In-situ low temperature N2O plasma annealing for high-dielectric Ta2O5 thin films

PECVD Ta2O5 him was deposited by using in-situ low temperature N2O plasma a nnealing during the film deposition. N2O plasma annealing led to excellent leakage current characteristics and good C-V characteristics of Ta2O5 films , especially, multi-step annealing was more effective in reducing the leaka ge current than single-step annealing. The low field leakage current of mul ti-step annealed films was significantly reduced to 10(-8) A/cm(2), for a n egative bias of 1 MV/cm, whereas that of single-step annealed films was 10( -4) A/cm(2). The stable dielectric constants, ranging from 23 similar to 25 , were obtained. Improvement of electrical properties was attributed to the filling of oxygen vacancy and the reduction of impurities, such as, carbon and hydrogen, included in the as-deposited films by N2O plasma annealing. Especially, multi-step annealed films showed lower level of impurities than those of single-step annealed films. As a result, in-situ multi-step N2O p lasma annealing is promising to ensure an excellent quality of Ta2O5 films at low temperature.