Si 結晶表面の KOH エッチングによる評価

抄録

Figures etched by KOH aqueous solutions were observed on a Si crystal surface, and the relations between the etch pits and surface defects were discussed. Surface roughness depended on the crystal orientation and concentration of the etching solution. Etching 4°off the (100) surface by 17% solution at 92℃ showed a folded pattern, consisting of rows small overlapping L shape pits. While by etching exactly on the (100) surface, this pattern was not seen. A lapped wafer with mechanical damage had an accelerated etch rate. This alkali etching is very sensitive to surface defects such as cracks and scratches, as delineated by square pits on the (100) surface. Surface contamination was appeared as small hillocks. A KOH etched (111) surface observed by an atomic force microscope revealed triangular pits and atomic steps with two atomic layers deep in spite of being exposed to air for several hours.