Methylsiloxane Spin-on-Glass Films for Low Dielectric Constant Interlayer Dielectrics

A new spin‐on‐glass (SOG) solution has been obtained by the hydrolysis of methyltriethoxysilane and dimethoxymethyl‐3,3,3‐trifluoropropylsilane. When the SOG film is cured at 360°C, it contains both trifluoropropyl and methyl groups and exhibits the dielectric constant of 3.0. Curing the SOG film at 450°C in nitrogen decomposes only the trifluoropropyl group. The resultant film shows the Brunauer‐Emmett‐Teller surface area of 250 m 2 / g indicative of a porous structure. The thermal decomposition of the trifluoropropyl groups gives few silanol groups, showing hydrophobic property in spite of the porous structure. The dielectric constant of the film is reduced to 2.3 owing to the pores introduced into the methylsiloxane network.