Silicon accelerometer responsive to three orthogonal force components and method for fabricating

Claim 1

An accelerometer responsive to three orthogonal components of an applied force, comprising: a supporting frame etched from a silicon substrate having top and bottom surfaces lying in a set of <100> crystalline planes; a first abutment etched from said substrate and having adjacent sidewalls lying substantially in a set of <111> crystalline planes; a second abutment etched from said substrate and having adjacent sidewalls lying substantially in a set of <111> crystalline planes; a first rectangular beam etched from said substrate and longitudinally extending from said first abutment for detecting the first orthogonal component of the applied force, said first rectangular beam having vertical sidewalls lying in a first crystalline plane of said <100> crystalline planes, said vertical sidewalls forming approximately a (b 135 degree angle with said first abutment; a second rectangular beam etched from said substrate and longitudinally extending from said second abutment for detecting the second orthogonal component of the applied force, said second rectangular beam having vertical sidewalls lying in a second crystalline plane of said <100> crystalline planes orthogonal to said first crystalline plane, said vertical sidewalls forming approximately a 135 degree angle with said second abutment; and a third rectangular beam etched from said substrate and longitudinally extending from said frame for detecting the third orthogonal component of the applied force, said third rectangular beam having horizontal sidewalls lying in a third crystalline plane of said <100> crystalline planes orthogonal to both said first and said second crystalline planes.