(Invited) Nano-Structure Controlled Very Low Resistivity Cu Wires By High Purity Plating and Realization of High Performance Lsis

Abstract

Resistivity increase in nano-level Cu wires is becoming critical issue for high speed ULSIs. In order to lower resistivity of Cu wires, researchers investigated how to reduce the thickness of high-resistivity barrier metals surrounding Cu. However, area percentage of barrier metals to entire Cu wires is less than 20%. This means that thinning barrier metals is not so effective against resistivity increase. Hence, reduction of resistivity in Cu wires is much more important. We have established the new manufacturing process utilizing very high-purity 9N electrolyte and additives to control nano-structures of Cu wires, and realized Cu wires with resistivity 50% lower than those made with conventional process used for practical use. We also have ascertained the reason for getting very low resistivity Cu wires by STEM analyses and first-principle simulation.