Journal of Vacuum Science & Technology A, Vol.24, No.6, 2192-2198, 2006
Vapor phase reactions in polymerization plasma for divinyisiloxane-bis-benzocyclobutene film deposition
Vapor phase reactions in plasma, polymerization of divinylsiloxane-bis-benzocyclobutene (DVS-BCB) low-k film depositions on 300 mm wafers were studied using mass spectrometry, in situ Fourier transform infrared, and a surface wave probe. Polymerization via Diels-Alder cycloaddition reaction was identified by the detection of the benzocyclohexene group. Hydrogen addition and methyl group desorption were also detected in DVS-BCB monomer and related large molecules. The dielectric constant k of plasma polymerized DVS-BCB with a plasma source power range up to 250 W was close to similar to 2.7 of thermally polymerized DVS-BCB, and increased gradually over 250 W. The electron density at 250 W was about 1.5 X 10(10) cm(-3). The increase of the k value at higher power was explained by the decrease of both large molecular species via multistep dissociation and incorporation of silica components into the polymer. It was found that the reduction of electron density as well as precursor residence time is important for the plasma polymerization process to prevent the excess dissociation of the precursor. (c) 2006 American Vacuum Society.