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《Chinese Journal of Sensors and Actuators》 2006-05
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Design of A Novel CMOS Capacitive Absolute Pressure Sensor

LIU Na,HUANG Qing-an,QIN Ming (Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China)  
A novel capacitive pressure sensor based on the post CMOS MEMS process is presented. The sensing part is a variable capacitor with a conductor/dielectric/conductor structure. The top and bottom layers are poly-gate and n-well Si in the CMOS process, respectively, while the center layer is the gate SiO_2. After CMOS process, selectively etching bulk silicon, PN junction self etch-stop, and anodic bonding to the glass are used to get the microstructure. Compared with the traditional capacitive pressure sensor, this structure has intrinsic larger initial capacitance value which benefits the following interface circuits and high sensitivity. A mechanical thermal model for the multi-layers was used to analyse the sensor structure, which was also simulated by ANSYS. After that, the capacitance change model was used to evaluate the sensitivity of the device. For the 800 μm×800 μm square membrane, the sensitivity is obtained to be 46 fF/hPa and the initial capacitance is 1 104 pF. Then the capacitive interface circuit was also designed to detect the change of the sensor capacitance.
【Fund】: 国家自然科学基金重点项目资助课题(90607002)
【CateGory Index】: TP212.1
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