A micro-electromechanical-system (MEMS) device may be formed to include an anti-stiction polysilicon layer on one or more moveable MEMS structures of a device wafer of the MEMS device to reduce, minimize, and/or eliminate stiction between the moveable MEMS structures and other components or structures of the MEMS device. The anti-stiction polysilicon layer may be formed such that a surface roughness of the anti-stiction polysilicon layer is greater than the surface roughness of a bonding polysilicon layer on the surfaces of the device wafer that are to be bonded to a circuitry wafer of the MEMS device. The higher surface roughness of the anti-stiction polysilicon layer may reduce the surface area of the bottom of the moveable MEMS structures, which may reduce the likelihood that the one or more moveable MEMS structures will become stuck to the other components or structures.

An accelerometer comprising: a frame; a first proof mass suspended from the frame by one or more flexures to move relative to the frame along a first axis; a first resonant element assembly fixed between the frame and the first proof mass, wherein movement of the proof mass along the first axis relative to the frame exerts a strain on the first resonant element that affects its resonant behaviour; a second proof mass suspended from the frame by one or more flexures to move relative to the frame along a second axis, a second resonant element assembly fixed between the frame and the second proof mass, wherein movement of the second proof mass along the second axis relative to the frame exerts a strain on the second resonant element that affects its resonant behaviour; wherein the second proof mass surrounds the first proof mass and the first resonant element assembly.

A microelectromechanical system (MEMS) sensor device includes a package housing having a top member, bottom member, and a spacer coupled the top member to the bottom member, defining a cavity. At least one sensor circuit and a MEMS sensor disposed within the cavity of the package housing. A first opening formed on the package housing a control device embedded within the package housing is electrically coupled to the sensor circuit and is controlled to tune the MEMS sensor from a directional mode to an omni-directional mode.

Methods and apparatuses are provided for evaluating or testing stiction in Microelectromechanical Systems (MEMS) devices utilizing a mechanized shock pulse generation approach. In one embodiment, the method includes the step or process of loading a MEMS device, such as a multi-axis MEMS accelerometer, into a socket provided on a Device-Under-Test (DUT) board. After loading the MEMS device into the socket, a series of controlled shock pulses is generated and transmitted through the MEMS device utilizing a mechanized test apparatus. The mechanized test apparatus may, for example, repeatedly move the DUT board over a predefined motion path to generate the controlled shock pulses. In certain cases, transverse vibrations may also be directed through the tested MEMS device in conjunction with the shock pulses. An output of the MEMS device is then monitored to determine whether stiction of the MEMS device occurs during each of the series of controlled shock pulses.

A method embodiment includes providing a MEMS wafer comprising an oxide layer, a MEMS substrate, a polysilicon layer. A carrier wafer comprising a first cavity formed using isotropic etching is bonded to the MEMS, wherein the first cavity is aligned with an exposed first portion of the polysilicon layer. The MEMS substrate is patterned, and portions of the sacrificial oxide layer are removed to form a first and second MEMS structure. A cap wafer including a second cavity is bonded to the MEMS wafer, wherein the bonding creates a first sealed cavity including the second cavity aligned to the first MEMS structure, and wherein the second MEMS structure is disposed between a second portion of the polysilicon layer and the cap wafer. Portions of the carrier wafer are removed so that first cavity acts as a channel to ambient pressure for the first MEMS structure.

This disclosure describes a microelectromechanical device comprising at least one mobile rotor. The rotor comprises a rotor measurement region and a rotor stopper region and a rotor isolation region which connects the rotor measurement region mechanically to the rotor stopper region and isolates the rotor measurement region electrically from the rotor stopper region.

A method of fabricating a MEMS device includes depositing an expandable material into a first recess of a cap wafer. The cap wafer includes a plurality of walls that surround and define the first recess and a second recess. The cap wafer is bonded to a MEMS wafer including a first MEMS device and a second MEMS device. The first MEMS device is encapsulated in the first recess, and the second MEMS device is encapsulated in the second recess. The expandable material is then heated to at least an activation temperature to cause the expandable material to expand after the first recess has been sealed. The expansion of the expandable material causes a reduction in volume of the first recess.

A nanosheet MEMS sensor device and method are described for integrating the fabrication of nanosheet transistors (61) and MEMS sensors (62) in a single nanosheet process flow by forming separate nanosheet transistor and MEMS sensor stacks (12A-16A, 12B-16B) of alternating Si and SiGe layers which are selectively processed to form gate electrodes (49A-C) which replace the silicon germanium layers in the nanosheet transistor stack, to form silicon fixed electrodes using silicon layers (13B-2, 15B-2) on a first side of the MEMS sensor stack, and to form silicon cantilever electrodes using silicon layers (13B-1, 15B-1) on a second side of the MEMS sensor stack by forming a narrow trench opening (54) in the MEMS sensor stack to expose and remove remnant silicon germanium layers on the second side in the MEMS sensor stack.

A vibration sensor/accelerometer includes, in various implementations, a MEMS die that includes a plate having an aperture, an anchor disposed within the aperture, a plurality of arms (e.g., rigid arms) extending from the anchor, and a plurality of resilient members (e.g., looped or folded springs with a carefully designed spring stiffness), each resilient member connecting the plate to an arm of the plurality of arms. The plate may be made from a solid layer in which the resilient members are etched from the same layer. The MEMS die may also include top and bottom wafers, and travel stoppers extending from the top and bottom wafers as well as through the plate.

A micro-electromechanical apparatus includes a rotary element, at least one restraint and at least two folded springs. The rotary element is capable of rotating with respect to an axis. The folded springs are symmetrically disposed about the axis. Each folded spring has a moving end and a fixed end, the moving end is connected to the rotary element, and the fixed end is connected to the at least one restraint. The moving end is not located on the axis, and the fixed end is not located on the axis. A moving distance is defined as a distance between the moving end and the axis, a fixed distance is defined as a distance between the fixed end and the axis. A spring length is defined as a distance between the moving end and the fixed end. The spring length is varied according to the rotation of the rotary element.