Study of rf-sputtered yttrium oxide films on silicon by capacitance measurements

Publisher Website
Google Scholar
Abstract
Yttrium oxide Y2O3 films are prepared by rf sputtering on to silicon substrates and characterized by current‐voltage I‐V, capacitance‐voltage C‐V and capacitance‐time C‐t measurements. Relative permittivity increases with substrate heating from room temperature to 600 °C. As‐deposited films show large flat‐band voltage and interface trap density, which improve upon annealing in oxygen or hydrogen ambient up to 600 °C. However, film resistivity degrades by about 1 order of magnitude. Large hysteresis is observed in the C‐V curves, particularly for films deposited at high substrate temperature. This observation is attributed to the interfacial polarization at the Y2O3/SiO2 (native) interface. By monitoring the device capacitance over time for a given applied voltage, the resultant curves can be fitted to an exponential time dependent relation: C(t)=α0−α1exp(−t/τ). The time constant is further found to exhibit a dependence on the applied voltage of the form τ=τ0exp(−V0/V). Comparison with electron‐beam deposited films is also made.