Characterization of self-formed Ti-rich interface layers in Cu(Ti)/low-k samples

Kazuyuki Kohama, Kazuhiro Ito, Susumu Tsukimoto, Kenichi Mori, Kazuyoshi Maekawa, Masanori Murakami

    Research output: Contribution to journalArticlepeer-review

    27 Citations (Scopus)


    In our previous studies, thin Ti-rich diffusion barrier layers were found to be formed at the interface between Cu(Ti) films and SiO 2/Si substrates after annealing at elevated temperatures. This technique was called self-formation of the diffusion barrier, and is attractive for fabrication of ultralarge-scale integrated (ULSI) interconnects. In the present study, we investigated the applicability of this technique to Cu(Ti) alloy films which were deposited on low dielectric constant (low-k) materials (SiO x C y ), SiCO, and SiCN dielectric layers, which are potential dielectric layers for future ULSI Si devices. The microstructures were analyzed by transmission electron microscopy (TEM) and secondary-ion mass spectrometry (SIMS), and correlated with the electrical properties of the Cu(Ti) films. It was concluded that the Ti-rich interface layers were formed in all the Cu(Ti)/dielectric-layer samples. The primary factor to control the composition of the self-formed Ti-rich interface layers was the C concentration in the dielectric layers rather than the enthalpy of formation of the Ti compounds (TiC, TiSi, and TiN). Crystalline TiC was formed on the dielectric layers with a C concentration higher than 17 at.%.

    Original languageEnglish
    Pages (from-to)1148-1157
    Number of pages10
    JournalJournal of Electronic Materials
    Issue number8
    Publication statusPublished - 2008 Aug


    • Barrier layer
    • Cu(Ti) alloy film
    • Low-k films
    • Reaction
    • Self-formation

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Electrical and Electronic Engineering
    • Materials Chemistry


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