Invensense, Inc.

Ian Flader

Dongyang Kang

Daesung Lee

Bongsang Kim

Alan Cuthbertson

Bei Zhu

Emad Mehdizadeh

Methods and systems for reducing stiction through roughening the surface and reducing the contact area in MEMS devices are disclosed. A method includes fabricating bumpstops on a surface of a MEMS device substrate to reduce stiction. Another method is directed to applying roughening etchant to a surface of a silicon substrate to enhance roughness after cavity etch and before removal of hardmask. Another embodiment described herein is directed to a method to reduce contact area between proof mass and UCAV ('upper cavity') substrate surface with minimal impact on the cavity volume by introducing a shallow etch process step and maintaining high pressure in accelerometer cavity. Another method is described as to increasing the surface roughness of a UCAV substrate surface by depositing a rough layer (e.g. polysilicon) on the surface of the substrate and etching back the rough layer to transfer the roughness.

Stiction reduction system and method thereof

A device includes a micro-electromechanical system (MEMS) device layer comprising a proof mass. The proof mass includes a first proof mass portion and a second proof mass portion. The first proof mass portion is configured to move in response to a stimuli. The second proof mass portion has a spring attached thereto. The device further includes a substrate disposed parallel to the MEMS device layer. The substrate comprises a bumpstop configured to limit motion of the first proof mass portion. The device includes a first electrode disposed on the substrate facing the second proof mass portion. The first electrode is configured to apply a pulling force onto the second proof mass portion and to move the second proof mass portion towards the first electrode.

Active stiction recovery

Provided herein is a method including forming a MEMS cap. A cavity is formed in the MEMS cap wafer, and a bond material is deposited on the MEMS cap wafer, wherein the bond material lines the cavity after the depositing. The MEMS cap wafer is bonded to a MEMS device wafer, wherein the bond material forms a bond between the MEMS cap wafer and the MEMS device wafer. A MEMS device is formed in the MEMS device wafer. The bond material is removed from the cavity.

Reduced MEMS cavity gap

A method for DRIE matched release and/or the mitigation of photo resist pooling, comprising: depositing a first mask layer over a first surface of a silicon substrate; exposing a first portion and second portion of the first mask layer to a first etch process, wherein the exposing forms a first exposed layer; depositing a second mask layer over the first mask layer; exposing a third portion of the second mask layer to a second etch process, wherein the exposing forms a second exposed mask layer, and wherein the third portion overlaps the first portion of the first mask layer; developing the second mask layer and etching the third portion of the second mask layer and developing the first portion of the first mask layer; etching the first portion of the first mask layer to a first depth; and developing the first mask layer to reveal exposed portions of the first mask layer and etching the second portion of the silicon substrate to a second depth.

Method of addressing dissimilar etch rates

A microelectromechanical (MEMS) system may comprise multiple sensors within cavities of the MEMS system. The operation of different sensors requires different pressures within the respective cavities. A first cavity may be sealed at a first pressure. A through-hole may be etched into a cap layer of the MEMS system to introduce gas into a second cavity such that the cavity has a desired pressure. The cavity may then be sealed by a MEMS valve to maintain the desired pressure in the second cavity.

Integrated MEMS cavity seal

A method includes fusion bonding a first side of a MEMS wafer to a second side of a first handle wafer. A TSV is formed from a first side of the first handle wafer to the second side of the first handle wafer and into the first MEMS wafer. A dielectric layer is formed on the first side of the first handle wafer. A tungsten via is formed in the dielectric layer. Electrodes are formed on the dielectric layer. A second MEMS wafer is eutecticly bonded with a first eutectic bond to the electrodes, wherein the TSV electrically connects the first MEMS wafer to the second MEMS wafer. Standoffs are formed on a second side of the first MEMS wafer. A CMOS wafer is eutecticly bonded with a second eutectic bond to the standoffs, wherein the second eutectic bond includes different materials than the first eutectic bond.

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Redwood City, CA, United States of America

Ian Flader