Temperature-dependent yield effects on composite beams used in CMOS MEMS

Abstract

This paper presents an experimentally verified analytical model of temperature-dependent yield effects on the curvatures of composite beam structures used in complementary metal-oxide semiconductor microelectromechanical systems (CMOS MEMS). The temperature-dependent effects on composite beam curvatures of a thermal process can be predicted by extracting key parameters from the measured curvatures of a limited number of CMOS MEMS composite-layer combinations. The effects due to thermal history in MEMS packaging, which change the characteristics of beam curvatures due to material yield, are further analyzed. The models are verified with measured results from beam structures fabricated by an application-specific integrated circuit-compatible 0.18 mu m 1P6M CMOS MEMS process using a white light interferometer. These models can be applied in electronic design automation tools to provide good prediction of temperature-dependent properties related to CMOS MEMS beam curvature, such as sensing capacitance, for monolithic sensor system on chip design.