Magnetron sputter-deposited TiBx films grown from TiB2 targets are typically highly overstoichiometric with x ranging from 3.5 to 2.4 due to differences in Ti and B preferential ejection angles and gasphase scattering during transport between the target and the substrate. The authors show that the use of highly magnetically unbalanced magnetron sputtering leads to selective ionization of sputter-ejected Ti atoms which are steered via an external magnetic field to the film, thus establishing control of the B/Ti ratio with the ability to obtain stoichiometric TiB2 films over a wide range in Ar sputtering pressures. (C) 2017 American Vacuum Society.