Design Of High Overload And Small Range Acceleration Sensitive Structure

In the late 1950 s,Richard Feynman proposed the concept of MEMS technology.In the early 1960 s,the first miniature pressure sensor was made.In the 1980 s,Roylance and others at Stanford University developed the first silicon piezoresistive type.Accelerometer.After decades of development,MEMS acceleration sensors now have more mature process technology support.Different types of acceleration sensors can meet the needs of many practical applications in military,medical,aviation,detection,transportation,electronic equipment Other applications have an irreplaceable status and have broad development prospects.In order to comply with the development trend of the future information age,MEMS acceleration sensors are developing in the direction of miniaturization,digitalization,high precision and high reliability.According to the application requirements of acceleration sensors in the field of geological exploration,this topic designs an acceleration-sensitive chip for detecting deep geological conditions.In this application field,acceleration sensors are used to detect the vibration of different positions after underground blasting.At present,capacitive acceleration sensors are basically used.The advantages are high sensitivity,but there are problems of poor linearity,complicated technology and low overload capacity..Aiming at the shortcomings of capacitive acceleration sensors,this paper chooses a piezoresistive acceleration sensitive structure.In order to compensate for the low accuracy of small signal measurement by piezoresistive acceleration sensors,a high overload and small range piezoresistive acceleration sensitivity based on MEMS technology is designed and optimized.chip.The chip is based on the acceleration-sensitive basic structure of the cantilever beam and the mass.The uniaxial piezoresistive acceleration-sensitive structure with microbeams and supporting beams is designed and optimized.At the same time,the process technology that can accurately produce sensitive structures is used to improve the piezoresistive type.The problem of low accuracy of signal processing commonly found in acceleration sensors not only solves the contradiction between sensitivity and natural frequency,but also improves the shock resistance of the sensitive chip,and achieves high-precision and high-resolution measurement of acceleration.It has the advantages of high overload capacity and low cost.The sensitive structure designed in this paper is a double-sided support beam and double-sided microbeam structure.The overall structure uses single crystal silicon as the main material.On the microbeams on both sides,the strain resistance formed by doping constitutes a Wheatstone bridge,which converts the change in stress into an electrical signal to achieve a sensitive function.The sensitive chip with a measuring range of 100 mg was optimized and a mask for chip manufacturing was given.The SOI substrate is used as the substrate,and the design of the sensitive chip processing and manufacturing scheme is completed through the main processes such as bonding,etching,doping,and LPCVD.Finally,through simulation analysis,the main performance parameters of the designed sensitive chip are given.The natural frequency is 659.07 Hz,the full-scale output is 109.21 mV,the sensitivity is 1.0921mV/mg,the overload capacity is 16.8g,and the lateral coupling is less than 3.2%.Design requirements.