Low-Temperature Plasma-Enhanced Atomic Layer Deposition of SiO ₂ Using Carbon Dioxide

In this work, we report the successful growth of high-quality SiO2 films by low-temperature plasma-enhanced atomic layer deposition using an oxidant which is compatible with moisture/oxygen sensitive materials. The SiO2 films were grown at 90 degrees C using CO2 and Bis(tertiary-butylamino)silane as process precursors. Growth, chemical composition, density, optical properties, and residual stress of SiO2 films were investigated. SiO2 films having a saturated growth-per-cycle of similar to 1.15 angstrom/cycle showed a density of similar to 2.1g/cm(3), a refractive index of similar to 1.46 at a wavelength of 632nm, and a low tensile residual stress of similar to 30MPa. Furthermore, the films showed low impurity levels with bulk concentrations of similar to 2.4 and similar to 0.17at. % for hydrogen and nitrogen, respectively, whereas the carbon content was found to be below the measurement limit of time-of-flight elastic recoil detection analysis. These results demonstrate that CO2 is a promising oxidizing precursor for moisture/oxygen sensitive materials related plasma-enhanced atomic layer deposition processes.