Method of removing photoresist and reducing native oxide in dual damascene copper process

摘要

A method of manufacturing metallic interconnects. A substrate has a copper line formed therein. An inter-metal dielectric layer is formed over the substrate and the copper line. A patterned photoresist layer is formed over the inter-metal dielectric layer. The inter-metal dielectric layer is etched to form a trench and a contact opening that exposes a portion of the copper line, wherein the contact opening is under the trench. At a low temperature and using a plasma derived from a gaseous mixture N2H2 (H2:4%)/O2, the photoresist layer is removed. Any copper oxide layer formed on the copper line in the process of removing photoresist material is reduced back to copper using gaseous N2H2 (H2:4%). A barrier layer conformal to the trench and the contact opening profile is formed. Copper is deposited to form a conformal first copper layer over the trench and the contact opening. Using the first copper layer as a seeding layer, a copper or a copperless electroplating is carried out so that a second copper layer is grown anisotropically over the first copper layer.