Correlation between SiO2 growth rate and difference in electronegativity of metal–oxide underlayers for plasma enhanced atomic layer deposition using tris(dimethylamino)silane precursor

Abstract

The growth rate of an SiO2 film on various metal–oxide (M–O) underlayers by plasma-enhanced atomic layer deposition (ALD) using tris(dimethylamino)silane precursor and O2 plasma gas is systematically investigated, and the effect of the difference in the electronegativity of the M–O underlayer on the ALD-SiO2 growth mechanism is also discussed. All data for the ALD-SiO2 film thickness on HfO2, TiO2, Al2O3, and SiO2 underlayers satisfied a linear relationship as a function of the ALD cycle. The growth per cycle (GPC) value of the ALD-SiO2 film increased in the following order: SiO2 (0.043 nm/cycle) < Al2O3 (0.14) < TiO2 (0.17) < HfO2 (0.22). On the other hand, the negative charge concentration of oxygen atoms in the M–O underlayer becomes higher in the following order: Si–O (1.76 eV) < Al–O (2.03) < Ti–O (2.18) < Hf–O (2.27) due to the electronegativity difference between the Si, Al, Ti, Hf, and O elements of the M–O underlayer. A correlation between the GPC of the ALD-SiO2 film and the difference in the electronegativity of the M–O underlayer was also determined.