A porous SiCOH (e.g., p-SiCOH) dielectric film in which the stress change caused by increased tetrahedral strain is minimized by post treatment in unsaturated Hydrocarbon ambient. The inventive p-SiCOH dielectric film has more —(CHx) and less Si—O—H and Si—H bondings as compared to prior art p-SiCOH dielectric films. Moreover, a stable pSiOCH dielectric film is provided in which the amount of Si—OH (silanol) and Si—H groups at least within the pores has been reduced by about 90% or less by the post treatment. Hence, the inventive p-SiCOH dielectric film has hydrophobicity improvement as compared with prior art p-SiCOH dielectric films. In the present invention, a p-SiCOH dielectric film is produced that is flexible since the pores of the inventive film include stabilized crosslinking —(CHx)— chains wherein x is 1,2 or 3 therein. The dielectric film is produced utilizing an annealing step subsequent deposition that includes a gaseous ambient that includes at least one C—C double bond and/or at least one C—C triple bond.