CN219950493U

CN219950493U - MEMS device

Info

Publication number: CN219950493U
Application number: CN202320151417.2U
Authority: CN
Inventors: 威廉姆斯·凯特; 洛伊德·史蒂芬; 蒋乐跃; 凌方舟
Original assignee: Meixin Semiconductor Tianjin Co ltd
Current assignee: Meixin Semiconductor Tianjin Co ltd
Priority date: 2023-01-31
Filing date: 2023-01-31
Publication date: 2023-11-03
Anticipated expiration: 2033-01-31

Abstract

The present utility model provides a MEMS device comprising: a first cavity configured for a first function; a second cavity configured for a second function; and a heater disposed at a periphery of the second cavity. The heating of the heater enables the peripheral material of the heater to release gas, and the released gas enters the second cavity, so that the pressure of the second cavity is changed. Thus, two cavities with different pressures can be formed on the same chip more conveniently.

Description

MEMS device

[ field of technology ]

The utility model relates to the field of MEMS (Micro-Electro-Mechanical System, micro-Electro-mechanical systems) devices, in particular to a MEMS device for locally releasing gas.

[ background Art ]

The MEMS capacitive accelerometer has small size, low cost and excellent performance, and is widely applied to the fields of consumer electronics, internet of things and industrial measurement. Consumer electronics competition is becoming more and more active, and new demands are being made on cost and integration. In order to achieve the purpose, the current 6-axis product (3-axis acceleration+3-axis gyroscope) is changed from the original accelerometer, wherein the gyroscopes are respectively positioned on two independent chips to a mode of processing the gyroscopes and the accelerometers on the same chip, and in the process, the air pressure problem is encountered, namely, the air pressure required by the cavities of the accelerometers is different from the air pressure required by the cavities of the gyroscopes. The accelerometer needs to have a cavity with higher air pressure to increase air damping, typically around 400mBar, improving the reliability of the device in impact environments. Whereas gyroscopes require cavities with a lower air pressure, typically < 5mBar, smaller cavities are better, and vacuum environments are preferred. When the accelerometer and the gyroscope are integrated on the same chip, the cavity of the accelerometer and the cavity of the gyroscope are simultaneously processed and molded, so that the internal pressure is increased and reduced simultaneously, and how to control the pressure of the two cavities is a problem encountered in the prior art.

Therefore, a new solution is needed to solve the above problems.

[ utility model ]

One of the purposes of the present utility model is to provide a MEMS device that locally releases gas, so that two cavities with different pressures can be more conveniently formed on the same chip.

To solve the above-mentioned problems, according to one aspect of the present utility model, the present utility model proposes a MEMS device comprising: a first cavity configured for a first function; a second cavity configured for a second function; and the heater is arranged at the periphery of the second cavity, and the heating of the heater enables the peripheral material of the heater to release gas, and the released gas enters the second cavity, so that the pressure of the second cavity is changed.

Compared with the prior art, the utility model carries out local heating through the heater, so that the peripheral material of the heater releases gas, and the released gas enters the second cavity, thereby changing the pressure of the second cavity.

[ description of the drawings ]

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, 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 utility model, 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 schematic top view of a MEMS device of the present utility model in one embodiment;

FIG. 2 is a schematic cross-sectional view of a MEMS device of the present utility model in one embodiment;

FIG. 3 is a flow chart of a method of fabricating a MEMS device according to an embodiment of the utility model.

[ detailed description ] of the utility model

In order that the above-recited objects, features and advantages of the present utility model will become more readily apparent, a more particular description of the utility model 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 utility model. 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 the present utility model, unless specifically stated and limited otherwise, the terms "connected," "coupled," and the like should be construed broadly; for example, they may be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

The present utility model provides a MEMS device that locally releases a gas. FIG. 1 is a schematic top view of a MEMS device of the present utility model in one embodiment. FIG. 2 is a schematic cross-sectional view of a MEMS device of the present utility model in one embodiment.

As shown in fig. 1 and 2, the MEMS device 100 includes a first cavity 110 and a second cavity 120. The first cavity 110 is configured for a first function. The second cavity 120 is configured for a second function. For example, the first function is a MEMS gyroscope and the second function is a MEMS accelerometer. In normal operation, the pressure in the first cavity is different from the pressure in the second cavity, the pressure in the first cavity is lower than a first predetermined threshold, the pressure in the second cavity is higher than a second predetermined threshold, and the first predetermined threshold is lower than the second predetermined threshold. For example, the first predetermined threshold is 5mBar, the second predetermined threshold is 400mBar, and the pressure of the second cavity is higher, which can improve the reliability of the device in an impact environment.

The MEMS device 100 also includes a heater 130. The heater 130 is disposed at the periphery of the second cavity 120, and the heating of the heater 130 causes the peripheral material of the heater 130 to release gas, and the released gas enters the second cavity 120, thereby changing the pressure of the second cavity 120.

In one embodiment, the heater 130 heats the surrounding silicon oxide to release gas, and the released gas from the silicon oxide enters the second cavity 120. The silicon oxide is formed by a plasma enhanced chemical vapor deposition PECVD process, and the silicon oxide generally contains a large amount of gas, and the gas can be released by heating the silicon oxide. The heater 130 includes a wire having a predetermined resistance value and a pad 140 connected to the wire, and heating is achieved by supplying current to the wire. As shown in fig. 2, the metal lines are disposed within the silicon oxide. Of course, in other embodiments, the metal lines may be disposed under the silicon oxide or on the silicon oxide. In other embodiments, the heater 130 may heat other materials around the periphery to release gas, so long as the material is capable of containing a certain amount of gas.

As shown in fig. 2, the MEMS device includes a substrate 170, a silicon oxide layer 160 formed on the substrate, and a cap 150. The cover 150 is disposed over the silicon oxide layer 160, and the cover 150 and the silicon oxide layer 160 together define a first cavity 110 and a second cavity 120. The metal line is disposed in the silicon oxide layer 160, or disposed under the silicon oxide layer 160, or disposed on the silicon oxide layer 160. Specifically, the silicon oxide layer 160 and the cover are eutectic bonded together. Corresponding grooves may be provided in the cover 150 in advance to form the first cavity 110 and the second cavity 120 when combined with the silicon oxide layer 160 and the substrate 170.

The pressure of the first cavity 110 is determined by the sealing ambient pressure at which the first cavity 110 is sealed. The pressure of the second cavity 120 is determined by the sealing ambient pressure at which the second cavity 120 is sealed and the released gas entering the second cavity 120. In one embodiment, the first cavity 110 and the second cavity 120 are sealed simultaneously at the same sealed ambient pressure. In another embodiment, the first cavity 110 and the second cavity 120 are sealed separately at different sealing ambient pressures, in particular, the first cavity is sealed at a first ambient pressure and the second cavity is sealed at a second ambient pressure. For example, the first environment may be a vacuum environment.

In one embodiment, the pressure of the second cavity 120 may be adjusted by controlling the heating temperature and heating duration of the heater 130 to control the amount of gas entering the second cavity 120. In some applications, after a period of use of the MEMS device, if the pressure of the second cavity decreases for various possible reasons, the pressure of the second cavity may be adjusted or calibrated by the heater 130. In other applications, after the second cavity is sealed, the pressure of the second cavity may be adjusted by the heater 130, followed by subsequent normal use.

According to another aspect of the present utility model, a method of manufacturing a MEMS device is provided. As shown in fig. 3, the manufacturing method includes the following steps.

At step 310, a base and a cover are provided, the base including a heater 130 therein.

As shown in fig. 2, the susceptor includes a substrate 170 and a silicon oxide layer 160 formed over the substrate 170. The silicon oxide layer is prepared by a plasma enhanced chemical vapor deposition process, and the silicon oxide layer contains gas. The heater 130 includes a wire having a predetermined resistance value and a pad 140 connected to the wire, and heating is achieved by supplying current to the wire. In one embodiment, the metal line is disposed within the silicon oxide layer, or disposed under the silicon oxide layer, or disposed on the silicon oxide layer.

Step 320, joining the base and the cover together, wherein a sealed first cavity 110 and a sealed second cavity 120 are formed between the base and the cover, wherein the heater is located at the periphery of the second cavity, wherein the first cavity is configured for a first function and the second cavity is configured for a second function.

The base and the cover are eutectic bonded together. The first function is a MEMS gyroscope and the second function is a MEMS accelerometer. For example, the base and the cover may be joined together at an ambient pressure.

Step 330 causes the heater 130 to heat, such that the peripheral material of the heater releases gas, and the released gas enters the second cavity, thereby changing the pressure of the second cavity.

The pressure of the first cavity is determined by the sealing ambient pressure at the time of sealing the first cavity, and the pressure of the second cavity is determined by the sealing ambient pressure at the time of sealing the second cavity and the released gas entering the second cavity.

The heater 130 heats the surrounding silicon oxide to release gas, and the released gas from the silicon oxide enters the second cavity.

According to the utility model, the heater is used for carrying out local heating, so that the peripheral material of the heater releases gas, and the released gas enters the second cavity, so that the pressure of the second cavity is changed.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present utility model. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Further, one skilled in the art may combine and combine the different embodiments or examples described in this specification.

While embodiments of the present utility model have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the utility model, and that variations, modifications and alternatives to the above embodiments may be made by those skilled in the art within the scope of the utility model.

Claims

1. A MEMS device, comprising:

a first cavity configured for a first function;

a second cavity configured for a second function;

a heater arranged at the periphery of the second cavity, wherein the heating of the heater causes the peripheral material of the heater to release gas, the released gas enters the second cavity, thereby changing the pressure of the second cavity,

the heater includes a wire and a pad connected to the wire, and heating is achieved by supplying current to the wire.

2. The MEMS device, as recited in claim 1, wherein,

the first function is a MEMS gyroscope,

the second function is a MEMS accelerometer.

3. The MEMS device, as recited in claim 1, wherein,

the heater heats the surrounding silicon oxide to release gas, and the released gas from the silicon oxide enters the second cavity.

4. The MEMS device of claim 3, wherein the silicon oxide is formed by a plasma enhanced chemical vapor deposition process, the silicon oxide comprising a gas,

the metal line has a predetermined resistance value,

the metal wire is arranged in the silicon oxide, or arranged under the silicon oxide, or arranged on the silicon oxide.

5. The MEMS device of claim 3, further comprising a substrate and a cap, wherein a silicon oxide layer is formed on the substrate,

the cover body is arranged on the silicon oxide layer, and the cover body and the silicon oxide layer jointly define a first cavity and a second cavity.

6. The MEMS device of claim 1, wherein the pressure of the first cavity is different from the pressure of the second cavity, the pressure of the first cavity is below a first predetermined threshold, the pressure of the second cavity is above a second predetermined threshold, the first predetermined threshold is below the second predetermined threshold,

the pressure of the first cavity is determined by the sealing ambient pressure at which the first cavity is sealed,

the pressure of the second cavity is determined by the pressure of the sealing environment when sealing the second cavity and the released gas entering the second cavity.

7. The MEMS device of claim 6, wherein,

the first cavity and the second cavity are sealed simultaneously at the same sealing ambient pressure.