A method of forming and controlling air gaps between adjacent raised features on a substrate includes forming a silicon-containing film in a bottom region between the adjacent raised features using a flowable deposition process. The method also includes forming carbon-containing material on top of the silicon-containing film and forming a second film over the carbon-containing material using a flowable deposition process. The second film fills an upper region between the adjacent raised features. The method also includes curing the materials at an elevated temperature for a period of time to form the air gaps between the adjacent raised features. The thickness and number layers of films can be used to control the thickness, vertical position and number of air gaps.