Micromachining of (hhl) silicon structures: experiments and 3D simulation of etched shapes

The micromachining of various (hhl) silicon plates in a 35% KOH-water etchant is studied. Experimental shapes for membranes and mesa etched with initially circular masks are discussed. Theoretical 3D etched shapes for such microstructures are derived from a numerical simulation based on the tensorial model for the anisotropic wet etching. Experimental and theoretical shapes show a fair agreement, indicating a satisfactory adjustment of the dissolution slowness surface related to the etching of silicon in KOH etchant. The interest of the 3D simulation for designing mask patterns is outlined.