Application of notching effect in the fabrication process of MEMS anemometer

Deep reactive ion etching is widely used in modern silicon micro-mechanical manufacture with high aspect ratio of etched features. During the DRIE of SOI wafer, an adverse reaction to etching rate and profile shape named "Notching effect" occurred. We take advantage of the "Notching effect" to fabricate an anemometer with suspended silicon sensing element. In our design, by some simple design rules, sacrificial silicon islands are placed near to the sensitive structures to release it by "Notching effect". Typical time constant measured for the sensor was 1.08 μs and the Temperature Coefficient of Resistant (TCR) value of the sensing element was measured to be 4738×10^-6/°C. For certain micromechanical applications, as described in this paper, "Notching effect" can be turned into an advantage to improve the variability of the fabrication process.