New high-k SrTa2O6 gate dielectrics prepared by plasma-enhanced atomic layer chemical vapor deposition

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 O-2 ambient are about 20 and 6.54 x 10(-8) C/cm(2), respectively. The interface trap density D-it at the midgap obtained from a quasistatic capacitance-voltage technique is estimated approximately to be in the low 10(11) cm(-2.)eV(-1) range and the leakage current is approximately 2.98 x 10(-9) A/cm(2) at 1 V bias in accumulation. The films annealed in N-2 ambient exhibit a relatively larger fixed charge and interface trap density than those annealed in O-2 ambient. These electrical properties support the possibility of STA oxide application to a new high-k gate dielectric.