Kuei-Bai Chen

Optimized process for tungsten chemical-mechanical planarization throughput improvement

Tungsten (W) chemical-mechanical planarization (CMP) characteristics are studied systematically for the optimization of process throughput and integration. By the advance surface analysis of tungsten film and polishing pad, the influence and deviation of surface roughness of tungsten film during CMP upon different hardness of pads were investigated. From the results of the experiment, this article attempts to address the key point of non-linear tungsten polishing performance, which is different from the linear polishing phenomena of oxide film. In addition, the phenomena provide the hint to fulfilling the optimized procedure to improve the throughput and cost; that is that multiple steps and pads could be required to resolve the redundant process and promote the throughput. Finally, the marathon test would prove the stability and flexibility of the optimized process. There is over 25% throughput improvement compared with vendors best-known method. The 30% /spl sim/ 50% efficiency of extended pad life and cost of reduced slurry could be enhanced. Details of the developed and optimized theory are demonstrated and appear to be reproducible on tungsten CMP.