摘要
提出了一种新型的采用标准CMOS工艺结合MEMS后处理工艺加工的电容式绝对压力传感器.传感器结构部分是由导体/介质层/导体组成的可变电容器.电容的上下极板分别为CMOS工艺中的多晶硅栅和n阱硅,中间介质层为栅氧化层.在CMOS工艺加工完之后,利用选择性的体硅腐蚀、pn结自停止腐蚀以及阳极键合等MEMS后处理工艺来得到传感器结构.与传统的电容式压力传感器相比,这种结构具有更大的初始固有电容,这样可以抑制寄生电容的影响,从而简化检测电路的设计.文中,应用多层膜理论模型分析了传感器的结构,并利用ANSYS有限元分析对模型进行了验证,并利用电容变化模型分析了传感器的灵敏度.对于边长为800μm的敏感方膜,初始电容值为1104pF,传感器灵敏度为46fF/hPa.同时,本文给出了传感器的电容检测电路的设计.
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 SiO2. 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.
出处
《传感技术学报》
CAS
CSCD
北大核心
2006年第05B期1863-1867,1870,共6页
Chinese Journal of Sensors and Actuators
基金
国家自然科学基金重点项目资助课题(90607002)
