Direct nitridation of high-k metal oxide thin films using argon excimer sources

Reported, for the first time, is the formation of metal oxynitride thin films via direct nitridation of the metal oxide films by active nitrogen species generated from molecular nitrogen with argon excimer sources. Preliminary results on TaO_xN_y thin films formed from 9 nm Ta₂O₅ films have exhibited excellent electrical properties with three orders magnitude lower leakage current density being achieved and 25% higher accumulation capacitance being obtained. The nitridation process for a specific film thickness can be optimised by adjusting the VUV irradiation time to achieve both increased accumulation capacitance and improved leakage property, without the need for the use of H₂O, NH₃ or high temperature substrate heating.