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

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) [1] or polyoxide films grown by electron cyclotron resonance (ECR) nitrous oxide plasma at 400°C [2]. The present film growth techniques utilize oxygen radicals (O*), rather than oxygen molecules (O ₂), which are used in the conventional processing. The oxygen radicals are generated by microwave (2.45 GHz) excited high-density plasma of Kr/O ₂ gas mixture.