New High-k SrTa2O6 Gate Dielectrics Prepared by Plasma-Enhanced Atomic Layer Chemical Vapor Deposition

Abstract

We report on the electrical characterization of SrTa2O6 (STA) films as alternative gate dielectrics deposited directly on Si by plasma-enhanced atomic layer chemical vapor deposition. The dielectric constant extracted from the accumulation capacitance and the fixed charge of the interface state for STA films annealed in O2 ambient are about 20 and 6.54×10-8 C/cm2, respectively. The interface trap density Dit at the midgap obtained from a quasistatic capacitance-voltage technique is estimated approximately to be in the low 1011 cm-2·eV-1 range and the leakage current is approximately 2.98×10-9 A/cm2 at 1 V bias in accumulation. The films annealed in N2 ambient exhibit a relatively larger fixed charge and interface trap density than those annealed in O2 ambient. These electrical properties support the possibility of STA oxide application to a new high-k gate dielectric.