AVS 45th International Symposium
    Vacuum Metallurgy Division Monday Sessions
       Session VM+TF-MoM

Paper VM+TF-MoM10
Novel (111)-Textured AlCu Growth by Ionized Metal Plasma (IMP) Ti Underlayer

Monday, November 2, 1998, 11:20 am, Room 328

Session: Ionized-PVD: Processes, Properties, and Applications
Presenter: J.-B. Lai, National Tsing-Hua University, Republic of China
Authors: J.-B. Lai, National Tsing-Hua University, Republic of China
L.-J. Chen, National Tsing-Hua University, Republic of China
C.-S. Liu, Taiwan Semiconductor Manufacturing Company, Republic of China
Correspondent: Click to Email
(111)-textured AlCu is well known to possess better electromigration resistance than those of (200) and random orientations. In general, stronger (111)-textured AlCu can be obtained with the deposition of Ti underlayer compared with AlCu deposited directly on oxide or TiN underlayer. The improved texture is attributed to the small lattice mismatch between (0002)Ti and (111)AlCu. In this paper, (111)-textured AlCu (0.5 at. %) enhanced by Ti had been investigated using Auger electron spectroscopy, x-ray diffraction, transmission electron microscope, high-resolution transmission electron microscope, four-point-probe and EM test. Using thicker ion metal plasma (IMP) sputtered titanium underlayer was found to enhance the stronger growth of (111)-textured AlCu compared to conventional and collimated Ti films because of stronger (0002) textured-Ti was formed and hence the growth of (111)-textured AlCu was facilitated. However, TiAl@sub 3@, about 50 µm@OMEGA@-cm in resistivity, was found in the samples annealed at 400 °C. As the samples were annealed at 450 °C, a continuous but not smooth TiAl@sub 3@ precipitate layer was observed. If the precipitates of TiAl@sub 3@ were discontinuous and restricted to grain boundaries, the (111)-textured Al was destroyed and local joule heating caused the early failure of AlCu line. TiN, as a barrier layer, can retard the growth of TiAl@sub 3@. In our study, TiN/IMP-Ti was also found to enhance the stronger tendency of the growth of (111)-textured AlCu than TiN/collimated-Ti and TiN/conventional-Ti. The growth of (111)-textured TiN was enhanced by (0002)Ti. AlCu/TiN/IMP-Ti samples were observed to possess longer EM lifetime compared with those of AlCu/TiN/collimated-Ti (or conventional-Ti).