A method of forming a low-carbon silicon-containing film by CVD on a substrate having trenches includes: introducing a silicon-containing compound having three or less hydrocarbon units in its molecule and having a boiling temperature of 35° C. to 220° C.; applying RF power to the gas; and depositing a film on a substrate having trenches wherein the substrate is controlled at a temperature such that components of the silicon-containing compound are at least partially liquidified on the substrate, thereby filling the trenches with the film.