Enhancing Yield and Reliability by Applying Dry Organic Acid Vapor Cleaning to Copper Contact Via-Bottom for 32-nm Nodes and Beyond

Via cleaning using gas-phase organic acid has a high potential for improving the reduction capability of copper oxides (CuO), not degrading porous ultra-low-k dielectrics, and reducing processing cost. We applied our via cleaning technique to intermediate and semi-global levels consisting of homogeneous interlayer dielectric architectures based on the 45-nm technology node. The CuO reduction rate was by a factor of 10, which was much higher compared with that using hydrogen. This allowed us to achieve a 100% yield for a mega-scaled via chain. Via chains treated with gas-phase organic acid also showed greater resistance against stress-induced voiding. In addition, we substantially reduced the via cleaning process cost by a factor of 10 compared with the cost of conventional wet chemical cleaning. In addition, organic acid is preferable because it occurs naturally and is thus ecologically friendly.