抄録
Electric characteristics of 25-nm-SiO2/Si films embedded with Ge nanoparticles were investigated by CV method. Ge nanoparticles were formed by negative ion implantation and subsequent thermal annealing. Ge atoms in the SiO2 were evaluated by high-resolution RBS and cross-sectional TEM. Ge atoms were implanted at 10 keV with 1×1015 and 5×1015 ions/cm2. The samples were annealed at 300, 500, 700 and 900°C for 1 h. After annealing at 900°C, Ge atoms diffused down to SiO2/Si interface, so the sample could not be evaluated by CV method. After annealing at 300°C, the voltage shift in the hysteresis of a CV curve was very small, so it could not be applied to the memory devices. While after annealing at 500°C, the voltage shifts of both samples implanted with doses of 1×1015 and 5×1015 ions/cm2 were wide. Calculations of charge and nanoparticle intensity from flat band shift and from implanted Ge dose show that each nanoparticle with about 3-nm diameter has only one electron. These results suggest that thin SiO2 films embedded with Ge nanoparticles formed with negative ion implantation can be applied to the memory devices.
