Anisotropic Etching of Silicon - 1
• Differing hybridized (sp3) orbital orientation on different
crystal planes causes drastic differences in etch rate.
• Typically, etch rates are: (100) > (110) > (111).
• The (111) family of crystallographic planes are normally
the “stop” planes for anisotropic etching.
• There are 8 (111) planes along the ± x ± y ± z unit vectors.
• Intersections of these planes with planar bottoms produce
the standard anisotropic etching structures for (100) Si
wafers:
– V-grooves
– pyramidal pits
– pyramidal cavities