Understanding of deposition mechanism of vanadium on LiF with large mismatch by facing target sputtering (FTS)

A drastic change in the spatial ion distribution in bipolar magnetron sputtering discharge is reported upon changing the magnetic field topology. In our case, a significant increase in ion number density at certain time delays is registered when topology is changed toward the unbalanced type. A transitory torch-shaped ionization zone consequently disappears, along with the low-energy part of the ion energy distribution, due to no additional ionization in this case.

Magnetic field topology for altering ion density in bipolar sputtering

We report several effects found in reactive bipolar high-power impulse magnetron sputtering (abbreviated as bipolar HiPIMS or BPH) discharges at the substrate level. The role of the negative peak current and the positive pulse voltage, U + , on the deposition flux at the electrically insulating substrate is discussed and the results are compared to conventional DC discharges. In particular, the normalized energy flux, ϕ n , delivered to the substrate is found higher under BPH conditions at U + = +300 V ( φn=3.43×1015 eV·nm−3) as compared to the HiPIMS ( φn=0.78×1015 eV·nm−3) and DCMS ( φn=1.23×1015 eV·nm−3) regimes which is assumed to be provoked by an intensification of the positive ion bombardment. Accordingly, the mean energy and the count of positively charged metal and gaseous ions increase in line with U + as measured by energy-resolved mass spectrometry. Contrariwise, our analysis has shown a significant decrease (≈20 %) of negative oxygen ion count under BPH conditions.

M. Michiels

Papers

On the relationship between the plasma characteristics, the microstructure and the optical properties of reactively sputtered TiO2 thin films