An electrostatic actuator includes a base, a movable electrode including a semiconductor and supported to the base to be displaceable in a first direction, and a fixed electrode including the semiconductor and fixed to the base, in which the fixed electrode faces the movable electrode in a state of being separated therefrom in the first direction. The electrostatic actuator includes a high-resistance region formed in at least a portion of each of respective facing surfaces of the movable electrode and the fixed electrode, and lower in impurity concentration than a surrounding region thereof.

Systems, devices, and methods for micro-electro-mechanical system (MEMS) tunable capacitors can include a fixed actuation electrode attached to a substrate, a fixed capacitive electrode attached to the substrate, and a movable component positioned above the substrate and movable with respect to the fixed actuation electrode and the fixed capacitive electrode. The movable component can include a movable actuation electrode positioned above the fixed actuation electrode and a movable capacitive electrode positioned above the fixed capacitive electrode. At least a portion of the movable capacitive electrode can be spaced apart from the fixed capacitive electrode by a first gap, and the movable actuation electrode can be spaced apart from the fixed actuation electrode by a second gap that is larger than the first gap.

A functional element includes: a substrate; a movable body that includes a movable electrode portion; a support portion that supports the movable body; a first fixed electrode portion that is disposed on the substrate and a portion of which faces a first portion as one of portions of the movable body; a second fixed electrode portion that is disposed on the substrate and a portion of which faces a second portion as the other portion of the movable body; and a third fixed electrode portion that is disposed on the substrate and a portion of which faces the first portion. An opening that faces a region of the substrate between the first fixed electrode portion and the third fixed electrode portion is provided in the movable body, and the width of the opening is equal to or more than the width of the region.

A microelectromechanical system (MEMS) device is disclosed. The MEMS device includes a device substrate with a top device surface and a bottom device surface having a MEMS component in a device region. A top device bond ring is disposed on the top device surface surrounding the device region and a bottom device bond ring is disposed on the bottom device surface surrounding the device region. A top cap with a top cap bond ring is bonded to the top device bond ring by a top eutectic bond and a bottom cap with a bottom cap bond ring is bonded to the bottom device bond ring by a bottom eutectic bond. The eutectic bonds encapsulate the MEMS device.

A microelectromechanical system (MEMS) device is disclosed. The MEMS device includes a device substrate with a top device surface and a bottom device surface having a MEMS component in a device region. A top device bond ring is disposed on the top device surface surrounding the device region and a bottom device bond ring is disposed on the bottom device surface surrounding the device region. A top cap with a top cap bond ring is bonded to the top device bond ring by a top eutectic bond and a bottom cap with a bottom cap bond ring is bonded to the bottom device bond ring by a bottom eutectic bond. The eutectic bonds encapsulate the MEMS device.

A method of fabricating a MEMS device includes an epi-polysilicon cap layer epitaxially growth on one of a substrate or a sacrificial layer deposited on the substrate. A portion of the epi-polysilicon cap layer has been removed to form a plurality of access openings. The sacrificial layer is etched away to form a cavity below the access openings. A barrier layer is deposited over the epi-polysilicon cap layer, inner walls of the cavity, and inner walls of the access openings using an atomic layer deposition (ALD) process. A refill epi-polysilicon layer is epitaxially grown in the access openings and seals the openings after the cavity is formed.

In described examples, a MEMS device is enclosed within a sealed package including nonmetal oxide gasses at levels greater than 1% by volume. In at least one example, the MEMS device is protected against premature failure from various causes, including charging, particle growth and stiction by moieties of the nonmetal oxide gasses reacting with various exposed surfaces within the package of the MEMS device and/or the adsorbed water layers on said surfaces.

Systems, devices, and methods for micro-electro-mechanical system (MEMS) tunable capacitors can include a fixed actuation electrode attached to a substrate, a fixed capacitive electrode attached to the substrate, and a movable component positioned above the substrate and movable with respect to the fixed actuation electrode and the fixed capacitive electrode. The movable component can include a movable actuation electrode positioned above the fixed actuation electrode and a movable capacitive electrode positioned above the fixed capacitive electrode. At least a portion of the movable capacitive electrode can be spaced apart from the fixed capacitive electrode by a first gap, and the movable actuation electrode can be spaced apart from the fixed actuation electrode by a second gap that is larger than the first gap.

A method and apparatus are provided to prevent or reduce stiction of a MEMS device. The MEMS device may include a protrusion extending from a surface of the MEMS device. During manufacture, the protrusion may be connected across an opening in the MEMS device to a sidewall of the substrate. Before manufacture of the MEMS device is completed, at least a portion of the protrusion connecting the MEMS device to the substrate may be removed. During operation, the protrusion may provide stiction prevention or reduction for the surface from which the first protrusion may extend. A plurality of protrusions may be formed along a plurality of surfaces for the MEMS device to prevent or reduce stiction along the corresponding surfaces. Protrusions may also be formed on devices surrounding or encapsulating the MEMS device to prevent or reduce stiction of the MEMS device to the surrounding or encapsulating devices.

In described examples, a MEMS device is enclosed within a sealed package including nonmetal oxide gasses at levels greater than 1% by volume. In at least one example, the MEMS device is protected against premature failure from various causes, including charging, particle growth and stiction by moieties of the nonmetal oxide gasses reacting with various exposed surfaces within the package of the MEMS device and/or the adsorbed water layers on said surfaces.