Effect of post CMP in-situ cleaning and its optimization on the defect improvement: CFM: Contamination free manufacturing

Abstract

Post CMP defect is a critical process parameter to yield enhancement and device reliability in sub-14nm semiconductor manufacturing as "killing" particle size has shrunk according to device shrinkage. In order to improve defect at post CMP step, CMP has an in-situ cleaning module, commonly composed of megasonic cleaning, brush scrubber cleanings, fluid jet cleaning and their combination. Among the module, brush scrubber cleaning is the most effective method in particle removal due to its physical force. Although many studies have been conducted to optimize particle removal efficiency of brush cleaning, its cross contamination effect has not been considered for the optimization of post CMP defects. In this paper, effect of brush scrubber cleaning on the post CMP defect and its optimization process are explored. In addition to cross contamination effect, equipment aspect of optimization is also investigated. Chemical spray bar position to the wafer and mechanical operation are key controlling factors. Brush motor torque analysis suggests how to optimize brush operation. Experimental results in this paper provide insight into post CMP cleaning optimization.