Maximizing stoichiometry control in reactive sputter deposition of TiO2

Thin films of amorphous TiO2 are grown by direct current (DC) reactive magnetron sputtering. Using modern models of DC reactive sputtering, conditions were established to maximize control of the O: Ti ratio by indirectly monitoring the change in ion-induced secondary electron emission of the Ti target. The Ti resistivity was continuously varied through over 12 orders of magnitude, and changes in stoichiometry were observed by Rutherford backscattering. Combining observed changes in stoichiometry with a predictive model of the composition, a percolative transition could be observed exhibiting universal and nonuniversal scaling parameters. (C) 2017 American Vacuum Society.