MEMS device and preparation method thereof

Abstract

The invention provides an MEMS device and a preparation method thereof. The MEMS device is characterized in that a first insulating layer is formed on the front surface of a substrate; a vibrating diaphragm and a polar plate are formed on the first insulating layer; a back cavity is formed on the back surface of the substrate; the back cavity exposes the vibrating diaphragm and is back to the gap,and a part of the first insulating layer is reserved as a supporting part of the vibrating diaphragm; the vibrating diaphragm is symmetrical relative to the projection center of the supporting part on the vibrating diaphragm, and remains the substrate, having an area opposite to the supporting part, in the back cavity as a supporting substrate of the supporting part; and when the vibrating diaphragm vibrates, the vibrating diaphragm vibrates at the middle position between the edge and the center of the vibrating diaphragm, so that the effective vibrating area is increased, and the sensitivityand the signal-to-noise ratio of the MEMS device are improved, and the vibration amplitude is reduced, and the fluctuation range of the sensitivity and the signal-to-noise ratio is reduced; and meanwhile, the force applied to the vibrating diaphragm in a mechanical reliability test is reduced, so that the reliability of the MEMS device is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a MEMS device and a preparation method thereof. Background technique [0002] MEMS (Micro-Electro-Mechanical System, Micro-Electro-Mechanical System) technology refers to a micro-system that can integrate mechanical components, drive components, optical systems, and electronic control systems into a whole. It uses microelectronics technology and micromachining technology ( Such as silicon body micromachining, silicon surface micromachining, wafer bonding, etc.) combined manufacturing process, to produce a variety of excellent performance, low price, miniaturized sensors (such as inertial sensors, pressure sensors, acceleration sensors, etc.), execution drives, drives and microsystems. [0003] Existing MEMS devices generally include a base, the base has a front and a back, and the base has a back cavity that runs through the front and the back, a vibrating membrane is for...

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Problems solved by technology

[0004] However, since the vibrating membrane is equivalent to a thin film in motion, a relatively large amplitude will be generated in a relatively small effective vibration area, and the large vibration amplitude will cause the sensitivity of the device and the fluctuation range of the signal-to-noise ratio to increase, and in some Mechanical reliability tests will exert relatively large force on the vibrating membrane, such as air pressure test or mechanical impact test, which may easily cause loss or damage of the vibrating membrane

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