Effects of vanadium and chromium on aluminum electromigration

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Abstract
A systematic study was made of electromigration in homogeneous Al-V and Al-Cr thin films. V and Cr concentrations were varied in the range of 0–2 wt. %, and films were prepared both with and without 1% Si. The addition of as little as 0.1% V caused significant improvements in lifetime relative to pure Al. In the most concentrated alloy studied, the activation energy of mass transport had increased from 0.54 eV for pure Al to 0.92 eV for Al-1.1% V. For the Al-Cr alloys, a maximum in lifetime was found at 0.4% Cr. Higher concentrations of Cr resulted in a gradual degradation of the enhanced lifetime. Lifetimes were reduced when 1% Si was added to either alloy system. Alloy microstructure was examined using transmission electron microscopy. Contrary to results for other Al alloys, lifetimes were reduced in films with extensive precipitation.