电容式微加速度计的刻度温漂的半解析模型

针对电容式微加速度计的刻度温漂,根据微加速度计的检测原理及热变形的分析结果,建立了刻度温漂的半解析模型,并在此基础上分析了刻度温漂的主要影响因素.分析结果表明,刻度温漂由两部分组成,第一部分主要由单晶硅的弹性模量的温度系数决定,可以通过高掺杂降低;第二部分由微加速度计的热变形引起,它的大小与封装胶的弹性模量、梳齿的宽度、大电容间隙与小电容间隙的比值以及固定梳齿锚点的位置相关;第一部分和第二部分分别是正数和负数,因此相互补偿.基于MEMS体硅微加工工艺,制造了微加速度计的实验样品,刻度温漂的测量结果验证了理论分析结果的正确性.

Semi-analytical Model for Scale Factor Thermal Drift of Capacitive Microaccelerometers

For the scale factor thermal drift(SFTD)of capacitive microaccelerometers,its semi-analytical model is established based on the detection principle and thermal deformation results of microaccelerometers. Then ,the main factors affecting SFTD are analyzed. The results show that SFTD is composed of two parts. The first part, which is mainly determined by the temperature coefficient of elastic modulus of silicon,can be reduced by heavy-doping. The second part caused by the thermal deformation has relationship with the elastic modulus of adhesives for packaging,finger width,the ratio between wide gap and narrow gap,and the location of the anchor for the fixed comb fingers. The first part and second part are positive and negative respectively,so they compensate each other. Based on the MEMS bulk silicon micromachining,experimental samples of microaccelerometers are fabricated. The testing results of SFTD verify the theoretical analysis results of SFTD.