Fabrication of convex corners in anisotropic etching of 100-silicon using aqueous KOH

In this paper, a method for the fabrication of convex corners in (100)-Silicon in KOH-etchant of (100)-Silicon is presented. Based on the identification of the planes accuring at convex corners during the etching in this solution and the determination of the etching rate ratio of these planes in relation to the rate of the (100)-planes, special structures suited for the compensation of the undercutting in the case of very narrow contoures were developed. With the help of these structures it is feasible to realize bent V-grooves of structures with a very low ratio between lateral expansion and etching depth, e.g. a descrete pyramid-trunk, formed by (111)-planes or (411)-planes, with minimum dimensions on the wafer surface.