Plasma-induced damage on sub-5 nm gate oxide by PECVD-Ti process

Plasma-induced damage by the PECVD-Ti process on the leakage current of sub-5 nm gate oxide was investigated. The plasma conditions during the deposition of PECVD-Ti critically affected characteristics of the gate oxide such as the leakage current and the breakdown voltage. Lowering of plasma power in a deposition step improves the gate oxide properties but cannot clearly reduce all gate oxide failure. According to plasma damage monitoring analysis, a large plasma damage during the plasma ignition step was observed, which indicates that failure of the gate oxide was due to the unbalanced plasma ignition in the deposition step. It is very important to optimize process parameters and to control system conditions to prevent the unbalanced plasma ignition during the PECVD-Ti process.