A method of forming a dielectric layer is described. The method first deposits a silicon-nitrogen-and-hydrogen-containing (polysilazane) layer by radical-component chemical vapor deposition (CVD). The silicon-nitrogen-and-hydrogen-containing layer is formed by combining a radical precursor (excited in a remote plasma) with an unexcited carbon-free silicon precursor. A silicon oxide capping layer may be formed from a portion of the carbon-free silicon-nitrogen-and-hydrogen-containing layer to avoid time-evolution of underlying layer properties prior to conversion into silicon oxide. Alternatively, the silicon oxide capping layer is formed over the silicon-nitrogen-and-hydrogen-containing layer. Either method of formation involves the formation of a local plasma within the substrate processing region.