Embodiments disclosed herein pertain to silicon dioxide deposition methods using at least ozone and tetraethylorthosilicate (TEOS) as deposition precursors. In one embodiment, a silicon dioxide deposition method using at least ozone and TEOS as deposition precursors includes flowing precursors comprising ozone and TEOS to a substrate under subatmospheric pressure conditions effective to deposit silicon dioxide-comprising material having an outer surface onto the substrate. The outer surface is treated effective to one of add hydroxyl to or remove hydroxyl from the outer surface in comparison to any hydroxyl presence on the outer surface prior to said treating. After the treating, precursors comprising ozone and TEOS are flowed to the substrate under subatmospheric pressure conditions effective to deposit silicon dioxide-comprising material onto the treated outer surface of the substrate. Other embodiments are contemplated.