Acceleration and vibration sensor and method of making the same

US5151763A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Jiri Marek · Reutlingen, DE
• Frank Bantien · Ditzingen, DE
• Dietmar Haack · Springe, DE
• Martin Warth · Winnenden, DE

Key dates

• Filing date: Dec 21, 1990
• Grant date: Sep 29, 1992
• Expiry date: Dec 21, 2010

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04R19/005
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A semiconductor plate having an epitaxial layer of a conductivity type opposite to that of the substrate on which it is formed has a depression, including one or more elongate channels. The depression is etched into a depth passing entirely through the epitaxial layer to isolate at least one tongue extending from a tongue pedestal into the etched depression and having parallel major sides which are perpendicular to the principal planes of the semiconductor plate. The tongue is under-etched so that it will be free to vibrate by motion in directions parallel to the principal planes of the plate. One of the major sides of the tongue faces a stationary electrode across a gap and the electrode and the tongue are insulated from each other, at least in one embodiment, by the fact that the etched depression extends all the way through the epitaxial layer in its depth. Deflection or vibration of the tongue changes the capacitance between the electrode and the tongue and contacts are provided for measuring the capacitance. Various embodiments utilizing multiple tongues and one or more electrodes are shown.