Oil-filled medium isolation packaging type silicon resonance pressure sensor and preparation method thereof

Abstract

The invention discloses an oil-filled medium isolation packaging type silicon resonance pressure sensor and a preparation method thereof, belongs to the technical field of MEMS pressure sensors, and solves the problem that an existing pressure sensor is liable to have intermittent faults. The device specifically comprises a tube body, a concave cavity is formed in the top of the tube body, and a silicon resonance chip is arranged in the concave cavity; a cap is mounted at the top of the tube body, an isolation diaphragm is arranged between the cap and the tube body, and silicone oil is filled between the isolation diaphragm and the tube body. According to the invention, a measurement medium enters the cap through the filler neck to extrude the isolation diaphragm, the isolation diaphragm generates micro deformation when sensing the pressure of the medium, the pressure is transmitted to the silicon resonance chip through silicone oil in the pipe body, and the silicon resonance chip converts the external pressure into a perceivable analog signal; in the process, an external measuring medium does not directly act on the silicon resonance chip, so that the problem of intermittent fault or complete failure of the silicon resonance sensor in a corrosive gas or liquid environment is avoided.

Description

Technical Field

[0001] This invention relates to the field of MEMS pressure sensor technology, and in particular to an oil-filled dielectric-isolated silicon resonant pressure sensor and its fabrication method. Background Technology

[0002] Silicon resonant pressure sensors are a novel type of sensor based on microelectromechanical systems (MEMS) technology. Their working principle involves sensing the measured pressure through changes in the mechanical vibration frequency of a silicon-based resonator. Silicon resonant sensors offer significant advantages such as high accuracy, fast response, strong anti-interference capability, small size, light weight, low power consumption, and ease of integration, leading to their increasingly widespread application in high-precision measurement fields such as aerospace, industrial control, and meteorological measurement. The silicon resonant pressure sensor employs a composite structure of a pressure-sensitive diaphragm and a resonator to sense pressure changes. The resonator is fixed at an appropriate position on the surface of the pressure-sensitive diaphragm and sealed within a reference pressure environment. When the measured pressure changes, the pressure-sensitive diaphragm deforms, causing a change in the elastic coefficient of the resonator. Pressure measurement is achieved by detecting the change in the resonator's natural frequency.

[0003] Currently, existing silicon resonant sensors measure non-corrosive gases. During operation, the measured medium is directly introduced into the sensor via a pressure interface, acting directly on the silicon resonant chip. For example, the silicon resonant pressure sensor disclosed in Chinese invention patent CN116007796A introduces the measured medium into the sensor tube via a pressure interface, acting directly on the surface of the silicon resonant chip. However, when the measured medium is a corrosive gas or liquid, it can lead to corrosion of the metal leads inside the silicon resonant sensor tube, reduced insulation performance of the insulating material, circuit failure, and damage to the silicon resonant chip, causing intermittent malfunctions or even complete failure of the silicon resonant pressure sensor. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an oil-filled dielectric-isolated encapsulated silicon resonant pressure sensor and its fabrication method, which solves the problem that silicon resonant sensors are prone to intermittent failures or even complete failures in corrosive gas or liquid environments.

[0005] Firstly, in order to achieve the above objectives, the technical solution adopted by the present invention is as follows: An oil-filled dielectric-isolated encapsulated silicon resonant pressure sensor includes a tube body, a cavity at the top of the tube body, and a silicon resonant chip disposed inside the cavity; a cap is installed on the top of the tube body, an isolation diaphragm is disposed between the cap and the tube body, and silicone oil is filled between the isolation diaphragm and the cavity of the tube body; a connector is connected to the cap.

[0006] In this design, the silicon resonant chip is encapsulated within a tube. The measuring medium enters the pressure-sensing chamber inside the cap through a connector, compressing and deforming the isolation diaphragm. When the isolation diaphragm senses the medium pressure, it undergoes a slight deformation, which is then transmitted to the silicon resonant chip via the silicone oil inside the tube. The silicon resonant chip converts the external pressure into a perceptible analog signal. During this process, the external measuring medium does not directly act on the silicon resonant chip, thus allowing its application in various environments, including harsh corrosive media, avoiding the problem of intermittent or complete failure of silicon resonant sensors in corrosive gas or liquid environments.

[0007] Furthermore, a lead hole is provided at the bottom of the tube, and a pin is inserted inside the lead hole. A tubular glass insulator is sintered between the lead hole and the pin, and the pin is electrically connected to the silicon resonant chip.

[0008] In this design, the signal of the silicon resonant chip is led out from the pins.

[0009] Furthermore, an oil injection hole is provided at the bottom of the pipe body. One end of the oil injection hole is connected to the cavity of the pipe body, and the other end of the oil injection hole is sealed with a steel ball.

[0010] In this design, an oil injection hole is incorporated to facilitate the filling of silicone oil into the tube after the silicon resonator chip is packaged.

[0011] Furthermore, the isolation diaphragm is a circular diaphragm with a flat welded section around its perimeter. The isolation diaphragm is welded to the cap and the tube body through the welded section; the middle of the welded section is a corrugated section.

[0012] In this design, when external pressure is introduced through the nozzle to compress the diaphragm, the corrugated part of the diaphragm deforms, and the pressure is transmitted to the silicon resonator chip through the silicone oil inside the tube. The design of the corrugated part makes the deformation response of the diaphragm faster and more sensitive, and the pressure detection accuracy is high.

[0013] Secondly, based on the oil-filled dielectric-isolated packaged silicon resonant pressure sensor provided in the first aspect, the present invention provides a method for fabricating an oil-filled dielectric-isolated packaged silicon resonant pressure sensor, comprising the following steps: Step S1: Install a glass insulator and a pin in the lead hole at the bottom of the tube; Step S2: Fix the silicon resonator chip inside the cavity of the tube; Step S3: Connect the silicon resonator chip and the pins using wire bonding; Step S4: Weld the cap, the diaphragm, and the outer ring of the tube together; Step S5: Under vacuum conditions, silicone oil is injected into the cavity of the tube through the oil filling hole, and the oil filling hole is sealed with steel balls to complete the fabrication of the oil-filled medium isolated silicon resonant pressure sensor.

[0014] Further, step S1 includes: Step S101: Nest the glass blank onto the pin; Step S102: Place the glass blank with the pin into the lead hole of the tube; Step S103: Sinter the glass blank and the tube body, so that the glass blank melts and resolidifies between the lead hole and the pin to form a glass insulator.

[0015] Furthermore, in step S2, the silicon resonant chip is bonded to the cavity of the tube using an adhesive.

[0016] Furthermore, in step S4, the cap, the isolation diaphragm, and the tube body are welded together by laser welding.

[0017] Furthermore, in step S5, the steel ball is welded onto the oil filling hole using resistance welding.

[0018] The beneficial effects of this invention are: In the oil-filled medium-isolated encapsulated silicon resonant pressure sensor provided by this invention, the pressure medium to be measured is introduced through the connector of the cap and acts on the isolation diaphragm. The corrugated part of the isolation diaphragm deforms, and the pressure of the pressure medium to be measured is transmitted to the silicon resonant chip through the silicone oil. The isolation diaphragm isolates the pressure medium to be measured from the silicon resonant chip, so that the silicon resonant chip does not come into direct contact with the pressure medium to be measured while measuring the pressure of the pressure medium, thus avoiding corrosion of the silicon resonant chip by the pressure medium to be measured. It is suitable for pressure detection in various harsh environments. Attached Figure Description

[0019] Figure 1 This is a cross-sectional structural diagram of an oil-filled dielectric isolated encapsulated silicon resonant pressure sensor according to the present invention.

[0020] 1. Tube body; 2. Silicon resonant chip; 3. Cap; 4. Silicone oil; 5. Isolating diaphragm; 6. Connecting nozzle; 7. Pin; 8. Glass insulator; 9. Steel ball; 10. Oil filling hole; Detailed Implementation The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Specific embodiments of the present invention are described below to facilitate understanding by those skilled in the art. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0021] Example 1 like Figure 1 As shown, this embodiment provides an oil-filled dielectric-isolated silicon resonant pressure sensor. This pressure sensor utilizes an oil-filled isolation encapsulation structure to address the problem of intermittent failures or malfunctions that easily occur in corrosive gas or liquid environments. Specifically, it includes: 1. Tube body; 2. Silicon resonant chip; 3. Cap; 5. Isolation diaphragm; and 6. Connecting nozzle. The tube body 1 has a recessed cavity at its top, inside which a silicon resonant chip 2 is housed. A cap 3 is mounted on the top of the tube body 1, and an isolation diaphragm 5 is positioned between the cap 3 and the tube body 1. Silicone oil 4 fills the space between the isolation diaphragm 5 and the recessed cavity of the tube body 1. A connector 6 is connected to the cap 3. The measuring medium enters the pressure-sensing chamber inside the cap 3 through the connector 6, compressing and deforming the isolation diaphragm 5. When the isolation diaphragm 5 senses the medium pressure, it undergoes a slight deformation, which is transmitted to the silicon resonant chip 2 through the silicone oil 4 inside the tube body 1. The silicon resonant chip 2 converts the external pressure into a perceptible analog signal. During this process, the external measuring medium does not directly act on the silicon resonant chip 2, thus allowing for application in various situations, including harsh corrosive media environments.

[0022] The bottom of the tube body 1 has a lead hole, and a pin 7 is inserted inside the lead hole. A tubular glass insulator 8 is sintered between the lead hole and the pin 7. The pin 7 is electrically connected to the silicon resonant chip 2. The signal of the silicon resonant chip 2 is led out from the pin 7.

[0023] An oil injection hole is provided at the bottom of the tube body 1. One end of the oil injection hole is connected to the cavity of the tube body 1, and the other end of the oil injection hole is sealed with a steel ball 9. The oil injection hole is designed to facilitate the filling of silicone oil 4 into the tube body 1 after the silicon resonant chip 2 is packaged.

[0024] The isolating diaphragm 5 is a circular diaphragm with a flat welded section around its perimeter. The isolating diaphragm 5 is welded to the cap 3 and the tube body 1 through the welded section; the center of the welded section is corrugated. When external pressure is introduced from the connector 6 to compress the isolating diaphragm 5, the corrugated section of the isolating diaphragm 5 deforms, and the pressure is transmitted to the silicon resonant chip 2 through the silicone oil 4 inside the tube body 1. The corrugated design makes the deformation response of the isolating diaphragm 5 faster and more sensitive, and the pressure detection accuracy is high.

[0025] The working principle of this embodiment is as follows: The pressure medium is introduced into the sealed pressure-sensing cavity between the cap 3 and the isolation diaphragm 5 through the connector 6. When the isolation diaphragm 5 senses the pressure of the medium, it undergoes a slight deformation, which is then transmitted to the silicon resonant chip through the silicone oil 4 inside the tube 1. The pressure-sensing diaphragm on the silicon resonant chip deforms under the pressure transmitted by the silicone oil 4, causing a change in the pressure frequency of the silicon resonant chip. The silicon resonant chip is bonded to the pin 7 via wire bonding, and the pressure frequency signal of the silicon resonant chip is transmitted through the pin 7.

[0026] Example 2 This embodiment, based on the oil-filled dielectric-isolated packaged silicon resonant pressure sensor provided in Embodiment 1, provides a method for fabricating an oil-filled dielectric-isolated packaged silicon resonant pressure sensor, including the following steps: Step S1: Install a glass insulator 8 and a pin 7 in the lead hole at the bottom of the tube 1; specifically including the following steps: Step S101: Nest the glass blank onto the insert 7; Step S102: Place the glass blank with the pin 7 into the lead hole of the tube 1; Step S103: Sinter the glass blank and tube 1, so that the glass blank melts and resolidifies between the lead hole and the pin 7 to form a glass insulator 8.

[0027] Step S2: Use adhesive to bond the silicon resonant chip 2 to the cavity of the tube body 1.

[0028] Step S3: Connect the silicon resonant chip 2 and the pin 7 using wire bonding.

[0029] Step S4: The cap 3, the isolation diaphragm 5 and the outer ring of the tube body 1 are welded together by laser welding to form a welded ring.

[0030] Step S5: Under vacuum conditions, silicone oil 4 is injected into the cavity of tube 1 through oil filling hole 10, and steel ball 9 is welded to oil filling hole 10 by resistance welding to seal oil filling hole 10, thus completing the preparation of oil-filled medium isolated silicon resonant pressure sensor.

[0031] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention and should be understood as not limiting the scope of protection of the invention to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed herein without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the invention.

Claims

1. A silicon resonant pressure sensor with oil-filled dielectric isolation encapsulation, characterized in that: The tube (1) includes a tube body (1) with a cavity at the top and a silicon resonant chip (2) inside the cavity; a cap (3) is installed on the top of the tube body (1), and an isolation diaphragm (5) is provided between the cap (3) and the tube body (1), and silicone oil (4) is filled between the isolation diaphragm (5) and the cavity of the tube body (1); a connector (6) is connected to the cap (3).

2. The oil-filled dielectric isolated encapsulated silicon resonant pressure sensor according to claim 1, characterized in that: The bottom of the tube (1) is provided with a lead hole, and a pin (7) is inserted inside the lead hole. A tubular glass insulator (8) is sintered between the lead hole and the pin (7). The pin (7) is electrically connected to the silicon resonant chip (2).

3. The oil-filled dielectric isolated encapsulated silicon resonant pressure sensor according to claim 1, characterized in that: The bottom of the tube (1) is provided with an oil injection hole (10), one end of the oil injection hole (10) is connected to the cavity of the tube (1), and the other end of the oil injection hole (10) is sealed with a steel ball (9).

4. The oil-filled dielectric isolated encapsulated silicon resonant pressure sensor according to claim 1, characterized in that: The isolation diaphragm (5) is a circular diaphragm with a flat welded part around it. The isolation diaphragm (5) is welded to the cap (3) and the tube body (1) through the welded part; the middle of the welded part is a corrugated part.

5. A method for fabricating an oil-filled dielectric-isolated encapsulated silicon resonant pressure sensor according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step S1: Install a glass insulator (8) and a pin (7) in the lead hole at the bottom of the tube (1); Step S2: Fix the silicon resonant chip (2) inside the cavity of the tube body (1); Step S3: Connect the silicon resonant chip (2) and the pin (7) using wire bonding; Step S4: Weld the cap (3), the isolation diaphragm (5), and the outer ring of the tube body (1) together; Step S5: Under vacuum conditions, silicone oil (4) is injected into the cavity of the tube (1) through the oil filling hole (10), and the oil filling hole (10) is sealed with steel balls (9) to complete the preparation of the oil-filled medium isolated silicon resonant pressure sensor.

6. The method for fabricating an oil-filled dielectric-isolated encapsulated silicon resonant pressure sensor according to claim 5, characterized in that: Step S1 includes: Step S101: Nest the glass blank into the insert (7); Step S102: Place the glass blank with the insert (7) into the lead hole of the tube body (1); Step S103: Sinter the glass blank and tube (1) so that the glass blank melts and resolidifies between the lead hole and the pin (7) to form a glass insulator (8).

7. The method for fabricating an oil-filled dielectric-isolated encapsulated silicon resonant pressure sensor according to claim 5, characterized in that: In step S2, the silicon resonant chip (2) is bonded to the cavity of the tube body (1) using an adhesive.

8. The method for fabricating an oil-filled dielectric-isolated encapsulated silicon resonant pressure sensor according to claim 5, characterized in that: In step S4, the cap (3), the isolation diaphragm (5), and the tube body (1) are welded by laser welding.

9. The method for fabricating an oil-filled dielectric-isolated encapsulated silicon resonant pressure sensor according to claim 5, characterized in that: In step S5, the steel ball (9) is welded onto the oil filling hole (10) by resistance welding.

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