MEMS device and process

Patent metadata

Field	Value
Publication number	US-9584903-B2
Application number	US-201314430466-A
Country	US
Kind code	B2
Filing date	Sep 19, 2013
Priority date	Sep 24, 2012
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

This application relates to MEMS devices, especially MEMS capacitive transducers and to processes for forming such MEMS transducer that provide increased robustness and resilience to acoustic shock. The application describes a MEMS transducer having a flexible membrane ( 101 ) supported relative to a first surface of a substrate ( 105 ) which has one or more cavities therein, e.g. to provide an acoustic volume. A stop structure ( 401, 402 ) is positioned so as to be contactable by the membrane when deflected so as to limit the amount of deflection of the membrane. The stop structure defines one or more openings to the one or more substrate cavities and comprises at least one narrow support element ( 401, 402 ) within or between said one or more openings. The stop structure thus limits the amount of membrane deflection, thus reducing the stress experienced at the edges and prevents the membrane from contacting a sharp edge of a substrate cavity. As the stop structure comprises narrow support elements any performance impact on the transducer is limited.

First claim

The invention claimed is:

1. A MEMS transducer comprising:
a flexible membrane supported relative to a first surface of a substrate, the substrate having one or more cavities therein; and
a stop structure positioned on one side of the membrane so as to be contactable by the membrane when deflected so as to limit the amount of deflection of the membrane, the MEMS transducer comprising a back-plate structure wherein the membrane layer is supported to be flexible with respect to said back-plate structure and the back-plate structure is on the opposite side of the membrane to the stop structure; wherein:
the stop structure defines one or more openings to said one or more cavities and comprises at least one narrow support element within or between said one or more openings; and
said at least one narrow support element forms a contact element positioned such that the membrane will make contact with the contact element if subject to a relatively large deflection towards the first surface.

2. A MEMS transducer as claimed in claim 1 wherein the total area of said one or more openings of the stop structure is greater than the total area of any openings in the back-plate structure.

Assignees

• Wolfson Microelectronics Plc
• Cirrus Logic Inc

Inventors

• Hoekstra Tsjerk
• Hesketh Mark

Classifications

• H04R19/005 Primary

  using semiconductor materials · CPC title

• H04R1/2892 Primary

  Mountings or supports for transducers · CPC title

• B81B2201/0257

  Microphones or microspeakers · CPC title

• B81B3/0021

  Transducers for transforming electrical into mechanical energy or vice versa (dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00) · CPC title

• H04R31/003

  for diaphragms or their outer suspension · CPC title