Anisotropic etching of {100} and {110} planes in (100) silicon

Anisotropic etching of (100) silicon using KOH with 45 degrees alignment to the primary (110) wafer flat was investigated. It was shown that in KOH so lution with isoplopyl alcohol added, high KOH concentration and temperature caused the selection of {100} instead of {110} walls, allowing reliable fa brication of(100) walls with improved surface smoothness due to the isoprop yl alcohol. TMAOH solutions with methanol and isopropyl alcohol were also f ound to produce both types of wall, with excellent surface smoothness for t he {110} walls. A new maskless etching technique was developed for corner c ompensation of structures bounded by {110} walls.