Ultrathin oxide grown on polysilicon by ECR (Electron Cyclotron Resonance) N2O plasma

We have developed a process of growing ultrathin oxide on polysilicon layer by using Electron Cyclotron Resonance (ECR) N₂ O plasma. Sub 4-nm thick polyoxide on n⁺ and p⁺ polysilicon layers were grown and characterized. These oxides had larger breakdown fields and smaller electron trapping characteristics than thermal polyoxides. Q_BD up to 1.5 C/cm² for polyoxide on n+ polysilicon under positive constant current density of 400 μA/cm² and up to 1.0 C/cm² for polyoxide on p+ polysilicon under positive constant current density of 800 μA/cm ² were obtained, respectively. These values were much larger than that of thermal polyoxides. Smaller electron trapping characteristics of ECR N₂O plasma polyoxides than that of thermal polyoxides at positive bias have resulted from smaller roughness of polysilicon surface after oxidation processes. These ultrathin plasma polyoxides are good candidates for future interpoly dielectrics and the gate oxides for thin film transistors