Nobutaka Kunimi

Plasma-enhanced co-polymerization of organo-siloxane and hydrocarbon for low-k/Cu interconnects

A plasma-enhanced co-polymerization technique was developed for low-k/Cu damascene integration on 300 mm wafers. This technique enables us to control dielectric film properties by introducing organo-siloxane and hydrocarbon into a He-plasma. The growth rate of the low-k film derived from divinyl siloxane–benzocyclobutene (DVS–BCB) as a matrix monomer is increased by adding C2H2 as a deposition acceleration monomer and the Youngs modulus was enhanced by adding diisopropenylbenzene (DIPB) or divinylbenzene (DVB) as a reinforcement monomer. Cu damascene interconnects with plasma polymerized low-k films were successfully fabricated on 300 mm wafers.

An Organic Low-k Film Deposited by Plasma-Enhanced Copolymerization

A plasma-enhanced copolymerization technology has been developed in which organic precursors are designed and synthesized to form polymerized films with low dielectric constants. In order to lower the dielectric constant, a tricyclodecane (TCD) group is introduced as an organic precursor molecule because TCD is a large aliphatic hydrocarbon group, which contributes to lowering the film density. The TCD precursors are liquid at room temperature and they have a sufficient saturated vapor pressure to be applicable to the vapor phase deposition. The optimized dielectric constant of the TCD polymer was less than 2.5. A solid 13 C nuclear magnetic resonance spectrum showed that the TCD moiety in the precursor was included in the polymer without changing the structure. The effect of the substrate temperature on the film structure was studied by analyzing Raman spectra. It was revealed that the dielectric constant was associated with sp 2 carbon content in the TCD-based polymer films.

Vapor phase reactions in polymerization plasma for divinylsiloxane-bis-benzocyclobutene film deposition

Vapor phase reactions in plasma polymerization of divinylsiloxane-bis-benzocyclobutene (DVS-BCB) low-k film depositions on 300mm 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 250W was close to ∼2.7 of thermally polymerized DVS-BCB, and increased gradually over 250W. The electron density at 250W was about 1.5×1010cm−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 polymeri...

Effect of Bridging Groups of Precursors on Modulus Improvement in Plasma-Enhanced Copolymerized Low-k Films

The mechanical strength of an organic silica low dielectric constant film was enhanced by introducing a reinforcement monomer into a matrix monomer under plasma polymerization deposition. The modulus improvement mechanism was investigated by using pyrolysis gas chromatography and mass spectrometry. Incorporation of a reinforcement monomer in the film matrix through copolymerization reactions was confirmed. Compositional analysis of the films showed that the extent of reinforcement was associated with the copolymerization ratio and the monomer content in the film. It is also found that the modulus enhancement depends on the content of three-dimensional aromatic bridged structure.