A Novel Peninsula-island Structure for Sensing Ultra-low Pressure Based on Dry-wet Combination Etching Process

An improved peninsula-island structured pressure sensor was presented with the novel dry-wet combination etching process. There were four pairs of segmented mass blocks attaching on the back of the diaphragm. Each segmented mass block was composed of a peninsula structure and an island structure with anisotropic-etching-induced sidewalls. The improved structure not only inherited the stress concentration feature of low strain energy dissipation but also improved the comprehensive ability of the sensor chip, including low fabrication cost, high etching uniformity, good temperature performance and low residual stress in the diaphragm. Also, the fabrication method combining DRIE (Deep Reactive Ion Etching) and anisotropic wet etching was verified by the simulation based on the Sentaurus 2013. The fabrication error caused by anisotropic wet etching was analyzed. Compared with the flat film of the same size, the proposed structure can increase the sensitivity by 225%, reduce the nonlinearity by 80.3%, and increase resonance frequency by 11%. In addition, the sensor structure can also be applied to pressure sensors with different working range, which will be helpful to design the pressure sensors with high efficiency and accuracy.