Cirrus Logic Inc.

Wolfson Microelectronics Limited

Cirrus Logic International Semiconductor Limited

Cirrus Logic International (uk) Limited

Colin Robert Jenkins

Tsjerk Hans Hoekstra

Euan James Boyd

Richard Ian Laming

Scott Lyall Cargill

Axel Thomsen

Anthony Traynor

Marek Sebastian Piechocinski

Colin Wei Hong Chung

Stephen Duffy

The application describes MEMS transducers having a patterned membrane electrode which incorporates a plurality of openings or voids. A conductive element is provided on the surface of the underlying membrane within the opening.

MEMS devices and processes

The present application relates to MEMS transducer comprising a membrane electrode and a backplate electrode. The membrane electrode comprises primary and secondary openings.

A MEMS capacitive transducer with increased robustness and resilience to acoustic shock. The transducer structure includes a flexible membrane supported between a first volume and a second volume, and at least one variable vent structure in communication with at least one of the first and second volumes. The variable vent structure includes at least one moveable portion which is moveable in response to a pressure differential across the moveable portion so as to vary the size of a flow path through the vent structure. The variable vent may be formed through the membrane and the moveable portion may be a part of the membrane, defined by one or more channels, that is deflectable away from the surface of the membrane. The variable vent is preferably closed in the normal range of pressure differentials but opens at high pressure differentials to provide more rapid equalisation of the air volumes above and below the membrane.

MEMS device and process

A MEMS transducer may comprise a membrane supported relative to a substrate, the membrane comprising a first region and a second region, wherein the first region comprises a central region and plurality of arms which extend laterally from the central region and wherein the second region is separated from the first region by a channel which extends through the membrane.

The application describes a MEMS transducer comprising a layer of conductive material provided on a surface of a layer of membrane material. The layer of conductive material comprises first and second regions, wherein the thickness and/or the conductivity of the/each first and second regions is different.

The application describes MEMS transducer having a flexible membrane and which seeks to alleviate and/or redistribute stresses within the membrane layer. A membrane having a first/active region and a second/inactive region is described.

MEMS transducer having stress diffusing structures provided in a flexible membrane

The application describes MEMS transducers having a vent structure provided in a flexible membrane of the vent structure The vent structure comprises at least one moveable portion and the vent structure is configured such that, in response to a differential pressure across the vent structure, the moveable portion is rotatable about first and second axes of rotation, which axes of rotation extend in the plane of the membrane.

A MEMS transducer structure comprises a substrate comprising a cavity. A membrane layer is supported relative to the substrate to provide a flexible membrane. A peripheral edge of the cavity defines at least one perimeter region that is convex with reference to the center of the cavity. The peripheral edge of the cavity may further define at least one perimeter region that is concave with reference to the center of the cavity.

The application describes improvements to (MEMS) transducers () having a flexible membrane () with a membrane electrode (), especially where the membrane is crystalline or polycrystalline and the membrane electrode is metal or a metal alloy. Such transducers may typically include a back-plate having at least one back-plate layer () coupled to a back-plate electrode (), with a plurality of holes () in the back-plate electrode corresponding to a plurality back-plate holes () through the back-plate. In embodiments of the invention the membrane electrode has at least one opening () in the membrane electrode wherein, at least part of the area of the opening corresponds to the area of at least one back-plate hole, in a direction normal to the membrane, and there is no hole in the flexible membrane at said opening in the membrane electrode. There may be a plurality of such openings. The openings effectively allow a reduction in the amount of membrane electrode material, e.g. metal, that may undergo plastic deformation and permanently deform the membrane. The openings are at least partly aligned with the back-plate holes to minimize any loss of capacitance.

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 at least one membrane layer () supported so as to define a flexible membrane. A strengthening layer () is mechanically coupled to the membrane layer and is disposed around the majority of a peripheral area of the flexible membrane but does not extend over the whole flexible membrane. The strengthening layer, which in some embodiments may be formed from the same material as the membrane electrode () being disposed in the peripheral area helps reduce stress in membrane at locations that otherwise may be highly stressed in acoustic shock situations. The membrane may be supported over a substrate cavity and the strengthening layer may be provided in an area of the membrane that could make contact with the edge () of the substrate cavity.

A MEMS capacitive transducer with increased robustness and resilience to acoustic shock. The transducer structure includes a flexible membrane supported between a first volume and a second volume, and at least one variable vent structure in communication with at least one of the first and second volumes. The variable vent structure includes at least one moveable portion which is moveable in response to a pressure differential across the moveable portion so as to vary the size of a flow path through the vent structure. The variable vent may be formed through the membrane and the moveable portion may be a part of the membrane, defined by one or more channels, that is deflectable away from the surface of the membrane. The variable vent is preferably closed in the normal range of pressure differentials but opens at high pressure differentials to provide more rapid equalization of the air volumes above and below the membrane.

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Livingston, United Kingdom

Colin Robert Jenkins