ZrO₂Gate Dielectric Deposited by Plasma-Enhanced Atomic Layer Deposition Method

Zirconium oxide (ZrO 2 ) films were investigated as a potential replacement for a silicon dioxide (SiO 2 ) gate dielectric and were successfully deposited by the atomic layer deposition (ALD) method using zirconium t-butoxide and oxygen as the Zr precursor and reactant gas, respectively. ZrO 2 films exhibited a relatively smooth surface and interface layer, and a stoichiometric structure. The ZrO 2 films deposited with the oxygen plasma state showed higher growth rate with lower carbon content than the films deposited with the oxygen gas phase. The leakage currents of the films deposited with the oxygen gas phase and oxygen plasma state were about 3.7 × 10 -7 and 2.7 × 10 -8 A/cm 2 at the gate bias voltage of -1.0 V with calculated equivalent oxide thicknesses of about 2.85 and 3.31 nm, respectively. The calculated interface state densities were 1.16 × 10 11 and 5.52 × 10 12 eV -1 cm -2 for the films deposited with the oxygen gas phase and oxygen plasma state, respectively. ZrO 2 films deposited with the oxygen plasma state showed generally improved film quality compared to the films deposited with the oxygen gas phase. This study demonstrated the possible application of the plasma-enhanced ALD technique for high-quality ZrO 2 gate dielectric thin film deposition.