The effect of isopropyl alcohol on etching rate and roughness of (100) Si surface etched in KOH and TMAH solutions

The etching process of (1 0 0) silicon wafers in KOH and TMAH solutions with isopropyl alcohol (IPA) has been studied. The etching rates of different crystallographic planes in the wide range of solutions concentration have been estimated. The mutual relations of the etching rates of these planes have been analysed. Special emphasis was put on the roughness of silicon surface obtained in effect of etching. It was proved that IPA added to the solution improves the morphology of resulted surface. Detailed indications about the solution composition, ensuring satisfactory surface quality have been given. On the basis of experimental results and theoretical considerations, some attempts were made to explain the etching behaviour of silicon in KOH and TMAH solutions with IPA addition. It was suggested that TMA(+) ions play similar role in the solution to IPA particles and participate in smoothening of the etched surface. (C) 2001 Elsevier Science B.V. All rights reserved.