Plasma process induced damage in sputtered TiN metal gate capacitors with ultra-thin nitrided oxide

A comprehensive study on plasma process induced damage (P2ID) in sputtered TiN metal-gated devices with 4nm N₂O-nitrided oxide was performed. It is observed that the post-deposition RTA temperature affects both the flat-band voltage (Vfb) and interface state density (Dit). The TiN metal-gated devices also show a 8 angstrom reduction in the effective oxide thickness, due to physical damage caused by sputtering and/or oxide consumption during the post annealing step. Finally, degradation in gate oxide integrity caused by severe charging damage during the additional plasma processes in the TiN metal gate process flow is also observed. The P2ID leads to significant degradation in charge-to-breakdown and gate leakage current increase, even for the genuinely robust nitrided oxide used in this study. Finally, N₂ plasma post-treatment is found to be effective in suppressing the gate leakage current.