WO2019153130A1

WO2019153130A1 - Pressure sensor

Info

Publication number: WO2019153130A1
Application number: PCT/CN2018/075495
Authority: WO
Inventors: 黄贤; 阮汤姆•T
Original assignee: 盾安传感科技有限公司
Priority date: 2018-02-06
Filing date: 2018-02-06
Publication date: 2019-08-15
Also published as: CN112020476A; CN112020476B

Abstract

A pressure sensor, comprising a body, wherein a cavity (1) is formed at an inner part of the body, a sidewall of a first side of the body corresponding to the cavity (1) is formed as a strain film (2), and the strain film (2) is provided thereon with a varistor (3); a first flow channel (4) and a second flow channel (5) are formed at an inner part of the body; one end of the first flow channel (4) is opened on a sidewall of a second side of the body; the first flow channel (4) communicates with the cavity (1) by means of the second flow channel (5); and one end of the second flow channel (5) communicating with the first flow channel (4) is formed with an offset area (6) used such that two streams of fluid from the first flow channel (4) hedge against each other so as to offset fluid spike impact pressure. Thus, the fluid spike impact pressure may be eliminated at the offset area (6), and instantaneous fluid spike pressures offset each other by means of a symmetric flow channel design at both sides of the second flow channel (5), thereby reducing, on the strain film (2) of a sensor chip, the instantaneous impact of a fluid that has a rapid pressure change, and improving the anti-pressure impact resistance of the sensor, such that sensor failure caused by rapid pressure changes may be prevented.

Description

Pressure Sensor

Technical field

The invention belongs to the field of sensor design of a microelectronic mechanical system, and relates to a MEMS pressure sensor chip.

Background technique

MEMS, a microelectronic mechanical system, is an emerging interdisciplinary field of high-tech research. Piezoresistive pressure sensors based on MEMS technology are widely used in modern markets due to their excellent precision and reliability and relatively inexpensive manufacturing costs. Since the piezoresistive properties of silicon materials were discovered in the mid-1950s, silicon-based piezoresistive pressure sensors have been widely used. The typical piezoresistive pressure sensor works by making four pressure-sensitive resistors by diffusion or ion implantation on a square or circular silicon strain film. For short, the varistor is connected, and the four resistor interconnections form the Wheatstone bridge. . When external pressure is applied to the silicon strain film, the varistor region generates stress due to strain of the strain film, and the piezoresistive characteristic of the varistor converts the stress into a change in the resistance value, and finally the resistance value is passed through the Wheatstone bridge. The change is converted to an output voltage, which can be measured by calibrating the output voltage and pressure values.

One problem with the design of pressure sensor chips today is that the strain diaphragm of the sensor chip experiences very rapid pressure changes when the external pressure changes drastically. This rapidly changing pressure may cause the strained membrane to completely exceed its yield point in a short period of time and permanently damage the diaphragm, eventually damaging the pressure sensor.

Summary of the invention

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pressure sensor that solves the problem that the rapidly changing pressure in the prior art may cause the strained film to completely exceed its yield point in a short time and permanently damage the diaphragm, eventually damaging the pressure sensor. .

In order to solve the above technical problem, as one aspect of the present invention, a pressure sensor including a body having a cavity formed therein, a side wall of a first side of the body corresponding to the cavity is provided Formed as a strain film, the strain film is provided with a varistor; a body of the body is formed with a first flow channel and a second flow channel, and one end of the first flow channel is opened on a side of the second side of the body a wall, the first flow passage is in communication with the cavity through the second flow passage, and two ends of the second flow passage communicating with the first flow passage are formed for causing two from the first flow passage The stock fluids are mutually opposed to counteract the offset region of the fluid spike impact pressure.

Preferably, the body includes a first base body and a second base body which are stacked and connected, the cavity is formed on a side of the first base body facing the second base body, and the first base body corresponds to The strained film is formed at a position of the cavity, and the first flow path extends in a thickness direction of the second base.

Preferably, the second flow passage is in communication with the first flow passage through a third flow passage.

Preferably, the first flow channel and/or the third flow channel are formed in the first flow channel and/or the second substrate.

Preferably, the third flow path extends in a direction parallel to an interface between the first substrate and the second substrate.

Preferably, the third flow passage is annular.

Preferably, the third flow passage has a circular shape, and the second flow passage extends in a radial direction of the circular shape.

Preferably, the third flow path has a polygonal shape, and the second flow path extends along a line connecting the center of the polygon to a vertex of its apex or its side line.

Preferably, the interior of the cavity is formed as a rib.

Preferably, one end of the second flow passage connected to the cavity is disposed at a middle or side edge of a side bottom of the prism.

Preferably, the number of the first flow channel and the second flow channel is one, and the first flow channel and the second flow channel are correspondingly disposed with respect to a center of the cavity, or the first flow channel and the second flow channel The flow channels are located on the same side of the cavity.

Preferably, the number of the first flow channel and the second flow channel are both plural, and the first flow channel and the second flow channel are alternately arranged in sequence.

Preferably, the first substrate is a single crystal silicon layer, and the second substrate is a single crystal silicon layer or a glass layer.

Preferably, the first flow channel, the second flow channel and the inner wall of the cavity are formed with a dielectric isolation layer.

By adopting the above technical solution, the present invention can eliminate the fluid spike impact pressure at the offset region, and the instantaneous fluid peak pressures offset each other through the symmetric flow passage design on both sides of the second flow passage, thereby reducing the fluid with rapid pressure change. The instantaneous impact on the strain gauge of the sensor chip enhances the sensor's resistance to pressure shock and can avoid sensor failure caused by rapid pressure changes.

DRAWINGS

Figure 1 is a schematic cross-sectional view of the present invention;

Figure 2 is a schematic plan view showing a first embodiment of the present invention;

Figure 3 is a schematic perspective view showing a second embodiment of the present invention;

Figure 4 is a schematic perspective view showing a third embodiment of the present invention;

Fig. 5 is a schematic perspective view showing a fourth embodiment of the present invention.

Reference numerals in the figure: 1, cavity; 2, strain film; 3, varistor; 4, first flow path; 5, second flow path; 6, offset area; 7, first substrate; Substrate; 9, third flow channel; 10, dielectric isolation layer; 11, electrode; 12, metal layer; 13, heavily doped contact region.

Detailed ways

The embodiments of the present invention are described in detail below, but the present invention may be embodied in many different ways as defined and covered by the appended claims.

In one aspect of the invention, a pressure sensor is provided, in particular a MEMS pressure sensor core, comprising a body, the interior of which is formed with a cavity 1 of which corresponds to the cavity 1 The side wall of one side is formed as a strain film 2, and the strain film 2 is provided with a varistor 3; the inside of the body is formed with a first flow path 4 and a second flow path 5, one end of the first flow path 4 Opening a sidewall of the second side of the body, the first flow channel 4 is in communication with the cavity 1 through the second flow channel 5, and the first flow channel 5 and the first flow channel 4 A counteracting region 6 is formed at one end of the communication for counteracting the two fluids from the first flow passage 4 against each other to counteract the fluid spike impact pressure. The varistor 3 is used to switch the stress signal to the resistance value signal, and the heavily doped contact region 13 is disposed on the corresponding electrical signal connecting member. The varistor 3 is connected to the electrode 11, and a metal layer 12 is further disposed at the bottom of the body. . Preferably, the first substrate 7 is a single crystal silicon layer, and the second substrate 8 is a single crystal silicon layer or a glass layer.

In use, the liquid enters the cavity 1 through the first flow path 4 and the second flow path 5, wherein when entering the second flow path 5 by the first flow path 4, the fluid is divided into two streams and flows in opposite directions. In the offset region 6, the two fluids are mutually opposed to cancel the fluid peak impact pressure, and then enter the cavity 1 from the second flow passage 5 to act on the strained membrane 2.

Due to the above technical solution, the present invention can eliminate the fluid spike impact pressure at the offset region 6, and the symmetric fluid passage path design on both sides of the second flow passage 5 cancels the instantaneous fluid peak pressures, thereby reducing the rapid pressure change. The instantaneous impact of the fluid on the strain gauge 2 of the sensor chip enhances the pressure shock resistance of the sensor and can avoid sensor failure caused by rapid pressure changes.

Preferably, the body includes a first base body 7 and a second base body 8 which are stacked and connected, and the cavity body 1 is formed on a side of the first base body 7 facing the second base body 8, the A strain film 2 is formed at a position corresponding to the cavity 1 of a substrate 7, and the first flow path 4 extends in the thickness direction of the second substrate 8.

More preferably, the second flow passage 5 communicates with the first flow passage 4 through the third flow passage 9. For example, the third flow path 9 extends in a direction parallel to the interface between the first substrate 7 and the second substrate 8. Preferably, the first flow channel 4 and/or the third flow channel 9 are formed in the first flow channel 4 and/or the second substrate 8. Specifically, in the implementation, the first flow channel 4 and the third flow channel 9 may also be formed in the first substrate 7, or may be formed in two different substrates, for example, the first flow channel 4 In the first substrate 7, the third flow channel 9 is in the second substrate 8; or the first flow channel is in the second substrate and the second flow channel is in the first substrate.

In a preferred embodiment, the third flow path 9 in the present invention is annular, and may be, for example, a circular structure formed of a circular shape or a regular polygonal shape.

In the embodiment shown in Figures 2, 4, 5, preferably, the third flow passage 9 is circular, and the second flow passage 5 extends in the radial direction of the circular shape. In the embodiment shown in Fig. 3, preferably, the third flow path 9 has a polygonal shape, and the second flow path 5 extends along a line connecting the center of the polygon to its apex or the midpoint of its side line. Referring to the embodiment shown in FIG. 3, in another embodiment, the third flow path 9 is polygonal, and the second flow path 5 can extend along the center of the claimed polygon and the midpoint of the edge line, and the first flow path is located in the polygon. The vertex position, this embodiment is similar to the embodiment of Figure 3, but the third flow path is interchanged with the position of the first flow path in Figure 3.

Referring to FIG. 1, preferably, the inside of the cavity 1 is formed as a rib. Of course, the cavity 1 can also be of other shapes, such as a cylindrical shape or a prismatic shape.

Preferably, one end of the second flow path 5 connected to the cavity 1 is disposed in the middle of the side bottom of the prism (as shown in FIGS. 4 and 5) or side edges (as shown in FIGS. 2 and 3) Show).

In the embodiment shown in FIG. 5, preferably, the number of the first flow channel 4 and the second flow channel 5 is one, and the first flow channel 4 and the second flow channel 5 are opposite to the cavity. The center of 1 is correspondingly disposed, or the first flow path 4 and the second flow path 5 are located on the same side of the cavity 1. In the embodiment shown in FIG. 2 to FIG. 4, preferably, the number of the first flow channel 4 and the second flow channel 5 is plural, and the first flow channel 4 and the second flow channel 5 are sequentially Alternate settings. This arrangement ensures that the flow paths between the third flow path 9 and the second flow path 5 on both sides of the first flow path 4 are symmetrically arranged for the purpose of cancellation. For example, the first flow channel 4 and the second flow channel 5 may also be located on the same side of the cavity 1. During the design, it is ensured that there are two (or more) paths in the third flow channel, and the paths are symmetrical to each other, so that the fluids can cancel each other. The same function can be achieved.

Referring to FIG. 1 , preferably, the first flow channel 4 , the second flow channel 5 , and the inner wall of the cavity 1 are formed with a dielectric isolation layer 10 . A dielectric isolation layer 10 may be disposed at an interface between the first substrate 7 and the second substrate 8 and outside of the first substrate 7 and the second substrate 8.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

A pressure sensor comprising a body, a cavity (1) formed inside the body, and a sidewall of the first side of the body corresponding to the cavity (1) is formed as a strain film ( 2), the strain film (2) is provided with a varistor (3); the inside of the body is formed with a first flow channel (4) and a second flow channel (5), the first flow channel (4) One end of the first flow channel (4) is connected to the cavity (1) through the second flow channel (5), the second flow channel (the second flow channel ( An offset region (6) for mutually opposing the two fluids from the first flow passage (4) to counteract the fluid peak impact pressure is formed at one end of the 5) communicating with the first flow passage (4).
The pressure sensor according to claim 1, wherein the body comprises a first base body (7) and a second base body (8) stacked and connected, the cavity body (1) being formed at the first a side of the base body (7) facing the second base body (8), the strained film (2) is formed at a position of the first base body (7) corresponding to the cavity (1), The first flow path (4) extends in the thickness direction of the second substrate (8).
The pressure sensor according to claim 2, characterized in that the second flow passage (5) communicates with the first flow passage (4) through a third flow passage (9).
The pressure sensor according to claim 3, characterized in that the first flow path (4) and/or the third flow path (9) are formed in the first flow path (4) and/or the second substrate (8) )in.
The pressure sensor according to claim 4, characterized in that the third flow path (9) extends in a direction parallel to the interface between the first substrate (7) and the second substrate (8).
The pressure sensor according to claim 3, characterized in that the third flow path (9) is annular.
The pressure sensor according to claim 3, characterized in that the third flow path (9) has a circular shape, and the second flow path (5) extends in a radial direction of the circular shape.
The pressure sensor according to claim 3, characterized in that the third flow path (9) is polygonal, and the second flow path (5) is along the center of the polygon and its apex or the midpoint of its side line The connection extends.
The pressure sensor according to claim 7 or 8, characterized in that the inside of the cavity (1) is formed as a rib.
The pressure sensor according to claim 9, characterized in that one end of the second flow path (5) connected to the cavity (1) is disposed at the middle or side edge of the side bottom of the rib .
The pressure sensor according to claim 1, wherein the number of the first flow channel (4) and the second flow channel (5) is one, the first flow channel (4) and the second flow channel (5) corresponding to the center of the cavity (1), or the first flow path (4) and the second flow path (5) are located on the same side of the cavity (1).
The pressure sensor according to claim 1, wherein the number of the first flow path (4) and the second flow path (5) is plural, and the first flow path (4) and the second The flow paths (5) are alternately arranged in order.
The pressure sensor according to claim 2, wherein the first substrate (7) is a single crystal silicon layer, and the second substrate (8) is a single crystal silicon layer or a glass layer.
The pressure sensor according to claim 1, wherein a dielectric separation layer (10) is formed on an inner wall of the first flow path (4), the second flow path (5), and the cavity (1).