Chemical interaction and ligand exchange between a [(CH3)3Si]3Sb precursor and atomic layer deposited Sb2Te3 films

The chemical interaction between the [(CH 3 ) 3 Si] 3 Sb precursor and atomic layer deposited Sb 2 Te 3 thin films was examined at temperatures ranging from 70 to 220 °C. The trimethylsilyl group [(CH 3 ) 3 Si] displays greater affinity for Te than for Sb, and this drives replacement of Te in the film with Sb from the [(CH 3 ) 3 Si] 3 Sb precursor, while eliminating volatile [(CH 3 ) 3 Si] 2 Te, especially at elevated temperatures. The compositions of the resulting Sb-Te layers lie on the Sb 2 Te 3 -Sb tie line. The incorporation behavior of [(CH 3 ) 3 Si] 3 Sb was explained in terms of a Lewis acid-base reaction. The exchange reactions occurred to relieve the unfavorable hard-soft Lewis acid-base pair between the trimethylsilyl group and Sb in [(CH 3 ) 3 Si] 3 Sb. Such a reaction could be usefully adopted to control the chemical composition of ternary Ge-Sb-Te thin films. The exchange reaction between the TMS group in [(CH 3 ) 3 Si] 3 Sb and Sb 2 Te 3 film formed [(CH 3 ) 3 Si] 2 Te, replacing Te in the film with Sb.