The dependence of the electromigration (EM) lifetime and the cross-sectional structure of interconnections after EM tests on linewidths was investigated in multi-level and single-level Al alloy interconnections consisting of a top–TiN/Ti/Al–0.5%Cu/TiN/Ti–bottom stack. In this study, an almost uniform Al3Ti intermetallic compound layer was formed by a well-known reaction between the Ti and Al. We found the following anomalous behavior: the mean time to failure (MTF) of EM in the multi-level interconnections with tungsten diffusion barriers decreased by increasing the linewidth. We also found that in the multi-level interconnections after EM tests, independent of linewidths, a local Al thickening formed near the anode end of the line and voids formed near the cathode end. On the other hand, in the single-level interconnections with bonding pads, the MTF of EM increased by increasing the linewidth and, after EM tests, a local Al thickening formed near the anode end even though no voids were observed near the cathode end. This directly opposed EM lifetime dependency on linewidth found in the multi-level and single-level interconnections and the observed Al thickening correlate closely with the fast diffusitivity of Al atoms at the interface between the Al3Ti and Al and/or between the Al3Ti and TiN.

MOCVD TiSiN was evaluated as a barrier for Cu interconnects application. The TiSiN f i l m was formed by Si% soaking of MOCVD TiN. The TiSiN film showed improved wetting and adhesion to Cu as well as less stress hysteresis in its integration with Cu. The low stress hysteresis yields higher resistance to Cu void generation during hot storage testing. Electrical tests on DLM Cu test structures demonstrated comparable line and via chain resistance and equivalent line-to-line leakage current in BTS testing compared to conventional PVD Ta(N).

Articles you may be interested inThe effect of current density, stripe length, stripe width, and temperature on resistance saturation during electromigration testing Effect of water absorption of dielectric underlayers on crystal orientation in Al-Si-Cu/Ti/TiN/Ti metallization

No abstract

Tribological properties of tin (Sn)-zinc (Zn) hybrid coating on bronze were evaluated in lubricated condition mating with a chromium alloy steel (Japanese Industrial Standards, JIS SUJ2) flat surface. A shot peening technique using Sn and Zn fine powders as the impact media was applied to the coating process. The resulted coating film thickness was approximately 1-2 µm. Tribological properties of mono-layered coating showed that the friction coefficient and the wear loss were considerably smaller than those of the bronze and that the transfer layer morphology was different depending on the coating material. Further decrease of the friction coefficient was found on the hybrid Sn-Zn coating surface and Zn transfer layer accompanying with oxygen reduced. Therefore, it is concluded that hybrid Sn-Zn coating is effective means to improve the tribological properties of bronze surface.