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Sai Boyapati, Kevin Chamness, Frank Smith, Patrick Cowan & John Crowley, Spansion, Inc., Austin, Texas, USA

ABSTRACT

Optimization of copper electroplating profiles is critical for effective copper Back-End-of-Line integration. Plating profiles should be optimized to ensure effective CMP removal rates, consistent end-point detection, and to minimize risks of copper residuals and over-polish. Plating profile optimization and control becomes even more critical when the CMP process is run on two different tool platforms with variable removal profiles and end-point systems. In order to effectively optimize and control plating profile an advanced plating process control system was developed, which ensures that wafers with different pattern densities running across different plating chambers all output plating profiles close to target. This controller eliminates radial thickness profile variability for the copper polishers and significantly reduces the risk of false endpoints and yield-limiting CMP defects. The plating thickness profile controller is based on modulating power supply channels of Semitool’s Raider Electrochemical Deposition system. This paper offers an insight into development and implementation of a fully automated advanced process controller for radial thickness control of ECD copper films.