Abstract: An oscillatory gyroscope is described with decoupled drive and sense oscillators and reduced cross-axis sensitivity. The gyroscope is fabricated using a plasma micromachining process on standard silicon wafers. The electrical isolation of the drive and sense functions of the gyroscope, contained within the same micromechanical element, reduce cross-coupling while obtaining high inertial mass and high sensitivity.

Abstract: A relay for switching an electrical signal includes switching elements, an actuator for closing the switch, and an actuator for opening the switch, the latter two of which are mechanically decoupled when the relay is in a mechanical rest position. When a relay close signal is applied, the closing actuator electrostatically drives the switching elements to complete a signal path between two terminals for the switched signal. In the process of closing the switch, the opening actuator remains stationary, i.e., no mass is displaced. Application of a switch open signal electrostatically drives the opening actuator, optionally in combination with a mechanical restoring force on the closing actuator, to open the switch to break the signal conduction path for the switched signal.

Abstract: A method of manufacturing an insulating micro-structure by etching a plurality of trenches in a silicon substrate and filling said trenches with insulating materials. The trenches are etched and then oxidized until completely or almost completely filled with silicon dioxide. Additional insulating material is then deposited as necessary to fill any remaining trenches, thus forming the structure. When the top of the structure is metallized, the insulating structure increases voltage resistance and reduces the capacitive coupling between the metal and the silicon substrate. Part of the silicon substrate underlying the structure is optionally removed further to reduce the capacitive coupling effect. Hybrid silicon-insulator structures can be formed to gain the effect of the benefits of the structure in three-dimensional configurations, and to permit metallization of more than one side of the structure.

Abstract: An accelerometer. A silicon wafer is etched to form a fixed portion, a movable portion, and a resilient coupling between, the fixed and movable portions generally arranged in the plane of the wafer, the mass of the movable portion being concentrated on one side of the resilient coupling. One of the fixed and moveable portions of the silicon structure includes a first electrode. The other of the fixed and moveable portions includes a second electrode oriented parallel to the axis of acceleration, and an electrically-conductive layer electrically connected as a third electrode coplanar and mechanically coupled with the second electrode. The second and third electrodes are arranged in capacitive opposition to the first electrode, the capacitance between the first electrode and third electrode increasing as the movable portion moves in a direction along the axis of acceleration relative to the fixed portion and decreasing as the movable portion moves in an opposite direction.

Abstract: An isolation process which enhances the performance of silicon micromechanical devices incorporates dielectric isolation segments within the silicon microstructure, which is otherwise composed of an interconnected grid of cantilevered beams. A metal layer on top of the beams provides interconnects and also allows contact to the silicon beams, electrically activating the device for motion or transduction. Multiple conduction paths are incorporated through a metal patterning step prior to structure definition. The invention improves manufacturability of previous processes by performing all lithographic patterning steps on flat topographies, and removing complicated metal sputtering steps required of most high aspect ratio processes. With little modification, the invention can be implemented with in grated circuit fabrication sequences for fully integrated devices.

Abstract: An isolation process which enhances the performance of silicon micromechanical devices incorporates dielectric isolation segments within the silicon microstructure, which is otherwise composed of an interconnected grid of cantilevered beams. A metal layer on top of the beams provides interconnects and also allows contact to the silicon beams, electrically activating the device for motion or transduction. Multiple conduction paths are incorporated through a metal patterning step prior to structure definition. The invention improves manufacturability of previous processes by performing all lithographic patterning steps on flat topographies, and removing complicated metal sputtering steps required of most high aspect ratio processes. With little modification, the invention can be implemented with integrated circuit fabrication sequences for fully integrated devices.

Abstract: A micromechanical capacitive accelerometer is provided from a single silicon wafer. The basic structure of the micromechanical accelerometer is etched in the wafer to form a released portion in the substrate, and the released and remaining portions of the substrate are coated with metal under conditions sufficient to form a micromechanical capacitive accelerometer. The substrate is preferably etched using reactive-ion etching for at least the first etch step in the process that forms the basic structure, although in another preferred embodiment, all etching is reactive-ion etching. The accelerometer also may comprise a signal-conditioned accelerometer wherein signal-conditioning circuitry is provided on the same wafer from which the accelerometer is formed, and VLSI electronics may be integrated on the same wafer from which the accelerometer is formed.

Abstract: A single-mask process for fabricating enclosed, micron-scale subsurface cavities in a single crystal silicon substrate includes the steps of patterning the substrate to form vias, etching the cavities through the vias, and sealing the vias. Single cavities of any configuration may be produced, but a preferred embodiment includes closely spaced cavity pairs. The cavities may be separated by a thin membrane, or may be merged to form an enlarged merged cavity having an overhanging bar to which electrical leads may be connected. A three-mask process for fabricating enclosed cavities with electrical contacts and electrical connections is also disclosed.

Abstract: A multistable tunable electromicromechanical resonator structure incorporates electrostatic actuators which permit modification of the resonant frequency of the structure. The actuators consist of sets of opposed electrode fingers, each set having a multiplicity of spaced, parallel fingers. One set is mounted on a movable portion of the resonator structure and one set is mounted on an adjacent fixed base or substrate, with the fingers in opposed relationship and their adjacent ends spaced apart by a gap. An adjustable bias voltage across the sets of electrodes adjusts the resonant frequency of the movable structure and shifts the structure to a bistable state. Application of an alternating drive signal drives the structure to chaotic oscillation.

Abstract: A tunable electromicromechanical resonator structure incorporates an electrostatic actuator which permits reduction or enhancement of the resonant frequency of the structure. The actuator consists of two sets of opposed electrode fingers, each set having a multiplicity of spaced, parallel fingers. One set is mounted on a movable portion of the resonator structure and one set is mounted on an adjacent fixed base on substrate, with the fingers in opposed relationship and their adjacent ends spaced apart by a gap. An adjustable bias voltage across the sets of electrodes adjusts the resonant frequency of the movable structure.

Abstract: A microelectromechanical accelerometer having submicron features is fabricated from a single crystal silicon substrate. The accelerometer includes a movable portion incorporating an axial beam carrying laterally-extending high aspect ratio released fingers cantilevered above the floor of a cavity formed in the substrate during the fabrication process. The movable portion is supported by restoring springs having controllable flexibility to vary the resonant frequency of the structure. A multiple-beam structure provides stiffness in the movable portion for accuracy.

Abstract: A microelectromechanical accelerometer having submicron features is fabricated from a single crystal silicon substrate. The accelerometer includes a movable portion incorporating an axial beam carrying laterally-extending high aspect ratio released fingers cantilevered above the floor of a cavity formed in the substrate during the fabrication process. The movable portion is supported by restoring springs having controllable flexibility to vary the resonant frequency of the structure. A multiple-beam structure provides stiffness in the movable portion for accuracy.