It was a major issue with aluminum interconnects. It was primarily addressed by switching to a different metal that exhibits less electromigration, namely coppe

It was a major issue with aluminum interconnects. It was primarily addressed by switching to a different metal that exhibits less electromigration, namely copper. But you have to be careful putting copper in a silicon fab, because if it gets into the silicon channel, it kills device performance (copper doping induces a deep trap in silicon).