Effective Cu surface pre-treatment for high-reliable 22 nm-node Cu dual damascene interconnects with high plasma resistant ultra low-k dielectric (k = 2.2)

Abstract

Effects of Cu surface treatment (NH 3 plasma irradiation) before the cap dielectric deposition on low-k surface damage and Cu surface cleaning were systematically investigated. From the blanket film surface damage evaluations of porous low-k film with high carbon content and the oxygen removal on blanket Cu film after chemical mechanical polishing (CMP), the optimized NH 3 plasma condition such as high RF power and high pressure exhibited the high efficiency for oxygen removal from the Cu surface without increasing the k-value of low-k film. The low-k/Cu interconnect (line/space = 40/40 nm) for 22 nm-node with the high plasma resistant low-k film and the optimized Cu surface treatment showed longer electro-migration lifetime without large degradation of RC performance. © 2011 Elsevier B.V. All rights reserved.