Integration of Al-Fill Processes for Contacts and VIAS

Today different Al-fill techniques are used for the fill of submicron contacts and vias. The integration aspects of the most promising approaches, Al-reflow, cold/hot Al-planarization and high pressure Al-fill (Forcefill) are compared to the widely used W-plug technique. The filling properties are discussed with respect to future applications in ULSI devices. Special attention is given to the barrier stability in contacts and the influence on patterning. Various electrical data and reliability results are compared to metallizations with W-plugs. The implications of the Al-fill processes on chip design, especially on the size and shape of holes, the pattern density, the possibility of producing stacked contacts/vias and the metal to contact/via overlap are considered also. In an outlook for future developments, e.g. the introduction of low k dielectrics, the inverse metallization architecture with (dual) damascene interconnects and the emerging Cu metallizations, Alfill processes are facing new challenges which will be discussed.