Methods for deposition of silicon carbide films on a substrate surface are provided. The methods include the use of vapor phase carbosilane precursors and may employ plasma enhanced atomic layer deposition processes. The methods may be carried out at temperatures less than 600° C., for example between about 23° C. and about 200° C. or at about 100° C. This silicon carbide layer may then be densified to remove hydrogen content. Additionally, the silicon carbide layer may be exposed to a nitrogen source to provide reactive N—H groups, which can then be used to continue film deposition using other methods. Plasma processing conditions can be used to adjust the carbon, hydrogen and/or nitrogen content of the films.