Eight-beam symmetrical silicon micro-accelerometer

Abstract

The invention provides an eight-beam symmetrical silicon micro-accelerometer. The capacitive micro-accelerometer comprises three portions of an upper silicon electrode plate, a sensitive chip and a lower silicon electrode plate from top to bottom, wherein the sensitive chip is of a micro-structure of 'mass block-cantilever beams'; eight cantilever beams are provided, and symmetrically distributed around a mass block, and the mass block is located at a middle horizontal position; the thickness of the mass block is the same as that of the adopted silicon slice, and the shape is a polygon so as to effectively utilize the space, thus the quality is greatly improved, and a lower device noise and a higher sensitivity can be obtained; the micro-accelerometer adopts an all-silicon process, the silicon electrode plates are bonded with the sensitive chip through silicon-silicon fusion, thus problems of thermal expansion coefficient mismatching and the like can be reduced; the patterns of the mass block and the beams are formed on the surface of the silicon slice through a double-layer SiO2 process, thus deep-groove photoetching is avoided. The eight-beam symmetrical silicon micro-accelerometer provided by the invention is high in stability, low in device noise, and capable of improving the measurement accuracy of the accelerometer.

Description

technical field [0001] The invention belongs to the technical field of micro-electro-mechanical systems, and in particular relates to an eight-beam symmetrical silicon micro-accelerometer, which has high precision, good linearity and good long-term stability. Background technique [0002] With the increasing development of markets such as navigation systems, oil exploration, gravity gradiometers, and seismic monitoring, the demand for micro-accelerometers with high precision and high stability (μg level) is becoming stronger and stronger. Various micro accelerometers for high precision and high stability are constantly being developed. Among them, silicon microcapacitive accelerometers have the advantages of high sensitivity, good noise performance, low drift, low temperature sensitivity, etc., so in the field of accelerometers Research on silicon microcapacitive accelerometers accounts for a considerable part. [0003] The basic working principle of the silicon microcapaci...

AI Technical Summary

Problems solved by technology

In this way, on the one hand, the difficulty of the process is increased to reduce the yield, and on the other hand, it is difficult to obtain a mass block with a large mass, which affects the improvement of the performance of the accelerometer.

For the general "mass block-cantilever beam" structure, the center of gravity of the mass block is not the center of gravity of the entire structure, so the stress at the connection part between the cantilever beam and the fixed end is very concentrated, which greatly affects the long-term stability of the accelerometer

Due to structural asymmetry, mechanical thermal noise, and limited weight of mass blocks, there are some problems in linearity and accuracy of micro accelerometers.

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