Plasma Enhanced Atomic Layer Deposition of TiC_xN_y Film with Various Reactive Gases

摘要

H_2/CH_4 mixture gas was introduced as a reactive gas for plasma enhanced atomic layer deposition (PEALD) to deposit TiC_xN_y film as a gate electrode, and it was compared withH_2 and NH3 PEALD. CH_4 stimulated the formation of TiC phase and suppressed the post deposition oxygen uptake to give similarly conductive film as NH3 PEALD but with lower work function. Too high concentration of CH_4 (> 1.5 mol%), however, increased the free carbon impurity content, and therefore, increased the film resistivity. The resistivity of the TiC_xN_y film was decreased with the increase of the plasma power and substrate temperature due to the change in film composition and crystallinity. The TiC_xN_(1-x) films deposited using H_2/CH_4 and NH3 PEALD showed stoichiometric composition and low resistivity (<1,000μΩ· cm). In contrast, the film deposited usingH_2 PEALD showed higher oxygen concentration and resistivity than other PEALD processes. The C-V curve measured with the capacitor of H_2/CH_4 PEALD TiC_xN_y film and hafnium silicate film was shifted -0.19 V away from the C-V curve of the NH3 PEALD film due to the work function difference, which was also confirmed by ultraviolet photoelectron spectroscopy (UPS).