Micromachining by maskless wet anisotropic etching {hkl} structures on {100} oriented silicon

The paper presents investigation of micromechanical technique using 3D anisotropically etched Si structures. Ridge-like structure oriented along (110) direction is first etched with mask following maskless etching in 25 wt. % TMAH solution in water at 80°C. The ridge structures investigated by maskless etching are convex prismatic edges included by {100} and {111} planes. Experimental results verify that the cutting planes developed at the ridge corners are {733} planes. From analytical relations applied to experiments, the ratio between the etching rates for the {733} (the fastest etching plane at the edge step) and {100} planes is found.