MEMS pressure sensor and manufacturing method thereof

Abstract

The invention discloses an MEMS pressure sensor and a manufacturing method thereof. The MEMS pressure sensor comprises an MEMS pressure sensing chip, wherein the MEMS pressure sensing chip is arranged at a Wheatstone bridge formed on the crystallographic orientation of a monocrystalline silicon film (110) by four polycrystalline silicon resistors, the monocrystalline silicon film comprises a lower silicon wafer, an upper silicon wafer and a purification layer, a cavity body is arranged on the lower silicon wafer, the lower silicon wafer and the upper silicon wafer are bonded together by hot melt silicon-silicon, the surface of the upper silicon wafer is provided with a passivation layer, the polycrystalline silicon resistors are arranged on the upper silicon wafer by a diffusion process, and a conducting wire of a metal film and a press welding block are etched on the upper silicon wafer. The pressure sensor adopting a silicon-silicon bonding structure can be made in a very small size, the number of chips on each silicon wafer can be increased by 50% or more, the silicon-silicon bonding strength is higher, and the air tightness is better. The cost of the sensor is greatly lowered, and the performance is more stable and reliable. The sensor belongs to a pressure sensor with low cost and high performance and has very extensive application.

Description

technical field [0001] The invention relates to a sensor, in particular to a pressure sensor using micro-electromechanical system (MEMS) technology, and also to a manufacturing method of the sensor chip. Background technique [0002] Pressure sensors are used in a wide range of applications, including petrochemical, hydraulic, food, medicine, machinery, metallurgy, mining, electrical appliances, and medical instruments, etc., in almost every industry. [0003] The engines of various diesel locomotives and the steam turbines of electric power units are lubricated by engine oil. Once the oil pressure is too low, dry friction will occur due to lack of oil, resulting in severe wear and heating, which may damage the engine or steam turbine and affect the diesel locomotive or The normal operation of the steam turbine, so the oil pressure is one of the important parameters of the engine or steam turbine. For cars, it is necessary to install an oil pressure gauge on the engine of t...

AI Technical Summary

Problems solved by technology

There are many kinds of pressure sensors currently used in automobiles, generally including a signal conditioning circuit board, a pressure sensitive diaphragm is set on the signal conditioning circuit board, the diaphragm directly bears the pressure of the engine oil, and then transmits the pressure signal of the engine oil to the signal The conditioning circuit board is processed by the signal conditioning circuit board into an electrical signal output, but the pressure sensitive diaphragm of the above structure is generally a thick film pressure sensitive diaphragm processed by machining, which is often large in size and weight, high in cost and low in accuracy. , they are very limited in application in power units and automobiles

Images