A method of forming a silicon oxide layer is described. The method first deposits a silicon-nitrogen-and-hydrogen containing (polysilazane) film by radical-component chemical vapor deposition (CVD). The silicon-nitrogen-and-hydrogen containing film is formed by combining a radical precursor (excited in a remote plasma) with m unexcited carbon-free silicon precursor. A capping layer is formed over the silicon-nitrogen-and-hydrogen-containing film to avoid time-evolution of underlying film properties prior to conversion into silicon oxide. The capping layer is formed by combining a radical oxygen precursor (excited in a remote plasma) with an unexcited silicon-and-carbon-containing-precursor. The films are converted to silicon oxide by exposure to oxygen-containing environments. The two films may be deposited within the same substrate processing chamber and may be deposited without breaking vacuum.