Low temperature atomic layer deposition of SiO2 thin films using di-isopropylaminosilane and ozone

Silicon dioxide (SiO2) films are deposited by atomic layer deposition (ALD) at low temperatures from 100 to 200 °C using di-isopropylaminosilane (SiH3N(C3H7)2, DIPAS) as the Si precursor and ozone as the reactant. The SiO2 films exhibit saturated growth behavior confirming the ALD process, showing a growth rate of 1.2 Å/cycle at 150 °C, which increases to 2.3 Å/cycle at 250 °C. The activation energy of 0.24 eV, extracted from temperature range of 100-200 °C, corresponds to the reported energy barrier for reaction between DIPAS and surface -OH. The temperature dependence of the growth rate can be explained in terms of the coverage and chemical reactivity of the thermally activated precursor on the surface. The ALD-SiO2 films deposited at 200 °C show properties such as refractive index, density, and roughness comparable to those of conventionally deposited SiO2, as well as low leakage current and high breakdown field. The fraction of Si-O bond increases at the expense of Si-OH at higher deposition temperature.