Characterization of anisotropic etching properties of single-crystal silicon: effects of KOH concentration on etching profiles

We have evaluated the orientation dependence in chemical anisotropic etching of single-crystal silicon. Etch rates for a number of crystallographic orientations were measured for a wide range of etching conditions, inducting KOH concentrations of 30 to 50% and temperatures of 40 to 90/spl deg/C. Though the etchants all consisted of the same components KOH and water, the orientation dependence varied considerably with change in etchant temperature and concentration. The resulting etch rate database allows numerical prediction of etch profiles of silicon, necessary for the process design of microstructures. Changing the KOH concentration yielded different etch profiles both analytically and experimentally.