A sub-micron-gap soi capacitive accelerometer array utilizing size effect

Abstract

This paper reports a 10×10 arrayed single-axis accelerometer, whose unit size is 1/10 of conventional accelerometers. From the theoretical calculation, we can increase sensitivity per sensing area volume by 10 times when decreasing all dimensions by 1/10. The negative resist pattern with a sub-õm gap was obtained by electron beam lithography. The reliability (stiction and pull-in) issue, which was more apparent on miniaturizing, was solved by a nonlinear programming method in the design. In this research in-plane size effect was demonstrated by a 10×10 array of 80-õm-square unit accelerometers that have the 0.5-õm gap in the sensing capacitance. The measured sensitivity is 0.99 fF/g, which is the same as that of conventional 3-õm gap accelerometers.