We have successfully demonstrated chemical vapor deposition of a silica film in which some of oxygen atoms of the pure silica network are replaced to methylene (-CH2-) groups. The as-deposited film was thermally unstable owing to the unwanted decomposition reaction of the methylene group with the dense H2O in the film. It was found that the film could be dehydrated without decomposition of the methylene group by low temperature annealing in a XeF2 ambient. The dehydrated film showed not only good insulating and low-k characteristics (resistivity of 10(15) Ohm cm, breakdown field of 3.3 MV/cm, and k of 2.8), but also good thermal properties, such as good thermal stability and high thermal conductivity.