Elimination of silicon hillocks using an alkaline complexant etching system

Abstract

This paper presents the results obtained in silicon hillock elimination using alkaline solutions: KOH, NaOH, LiOH·H₂O with an added complexant. The added complexant in alkaline solutions is azocalix[4]arene. The alkaline solutions were compared and analysed with and without added complexant for their effect on hillocks. The behaviour of these solutions is explained using the theory of molar conductivity. The results show that use of the complexant permits control of the etching process, yielding a smooth silicon surface, almost free of hillocks. A comparison between the alkaline etchants (KOH, NaOH, LiOH·H₂O) is made and the influence of the cations in silicon etching process is explained.