Thin inter-polyoxide films for flash memories grown at low temperature (400/spl deg/C) by oxygen radicals

Thin polyoxide films grown at 400/spl deg/C on n/sup +/-poly-Si films, used as gate insulators in MOS capacitors, are shown to exhibit superior performance, with respect to conventional, thermally grown polyoxide films at 900/spl deg/C, i.e., they possess lower leakage currents and can sustain higher electrical fields. They are also shown to be superior to, either polyoxide films grown at 980/spl deg/C on substrates treated by chemical mechanical polishing (CMP) or polyoxide films grown by electron cyclotron resonance (ECR) nitrous oxide plasma at 400/spl deg/C. The present film growth techniques utilize oxygen radicals (O*), rather than oxygen molecules (O/sub 2/), which are used in conventional processing. The oxygen radicals are generated by microwave (2.45 GHz) excited high-density plasma of Kr/O/sub 2/ gas mixture.