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

Abstract

Silicon dioxide (SiO2) films are deposited by atomic layer deposition (ALD) at low temperatures from 100 to 200 degrees 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 angstrom/ cycle at 150 degrees C, which increases to 2.3 angstrom/cycle at 250 degrees C. The activation energy of 0.24 eV, extracted from temperature range of 100-200 degrees 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 degrees 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.