Improvement of electromigration resistance of layered aluminum conductors

The electromigration of layered fine Al conductors (AlSi/TiN, AlSi/W, over/under) is discussed. The study indicates that (1) layering with refractory metals degrades the migration immunity of the Al layer, (2) refractory metal layers tend to suppress Al grain growth and crystal orientation, (3) by improving the film properties of refractory metals and optimizing the layer structure to minimize this grain growth suppression, conductor lifetimes can be lengthened by one or more orders of magnitude over those of conventionally layered or monolayer conductors.<
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