Comparison of Missing Metal Defect Formation on He In-Situ and Furnace Annealed Electroplated Copper Films

Copper electrochemical plating (ECP) has contributed to a significant rise in both systematic and random defects. A "missing metal" defect is a critical problem for the 0.13*#x003BC;m node and normally will only be detected after chemical-mechanical polishing (CMP). Meanwhile, this defect is also strongly dependent on post-electrochemical plating. In addition, Cu films characteristics depend critically on anneal, plating conditions and bath chemistry. This paper presents a comparison of missing metal defect formation on samples annealed using furnace versus He in-situ anneal. All copper deposition and He in-situ anneal processing was performed on the
Applied

Materials

SlimCell^™
ECP system. A post-ECP He in-situ anneal processing was carried out over a 60°C to 180°C temperature range, with anneal duration times ranging from 6 s to 2 hours. In the He in-situ anneal process, the wafers began to be ramped at over 100°C with less than a minute soak time. For the furnace anneal, the wafers were loaded for almost an hour with less than 200°C soak temperature. After the annealing process, Cu CMP partial polish was applied as a final step before analyzing the wafers with scanning electron microscope (SEM). Our conclusion is that the missing metal defect levels for furnace and He in-situ anneal are found to be comparable and have no correlation with reflectivity or stress. In this paper we compare the capabilities and performance of different types of annealing processes and their impact on missing metal defect (MMD), an in-line technique developed to reduce total defect count. We will also present correlations of these defects to plating and anneal process parameters.