Effect of friction on CMP in-situ brush cleaning: CFM: Contamination free manufacturing

Post CMP in-situ cleaning plays a critical role in the yield enhancement at sub 14nm semiconductor manufacturing. CMP in-situ cleaning is conducted in the CMP equipment at post polishing. Typically CMP equipment has a brush scrubber cleaner module to remove post polish byproducts, with the fundamental mechanism of particle removal by using physical force. Therefore, high friction and high contact are considered as effective conditions for cleaning wafers post polishing, however, cross contamination effect occurs during this process. Furthermore, the dynamic process of brush cleaning makes it difficult to optimize brush cleaning conditions. In this study, brush torque (friction) is monitored during brush cleaning and effects of frictional behavior of brush on post CMP defects is explored. Experimental results suggest optimized friction force with minimized friction variation during brush cleaning is important to post CMP defect reduction. These results also show torque monitoring is important for brush cleaning efficiency control.