Effects of insulator surface roughness on Al-alloy film properties and crystallographic orientation in Al-alloy/Ti/insulator structure

The effects of insulator surface roughness on the overlying Al-alloy properties on Al-alloy/Ti layered interconnects have been investigated. The Al-alloy surface roughness and Al(111) preferred orientation depends strongly on the underlying insulator roughness, especially at elevated Al-alloy deposition temperature. The planarization of underlying insulator down to the nm level is considered to improve the overlying Al-alloy film properties, not only the surface roughness but also the crystallographic orientations. It can be concluded that Al-alloy/Ti layered interconnect prepared on the underlying insulator with a very smooth surface on which Al-alloy film has a highly preferred (111) texture, has a higher resistance against electromigration induced failure than that on a rough insulator surface.