CN217591086U - MEMS structure - Google Patents

Abstract

The application discloses MEMS structure includes: a substrate having a cavity; a vibration support layer formed over the substrate and covering the cavity; a functional layer formed over the vibration support layer and suspended over the cavity, the functional layer having a dividing line dividing the functional layer into at least two portions; wherein the vibration support layer further has an edge pleat having a first portion surrounding the functional layer and a second portion that is more outwardly enlarged relative to the first portion, the second portion being located at a position corresponding to the position of the dividing line. This application sets up the first part and the second part of different curvatures on the vibration supporting layer, releases the stress of functional layer edge and cut-off line department respectively to improve the uneven problem of vibration supporting layer stress distribution of MEMS structure, improve the sensitivity and the stability of MEMS structure.

Description

MEMS structure

Technical Field

The present disclosure relates to the field of Micro-Electro-Mechanical systems, and more particularly, to a Micro-Electro-Mechanical System (MEMS) structure.

Background

MEMS microphones include mainly capacitive and piezoelectric types. The MEMS piezoelectric microphone is prepared by utilizing a micro-electro-mechanical system technology and a piezoelectric film technology, and has small size, small volume and good consistency due to the adoption of semiconductor planar technology, bulk silicon processing technology and other technologies. In the prior art, in order to obtain the maximum output voltage, when the size of the diaphragm is constant, the functional layer of the MEMS piezoelectric microphone is disposed in the middle area of the diaphragm, so that voltage loss caused by opposite charges generated in the middle and edge areas of the diaphragm in the vibration process is avoided. However, the functional layer is unevenly distributed on the diaphragm, so that the boundary of the functional layer generates a large tensile force on the diaphragm, and the edge area of the diaphragm becomes wrinkled. The corrugations of the diaphragm cause uncertainty in the output stability of the device.

SUMMERY OF THE UTILITY MODEL

To address the problems in the related art, the present application provides a MEMS structure that can increase sensitivity and stability.

The technical scheme of the application is realized as follows:

according to an aspect of the present application, there is provided a MEMS structure comprising:

a substrate having a cavity;

a vibration support layer formed over the substrate and covering the cavity;

a functional layer formed over the vibration support layer and suspended over the cavity, the functional layer having a dividing line dividing the functional layer into at least two portions;

wherein the vibration support layer further has an edge pleat having a first portion surrounding the functional layer and a second portion that is more outwardly enlarged relative to the first portion, the second portion being located at a position corresponding to the location of the dividing line.

Wherein the edge fold is undulated in an uneven pattern and is formed over the cavity.

Wherein, from a top view, the functional layer is circular, the first portion is circular arc shaped, and the second portion is circular arc shaped.

Wherein the first portion and the second portion are continuous.

Wherein the functional layer comprises:

a first electrode layer formed over the vibration support layer;

a piezoelectric layer formed over the first electrode layer;

a second electrode layer formed over the piezoelectric layer, the dividing line dividing the first electrode layer and the second electrode layer into at least two parts.

Wherein the dividing line is disposed on the first electrode layer and the second electrode layer.

Wherein the MEMS structure further comprises a barrier layer disposed between the substrate and the vibrating support layer.

Wherein the area of the functional layer is smaller than the area of the cavity.

In conclusion, the first part and the second part with different curvatures are arranged on the vibration supporting layer, and stress at the edge of the functional layer and stress at the dividing line are released respectively, so that the problem of uneven stress distribution of the vibration supporting layer of the MEMS structure is solved, and the sensitivity and the stability of the MEMS structure are improved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 illustrates a perspective view of a MEMS structure provided in accordance with some embodiments;

FIG. 2 illustrates a top view of a MEMS structure provided in accordance with some embodiments.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application are within the scope of protection of the present application.

Referring to fig. 1, according to an embodiment of the present application, a MEMS structure is provided, which can be applied to a sensor such as a microphone or a speaker, and can also be applied to an actuator. The MEMS structure comprises a substrate 10, a vibrating support layer 20 and a functional layer. The MEMS structure will be described in detail below.

The substrate 10 has a cavity (not shown in the figure). The substrate 10 comprises silicon or any suitable silicon-based compound or derivative (e.g., silicon wafer, SOI, polysilicon on SiO 2/Si).

A vibration support layer 20 is formed over the substrate 10 and covers the cavity. In some embodiments, the vibration support layer 20 comprises a single or multi-layer composite membrane structure of silicon nitride (Si 3N 4), silicon oxide, single crystal silicon, polycrystalline silicon, or other suitable support material.

The functional layer is formed over the vibration support layer 20 and suspended over the cavity, the functional layer having a dividing line 25 dividing the functional layer into at least two parts. The area of the functional layer is smaller than the area of the cavity.

In some embodiments, the functional layers include a first electrode layer 21 formed over the vibration support layer 20, a piezoelectric layer 22 formed over the first electrode layer 21, a second electrode layer 23 formed over the piezoelectric layer 22, and a dividing line 25 dividing the first electrode layer 21 and the second electrode layer 23 into at least two parts. In some embodiments, the dividing line 25 is disposed on the first electrode layer 21 and the second electrode layer 23. The piezoelectric layer 22 may convert the applied pressure into a voltage, and the first electrode layer 21 and the second electrode layer 23 may transmit the generated voltage to other integrated circuit devices. In some embodiments, the piezoelectric layer 22 comprises zinc oxide, aluminum nitride, an organic piezoelectric film, lead zirconate titanate (PZT), a perovskite-type piezoelectric film, or other suitable material. The first electrode layer 21 and the second electrode layer 23 include aluminum, gold, platinum, molybdenum, titanium, chromium, and a composite film composed of them or other suitable materials.

Referring to fig. 2, the vibration support layer 20 preferably also has an edge corrugation having a first portion 241 surrounding the functional layer and a second portion 242 more outwardly flared with respect to the first portion 241, the position of the second portion 242 corresponding to the position of the division line 25.

In some embodiments, the edge folds are undulated and the edge folds are formed over the cavity.

In some embodiments, the functional layer is circular in plan view, the first portion 241 is circular in arc shape, and the second portion 242 is circular in arc shape. In some embodiments, the first portion 241 and the second portion 242 are continuous. As can be seen in fig. 2, the first portion 241 includes a plurality of arc segments in a radial direction, and the second portion 242 includes a plurality of arc segments in a radial direction. The edge corrugation formation process includes forming a trench in the substrate 10 and then conformally forming the material of the vibration support layer 20 over the substrate 10 with the trench, thereby forming an edge corrugation over the trench.

In some embodiments, the MEMS structure further comprises a barrier layer 30, the barrier layer 30 being disposed between the substrate 10 and the vibrating support layer 20. The barrier layer 30 serves to isolate the vibrating support layer 20 from the substrate 10.

In summary, the present application provides the dividing line 25 on the first electrode layer 21 and the second electrode layer 23 to improve the sensitivity of the MEMS structure. But the concentration of stress on the vibration support layer 20 at the parting line 25 will result in wrinkling of the vibration support layer 20. According to the MEMS structure, the first part 241 and the second part 242 with different curvatures are arranged on the vibration supporting layer 20, and the stress at the edge of the functional layer and the stress at the division line 25 are released respectively, so that the problem of uneven stress distribution of the vibration supporting layer 20 of the MEMS structure is solved, and the sensitivity and the stability of the MEMS structure are improved.

The present invention is not intended to be limited to the particular embodiments shown and described, and various modifications, equivalents, improvements and the like, which are within the spirit and scope of the present invention, are intended to be included within the scope of the present invention.

Claims (8)

1. A MEMS structure, comprising:

a substrate having a cavity;

a vibration support layer formed over the substrate and covering the cavity;

a functional layer formed over the vibration support layer and suspended over the cavity, the functional layer having a dividing line dividing the functional layer into at least two portions;

wherein the vibration support layer further has an edge pleat having a first portion surrounding the functional layer and a second portion that is more outwardly enlarged relative to the first portion, the second portion being located at a position corresponding to the position of the dividing line.

2. The MEMS structure of claim 1, wherein the edge folds are rugged corrugated and formed over the cavity.

3. The MEMS structure of claim 1, wherein the functional layer is circular in plan view, the first portion is circular in shape, and the second portion is circular in shape.

4. The MEMS structure of claim 1, wherein the first portion and the second portion are continuous.

5. The MEMS structure of claim 1, wherein the functional layer comprises:

a first electrode layer formed over the vibration support layer;

a piezoelectric layer formed over the first electrode layer;

a second electrode layer formed over the piezoelectric layer, the dividing line dividing the first electrode layer and the second electrode layer into at least two parts.

6. The MEMS structure of claim 5, wherein the dividing line is disposed on the first electrode layer and the second electrode layer.

7. The MEMS structure of claim 1, further comprising a barrier layer disposed between the substrate and the vibrating support layer.

8. The MEMS structure of claim 1, wherein the functional layer has a smaller areal area than the cavity.

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