Plasma enhanced atomic layer deposition of SrTiO3 thin films with Sr(tmhd)2 and Ti(i-OPr)4

SrTiO 3 (STO) thin films were deposited in the deposition temperature range of 250–350 °C by plasma enhanced atomic layer deposition (PEALD) with Sr(tmhd)2 (tmhd=tetramethyl heptanedionate) and Ti(i-OPr)4 (i-OPr=iso-propoxide) as a precursor. Two precursors were dissolved in tetrahydrofuran, delivered into the vaporizer separately by a newly developed pulse injection method, and the vapor mixture was introduced into the reactor. An argon purge was inserted after the precursor injection and afterward, plasma was generated with the oxygen introduction. Deposition rate was saturated at 0.3–0.4 Å/cycle. Despite the poor volatility of Sr(tmhd)2, SrTiO3 thin films were reproducibly deposited and using plasma activated O2 gas as an oxidant, films could be deposited at low temperature with carbon residue of STO thin films minimized. Step coverage of both SrO and SrTiO3 were above 90% due to the self-limiting growth behavior of atomic layer deposition process.