AVS 50th International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS+TF-TuM

Paper PS+TF-TuM5
Characterization of TaN Diffusion Barrier Layers Prepared by Chemical-Enhanced Physical Vapor Deposition (CEPVD)

Tuesday, November 4, 2003, 9:40 am, Room 315

Session: Plasma Enchanced Chemical Vapor Deposition
Presenter: N. Li, University of Illinois, Urbana-Champaign
Authors: N. Li, University of Illinois, Urbana-Champaign
D.N. Ruzic, University of Illinois, Urbana-Champaign
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CEPVD of TaN is a novel process attempting to deposit diffusion barrier layers with both high conformal step coverage (as in CVD) and superior quality (as in PVD). The experiments are performed by sputtering a Ta target in a modified conventional PVD instrument and simultaneously adding a certain amount of chemical precursor, TBTDET, in the vicinity of the substrate at elevated temperature (330@degree@C) in combination with a carrier gas (N2), reducing agent (H2), non-reactive sputtering gas (Ar) and a RF-powered secondary ionization plasma. Different combinations of RF power, N2, H2, Ar flow and bias voltage result in distinct resistivity regimes. Increasing H2 flow rate from 5 sccm to 10 sccm allows more hydrocarbon formation and thus results in significant resistivity variation. The addition of 10sccm Ar increases target sputtering and more Ta flux, producing film with relatively lower resistivity (5200 μ -cm compared to 62,000 μ -cm). The addition of Ar also produces a more columnar and porous structure. N2 flow rate determines precursor residence time and so controls growth density and deposition rate. Biasing the substrate with -60 V drops resistivity one order of magnitude. Patterned wafers with various trench aspect ratios are lined to compare the step coverage under different processing conditions. Four point probe, SEM, AES, XRD and XPS are utilized to characterize the film properties and the analysis reveals the balance between energetic Ta flux, TBTDET breakup and impurity volatilization. The synergy between PVD and CVD is clearly demonstrated.