AVS 49th International Symposium
    Thin Films Thursday Sessions
       Session TF-ThA

Paper TF-ThA5
Electrical and Physical Properties of Very Thin, Nearly Epitaxial Cu (100) Sputter-deposited at Room Temperature

Thursday, November 7, 2002, 3:20 pm, Room C-101

Session: Ultra Thin Films
Presenter: S.M. Rossnagel, IBM T.J. Watson Research Center
Authors: C. Detavernier, IBM T.J. Watson Research Center
S.M. Rossnagel, IBM T.J. Watson Research Center
C. Noyan, IBM T.J. Watson Research Center
C. Lavoie, IBM T.J. Watson Research Center
T.S. Kuan, SUNY-Albany
D. Deduytche, Universiteit Gent, Belgium
R.L. Van Meirhaeghe, Universiteit Gent, Belgium
Correspondent: Click to Email
The sputter deposition of high purity Cu onto HF-cleaned Si(100) substrates at room temperature or below results in very highly oriented, nearly epitaxial Cu (100) films with good electrical properties. Using XRD, we could only observe the Si(400) and Cu(200) peaks, indicating that the Cu is strongly textured. The resistivity of these films is found to be much smaller than the typical resistivity values obtained for unannealed polycrystalline PVD Cu films; approximately 1.9 micro-ohm-cm for films > 100 nm thickness, dropping to 1.7 micro-ohm-cm for >200 nm films deposited at 90C. The electrical resistivity increases as the film thickness is decreased, consistent with the non-specular electron-surface scattering. The resistivity increase exceeds the size-effect alone for very thin films which may be indicative of the presence of line defects or low angle grain boundaries. These defects would also explain the broadening of the XRD peaks that we observed for thinner films. The films were stable with time, unlike companion films deposited on silicon dioxide which undergo grain growth on the scale of days resulting in reduced electrical resistivity. TEM analysis shows a high dislocation density in the films, but good evidence of epitaxy. The grain size for 30 nm films is many hundreds of nm. The Cu(100) films are ideal for the study of size effects, specular scattering and any electrical anisotropies due to their near-bulk resistivity, lack of grain boundary effects, and crystalline stability.