Thin inter-polyoxide films for flash memories grown at lowtemperature (400°C) by oxygen radicals

Thin polyoxide films grown at 400°C on n⁺-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°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°C on substrates treated by chemical mechanical polishing (CMP) or polyoxide films grown by electron cyclotron resonance (ECR) nitrous oxide plasma at 400°C. The present film growth techniques utilize oxygen radicals (O*), rather than oxygen molecules (O₂), which are used in conventional processing. The oxygen radicals are generated by microwave (2.45 GHz) excited high-density plasma of Kr/O₂ gas mixture