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

H-2/CH4 mixture gas was introduced as a reactive gas for plasma enhanced atomic layer deposition (PEALD) to deposit TiCxNy film as a gate electrode, and it was compared with H-2 and NH3 PEALD. CH4 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 CH4 (>1.5 mol%), however, increased the free carbon impurity content, and therefore, increased the film resistivity. The resistivity of the TiCxNy film was decreased with the increase of the plasma power and substrate temperature due to the change in film composition and crystallinity. The TiCxN1-x films deposited using H-2/CH4 and NH3 PEALD showed stoichiometric composition and low resistivity (<1,000 mu Omega . cm). In contrast, the film deposited using H-2 PEALD showed higher oxygen concentration and resistivity than other PEALD processes. The C-V curve measured with the capacitor of H-2/CH4 PEALD TiCxNy 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). (C) 2014 The Electrochemical Society. All rights reserved.