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

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.