Method of localized etching of Si crystals

Claim 1

A process for producing a semiconductor arrangement from a monocrystalline silicon substrate for use in an integrated circuit, comprising: orientating a monocrystalline silicon substrate so that a (100)-plane of the silicon crystal lattice substantially coincides with a surface of the substrate being etched; applying a protective etch mask onto the orientated substrate surface to be etched, said etch mask having a pattern of groove-shaped openings therein; and contacting the masked orientated surface with a liquid etchant at a temperature in the range of about 18° to 30°C. and for a time period sufficient to from groove-shaped recesses in the masked orientated surface in accordance with said pattern of openings in the etch mask, said groove-shaped recesses having side walls which are obliquely inclined relative to the masked orientated surface so that the angle between the masked orientated surface and said side walls is larger than about 90°, said liquid etchant being composed of a mixture of HF, HNO 3 , CH 3 COOH and H 2 O wherein for every 4 gr of HF present in said mixture, there are 100 gr of HNO 3 , 110 gr ± 20% of CH 3 COOH and 20 gr ± 50% of H 2 O.