Performance Optimization And Structure Design Of Piezoresistive Pressure Sensor

Pressure sensor is used to measure the ambient pressure,external pressure value can be converted to electrical signal output by sensor,now the sensors can be used in field of biomedical?aerospace control and industrial detection and so on.Pressure sensors can be divided into two major categories of piezoresistive and capacitive sensor,piezoresistive pressure sensor uses resistance to transform pressure values into electrical signals,capacitive pressure sensor uses capacitance changes,each has own advantages and disadvantages,as a result of the technology of the piezoresistive pressure sensor is simple and convenient,it has been widely used in many fields at present.The technology of traditional piezoresistive pressure sensor uses top-down method,firstly,use ion implantation on monocrystalline silicon to form piezoresistances and then generates film can be moved up and down by using anisotropic etching from the bottom of the silicon substrate,finally the silicon substrate and the glass substrate bond to form seal cavity.Based on the Deep Reactive Ion Etching(DRIE)method to form cavity,reduces the size of the pressure sensor,avoids waste of the horizontal space of sensor and this method can control thickness and size of film precisely,makes the flatness of thin movable membrane of the pressure sensor be better than that of the wet etching,shorts production cycle of sensor.In this paper,we gave the test of the piezoresistive pressure sensor,results showed that the sensitivity of pressure sensor was 0.031mv/Kpa·v and nonlinearity was 0.17%,the size of the pressure sensor was reduced,we reached the expected goal of sensors.The main work is as follows:First of all,the theory modeling of piezoresistive pressure sensor is given,the relationship between stress and the stress distribution and deflection change under the condition of the external pressure load is analyzed,the performance parameters of the sensor is optimized.Secondly,the performance of the piezoresistive pressure sensor is simulated through ANSYS finite element simulation software,including membrane stress distribution and deflection change of.pressure sensor under external pressure load by around fixed boundary conditions,and we simulate the change of the output voltage signal under the loaded pressure.Thirdly,based on technological parameters of instrument and equipment in SINANO,CAS(Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences),the process flow of the pressure sensor is designed,and the device has been fabricated.Fourthly,the sensors are packaged and measured.Testing results show that sensitivity is 0.031 mv/Kpa·v and nonlinearity is 0.17%,which can reach the goals of traditional pressure sensor performance parameter.