Anisotropic etching of Si

In this paper, the structure of silicon crystal and the course of anisotropic etching have been presented in a simple way. Connections between etching anisotropy and surface morphology along with these between etching anisotropy and solution composition are shown. Correlation between solution composition and both morphology of the etched surface and shape of structures etched anisotropically using an oxide mask is analyzed. A simple scheme for designing cross-sections of etched structures and a simplified geometrical model of etching concave and convex structures are demonstrated. KOH and TMAH etching solutions, along with solutions containing additions of tensioactive compounds are compared. Special attention is paid to differences among these solutions.