摘要:
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.
摘要:
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.
摘要:
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. The micromechanical capacitive accelerometer can be used for airbag deployment, active suspension control, active steering control, anti-lock braking, and other control systems requiring accelerometers having high sensitivity, extreme accuracy and resistance to out of plane forces.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
A single mask, low temperature reactive ion etching process for fabricating high aspect ratio, released single crystal microelectromechanical structures independently of crystal orientation.
摘要:
A single mask, low temperature reactive ion etching process for fabricating high aspect ratio, released single crystal microelectromechanical structures independently of crystal orientation.
摘要:
Improved fabrication processes for microelectromechanical structures, and unique structures fabricated by the improved processes are disclosed. In its simplest form, the fabrication process is a modification of the know SCREAM process, extended and used in such a way as to produce a combined vertical etch and release RIE process, which may be referred to as a “combination etch”. Fabrication of a single-level micromechanical structure using the process of the present invention includes a novel dry etching process to shape and release suspended single crystal silicon elements, the process combining vertical silicon reactive ion etching (Si-RIE) and release etches to eliminate the need to deposit and pattern silicon dioxide mask layers on the sides of suspended structures and to reduce the mechanical stresses in suspended structures caused by deposited silicon dioxide films.