Low dielectric constant insulating film and method for forming the same

A low dielectric constant insulating film formed of a polymer containing Si atoms, O atoms, C atoms, and H atoms, which comprises:

• straight chain molecules in which a plurality of basic molecules with an SiO structure are linked in a straight chain;
• and
• binder molecules with an SiO structure linking a plurality of the straight chain molecules,
• wherein the area ratio of a signal indicating a linear type SiO structure is 49% or more, when the total of the signal areas of a peak signal indicating a linear SiO structure appearing in the vicinity of wavenumber of 1020 cm−1, a peak signal indicating a network SiO structure appearing in the vicinity of wavenumber of 1080 cm−1, and a peak signal indicating a cage SiO structure appearing in the vicinity of wavenumber of 1120 cm− from among the peak signals of a spectrum obtained by analyzing said low dielectric constant insulating film by a Fourier transform infrared spectroscopy, is 100%,
• the signal amount of the signal indicating Si(CH3)2 is 66% or more, when the total of the signal amounts of a signal indicating Si(CH3) appearing in the vicinity of wavenumber of 770 cm−1 and a signal indicating Si(CH3)2 appearing in the vicinity of wavenumber of 800 cm−1 from among the peak signals of said spectrum, is 100%, and
• the low dielectric constant insulating film has a dielectric constant k of 2.2 or less.