The Research On SOI Pressure Sensitive Chip Based On Sacrificial Layer Technology

Pressure sensor is one of the important devices in the field of micro electromechanical systems.By analyzing and contrasting the development status of MEMS pressure sensors in home and abroad,the SOI pressure sensitive chip based on sacrificial layer technology is designed,and the device structure and parameters has also been optimized for the automotive electronics field.First of all,the SOI technology is used in this paper to complete the design of pressure sensor which is real suitable for making the high temperature pressure sensors.Secondly,based on the finite element simulation results of pressure sensitive structure,it is found that with the change of diaphragm size,the overload capacity will be changed significantly.The promoting scope of overload capacity is related to the range of sensor where the increasin g scope of overload capacity is greater with the smaller sensor range.Combining with the relationship between size parameters and overload capacity of the sensitive structure,the overload capacity can be improved by adjusting sensitive structure size under the premise that the sensitivity of the sensor remains unchanging.Then,in order to obtain the relatively small size of chip meanwhile get the average stress of resistance as large as possible,the silicon strain resistance is designed where the silico n has high sensitivity,repeatability and stability.By calculating,it can be determined that by using bending resistors,each 1/2 resistance of the length and width are 8?m.The sensor range in this paper is 0.5MPa.The length of the elastic membrane was determined according to the relationship between the film size and the overload capacity,and the size of resistor.The length of the elastic membrane was 200?m and the width was 100?m.The layout of the varistor was determined by the means of linear static analysis.The method of determining the thickness of the film was obtained by geometric nonlinearity and contact nonlinearity analysis,and the film thickness was designed to be 4?m.Then the cavity height was designed to be 0.3?m,and when a constant current source of 1 mA was used for power supplying,the sensitivity of the pressure sensitive chip is 178.74 mV / MPa,the full scale output is 89.37 mV,and the overload capacity is 12.21 MPa.In this paper,the SOI pressure sensitive chip based on the sacrificial layer technology is designed and optimized.The design of the structure size and the resistance layout make the parameters of the sensor reach the expected design index.In addition,based on the sacrificial layer technology and SOI technology,the process of pressure sensitive chip is given,and the key technology in the process is analyzed and summarized.Finally,the layout of the sensor is given,which can provide the design proposal for the production of the sensor design.