Nitridation of thermal SiO2 films by radio-frequency plasma assisted electron cyclotron resonance: Layer structure and composition

Thermally grown silicon dioxide (SiO2) films were nitrided using dual-frequ ency electron cyclotron resonance (ECR) and rf discharges. The structure an d composition of the layers were studied by atomic force microscopy, spectr oscopic ellipsometry, Fourier transform infrared spectroscopy, and Auger el ectron spectroscopy. A two-layer structure consisting of a silicon oxynitri de (SiOxNy) outer layer and a SiO2 inner layer was found. The Si-SiO2 inter face was found to be a suboxide (SiOx, x<2). The ECR/rf plasma mode enabled production of a more thermally stable structure and composition, when comp ared to rf plasma alone, due to incorporation of more bonded nitrogen. (C) 2001 American Vacuum Society. [DOI: 10.1116/1.1333084].