Piezoresistive acceleration sensor with full-bridge micro-beam structure

Abstract

The invention discloses a piezoresistive acceleration sensor with a full-bridge micro-beam structure. The piezoresistive acceleration sensor with the full-bridge micro-beam structure comprises a framework, a cantilever beam, micro-beams and a mass block, wherein the cantilever beam is arranged on the axis of symmetry of the mass block; and four micro-beams are symmetrically distributed on the edge of the mass block by taking an axis on which the cantilever beam is positioned as the axis. The structure is provided with the four micro-beams, piezoresistive sensitive resistors are arranged on the four micro-beams, and the four piezoresistive sensitive resistors form a Wheatstone full-bridge circuit; on one hand, the stress of the cantilever beam is amplified to improve the sensitivity; on the other hand, the four piezoresistive sensitive resistors are all arranged in a chip, influence on the circuit due to resistance value drifting caused by the measurement environment temperature variation can be mutually offset in the full-bridge circuit, and therefore, the temperature stability is improved; and restriction on the mass block vibration is increased by the four micro-beams to improve the first-order resonant frequency.

Description

technical field [0001] The invention relates to the technical field of acceleration sensors, in particular to a piezoresistive acceleration sensor with a full-bridge micro-beam structure. Background technique [0002] Silicon has excellent mechanical properties and electrical properties, and has ready-made technology in microelectronic processing technology, so it is widely used in various MEMS devices. Acceleration measurement sensors with high sensitivity and wide frequency response have important applications in both military and civilian fields. Traditional MEMS acceleration sensors generally use silicon cantilever beams and piezoresistive sensitive elements on the beams as the core components. In this structure, only a small part of the potential energy stored in the cantilever beam due to bending is transmitted to the piezoresistive sensitive elements, resulting in low sensitivity. By changing The parameters of the beam and mass block can improve the sensitivity to ...

AI Technical Summary

Problems solved by technology

Traditional MEMS acceleration sensors generally use silicon cantilever beams and piezoresistive sensitive elements on the beams as the core components. In this structure, only a small part of the potential energy stored in the cantilever beam due to bending is transmitted to the piezoresistive sensitive elements, resulting in low sensitivity. By changing The parameters of the beam and the mass block can improve the sensitivity to a certain extent, but at the same time, the increase in sensitivity usually leads to a decrease in the resonance frequency, which cannot meet the requirements of high precision, small mechanical measurement, and wide frequency response at the same time

[0003] For example, the Chinese invention patent "Monolithic Integrated CZC Microbeam Structure Piezoresistive Acceleration Sensor and Manufacturing Method" (application number: 02151296.5) precisely designs the positions of two microbeams to make it a CZC microbeam, It requires high manufacturing precision; and only two piezoresistors constitute the Wheatstone half-bridge, and the other two resistances of the Wheatstone bridge are provided by an external circuit. Only two piezoresistors are more sensitive to the temperature of the measurement environment, and their resistance The value drifts significantly with temperature, and the formed Wheatstone bridge is easily affected by temperature and unbalanced, thus affecting the measurement results

The U.S. invention patent "Single-mask Fabrication Process For Linear and Angular Piezoresistive Accelerometers" ("Single-mask Fabrication Process for Linear and Angular Piezoresistive Accelerometers" patent number: US 7939355 B2) also has the above-mentioned defects, and piezoresistors only constitute Whiston half bridge, lack of temperature compensation mechanism, poor sensitivity

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