Reducing DRIE-Induced Trench Effects in SiC Pressure Sensors Using FEA Prediction

Burst force of several 4H-SiC pressure sensor diaphragms fabricated by reactive ion etching (RIE) is measured and coupled with finite-element (FE) analyses to extract a fracture strength of 786 ± 0.3 MPa. The result, which was in relative agreement with previously published values, was applied in various failure prediction models for RIE-induced trench defects that were responsible for the premature failures observed in SiC pressure sensors. The FE model associated with trench-free diaphragms was experimentally validated to prevent such failure, thereby resulting in the expansion of the sensor pressure handling capacity by more than twofold. The RIE fabrication process conditions for this model have been successfully implemented as a standard process. This result was extended further into developing failure prediction models for other observed RIE-induced etch characteristics.