Abstract:
A pendulous accelerometer wherein the active reaction mass is pendulously mounted external to a fixed support structure and may include sensor cover or covers in the total active reaction mass.
Abstract:
A sensor having high sensitivity is formed using a suspended structure with a high-density tungsten core. To manufacture it, a sacrificial layer of silicon oxide, a polycrystal silicon layer, a tungsten layer and a silicon carbide layer are deposited in succession over a single crystal silicon body. The suspended structure is defined by selectively removing the silicon carbide, tungsten and polycrystal silicon layers. Then spacers of silicon carbide are formed which cover the uncovered ends of the tungsten layer, and the sacrificial layer is then removed.
Abstract:
A micromachining method is disclosed for forming a suspended micromechanical structure from {111} crystalline silicon. The micromachining method is based on the use of anisotropic dry etching to define lateral features of the structure which are etched down into a {111}-silicon substrate to a first etch depth, thereby forming sidewalls of the structure. The sidewalls are then coated with a protection layer, and the substrate is dry etched to a second etch depth to define a spacing of the structure from the substrate. A selective anisotropic wet etchant (e.g. KOH, EDP, TMAH, NaOH or CsOH) is used to laterally undercut the structure between the first and second etch depths, thereby forming a substantially planar lower surface of the structure along a {111} crystal plane that is parallel to an upper surface of the structure. The lateral extent of undercutting by the wet etchant is controlled and effectively terminated by either timing the etching, by the location of angled {111}-silicon planes or by the locations of preformed etch-stops. This present method allows the formation of suspended micromechanical structures having large vertical dimensions and large masses while allowing for detailed lateral features which can be provided by dry etch definition. Additionally, the method of the present invention is compatible with the formation of electronic circuitry on the substrate.
Abstract:
A semiconductor device with a force and/or acceleration sensor (12), which has a spring-mass system (14, 16) responsive to the respective quantity to be measured and whose mass (16) bears via at least one resilient support element (14) on a semiconductor substrate (20). The semiconductor substrate (20) and the spring-mass system (14, 16) are integral components of a monocrystalline semiconductor crystal (10) with a IC-compatible structure. The three-dimensional structural form of the spring-mass system (12) is produced by anisotropic semiconductor etching, defined P/N junctions of the semiconductor layer arrangement functioning as etch stop means in order to more particularly create a gap (22) permitting respective movement of the mass (16) between the mass (16) and the semiconductor substrate (20).
Abstract:
A surface layer and a sacrificial layer are deposited on a substrate. A conductive structural layer bridges over the sacrificial layer and is anchored to the surface layer for creating paired conductive areas. A backside opening is etched in the substrate for defining a flexible diaphragm layer of reduced thickness. The sacrificial layer is removed so that pressures exerted on the backside opening will cause a change in capacitance between the paired conductive areas. Temporary posts support the conductive structural layer as the sacrificial layer is removed.
Abstract:
A new bulk resonator may be fabricated by a process that is readily incorporated in the traditional fabrication techniques used in the fabrication of monolithic integrated circuits on a wafer. The resonator is decoupled from the wafer by a cavity etched under the resonator using selective etching through front openings (vias) in a resonator membrane. In a typical structure the resonator is formed over a silicon wafer by first forming a first electrode, coating a piezoelectric layer over both the electrode and the wafer surface and forming a second electrode opposite the first on the surface of the piezoelectric layer. After this structure is complete, a number of vias are etched in the piezoelectric layer exposing the surface under the piezoelectric layer to a selective etching process that selectively attacks the surface below the piezoelectric layer creating a cavity under the resonator.
Abstract:
PROBLEM TO BE SOLVED: To provide an apparatus and etching method allowing increase of mask selection ratio, improving anisotropy and enabling a deeper etching.SOLUTION: The etching apparatus is provided with: a floating electrode that is disposed opposite to a substrate electrode 6 provided in a vacuum chamber 1 and is kept in an electro-potentially floating state; a material 13, which is used for forming an etching protection film, disposed on a side of the floating electrode, the side facing the substrate electrode; and control means 14 for intermittently applying high-frequency power to the floating electrode. In the etching method, a spatter film is formed on a substrate by applying high-frequency power to the floating electrode using only a rare gas for the main gas and a material for forming an etching protection film as target member, the material disposed on a side of a floating electrode disposed opposite to a substrate electrode, the side facing the substrate electrode. Subsequently, a substrate is etched by stopping the application of the high-frequency power to the floating electrode and introducing an etching gas to a vacuum chamber. Then, the formation of the spatter film on the substrate and the etching the film are repeated in accordance with a scheduled sequence.