A high-sensitivity three-axis mems accelerometer and its manufacturing process

Abstract

A method for fabricating a tri-axial MEMS accelerometer that has 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.

Description

technical field [0001] The invention relates to the field of sensors, in particular to an accelerometer Background technique [0002] Today, accelerometers are used in many applications, such as measuring the intensity of earthquakes and collecting data, detecting the impact strength of automobile collisions, and detecting the angle and direction of tilt in mobile phones and game consoles. With the continuous advancement of microelectromechanical systems (MEMS) technology, many small accelerometers at the nanometer scale have been widely used commercially. [0003] Commonly used MEMS accelerometers are divided into two types: piezoresistive and capacitive. For example, the piezoresistive accelerometer is a Chinese invention patent application with application number 200480003916.7 and a publication date of March 15, 2006. A piezoresistive accelerometer generally consists of a cantilever beam and a mass block, and a force sensitive resistor is arranged on the cantilever beam...

AI Technical Summary

Problems solved by technology

But only when there is acceleration in the horizontal direction, such as shaking from side to side, the detection accuracy of this accelerometer decreases

[0005] Moreover, the above two technical solutions mainly measure the acceleration in a single plane direction. If you want to measure the acceleration in three directions, you need to install three accelerometers, which not only increases the cost, but also requires higher installation accuracy.

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