Cantilevered piezoelectric microelectromechanical systems microphone with stress compensation

Patent metadata

Field	Value
Publication number	US-12570520-B2
Application number	US-202217810871-A
Country	US
Kind code	B2
Filing date	Jul 6, 2022
Priority date	Jul 9, 2021
Publication date	Mar 10, 2026
Grant date	Mar 10, 2026

Abstract

A piezoelectric microelectromechanical systems (MEMS) microphone is provided comprising a substrate including walls defining a cavity and at least one of the walls defining an anchor region, a piezoelectric film layer supported by the substrate at the anchor region such that the piezoelectric film layer is cantilevered, the piezoelectric film layer being formed to introduce differential stress between a front surface of the piezoelectric film layer oriented away from the cavity and a back surface of the piezoelectric film layer oriented towards the cavity such that the piezoelectric film layer is bent into the cavity, and an electrode disposed over the piezoelectric film layer and adjacent the anchor region. A method of manufacturing such a MEMS microphone is also provided.

First claim

What is claimed is:

1 . A piezoelectric microelectromechanical systems (MEMS) microphone, comprising:
a substrate including walls defining a cavity and at least one of the walls defining an anchor region; a piezoelectric film layer supported by the substrate at the anchor region such that the piezoelectric film layer is cantilevered, the piezoelectric film layer being formed to introduce differential stress between a front surface of the piezoelectric film layer oriented away from the cavity and a back surface of the piezoelectric film layer oriented towards the cavity such that the piezoelectric film layer is bent into the cavity; and an electrode disposed over the piezoelectric film layer and adjacent the anchor region.

2 . The piezoelectric MEMS microphone of claim 1 further comprising a second piezoelectric film layer.

3 . The piezoelectric MEMS microphone of claim 2 wherein the piezoelectric film layer and the second piezoelectric film layer have different average stresses to provide the differential stress.

4 . The piezoelectric MEMS microphone of claim 3 wherein one of the two piezoelectric film layers has an average stress of −125 MPa and the other piezoelectric film layer has an average stress of 300 MPa.

5 . The piezoelectric MEMS microphone of claim 1 wherein the piezoelectric film layer has a mean bend of 10 micrometers into the cavity.

6 . The piezoelectric MEMS microphone of claim 1 wherein the piezoelectric film layer is 300-500 micrometers in length.

7 . The piezoelectric MEMS microphone of claim 1 further comprising a second electrode disposed under the piezoelectric film layer.

8 . The piezoelectric MEMS microphone of claim 2 further comprising a third electrode disposed between the piezoelectric film layer and the second piezoelectric film layer.

9 . The piezoelectric MEMS microphone of claim 1 wherein the piezoelectric film layer is formed of aluminum nitride.

10 . A wireless mobile device comprising:
one or more antennas; a front end system that communicates with the one or more antennas; and one or more piezoelectric microelectromechanical systems microphones, each microphone including a substrate having walls defining a cavity and at least one of the walls defining an anchor region, a piezoelectric film layer supported by the substrate at the anchor region such that the piezoelectric film layer is cantilevered, the piezoelectric film layer being formed to introduce differential stress between a front surface of the piezoelectric film layer oriented away from the cavity and a back surface of the piezoelectric film layer oriented towards the cavity such that the piezoelectric film layer is bent into the cavity, and an electrode disposed over the piezoelectric film layer and adjacent the anchor region.

11 . The wireless mobile device of claim 10 further comprising a second piezoelectric film layer.

12 . The wireless mobile device of claim 11 wherein the piezoelectric film layer and the second piezoelectric film layer have different average stresses to provide the differential stress.

13 . The wireless mobile device of claim 10 wherein the piezoelectric film layer has a mean bend of 10 micrometers into the cavity.

Assignees

• Skyworks Solutions Inc

Inventors

• Qian You
• Kumar Rakesh
• Chen Guofeng

Classifications

• B81B2203/0307

  Anchors · CPC title

• B81B2203/0118

  Cantilevers · CPC title

• B81B2203/0315

  Cavities · CPC title

• B81C2201/014

  by depositing an etch stop layer, e.g. silicon nitride, silicon oxide, metal · CPC title

• B81C2201/0132

  Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling · CPC title