Optimization of sensitive films for pressure sensors based on wet corrosion

Given the critical role of sensitive membrane roughness in pressure sensor performance, wet etching experiments were conducted on <100> grain-oriented silicon. The study systematically examined the effects of varying temperatures (60°C, 70°C, 80°C, 90°C) and tetramethylammonium hydroxide (TMAH) concentrations (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) on the etching morphology and rate using the controlled-variable method. The influence of three additives, ammonium persulfate (APS), isopropanol (IPA), and Triton X-100, was investigated on the silicon surface morphology and etching rate. Notably, a high etching rate of 23.63 μm/h was obtained by adding Triton X-100 to a 25 wt% TMAH solution at 80°C, characterized by excellent wafer uniformity (variance of 0.19) and a smooth morphology with a roughness of 3.2673 nm. This method was successfully applied to the fabrication of sensitive thin films for pressure sensors. It was found to be effective in improving the sensitivity of the pressure sensors compared to 80°C 5 wt% TMAH conditions, effectively reducing the problem of lower sensitivity caused by uneven stress distribution.