Forming a rounded etched profile by using two-step anisotropic wet etching

We used a numerical simulation system to investigate the use of chemical anisotropic etching to fabricate diaphragm structures with a rounded profile at the edge. The rounded-shape was formed by using a two-step KOH etching procedure. The etched profiles were categorized into five types and their shapes were determined by three parameters: the first etching depth, the second etching depth, and mask offset between the first and second etching steps. According to the simulation results, we made a rounded concaved shape at the periphery of a diaphragm structure in order to reduce the concentration of stress there.