A low temperature integrated aluminum metallization technology for ULSI devices

Abstract An integrated aluminum metallization process (Cool Al technology) was successfully applied to fabricate device wafers for the 0.25-μm technology. This new technology integrates CVD and PVD aluminum thin film deposition processes into a high vacuum cluster tool, the applied materials’ Endura, and is capable of reliable contact and via fills of high aspect ratio (>8:1) structures at low temperatures, typically around 330–400°C. Two different Cool Al integration sequences employing CVD TiN and Ti as liners were used to process device wafers with 0.3 and 0.4×1.2 μ m via structures. The fill performance and electrical and reliability characteristics of the devices were evaluated. Void-free fills of all via structures were achieved. In comparison with a standard W-plug process, both Cool Al splits show more than five times reduction in via resistance. The two Cool Al sequences yielded excellent electromigration (EM) reliability, equivalent or better than a standard W-plug process. Interestingly, the two Cool Al splits, with very different aluminum crystal textures, resulted in similar EM performance.