Formation of Ti diffusion barrier layers in thin Cu(Ti) alloy films

S. Tsukimoto, T. Morita, M. Moriyama, Kazuhiro Ito, Masanori Murakami

    Research output: Contribution to journalArticlepeer-review

    66 Citations (Scopus)

    Abstract

    In order to study a formation mechanism of thin Ti-rich layers formed on the surfaces of Cu(Ti) wires after annealing at elevated temperatures, the 300-nm-thick Cu(Ti) alloy films with Ti concentration of 1.3 at.% or 2.9 at.% were prepared on the SiO2/Si substrates by a co-sputter deposition technique. The electrical resistivity and microstructural analysis of these alloy films were carried out before and after annealing at 400°C. The Ti-rich layers with thickness of ∼15 nm were observed to form uniformly both at the film surface and the substrate interfaces in the Cu(2.9at.%Ti) films after annealing (which we call the self-formation of the layers) using Rutherford backscattering spectrometry (RBS) and transmission electron microscopy (TEM). Both the resistivities and the microstructures of these Cu(Ti) films were found to depend strongly on the Ti concentrations. The resistivities of the films decreased upon annealing due to segregation of the supersaturated Ti solutes in the alloy films to both the top and bottom of the films. These Ti layers had excellent thermal stability and would be applicable to the self-formed diffusion barrier in Cu interconnects of highly integrated devices. The selection rules of the alloy elements for the barrier self-formation were proposed based on the present results.

    Original languageEnglish
    Pages (from-to)592-599
    Number of pages8
    JournalJournal of Electronic Materials
    Volume34
    Issue number5
    DOIs
    Publication statusPublished - 2005 May

    Keywords

    • Alloy element
    • Barrier layer
    • Cu(Ti) film
    • Selection rule
    • Self-formation

    ASJC Scopus subject areas

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

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