A High Productivity and Low Topography W CMP Process Enabled by a Dual Endpoint System and Novel Pad Conditioning

The growth of the flash memory market is driving the priority for new cost reduction methods for tungsten CMP. This paper focuses on productivity enhancements that boost the wafer throughput by 82% while achieving good results for topography, rate stability, non uniformity, and defects. A dual endpoint system is described that utilizes both an eddy current sensor for real-time thickness feedback and an optical sensor to signal transition points between materials. The dual endpoint system enables an improvement in platen time balancing and contributes to better erosion results. In addition, a new approach is developed for ex situ pad conditioning that results in a further reduction in cycle time.