Development of MEMS-based piezoresistive 3D stress/strain sensor using strain technology and smart temperature compensation

摘要

This paper presents the microfabrication and testing of a membrane-free eight-element single-polarity (n-type) sensing rosette integrated with strained silicon technology over (111) silicon plane to measure the full 3D stress/strain tensor with full temperature compensation. Such n-type piezoresistive (PR) sensor has low sensitivity to the out-of-plane components compared to the in-plane components. To improve the sensitivity of such sensors to the out-of-plane components, a strained silicon technique was integrated into the sensing rosette during the microfabrication process using a highly compressive film produced by plasma enhanced chemical vapor deposition silicon nitride. For experimental verification, a prototype device featuring the proposed sensing rosette was microfabricated using semiconductors fabrication processes. The experimental analysis applied both, in-plane and out-of-plane stresses at different temperatures over a range from -20 degrees C to 60 degrees C. In this work, a smart sensing calibration algorithm, utilizing machine learning, is employed to reduce the temperature impact on both sensitivity and resistance of PR coefficients during stress measurement. The developed sensor is capable of accurately extracting the applied stress/strain components with temperature compensation.