Ion fraction and energy distribution of Ti flux incident to substrate surface in RF-plasma enhanced magnetron sputtering

• Published in: Vacuum 2000-11, Vol.59 (2), p.586-593
• Main Authors: Fukushima, K, Kusano, E, Kikuchi, N, Saito, T, Saiki, S, Nanto, H, Kinbara, A
• Format: Article
• Language: English
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/S0042-207X(00)00320-1

Effects of plasma conditions on ion fraction and ion energy distribution of Ti flux have been investigated in RF-plasma enhanced magnetron sputtering. The ion fraction of Ti flux reaching to the substrate increases to >30% with increasing the coil RF power for an Ar pressure of 1.0 Pa, while it is nearly independent of the coil RF power for Ar pressure of 0.3 Pa. The electron density and temperature measured by a single-probe method increase with increasing the coil RF power. The increase in the ion fraction strongly correlates with the increase in electron density and temperature. This is more significant for a high Ar pressure. The peak energy of ion spectra of Ti + flux also increases with increasing the coil RF power in accordance with the increase in the plasma potential for a constant Ar pressure. As a result of the increase in the ion fraction and plasma potential, the energy delivered to the substrate as kinetic energy of the Ti ions arriving to the substrate increases drastically with increasing the coil RF power. The strong dependence of ion fraction on Ar pressure at a relatively low electron density emphasizes the role of Penning ionization mechanism in sputtered Ti ionization.