TRI-AXIAL MEMS ACCELEROMETER

摘要

A tri-axial MEMS accelerometer includes a top cap silicon wafer and a bottom cap silicon wafer coupled with a measurement mass. The measurement mass has a two level structure, each level having an inner frame coupled to an outer frame by a plurality of first elastic beams, a mass coupled to the inner frame by a plurality of second elastic beams, and a comb coupling structure between the mass and the inner frame. The comb coupling structures are arranged in an orthogonal orientation. The top level and bottom level measurement masses measure acceleration in perpendicular directions. The top level and bottom level measurement masses and the inner frame form an integral unit which moves along a third direction. Acceleration in the third direction is measured from the change in capacitance between the integral unit and the top cap silicon wafer and bottom cap silicon wafer.

主权项

1. A tri-axial MEMS accelerometer, comprising:
a top level measurement structure and a bottom level measurement structure, each measurement structure including:
an outer frame;an inner frame located within the outer frame;a mass coupled with the inner frame; anda comb coupling the mass and the inner frame,wherein, on a projection plane, the orientation of the comb on the top level measurement structure is orthogonal to the orientation of the corresponding comb on the bottom level measurement structure;wherein the inner frame is coupled with the outer frame by a plurality of first elastic beams, and the inner frame is coupled to the mass by a plurality of second elastic beams; a top cap silicon wafer coupled with the top level measurement structure; and a bottom cap silicon wafer coupled with the bottom level measurement structure; wherein, the top level measurement structure and the bottom level measurement structure allow measurement of acceleration in respective perpendicular directions as a change in capacitance between the mass and the inner frame for each level; and wherein the top level measurement mass, the bottom level measurement mass, and the respective inner frames move together along a third direction, wherein the acceleration in the third direction can be determined by measuring the change in capacitance between the top and bottom level measurement masses and respective inner frames as a unit, and the top and bottom cap silicon wafers.