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CN117433671A - MEMS pressure sensor and manufacturing method thereof - Google Patents

MEMS pressure sensor and manufacturing method thereof Download PDF

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Publication number
CN117433671A
CN117433671A CN202210834448.8A CN202210834448A CN117433671A CN 117433671 A CN117433671 A CN 117433671A CN 202210834448 A CN202210834448 A CN 202210834448A CN 117433671 A CN117433671 A CN 117433671A
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CN
China
Prior art keywords
substrate
cavity
front side
pressure sensor
mems pressure
Prior art date
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Pending
Application number
CN202210834448.8A
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Chinese (zh)
Inventor
马清杰
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Suzhou Yuexin Micro Sensing Technology Co ltd
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Suzhou Yuexin Micro Sensing Technology Co ltd
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Priority to CN202210834448.8A priority Critical patent/CN117433671A/en
Publication of CN117433671A publication Critical patent/CN117433671A/en
Pending legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B81B7/0009—Structural features, others than packages, for protecting a device against environmental influences
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
    • B81C1/00158—Diaphragms, membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/02—Sensors
    • B81B2201/0264—Pressure sensors

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Measuring Fluid Pressure (AREA)
  • Pressure Sensors (AREA)

Abstract

The invention provides a MEMS pressure sensor and a manufacturing method thereof. The MEMS pressure sensor, comprising: a first substrate having a front surface and a back surface; a second substrate having a front side and a back side, the second substrate being opposite the first substrate, and the front side of the second substrate being adjacent the front side of the first substrate; a back cavity penetrating through the first substrate from the back surface of the first substrate; and the sensitive structure is positioned on the back surface of the second substrate and is opposite to the back cavity. In this way, the location, size, thickness and uniformity of the strained film can be precisely controlled.

Description

MEMS pressure sensor and manufacturing method thereof
[ field of technology ]
The invention relates to the technical fields of sensors and micro-electromechanical systems, in particular to a micro differential pressure MEMS pressure sensor and a manufacturing method thereof.
[ background Art ]
Along with the development demand of social intelligence, the application field of the pressure sensor is wider and wider, and the demand is larger and larger; pressure sensors currently manufactured by MEMS (Micro Electro Mechanical Systems ) technology have become the dominant one, but the manufacture of micro-differential pressure MEMS pressure sensors has been an industry challenge.
In the prior art, one manufacturing method of the micro differential pressure MEMS pressure sensor is as follows: and manufacturing a sensitive structure on the processing surface of the silicon substrate, and performing wet or dry deep silicon etching on the projection area of the sensitive structure on the other surface of the substrate to form a strain film. Disadvantages: the film thickness is difficult to control accurately, and the uniformity is poor (the sensitivity of the pressure sensor is very sensitive to the film thickness); the method is anisotropic etching, and the film forming position is difficult to accurately align with the sensitive structure.
In the prior art, another manufacturing method of the micro differential pressure MEMS pressure sensor is as follows: and manufacturing an SOI (Silicon-On-Insulator) substrate (a film layer covering the vacuum cavity is a strain film) with the vacuum cavity, manufacturing a sensitive structure On the surface of the strain film at the projection position of the vacuum cavity, and finally performing deep Silicon etching On the projection area of the vacuum cavity On the other surface of the substrate to open the vacuum cavity. Disadvantages: because the cavity is vacuum, when the sensitive structure is manufactured, the strain film is in a serious deformation state, the MEMS process is a planar process, and the problem of poor uniformity is caused when the sensitive structure is manufactured on a non-planar surface; after the vacuum cavity is opened, the strain film can recover deformation, larger zero output can be generated at the moment, and zero output deviation among products is large.
Therefore, there is a need to propose a solution to overcome the above-mentioned problems.
[ invention ]
An object of the present invention is to provide a MEMS pressure sensor and a method for manufacturing the same, in which the position, size, thickness and uniformity of a strained film can be precisely controlled.
According to one aspect of the present invention, there is provided a MEMS pressure sensor comprising: a first substrate having a front surface and a back surface; a second substrate having a front side and a back side, the second substrate being opposite the first substrate, and the front side of the second substrate being adjacent the front side of the first substrate; a back cavity penetrating through the first substrate from the back surface of the first substrate; and the sensitive structure is positioned on the back surface of the second substrate and is opposite to the back cavity.
According to one aspect of the present invention, there is provided a method for manufacturing a MEMS pressure sensor, comprising: providing a first substrate having a front side and a back side; forming a second cavity on the front surface of the first substrate, wherein the second cavity extends from the front surface of the first substrate into the first substrate; filling up the second cavity on the front surface of the first substrate with a sacrificial layer; providing a second substrate having a front side and a back side; bonding the front surface of the first substrate filled with the sacrificial layer with the front surface of the second substrate; thinning the second substrate from the back side of the second substrate; forming a sensitive structure on the back surface of the thinned second substrate; forming a first cavity on the back surface of the first substrate, wherein the first cavity penetrates through the first substrate from the back surface of the first substrate and is terminated at the sacrificial layer; performing release etching on the sacrificial layer in the second cavity through the first cavity to form a back cavity and a strain film structure suspended on the back cavity; wherein a perpendicular projection of the back cavity on the front side of the first substrate covers a perpendicular projection of the sensitive structure on the front side of the first substrate.
Compared with the prior art, the MEMS pressure sensor and the manufacturing method thereof can accurately control the position, the size, the thickness and the uniformity of the strain film, so that the product has high sensitivity, good linearity, good consistency and small zero output variation.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:
FIG. 1 is a flow chart of a method of fabricating a MEMS pressure sensor in one embodiment of the invention;
FIGS. 2-11 are longitudinal cross-sectional views of structures corresponding to the steps shown in FIG. 1 in one embodiment of the present invention;
FIG. 12 is a longitudinal cross-sectional view of a MEMS pressure sensor in one embodiment of the invention.
[ detailed description ] of the invention
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Unless specifically stated otherwise, the terms connected, or connected herein denote an electrical connection, either directly or indirectly.
In order to overcome the problems of the micro differential pressure MEMS pressure sensor in the prior art, the invention provides an MEMS pressure sensor and a manufacturing method thereof. The MEMS pressure sensor in the invention can be a micro differential pressure MEMS pressure sensor or a conventional MEMS pressure sensor.
Fig. 1 is a schematic flow chart of a method for manufacturing a MEMS pressure sensor according to an embodiment of the invention; referring to fig. 2-11, there are shown longitudinal sectional views of a structure according to the present invention corresponding to the steps shown in fig. 1 in one embodiment. The method for manufacturing the MEMS pressure sensor shown in FIG. 1 comprises the following steps.
Step 110, as shown in fig. 2, a first substrate 210 having a front side and a back side is provided.
In step 120, as shown in fig. 3, a second cavity 220 is formed on the front surface (or referred to as a processing surface) of the first substrate 210, and the second cavity 220 extends from the front surface of the first substrate 210 into the first substrate 210.
In the embodiment shown in fig. 2 and 11, the first substrate 210 is a silicon substrate; the second cavity 220 is formed on the front surface of the first substrate 210 by etching using a photolithography process; the depth of the second cavity 220 is 1-100um.
In step 130, as shown in fig. 4, a sacrificial layer 230 is grown on the front surface of the first substrate 210 where the second cavity 220 is formed, and the sacrificial layer 230 fills the second cavity 220 and covers the front surface of the first substrate 210. It can be said that a sacrificial layer 230 is grown on the entire front surface of the first substrate 210 where the second cavity 220 is formed, and the thickness of the sacrificial layer 230 is thicker than the depth of the second cavity 220.
In step 140, as shown in fig. 5, the sacrificial layer 230 above the front surface of the first substrate 210 is polished flat and the front surface of the first substrate 210 is exposed, so that the first cavity 210 is filled with the sacrificial layer 230. In one embodiment, the sacrificial layer 230 over the front side of the first substrate 210 is polished flat and exposes the front side surface of the first substrate 210 using a CMP (Chemical Mechanical Polishing ) process, such that the first cavity 210 is filled with the sacrificial layer 230.
It should be specifically noted that the functions of step 130 and step 140 are: the second cavity 220 located on the front side of the first substrate 210 is filled with a sacrificial layer 230. In other embodiments, the second cavity 220 located on the front surface of the first substrate 210 may be filled with the sacrificial layer 230 by other manners in the prior art, which will not be described herein. In the embodiment shown in fig. 2 and 11, the sacrificial layer 230 is a silicon oxide layer.
Step 150, as shown in fig. 6, providing a second substrate 240 having a front surface and a back surface, bonding the front surface of the first substrate 210 filled with the sacrificial layer 230 with the front surface of the second substrate 240, thereby forming the first substrate 210 and the second substrate 240 into a whole. In the embodiment shown in fig. 2 and 11, the second substrate 240 is a silicon substrate.
Step 160, as shown in fig. 7, the second substrate 240 is thinned from the back side of the second substrate 240. Wherein the thickness of the thinned second substrate 240 is smaller than the thickness of the first substrate 210.
Step 170, as shown in fig. 8, is performed to dope the thinned back surface of the second substrate 240 to form a doped layer 280.
The doping is P-type doping, which can be P-type heavy doping, P-type light doping or P-type gradient doping formed by P-type light doping and then P-type heavy doping. The second substrate 240 is an N-type substrate.
In step 180, as shown in fig. 9, a photolithography process is used to etch the back surface of the doped second substrate 240 (or etch the doped layer 280) to form the sensitive structure 250. It can also be said that the sensitive structure 250 is formed by patterning the doped layer 280 on the back side of the second substrate 240. Wherein the perpendicular projection of the second cavity 220 onto the front side of the first substrate 210 covers the perpendicular projection of the sensitive structure 250 onto the front side of the first substrate 210.
The sensitive structure 250 includes one or more stripe-shaped protrusions 251 (4 stripe-shaped protrusions 251 in the embodiment shown in fig. 2-11), the sidewalls of which expose at least the doped layer 280 (e.g., exposing the P-type doped layer). The sensing structure 250 further includes a plurality of electrodes, each electrode is used for each strip-shaped protrusion 251 to access and output an electrical signal, and each electrode and each strip-shaped protrusion 251 form a wheatstone bridge. For the detailed structure, principle and formation of the sensitive structure 250, reference may be made to another chinese patent application of applicant, having application number 202110710324.4 and application date 2021, 6 and 25.
It should be specifically noted that, the functions of step 170 and step 180 are to form the sensitive structure 250 on the back surface of the thinned second substrate 240, and in other embodiments, other manners in the prior art may also be used to form the sensitive structure 250 on the back surface of the thinned second substrate 240, which is not described herein.
Step 190, as shown in fig. 10, the first substrate 210 is etched from the vertically projected region of the second cavity 220 on the back side of the first substrate 210, and the etching is terminated at the sacrificial layer 230. It can be said that the first cavity 260 is formed on the back surface of the first substrate 210, and the first cavity 260 penetrates the first substrate 210 from the back surface of the first substrate 210 and terminates in the sacrificial layer 23. In the embodiment shown in fig. 2 and 11, the vertical projection of the first cavity 260 on the front side of the first substrate 210 is within the vertical projection of the second cavity 220 on the front side of the first substrate 210; the perpendicular projection of the second cavity 220 onto the front side of the first substrate 210 covers the perpendicular projection of the sensitive structure 250 onto the front side of the first substrate 210. In a preferred embodiment, the first cavity 260 is formed using a dry deep silicon etch or a wet deep silicon etch.
Step 200, as shown in fig. 11, the sacrificial layer 230 in the second cavity 220 is subjected to release etching through the first cavity 260 to form a back cavity 270 and a strained thin film structure (not shown) suspended over the back cavity 270. In the embodiment shown in fig. 2 and 11, the back cavity 270 includes a first cavity 260 and a second cavity 220; the first cavity 260 extends from the back surface of the first substrate 210 into the first substrate 210; the second cavity 220 extends from a face of the first cavity 260 adjacent the front face of the first substrate 210 to the front face of the first substrate 210; the perpendicular projection of the back cavity 270 onto the front side of the first substrate 210 covers the perpendicular projection of the sensitive structure 250 onto the front side of the first substrate 210; the portion of the second substrate 240 suspended over the back cavity 270 forms a strained thin film; the thickness of the thinned second substrate 240 is less than the thickness of the first substrate 210. In a preferred embodiment, the sacrificial layer 230 is subjected to a release etch using a dry or wet process.
It should be noted that, in another embodiment of the present invention, the vertical projection of the first cavity 260 on the front surface of the first substrate 210 completely coincides with the vertical projection of the second cavity 220 on the front surface of the first substrate 210.
According to another aspect of the present invention, a MEMS pressure sensor is provided. The MEMS pressure sensor is preferably a micro-differential MEMS pressure sensor. Referring to FIG. 12, a longitudinal cross-sectional view of a MEMS pressure sensor in accordance with one embodiment of the present invention is shown. The MEMS pressure sensor shown in fig. 12 is manufactured by the manufacturing method of the MEMS pressure sensor shown in fig. 1.
The MEMS pressure sensor shown in fig. 12 includes a first substrate 210, a second substrate 240, a back cavity 270, and a sensitive structure 250.
The first substrate 210 has a front side and a back side. The second substrate 240 has a front surface and a back surface, the second substrate 240 is opposite to the first substrate 210, and the front surface of the second substrate 240 is adjacent to the front surface of the first substrate 210; the back cavity 270 penetrates the first substrate 210 from the back surface of the first substrate 210; the sensitive structure 250 is located on the back side of the second substrate 240 opposite the back cavity 270.
In the embodiment shown in fig. 12, the front side of the second substrate 240 is immediately adjacent to the front side of the first substrate 210;
the front surface of the first substrate 210 and the front surface of the second substrate 240 are bonded, thereby forming the first substrate 210 and the second substrate 240 as a unit. The back cavity 270 extends through the first substrate 210 from the back surface of the first substrate 210 and terminates at the front surface of the second substrate 240; the portion of the second substrate 240 suspended over the back cavity 270 forms a strained thin film.
In the particular embodiment shown in fig. 12, the back cavity 270 includes a first cavity 260 and a second cavity 220,
the first cavity 260 extends from the back surface of the first substrate 210 into the first substrate 210; the second cavity 220 extends from a face of the first cavity 260 adjacent the front face of the first substrate 210 to the front face of the first substrate 210; the vertical projection of the first cavity 260 on the front side of the first substrate 210 is within the vertical projection of the second cavity 220 on the front side of the first substrate 210; the perpendicular projection of the second cavity 220 onto the front side of the first substrate 210 covers the perpendicular projection of the sensitive structure 250 onto the front side of the first substrate 210.
In the particular embodiment shown in fig. 12, the thickness of the second substrate 240 is less than the thickness of the first substrate 210; the first substrate 210 is a silicon substrate; the second substrate 240 is a silicon substrate.
In one embodiment shown in FIG. 12, the second cavity 220 has a depth of 1-100um; the sensitive structure 250 is made by patterning the doped layer 280 on the back side of the second substrate 240. The sensitive structure 250 includes one or more stripe-shaped protrusions 251, and sidewalls of the stripe-shaped protrusions 251 expose at least the doped layer 280 (e.g., expose the P-type doped layer). The sensing structure 250 further includes a plurality of electrodes, each electrode is used for each bar-shaped protrusion 251 to access and output an electrical signal, and each electrode and each bar-shaped protrusion 251 form a wheatstone bridge. For the detailed structure, principle and formation of the sensitive structure 250, reference may be made to another chinese patent application of applicant, application number 202110710324.4, application date 2021, month 6 and 25.
As can be seen from fig. 1 to 12, the MEMS pressure sensor and the method for manufacturing the same according to the present invention have the following advantages.
1. Since the present invention thins the second substrate 240 from the back side of the second substrate 240, and the process of forming the back cavity of the present invention is: first, the first substrate 210 is etched from the back side of the first substrate 210, and the etching is terminated at the sacrificial layer 230 to form a first cavity 260; then, the sacrificial layer 230 in the second cavity 220 is released and etched through the first cavity 260 to form a back cavity 270 and a strained thin film structure (not identified) suspended on the back cavity 270, so that the thickness, the size, the position and the uniformity of the strained thin film finally obtained in the invention can be precisely controlled, and the problem of poor manufacturing uniformity of the micro-pressure differential pressure sensor is solved.
2. The invention forms the sensitive structure 250 on the back of the thinned second substrate 240, and then etches the first substrate 210 and the sacrificial layer 230 sequentially from the back of the first substrate 210 to form the back cavity 270 and the strained thin film structure suspended on the back cavity 270. In the process, the strain film structure is always in a plane state, and the sensitive structure 250 is manufactured on an absolute plane, so that the problem of overlarge zero offset of the micro differential pressure sensor is solved.
3. The invention arranges a second cavity 220 on the front surface of a first substrate 210, and fills up the second cavity 220 with a sacrificial layer 230; etching the first substrate 210 from the back side of the first substrate 210, and the etching is terminated at the sacrificial layer 230; the sacrificial layer 230 in the second cavity 220 is released and etched through the first cavity 260 to form a back cavity 270 and a strained thin film structure (not identified) suspended on the back cavity 270, so that the cross section of the back cavity 270 near the front surface of the first substrate 210 is larger than the cross section of the back cavity 270 near the back surface of the first substrate 210, the structural strength of the back cavity 270 is enhanced as much as possible while the area of the strained thin film structure suspended on the back cavity 270 is ensured, and the mounting area is increased, thereby solving the problem of larger size of the conventional micro differential pressure sensor.
4. The present invention forms the second cavity 220 on the front surface (or the processing surface) of the first substrate 210 and fills up the second cavity 220 with the sacrificial layer 230, wherein the second cavity 220 filled with the sacrificial layer 230 defines the position of the strained thin film structure suspended on the back cavity 270, so that the position, size, thickness and uniformity of the strained thin film can be precisely controlled for manufacturing the strained thin film.
In summary, the MEMS pressure sensor and the manufacturing method thereof can accurately control the position, the size, the thickness and the uniformity of the strain film, so that the product has high sensitivity, good linearity, good consistency and small zero output variation.
In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element in question must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
The above description is merely of preferred embodiments of the present invention, and the scope of the present invention is not limited to the above embodiments, but all equivalent modifications or variations according to the present disclosure will be within the scope of the claims.

Claims (14)

1. A MEMS pressure sensor, comprising:
a first substrate having a front surface and a back surface;
a second substrate having a front side and a back side, the second substrate being opposite the first substrate, and the front side of the second substrate being adjacent the front side of the first substrate;
a back cavity penetrating through the first substrate from the back surface of the first substrate;
and the sensitive structure is positioned on the back surface of the second substrate and is opposite to the back cavity.
2. The MEMS pressure sensor, as recited in claim 1,
the front side of the second substrate is adjacent to the front side of the first substrate;
the back cavity penetrates through the first substrate from the back surface of the first substrate and is terminated at the front surface of the second substrate;
the portion of the second substrate suspended over the back cavity forms a strained film.
3. The MEMS pressure sensor, as recited in claim 1,
the front surface of the first substrate and the front surface of the second substrate are bonded, so that the first substrate and the second substrate form a whole.
4. A MEMS pressure sensor according to any one of claims 1-3, wherein,
the back cavity comprises a first cavity and a second cavity,
the first cavity extends from the back surface of the first substrate into the first substrate;
the second cavity extends from a face of the first cavity adjacent to the front face of the first substrate;
a vertical projection of the first cavity on the front side of the first substrate is located within a vertical projection of the second cavity on the front side of the first substrate;
a perpendicular projection of the second cavity on the front side of the first substrate covers a perpendicular projection of the sensitive structure on the front side of the first substrate.
5. The MEMS pressure sensor, as recited in claim 4,
the depth of the second cavity is 1-100um; and/or
The sensitive structure is made by patterning a doped layer on the back side of the second substrate,
the sensitive structure comprises: the electrode is used for connecting the electric signals to and outputting the electric signals from the strip-shaped bulges, and the electrode and the strip-shaped bulges form a Wheatstone bridge.
6. The MEMS pressure sensor, as recited in claim 1,
the thickness of the second substrate is smaller than that of the first substrate;
the first substrate is a silicon substrate; and/or
The second substrate is a silicon substrate.
7. A method of making a MEMS pressure sensor, comprising:
providing a first substrate having a front side and a back side;
forming a second cavity on the front surface of the first substrate, wherein the second cavity extends from the front surface of the first substrate into the first substrate;
filling up the second cavity on the front surface of the first substrate with a sacrificial layer;
providing a second substrate having a front side and a back side;
bonding the front surface of the first substrate filled with the sacrificial layer with the front surface of the second substrate;
thinning the second substrate from the back side of the second substrate;
forming a sensitive structure on the back surface of the thinned second substrate;
forming a first cavity on the back surface of the first substrate, wherein the first cavity penetrates through the first substrate from the back surface of the first substrate and is terminated at the sacrificial layer;
performing release etching on the sacrificial layer in the second cavity through the first cavity to form a back cavity and a strain film structure suspended on the back cavity;
wherein a perpendicular projection of the back cavity on the front side of the first substrate covers a perpendicular projection of the sensitive structure on the front side of the first substrate.
8. The method of manufacturing a MEMS pressure sensor as claimed in claim 7, wherein,
the back cavity comprises a first cavity and a second cavity,
a vertical projection of the first cavity on the front side of the first substrate is located within a vertical projection of the second cavity on the front side of the first substrate;
a perpendicular projection of the second cavity on the front side of the first substrate covers a perpendicular projection of the sensitive structure on the front side of the first substrate.
9. The method of manufacturing a MEMS pressure sensor as claimed in claim 8, wherein,
the "filling up the second cavity located on the front surface of the first substrate with a sacrificial layer" includes:
growing a sacrificial layer on the front surface of the first substrate with the second cavity, wherein the sacrificial layer fills the second cavity and covers the front surface of the first substrate;
and grinding the sacrificial layer above the front surface of the first substrate and exposing the front surface of the first substrate, so that the first cavity is filled by the sacrificial layer.
10. The method of manufacturing a MEMS pressure sensor as claimed in claim 7, wherein,
the second cavity is formed on the front surface of the first substrate by adopting a photoetching process through etching; and/or
The depth of the second cavity is 1-100um.
11. The method of claim 7, wherein the first cavity is formed by dry deep silicon etching or wet deep silicon etching;
and carrying out release etching on the sacrificial layer by adopting a dry method or a wet method.
12. The method of claim 7, wherein forming a sensitive structure on the thinned back side of the second substrate comprises:
doping the back surface of the thinned second substrate to form a doped layer;
and etching the doped layer by adopting a photoetching process to form the sensitive structure.
13. The method of manufacturing a MEMS pressure sensor as claimed in claim 12, wherein,
the sensitive structure comprises:
one or more strip-shaped protrusions, the sidewalls of which expose at least the doped layer;
and each electrode is used for connecting the strip-shaped protrusion with the electric signal and outputting the electric signal, and each electrode and each strip-shaped protrusion form a Wheatstone bridge.
14. The method of manufacturing a MEMS pressure sensor as claimed in claim 7, wherein,
a portion of the second substrate suspended over the back cavity forms a strained thin film;
the thickness of the thinned second substrate is smaller than that of the first substrate;
the sacrificial layer is a silicon oxide layer;
the first substrate is a silicon substrate; and/or
The second substrate is a silicon substrate.
CN202210834448.8A 2022-07-14 2022-07-14 MEMS pressure sensor and manufacturing method thereof Pending CN117433671A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210834448.8A CN117433671A (en) 2022-07-14 2022-07-14 MEMS pressure sensor and manufacturing method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210834448.8A CN117433671A (en) 2022-07-14 2022-07-14 MEMS pressure sensor and manufacturing method thereof

Publications (1)

Publication Number Publication Date
CN117433671A true CN117433671A (en) 2024-01-23

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210834448.8A Pending CN117433671A (en) 2022-07-14 2022-07-14 MEMS pressure sensor and manufacturing method thereof

Country Status (1)

Country Link
CN (1) CN117433671A (en)

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