Copper has long been popular for metallization, but it is running into problems at finer linewidths. Cobalt and ruthenium are two popular alternatives being res

Copper has long been popular for metallization, but it is running into problems at finer linewidths. Cobalt and ruthenium are two popular alternatives being researched. I don't follow the industry closely enough to know if anyone is using them in volume manufacturing yet. "Imec Presents Copper, Cobalt and Ruthenium Interconnect Results" https://semiwiki.com/semiconductor-services/ic-knowledge/7569-iitc-imec-presents-copper-cobalt-and-ruthenium-interconnect-results/ https://semiwiki.com/semiconductor-services/ic-knowledge/756... Cobalt needs a barrier to prevent mixing under some circumstances where it contacts copper. Ruthenium doesn't need any barriers but chemical mechanical polishing (CMP) processes for it still have problems.