

In summary, the piezoresistive pressure sensor formed by arranging the beam film structure with linear gradual change, the piezoresistor, the heavily doped contact area and the metal lead on the front surface of the silicon substrate and arranging the cavity on the back surface of the silicon substrate and bonding the glass base is adopted, so that the aims of improving the linearity of the pressure sensor and reducing the difficulty of later-stage debugging compensation are fulfilled by adjusting the linear change proportion of the gradual change beam structure, and the aim of improving the sensitivity is fulfilled by adjusting the size between the piezoresistor and the gradual change beam structure; in addition, the piezoresistive pressure sensor has good practicability and high cost performance, and is worthy of being widely popularized and used.

In addition, the manufacturing method of the invention adopts the steps of firstly photoetching and etching the front surface of the silicon substrate to manufacture the linear gradient beam film structure, manufacturing the piezoresistor, the heavily doped contact area, the lead hole and the metal lead which are connected with each other, then etching the back surface of the silicon substrate to form the cavity, and bonding the glass base, thereby not only effectively reducing the risk of breaking the strain diaphragm caused by larger radial depth error of large-size deep silicon etching, but also reducing the manufacturing cost; meanwhile, the defect of a beam film type can be made up in the manufacturing process, the linear change shape of the gradual change beam is adjusted, the risk of strain membrane fragment caused by large-size deep silicon etching radial depth error (over etching) is reduced, the maximum displacement of the center and surrounding dangerous areas is 0.42um originally, and the gradual change beam can be reduced to 0.39um or even smaller.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.