CN-121974289-A - MEMS device and preparation method thereof

CN121974289ACN 121974289 ACN121974289 ACN 121974289ACN-121974289-A

Abstract

The application provides a MEMS device and a preparation method thereof, wherein a back cavity is formed on a substrate, so that a part of a diaphragm is suspended to form a plurality of suspended parts, gaps are formed among the suspended parts, thereby improving the sensitivity of the diaphragm and fully releasing residual stress. Then, a viscoelastic film layer is arranged on the diaphragm, and the slit is covered and closed by the viscoelastic film layer, so that on one hand, the slit can be closed to establish stable pressure difference, fluctuation and drift of signal output are reduced, and on the other hand, the influence of the viscous part in the viscoelastic film layer on deformation of a suspended part in the diaphragm can be remarkably improved, so that the sensitivity of the diaphragm after the slit is closed is still in an ideal interval, weak signals can be captured, and meanwhile, the fluidity of the viscoelastic film layer is reduced by the elastic part in the viscoelastic film layer, and the structural stability of the diaphragm is maintained. And finally, stable signal output, higher sensitivity and stability of a device structure are realized.

Inventors

WANG TAO
You huan
YU LINGCHEN
HE JIA
QI QUANYAO
MA YANYUAN

Assignees

成都纤声科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260212

Claims (10)

1. A MEMS device, comprising: a substrate having a back cavity; The diaphragm is arranged on the substrate and provided with a plurality of hanging parts positioned in the back cavity, and gaps communicated with the back cavity are formed between the adjacent hanging parts; and the viscoelastic film layer is arranged on the diaphragm and seals the back cavity at the gap.
2. The MEMS device of claim 1, wherein the viscoelastic film layer comprises an adhesive body and an elastic skeleton, the adhesive body being filled into the elastic skeleton.
3. The MEMS device of claim 2, wherein the elastic skeleton is a solid network structure that encapsulates the viscous body.
4. The MEMS device of claim 1, wherein the suspended portion has opposite root portions and free end portions, the suspended portion being connected to the substrate via the root portions, the free end portions being located at an end of the suspended portion remote from the root portions, the free end portions being adjacent at least a portion of the gaps, the thickness of the viscoelastic film layer at the free end portions being greater than the thickness of the viscoelastic film layer at the root portions.
5. The MEMS device of claim 4, wherein, The viscoelastic film layer extends along the direction of the free end portion toward the root portion, and the thickness of the viscoelastic film layer gradually decreases along the direction of the free end portion toward the root portion; and/or, at least part of the free end of the suspended part is positioned at the junction of the gaps, and the thickness of the viscoelastic film layer positioned at the junction of the gaps is larger than that of the viscoelastic film layer positioned at the root.
6. A MEMS device as claimed in any one of claims 1 to 5, wherein, The width of the gap ranges from 0.5um to 10um; And/or, the viscoelastic film layer is in an arch structure; And/or the viscoelastic film layer covers the suspended portion of the diaphragm and the slit.
7. A method of manufacturing a MEMS device, the method comprising: Forming a membrane on a substrate; Forming a slit on the diaphragm to divide the diaphragm into a plurality of suspended portions; etching the substrate to form a back cavity communicated with the gap, wherein a plurality of suspended parts are exposed in the back cavity; and forming a viscoelastic film layer on the diaphragm, wherein the viscoelastic film layer seals the back cavity at the gap.
8. The method of manufacturing a MEMS device according to claim 7, wherein the forming a viscoelastic film layer on the membrane comprises: forming a liquid film layer on the diaphragm; The liquid film layer is cured to form the viscoelastic film layer.
9. The method of manufacturing a MEMS device according to claim 8, wherein the forming a liquid film layer on the membrane comprises: forming a liquid body at the center of the diaphragm through a dispensing or glue spraying process above the diaphragm; The liquid diffuses from the center of the diaphragm to the edge to form the liquid film layer at the gap.
10. The method of manufacturing a MEMS device according to claim 8, wherein the forming the viscoelastic film layer from the liquid film layer via a curing process comprises: In a heating environment, one part of the liquid film layer is crosslinked to form a solid network structure, and the other part of the liquid film layer is formed into a viscous body, and the viscous body is wrapped by the solid network structure to serve as the viscoelastic film layer.

Description

MEMS device and preparation method thereof Technical Field The application relates to the technical field of micro-electromechanical systems, in particular to an MEMS device and a preparation method thereof. Background Microelectromechanical systems (MEMS, micro-Electro-MECHANICAL SYSTEM) technology provides a core solution for high-precision sensing and measurement of various physical quantities and chemical quantities by integrating mechanical structures and electronic circuits into a microchip. The mechanism is generally dependent on the deformation or displacement of the sensitive diaphragm of the MEMS device, and thus outputs a detection signal. Therefore, the response sensitivity and stability of the sensitive diaphragm to external signals are key to determining the performance of the whole MEMS device. The traditional sensitive diaphragm adopts a whole complete film structure, but the sensitivity is limited, and in order to improve the detection sensitivity of the sensitive diaphragm to weak signals, the current optimized design thought is to introduce a gap, and divide the sensitive diaphragm into cantilever sub-films, so that the cantilever sub-films have more free ends, and can capture the weak signals, thereby improving the sensitivity of MEMS devices. However, when the MEMS device with the slit works in a fluid medium (such as gas or liquid) environment, the fluid medium at two sides of the sensitive diaphragm will flow through the slit of the sensitive diaphragm due to the pressure difference, the slit expands with the increase of the pressure difference, so that a stable pressure difference cannot be established at two sides of the sensitive diaphragm, and the signal output by the device is greatly fluctuated and drifted, which affects the accuracy and reliability of the sensing result. Disclosure of Invention The application aims to overcome the defects in the prior art, and provides an MEMS device and a preparation method thereof, wherein the improved MEMS device has good sensitivity and can improve the fluctuation amplitude of an output signal. In order to achieve the above purpose, the technical scheme adopted by the embodiment of the application is as follows: in one aspect of the embodiment of the application, the MEMS device comprises a substrate, a diaphragm and a viscoelastic film layer, wherein the substrate is provided with a back cavity, the diaphragm is arranged on the substrate and provided with a plurality of hanging parts positioned in the back cavity, gaps communicated with the back cavity are formed between adjacent hanging parts, and the viscoelastic film layer is arranged on the diaphragm and seals the back cavity at the gaps. Optionally, the viscoelastic film layer includes an adhesive body and an elastic skeleton, the adhesive body being filled into the elastic skeleton. Optionally, the elastic framework is a solid network structure, and the solid network structure wraps the adhesive body. Optionally, the suspended portion has a root portion and a free end portion opposite to each other, the suspended portion is connected to the substrate via the root portion, the free end portion is located at an end of the suspended portion away from the root portion, the free end portion is adjacent to at least a portion of the slit, and the thickness of the viscoelastic layer at the free end portion is greater than the thickness of the viscoelastic layer at the root portion. Optionally, the viscoelastic film layer extends in a direction of the free end toward the root, and the viscoelastic film layer gradually decreases in thickness in the direction of the free end toward the root. Optionally, at least a portion of the free end of the suspended portion is at the intersection of the slits, and the viscoelastic film layer is located at the intersection of the slits to a thickness greater than the thickness of the viscoelastic film layer at the root. Optionally, the slit has a width in the range of 0.5um to 10um, and/or the viscoelastic film layer has an arched structure, and/or the viscoelastic film layer covers the suspended portion of the diaphragm and the slit. In another aspect of the embodiments of the present application, a method for manufacturing a MEMS device is provided, including: Forming a membrane on a substrate; forming a slit on the diaphragm to divide the diaphragm into a plurality of suspended portions; etching the substrate to form a back cavity communicated with the gap, wherein a plurality of suspended parts are exposed in the back cavity; a viscoelastic film layer is formed on the diaphragm, and the viscoelastic film layer seals the back cavity at the gap. Optionally, forming the viscoelastic film layer on the membrane comprises: Forming a liquid film layer on the diaphragm; The liquid film layer is solidified to form a viscoelastic film layer. Optionally, forming the liquid film layer on the membrane includes: Forming a liquid body at the center of the diaphragm th