一个新型的大检测电容结构的MEMS惯性传感器研究

A novel MEMS inertial sensor with enhanced sensing capacitors is developed. The designed fabricated process of the sensor is a deep RIE process, which can increase the mass of the seismic to reduce the mechanical noise, and the designed capacitance sensing method is changing the capacitance area, which can reduce the air damping between the sensing capacitor plates and reduce the requirement for the DRIE process precision, and reduce the electronic noise by increasing the sensing voltage to improve the resolution. The design and simulation are also verified by using the FEM tool ANSYS. The simulated results show that the transverse sensitivity of the sensor is approximately equal to zero. Finally, the fabricated process based on silicon-glass bonding and the preliminary test results of the device for testing grid capacitors and the novel inertial sensor are presented. The testing quality factor of the testing device based on the slide-film damping effect is 514, which shows that the enhanced capacitors can reduce mechanical noise. The preliminary testing result of the sensitivity is 0.492pf/g.     

低真空封装的新型变电容面积MEMS惯性传感器阶跃响应特性分析

一种新型变电容面积MEMS惯性传感器与传统的梳齿电容传感器相比,具有对梳齿电容不平行敏感度低,可加测试电压高等优点.通过对该传感器在低真空封装条件下的惯性阶跃响应特性分析,着重研究了不同梳齿电容倾斜角度对该传感器的阶跃惯性信号响应的影响,以及不同倾斜角度梳齿的位移响应和测试电压、空气真空度的关系,并把该结果和梳齿结构的情况进行比较.结果表明,工艺因素对变电容面积MEMS惯性传感器在低真空封装下的阶跃惯性响应影响很小;另外,该结构上可加的测试电压可以是梳齿电容结构上可加测试电压的近10倍,这有利于减小接口电路的噪声.以上分析论证了该新型传感器有利于降低器件的工艺要求和提高传感器的分辨率.     

一种新型的带栅形条电容和可变间距电容的惯性信号检测结构

The comb capacitances fabricated by deep reactive ion etching （RIE） process have high aspect ratio which is usually smaller than 30 ： 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate＇s effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio （30 ： 1） of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy （FEM） tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.     

低真空封装的新型变电容面积MEMS惯性传感器阶跃响应特性分析

一种新型变电容面积MEMS惯性传感器与传统的梳齿电容传感器相比,具有对梳齿电容不平行敏感度低,可加测试电压高等优点。通过对该传感器在低真空封装条件下的惯性阶跃响应特性分析,着重研究了不同梳齿电容倾斜角度对该传感器的阶跃惯性信号响应的影响,以及不同倾斜角度梳齿的位移响应和测试电压、空气真空度的关系,并把该结果和梳齿结构的情况进行比较。结果表明,工艺因素对变电容面积MEMS惯性传感器在低真空封装下的阶跃惯性响应影响很小;另外,该结构上可加的测试电压可以是梳齿电容结构上可加测试电压的近10倍,这有利于减小接口电路的噪声。以上分析论证了该新型传感器有利于降低器件的工艺要求和提高传感器的分辨率。