A Novel Method for Evaluating the Thickness of Silicon Membrane Using a Micromachined Acoustic Wave Sensor

This work presents a novel method based on the micromachined acoustic wave sensor for evaluating silicon membrane thickness. Like pressure sensors, accelerometers, micro flow sensors and micropumps, many micro-electro-mechanical systems (MEMS) devices require that silicon membrane thickness be known exactly. Precisely controlling silicon membrane thickness during wet etching is important, because the thickness strongly affects device performance and post-processing. The proposed method for evaluating silicon membrane thickness is novel, simple to implement, and can be monitored in-situ and mass-produced. The spectral analysis of surface waves (SASW), detailed process flows, measurement set-up and the experimental results also are presented.