Impact of ion energies in Ar/H2 capacitively coupled radio frequency discharges on PEALD processes of titanium films

Abstract A plasma enhanced atomic layer deposition (PEALD) process combined with ion energy control of capacitively couples radio frequency (CCRF) discharges in Ar/H 2 gas mixture for fabricating Ti films was performed, and the impact of the ion energies on the film characteristics was evaluated. Titanium tetrachloride (TiCl 4 ) was adsorbed on a silicon wafer and Ti films were synthesized via the reduction of Cl atoms from TiCl 4 via the CCRF discharges. The growth per cycle of the films clearly increases with increasing the mean ion energy, ⟨ e i ⟩, suggesting that increase in the ion energies of the discharges promotes the reduction process of Cl atoms. Also, the film stress shows a clear dependence on ⟨ e i ⟩; it changes towards compressive with increasing ⟨ e i ⟩. On the other hand, the resistivity and the film density are almost constant independent of ⟨ e i ⟩, which indicates that the reduction reaction is saturated through the sequential PEALD cycles independent of ⟨ e i ⟩. In this paper, a simulation model based on one-dimensional (1D) Particle-in-Cell/Monte Carlo Collision (PIC/MCC) has been utilized for CCRF discharges in Ar/H 2 gas mixture.