Seven kinds of commercially available organic spin-on glass (SOG) were evaluated and analyzed to reveal a relationship between film properties and their chemical composition. Film properties evaluated were shrinkage, refractive index, wet/dry etching rates, and adhesion strength. The structure of SOG solute was analyzed by Si-29-nuclear magnetic resource (NMR) spectroscopy. Composition of the solution was assayed in terms of GC-MS as well as H-1- and C-13-NMR. The properties were widely distributed among seven SOC films, which could be explained on the basis of the concentration of Si-C direct bond in the solute calculated from Si-29-NMR spectroscopy. Important parameters corresponding to the film quality such as film shrinkages, wet and dry etching rates decreased, with an increase of Si-C direct bonding. From this point of view, SOG solute having a high organic content is favorable for forming film with high cracking resistance and good planarization of the underlayer topology. The composition of the solvent appears to affect the viscosity of the solution, which dominates the properties during coating such as occurrence of striation or film thickness per coat.