Symmetrical straight beam structure condenser type micro-acceleration sensor and manufacturing method thereof

Abstract

The present invention relates to a capacitance type micro-acceleration sensor with a symmetrical and straight-girder structure and a manufacturing method thereof. The characteristics reside in that said acceleration sensor consists of a centrosymmetric quality block, an external supporting frame, eight direct elastic girders which are up-down symmetrical for connecting the quality block and the external supporting frame, an upper cover board and a lower cover board. On end of each direct elastic girder is connected to the top or the lateral of the bottom of the quality block that is parallel with the elastic girder, while the other end is connected to inner surface of the external supporting frame vertical to the elastic girder. The capacitance type micro-acceleration sensor with a symmetrical and straight-girder structure can improve the sensitivity at the same time of reducing the transversal effect remarkably. The capacitance type micro-acceleration sensor with a symmetrical and straight-girder structure is made by using the technology of a micro-electronics mechanism system and is a micro-mechanism acceleration sensor with a high performance.

Description

technical field [0001] The invention relates to a capacitive micro-acceleration sensor with a symmetrical straight beam structure and a manufacturing method thereof, belonging to the field of micro-electromechanical systems. Background technique [0002] Acceleration sensors manufactured using micromechanical technology have the advantages of small size, light weight, low cost, high reliability, mass production, and easy integration with electronic circuits, and can be widely used in many fields such as aviation, aerospace, automobiles, robots, and oil exploration. , has a huge market application prospect. At present, the micromachined acceleration sensor has become the mainstream development direction. According to the sensitive principle, micro-mechanical acceleration sensors can be divided into capacitive, piezoresistive, piezoelectric, electromagnetic, thermal convection and resonant. Compared with the piezoresistive or piezoelectric type, the capacitive acceleration s...

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Problems solved by technology

But usually the elastic beam of this structure is not in the same plane as the center of the sensitive mass block, which will cause a large lateral sensitivity, that is, the acceleration signal in the non-sensitive direction will also cause a large output, such as Kampen R.P.V., Wolffenbuttel R.F., Modeling the mechanical behavior of bulk-micromachined silicon ccelerometers, Sensors and Actuators, A64, 1998, 137-150. In order to reduce the lateral effect, the two silicon wafers were etched on one side of the quality block pattern and then silicon-silicon bonded. Erosion forms an intermediate mass with elastic beams on both sides, such as Henrion W.S., et.al, Sensors structure with L-shaped spring legs, US Patent No. 5,652,384, because its elastic beam is an L-shaped beam, the first order mode is Detection mode, the frequency of the second and third modes is about 3-4 times of the frequency of the first mode, which cannot significantly reduce the cross-axis sensitivity of the device

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