Surface morphology of anisotropically etched single-crystal silicon

We investigated the surface morphology of an anisotropically etched single-crystal silicon surface using a hemispherical specimen. The facet structures that appeared on the specimen surface were classified into three pattern types. Each pattern originated from one of three principal planes. The (100) plane-originated area had a smooth surface and expanded towards a(lll)plane. The (110) plane-originated area was covered with triangular column structures. The (111) plane-originated area was covered with step structures. We made a map of the facet-structure pattern for all crystallographic orientations and showed that it corresponds to the distribution pattern of the etching rates. The facet structures that appear on an etched surface are thus strongly related to the anisotropic etching rates.