A resonant pressure sensor and its manufacturing process

Abstract

A resonant pressure sensor includes a silicon wafer, a film part, a resonant part, a resonant part fixing point, a back hole, a cap, a getter layer, a supporting silicon layer, a buried oxide layer, a top silicon film, and a polysilicon film and an oxide film alternately deposited film; the SOI wafer is composed of a top silicon film, a buried oxide layer and a supporting silicon layer; a silicon wafer or an SOI wafer is used as a substrate to form the film part of the resonant pressure sensor, or a top silicon film, a polysilicon film and an oxide film are alternately deposited on the SOI wafer substrate to form the film part of the resonant pressure sensor. A manufacturing process for a resonant pressure sensor, the resonant part is realized by depositing an epitaxial / polysilicon layer, and the substrate is formed by an etching process to form a channel for fluid to enter the film - the back hole of the resonant pressure sensor. The advantages of the present invention are: compact overall structure, high precision, simple manufacturing process, easy control, and a wide range of product applications.

Description

Technical Field

[0001] The invention relates to the field of sensors, and in particular to a resonant pressure sensor and a manufacturing process. Background Art

[0002] Traditional pressure sensors are large in size, low in accuracy, narrow in scope of application, and provide poor user experience. Summary of the invention

[0003] The purpose of the present invention is to improve accuracy, reduce volume, and enhance user experience, and a resonant pressure sensor and a manufacturing process are specially provided.

[0004] The present invention provides a resonant pressure sensor, characterized in that: the resonant pressure sensor comprises a silicon wafer 1, a thin film part 2, a resonant part 3, a resonant part fixing point 4, a back hole 5, a cap 6, a getter layer 7, a supporting silicon layer 8, a buried oxide layer 9, a top silicon film 10, and a polysilicon film and an oxide layer film alternately deposited film 11;

[0005] Wherein: SOI wafer 12 is composed of top silicon film 10, buried oxide layer 9 and supporting silicon layer 8; silicon wafer 1 or SOI wafer 12 is used as substrate, oxide layer or polysilicon layer is deposited alternately on silicon wafer 1 substrate for multiple times to form thin film part 2 of resonant pressure sensor, or film 11 is deposited alternately on SOI wafer 12 substrate by top silicon film 10 or by top silicon film 10, polysilicon film and oxide layer film on SOI wafer to form thin film part 2 of resonant pressure sensor;

[0006] The SOI wafer 12 is located at the bottom, and the upper part is the resonance part 3 connected through the resonance part fixing point 4. The outside of the resonance part 3 is a shell, and the upper part of the shell is a cap 6.

[0007] A manufacturing process of a resonant pressure sensor, wherein the resonant part 3 is realized by depositing an epitaxial / polysilicon layer, and the substrate is etched to form a channel for fluid to enter the film - a back hole 5 of the resonant pressure sensor.

[0008] The capping process is completed on another substrate to form a sensor cap 6, and a getter layer composed of an alloy of one or several metals or their metal oxides is deposited inside the cap by physical vapor deposition and stripping processes, and finally the cap and the sensor part are combined together by a bonding process.

[0009] The back hole 5 of the resonant pressure sensor is realized by a wet etching process or a deep reactive ion etching process; the cap 6 is realized on another wafer by a wet / plasma etching process, and the cap and other parts of the sensor are combined together by a wafer bonding process.

[0010] The getter layer 7 is deposited inside the cap by physical vapor deposition and stripping process, and is composed of an alloy of one or several metals or their metal oxides, and its main function is to maintain the vacuum environment in the cap.

[0011] The main process flow of resonant pressure sensor:

[0012] Substrate part: Silicon wafer 1 / SOI wafer 12

[0013] Thin film part: Polysilicon and oxide layer structures are alternately deposited on the substrate by chemical vapor deposition or plasma enhanced chemical vapor deposition, such as Figure 2 , 11. Polysilicon can be used as the lower electrode of the resonance part, and can also be used as an electrical connection layer.

[0014] Resonance part 3: On the thin film layer, a polysilicon layer is grown by an epitaxial process as the main structure of the resonance part, and a release hole is etched on the resonance body by a plasma etching process, and then the sacrificial layer is etched away by a gaseous hydrofluoric acid release process, finally forming the resonance part and the thin film part.

[0015] The back hole portion is etched using a deep reactive ion etching or wet etching process 5.

[0016] The cap 6 is formed by plasma etching or solid etching of a silicon wafer, and the cap wafer 6 and the resonant wafer are bonded 1 or 12 together by silicon-silicon bonding, eutectic bonding, etc. And according to different cap bonding methods, metal is deposited by physical vapor deposition for bonding. Before bonding, a getter layer 7 is grown inside the cap wafer by physical vapor deposition, and the component of the getter layer is an alloy of one or more metals or their oxides.

[0017] The resonance pressure sensor involved can be a stand-alone sensor or integrated into a chip with a 6-axis inertial measurement unit or a 9Dof sensor. Because the process flow of the resonant pressure sensor is the same as that of the inertial measurement unit and the 9Dof sensor, the two devices can be prepared at the same time using the same process, so the two devices can be prepared into one chip to form a 7Dof device or a 10Dof device.

[0018] Advantages of the present invention:

[0019] The resonant pressure sensor and the manufacturing process described in the present invention have a compact overall structure, high precision, a simple manufacturing process, are easy to control, and have a wide range of product applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0021] Figure 1This is a schematic diagram of the structure of a silicon substrate resonant pressure sensor;

[0022] Figure 2 This is a schematic diagram of the structure of a resonant pressure sensor using SOI wafer as the substrate material;

[0023] Figure 3 Schematic diagram of the structure of a resonant pressure sensor with the top silicon of the SOI wafer as a thin film. DETAILED DESCRIPTION

[0024] Example 1

[0025] The present invention provides a resonant pressure sensor, characterized in that: the resonant pressure sensor comprises a silicon wafer 1, a thin film part 2, a resonant part 3, a resonant part fixing point 4, a back hole 5, a cap 6, a getter layer 7, a supporting silicon layer 8, a buried oxide layer 9, a top silicon film 10, and a polysilicon film and an oxide layer film alternately deposited film 11;

[0026] Wherein: SOI wafer 12 is composed of top silicon film 10, buried oxide layer 9 and supporting silicon layer 8; silicon wafer 1 or SOI wafer 12 is used as substrate, oxide layer or polysilicon layer is deposited alternately on silicon wafer 1 substrate for multiple times to form thin film part 2 of resonant pressure sensor, or film 11 is deposited alternately on SOI wafer 12 substrate by top silicon film 10 or by top silicon film 10, polysilicon film and oxide layer film on SOI wafer to form thin film part 2 of resonant pressure sensor;

[0027] The SOI wafer 12 is located at the bottom, and the upper part is the resonance part 3 connected through the resonance part fixing point 4. The outside of the resonance part 3 is a shell, and the upper part of the shell is a cap 6.

[0028] A manufacturing process of a resonant pressure sensor, wherein the resonant part 3 is realized by depositing an epitaxial / polysilicon layer, and the substrate is etched to form a channel for fluid to enter the film - a back hole 5 of the resonant pressure sensor.

[0029] The capping process is completed on another substrate to form a sensor cap 6, and a getter layer composed of an alloy of one or several metals or their metal oxides is deposited inside the cap by physical vapor deposition and stripping processes, and finally the cap and the sensor part are combined together by a bonding process.

[0030] The back hole 5 of the resonant pressure sensor is realized by a wet etching process or a deep reactive ion etching process; the cap 6 is realized on another wafer by a wet / plasma etching process, and the cap and other parts of the sensor are combined together by a wafer bonding process.

[0031] The getter layer 7 is deposited inside the cap by physical vapor deposition and stripping process, and is composed of an alloy of one or several metals or their metal oxides, and its main function is to maintain the vacuum environment in the cap.

[0032] The main process flow of resonant pressure sensor:

[0033] Substrate part: Silicon wafer 1 / SOI wafer 12

[0034] Thin film part: Polysilicon and oxide layer structures are alternately deposited on the substrate by chemical vapor deposition or plasma enhanced chemical vapor deposition, such as Figure 2 , 11. Polysilicon can be used as the lower electrode of the resonance part, and can also be used as an electrical connection layer.

[0035] Resonance part 3: On the thin film layer, a polysilicon layer is grown by an epitaxial process as the main structure of the resonance part, and a release hole is etched on the resonance body by a plasma etching process, and then the sacrificial layer is etched away by a gaseous hydrofluoric acid release process, finally forming the resonance part and the thin film part.

[0036] The back hole portion is etched using a deep reactive ion etching or wet etching process 5.

[0037] The cap 6 is formed by plasma etching or solid etching of a silicon wafer, and the cap wafer 6 and the resonant wafer are bonded 1 or 12 together by silicon-silicon bonding, eutectic bonding, etc. And according to different cap bonding methods, metal is deposited by physical vapor deposition for bonding. Before bonding, a getter layer 7 is grown inside the cap wafer by physical vapor deposition, and the component of the getter layer is an alloy of one or more metals or their oxides.

[0038] The resonance pressure sensor involved can be a stand-alone sensor or integrated into a chip with a 6-axis inertial measurement unit or a 9Dof sensor. Because the process flow of the resonant pressure sensor is the same as that of the inertial measurement unit and the 9Dof sensor, the two devices can be prepared at the same time using the same process, so the two devices can be prepared into one chip to form a 7Dof device or a 10Dof device.

Claims

1. A resonant pressure sensor, characterized in that: The resonant pressure sensor comprises a silicon wafer (1), a thin film part (2), a resonant part (3), a resonant part fixing point (4), a back hole (5), a cap (6), a getter layer (7), a supporting silicon layer (8), a buried oxide layer (9), a top silicon film (10), and a polysilicon film and an oxide layer film alternately deposited film (11); The top silicon film (10), the buried oxide layer (9) and the supporting silicon layer (8) together constitute an SOI wafer (12); a silicon wafer (1) or an SOI wafer (12) is used as a substrate, and an oxide layer or a polysilicon layer is deposited alternately on the silicon wafer (1) substrate for multiple times to form a thin film part (2) of a resonant pressure sensor; a thin film part (2) of a resonant pressure sensor is formed on the SOI wafer (12) substrate by a single top silicon film (10) or a top silicon film (10) on the SOI wafer and a polysilicon film and an oxide layer film are deposited alternately (11); the SOI wafer (12) is located at the bottom, and the upper part is a resonant part (3) connected through a resonant part fixing point (4); the outer part of the resonant part (3) is a shell, and the upper part of the shell is a cap (6).

2. A process for manufacturing a resonant pressure sensor as claimed in claim 1, characterized in that: The substrate of the resonant part (3) is etched to form a channel for the fluid to enter the film, namely, a back hole (5) of the resonant pressure sensor.

3. The manufacturing process of the resonant pressure sensor according to claim 2, characterized in that: The capping process is completed on another substrate to form a sensor cap (6), and a getter layer composed of an alloy of one or several metals or their metal oxides is deposited inside the cap by physical vapor deposition and stripping processes, and finally the cap and the sensor part are combined together by a bonding process.

4. The manufacturing process of the resonant pressure sensor according to claim 2, characterized in that: The back hole (5) of the resonant pressure sensor is realized by a wet etching process or a deep reactive ion etching process; the cap (6) is realized on another wafer by a wet / plasma etching process, and the cap and other housing parts of the sensor are combined together by a wafer bonding process.

5. The manufacturing process of the resonant pressure sensor according to claim 2, characterized in that: The getter layer (7) is deposited inside the cap by physical vapor deposition and stripping process, and is composed of an alloy of one or several metals or metal oxides thereof, and functions to maintain a vacuum environment in the cap.

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