A plasma polymerized thin film having low dielectric constant prepared by depositing a first precursor material represented by the following Chemical Formula 1: wherein in the above Chemical Formula 1, R1 to R14 are each independently H or a substituted or non-substituted C1-C5 alkyl group, and when the R1 to R14 are substituted, their substituents comprise an amino group, a hydroxyl group, a cyano group, a halogen group, a nitro group, or a methoxy group.