Instrument for measuring accelerations and process of making the same
First Claim
1. An instrument for measuring accelerations, comprising a reset element, a mechano-electric converter, and three micromechanical sensors, each consisting of an inert mass and sensitive to a motion in one direction to define multiple directions of sensitivity, integrated in a crystal surface layer, wherein the multiple directions of sensitivity of the sensors point in different directions and do not lie in one plane.
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Accused Products
Abstract
Disclosed is an instrument for measuring accelerations, with the aid of which changes in motion in the three axes of space can be measured with selective sensitivity.
In order to detect multi-dimensional changes in motion, three micromechanical sensors, each sensitive to the acceleration in a selected direction, are integrated in a crystal. The sensors are composed of torsion bars having masses eccentrically attached thereto, which, in the event of changes in motion, exercise torques about the axes of the torsion bars. The torques are measured with the aid of integrated piezo-resistances. The planar integration of the acceleration meter permits integrating the evaluation circuit on the same semiconductor surface.
Acceleration meters of this kind are fabricated with the prescribed process in planar technology with the aid of epitaxy, lithography and anisotropic etching methods.
High precision and high miniaturization make this acceleration meter suited for application in overland and aviation navigation and for component positioning in robotry.
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Citations
12 Claims
- 1. An instrument for measuring accelerations, comprising a reset element, a mechano-electric converter, and three micromechanical sensors, each consisting of an inert mass and sensitive to a motion in one direction to define multiple directions of sensitivity, integrated in a crystal surface layer, wherein the multiple directions of sensitivity of the sensors point in different directions and do not lie in one plane.
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9. A process for making an instrument for measuring accelerations having a reset element, a mechano-electric converter and three micromechanical sensors, each consisting of an inert mass and sensitive to a motion in one direction to define multiple directions of sensitivity, integrated in a crystal surface layer, wherein the multiple directions of sensitivity of the sensors point in different directions and do not lie in one plane, comprising the process steps of:
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precipitating a semiconducting epitaxy layer having impurities of one kind onto a silicon wafer doped with impurities of a second kind to form a pn-transition, precipitating a passivation layer of silicon nitride on the silicon wafer, integrating piezo-resistances on a side of the wafer, photolithographic structuring on the front and rear sides of the wafer, etching the passivation layer, metallizing said front side of said wafer, Anisotropic electro-chemical etching of said rear side of said wafer in a KOH-H2 O etching solution, with the etching process stopping automatically at the pn-transition, passivating said rear side of said wafer, removing said metallizing layer from said front side, anisotropic etching said epitaxy layer on said front side of said wafer, and removing said passivation layer on said rear side. - View Dependent Claims (10, 11, 12)
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Specification