Micromechanical accelerometer having a peripherally suspended proof mass
First Claim
1. An accelerometer for detecting acceleration along at least one acceleration sensitive axis comprising:
- a substrate having a first surface;
at least two electrodes disposed on said substrate first surface;
at least one central anchor disposed on said substrate first surface;
at least two flexible elements extending from said at least one central anchor, above and substantially parallel to said substrate first surface;
at least two support member anchors disposed on said substrate first surface;
at least two support members each extending from a respective support member anchor, above and substantially parallel to said substrate first surface, and orthogonal to said at least one acceleration sensitive axis; and
a peripherally suspended proof mass disposed about said at least one central anchor, said proof mass suspended above and substantially parallel to said substrate first surface by said at least two flexible elements and said at least two support members and having an inner surface and an outer surface,wherein each of said at least two flexible elements is generally collinear with said at least one acceleration sensitive axis and disposed proximate a respective one of said at least two electrodes formed on said substrate first surface.
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Accused Products
Abstract
A monolithic, micromechanical vibrating beam accelerometer with a trimmable resonant frequency is fabricated from a silicon substrate which has been selectively etched to provide a resonant structure suspended over an etched pit. The resonant structure comprises an acceleration sensitive mass and at least two flexible elements having resonant frequencies. Each of the flexible elements is disposed generally collinear with at least one acceleration sensitive axis of the accelerometer. One end of at least one of the flexible elements is attached to a tension relief beam for providing stress relief of tensile forces created during the fabrication process. Mass support beams having a high aspect ratio support the mass over the etched pit while allowing the mass to move freely in the direction collinear with the flexible elements. Also disclosed is a method for fabricating such an accelerometer. Further disclosed is an alternative embodiment of the aforementioned accelerometer characterized by a low profile, and alternative planar processing methods for fabrication of these and other embodiments.
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Citations
22 Claims
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1. An accelerometer for detecting acceleration along at least one acceleration sensitive axis comprising:
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a substrate having a first surface; at least two electrodes disposed on said substrate first surface; at least one central anchor disposed on said substrate first surface; at least two flexible elements extending from said at least one central anchor, above and substantially parallel to said substrate first surface; at least two support member anchors disposed on said substrate first surface; at least two support members each extending from a respective support member anchor, above and substantially parallel to said substrate first surface, and orthogonal to said at least one acceleration sensitive axis; and a peripherally suspended proof mass disposed about said at least one central anchor, said proof mass suspended above and substantially parallel to said substrate first surface by said at least two flexible elements and said at least two support members and having an inner surface and an outer surface, wherein each of said at least two flexible elements is generally collinear with said at least one acceleration sensitive axis and disposed proximate a respective one of said at least two electrodes formed on said substrate first surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification