Fabrication of Ultrathin SiO2 Gate Dielectric by Direct Nitrogen Implantation into Silicon Substrate

Nitrogen implantation in silicon substrate at fixed energy of 35keV and split dose of 1e14～5×1e14cm－2 is performed before gate oxidation.The experiment results indicate that with the increasing of implantation dose of nitrogen,oxidation rate of gate decreases.The retardation in oxide growth is weakened due to thermal annealing after nitrogen implantation.After nitrogen is implanted at the dose of 2×1e14cm－2,initial O2 injection method which is composed of an O2 injection/N2 annealing/main oxidation,is applied for preparation of 3.4nm gate oxide.Compared with the control process,which is composed of N2 annealing/main oxidation，initial O2 injection process suppresses leakage current of the gate oxide.But Qbd and HF C-V characteristics are almost identical for the samples fabricated by two different oxidation processes.