Pt-Ti/ALD-Al2O3/p-Si MOS CAPACITORS FOR FUTURE ULSI TECHNOLOGY

The high dielectric constant (high-k) thin film of Al2O3 was deposited by using Plasma enhanced atomic layer deposition (PE-ALD) technique. The electron beam evaporation system was used to deposit the Pt-Ti metal to fabricate the Pt-Ti/Al2O3/Si MOS capacitors. Thickness measurement of Al2O3 gate dielectric was carried out with variable angle spectroscopic ellipsometry, which is measured to be 2.83 nm. The MOS capacitors were characterized to evaluate the electrical properties using capacitance voltage (C-V) analyzer at different measurement frequencies. Capacitance voltage measurement shows that, dielectric constant k ranges from 7.87 to 10.44. In CV curve a slight negative shift is observed in the flatband voltage because of presence of trap charges in the Al2O3 MOS capacitor. A lower equivalent oxide thickness (EOT) of 1.057 nm is obtained for the fabricated Pt-Ti/Al2O3/Si MOS capacitors.