Deposition of rutile (TiO2) with preferred orientation by assisted high power impulse magnetron sputtering

The effect of energetic ion bombardment on TiO2 crystallographic phase formation was studied. Films were deposited using high-power impulse magnetron sputtering (HiPIMS) assisted by an electron cyclotron wave resonance (ECWR) plasma. The ECWR assistance allows a significant reduction of pressure down to 0.075 Pa during reactive HiPIMS deposition and subsequently enables control of the energy of the deposited species over a wide range. Films deposited at high ion energies and deposition rates form rutile with (101) a preferred orientation. With decreasing ion energy and deposition rates, rutile is formed with random crystallite orientation, and finally at low ion energies the anatase phase occurs. It is supposed that particles gain high energy during the HiPIMS pulse while the ECWR discharge is mostly responsible for substrate heating due to dissipated power. However, the energetic contribution of the ECWR discharge is not sufficient for annealing and phase transformation.

► HiPIMS assisted by ECWR plasma was used for TiO2 deposition.
► ECWR assistance allows significant pressure reduction during reactive HiPIMS.
► Energy of ionized sputtered species can be controlled by the pressure and substrate distance.
► Rutile with (101) preferred orientation is deposited at high energies of incoming ions.
► Ions gain high energy during HiPIMS pulses operated at low pressure.