Growth characteristics and electrical properties of La2O3 gate oxides grown by thermal and plasma-enhanced atomic layer deposition

We comparatively investigated thermal and plasma-enhanced atomic layer deposition (T-ALD and PE-ALD, respectively) of lanthanium oxide (La2O3) films using tris(isopropyl-cyclopentadienyl)lanthanum [La(iPrCp)3] as a La precursor. H2O and O2 plasma were used as reactants for T-ALD and PE-ALD La2O3, respectively. Both of the processes exhibited ALD mode growth with good self-saturation behavior and produced pure La2O3 films. However, PE-ALD La2O3 showed higher growth rate and dielectric constant value than those of T-ALD La2O3. In addition, lower leakage current density and interface state density were observed for PE-ALD La2O3, compared to those of the T-ALD La2O3. These experimental results indicate that the PE-ALD La2O3 process using La(iPrCp)3 precursor can be one of the viable options applicable into future microelectronic industry.