Research And Design Of SiC Pressure Sensor

Due to its excellent electrical properties,mechanical properties,and chemical inertness,SiC is an excellent choice for making pressure sensors.Based on the pressure sensor development project undertaken by the National Sensor Center of Sensors,the structure design,process design,production,and testing of SiC piezoresistive pressure sensor chips are carried out.Firstly,the SiC pressure sensors current research status with the different structures are in detail investigated.After the structure and the preparation process of 3C-SiC,4H-SiC,and6H-SiC pressure sensors are analyzed,3C-SiC material is adopted for a piezoresistive pressure sensor,is evaluated on account of the MEMS process capability of the National Sensor Engineering Center.By analyzing the characteristics of SiC material and the working principle of the sensor,two types of piezoresistive pressure sensor chips are designed.3C-SiC strain resistors are fabricated on Si substrate and SOI substrate.The 3C-SiC piezoresistive pressure sensor is simulated with ANSYS finite element method.According to the actual process,the chip size,diaphragm thickness,and the location of the stain resistance are determined.Based on the process conditions,the process flow of the 3C-SiC piezoresistive pressure sensor is in detailed designed,and the layout is completed by using L-Edit software.The epitaxy 3C-SiC silicon carbide material on silicon substrate/SOI substrate carbon is applied,and the resistance figure is etched with the ICP process.The multi-layer metal electrode is made by the sputtering process,and the silicon cup is etched with KOH etching solution.The packaging process and the aging process are carried out.Finally,a preliminary test is carried out on the 3C-SiC piezoresistive pressure sensor with a measuring range of 1 MPa powered by a 1 m A constant current source.The sensitivity was 35.13 m V/MPa,the non-linearity was 2.94%FS,and the hysteresis was 5.84%FS.The research work provided a reference for the later development of the SiC piezoresistive pressure sensor.