Suspended gate field effect transistor type microelectromechanical systems resonators modelling with micro-Raman spectroscopy measured residual stress

Presented is an improved model of doubly-clamped microelectromechanical systems (MEMS) resonators implemented in very high-speed integrated circuit hardware description language for analogue and mixed-signal (VHDL-AMS). The model includes the effect of residual stress, which may severely shift the resonant frequency of the MEMS resonator from the analytical pre-designed value if the magnitude of intrinsic residual stress is imprecisely predicted. As the stress is not only determined by the fabrication process but also related to the structural dimensions of the resonators, in this work micro-Raman spectroscopy was utilised to measure and characterise the residual stress of a series of fabricated doubly-clamped polysilicon suspended gate field effect transistor type resonators with varying sizes. Combined with the experimentally determined residual stress, the proposed VHDL-AMS analytical model provides an error of <; 3.5% resonant frequency shift with respect to the experimental result.