Investigations on the morphology of silicon surfaces anisotropically etched with TMAH

The formation and transformation of hillocks during the anisotropic etching of (100) silicon are investigated. Hillocks start as pyramids and grow in size as the surface etches down. The main pyramid edges become bevelled in the process, and when the bevelling planes meet, 〈101〉 ledges are formed which propagate and transform the {111} faces to ones with a characteristic bow. Such bowed face hillocks appear to be quasi-stable and form the majority of the population of the hillocks observed.