AVS 45th International Symposium
    Thin Films Division Friday Sessions
       Session TF-FrM

Paper TF-FrM2
Polymerized C-Si Films on Metal Substrates: Cu Adhesion/Diffusion Barriers for ULSI?

Friday, November 6, 1998, 8:40 am, Room 310

Session: Thin Film Deposition from Chemical Precursors
Presenter: J.A. Kelber, University of North Texas
Authors: L. Chen, University of North Texas
J.A. Kelber, University of North Texas
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The increasing demands of ULSI have created a need for Cu diffusion/adhesion barriers which are consistently effective at thicknesses of several hundred angstroms or less. Further, the integration of Cu with low-dielectric polymers requires the reliable adhesion at the Cu/polymer interface. We have recently synthesized polymeric C-Si films which are resistant to thermal diffusion of Cu at temperatures below 800 K, even at thicknesses less than 100 Å. These films also show potential for providing a covalently bonded interphase between Cu and, e.g., fluoropolymer dielectrics. The films are created by electron or UV photon bombardment of condensed vinyl silane derivatives. The films are not SiC, and have chemical compositions very close to those of the vinyl silane precursors (e.g., Si:C = 1:4 for vinyltrimethylsilane(VTMS)-derived films). TPD data show that polymerization occurs via the vinyl group. Films derived from VTMS are adherent and stable on Ta substrates until 1000 K in UHV. Diffusion of Cu is not observed below 800 K. Cu adhesion to the substrate is relatively good, with dewetting of deposited overlayers occuring only at temperatures above 600 K in UHV. Perfluorobenzene moieties can also be incorporated into the growing film with good thermal stability, indicating that these films have potential to adhesively couple Cu surfaces to vapor-deposited fluoropolymer films. Opportunities for molecular tailoring of electronic and mechanical properties via systematic variation of precursor structure will be discussed.