Thermal Atomic Layer Deposition of Device-Quality SiO₂ Thin Films under 100 °C Using an Aminodisilane Precursor

SiO 2 is one of the most important dielectric materials that is widely used in the microelectronics industry, but its growth or deposition requires high thermal budgets. Herein, we report a low-temperature thermal atomic layer deposition (ALD) process to fabricate SiO 2 thin films using a novel aminodisilane precursor with a Si–Si bond, 1,2-bis(diisopropylamino)disilane (BDIPADS), together with ozone. To compare the film quality, ALD SiO 2 films grown at various temperatures from 250 down to 50 °C were systematically investigated. Our data suggest that even without the aid of plasma-enhanced or catalyzed surface reactions, high-quality SiO 2 films with relatively high growth rates, high film densities, and low impurity contents compared to conventional Si precursors can be attained through our process at a low growth temperature (∼50 °C). Chemical analyses via Auger electron spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy confirm the formation of stoichiometric SiO 2 films without noticeable impurity contents of nitrogen and carbon, regardless of the growth temperature. However, low-temperature growth of the SiO 2 film (≤80 °C) results in a slight ingress of SiH-related moieties during the ALD processes that is not observed at temperatures over 80 °C. Density functional theory calculations show that the Si–Si bond present in the BDIPADS precursor is easier to be oxidized compared to the Si–H bonds. Through electrical characterization of the SiO 2 films grown at different temperatures, we confirm only slight degradation in the dielectric constants, leakage currents, and breakdown fields with decreasing growth temperature, which may be due to the slightly decreased film density and the increased defect density of SiH-related bonds.