Plasma-process-induced damage in sputtered TiN metal-gate capacitors with ultrathin nitrided oxides

A comprehensive study on plasma-process-induced damage (P21D) in sputtered TiN metal-gated devices with 4 nm N2O-nitrided oxide was performed. We foun d that the TiN metal-gated devices exhibit a significant 8 Angstrom reducti on in the effective oxide thickness, due to physical damage caused by sputt ering and/or oxide consumption during the postannealing step. We also found that the postdeposition rapid thermal annealing (RTA) temperature affects both the flat-band voltage (V-fb) and the interface state density (Di,). Fu rthermore, degradation in the gate-oxide integrity caused by severe chargin g damage by the additional plasma processes in the TiN metal gate process f low was also observed. The P2ID leads to significant degradation in the cha rge-to-breakdown and a gate leakage current increase, even for the genuinel y robust nitrided oxide used in this study. Finally, Nz plasma posttreatmen t was proposed as an effective method for suppressing the gate leakage curr ent.