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.