LAUSR

Tungsten contact chemical mechanical polishing is a critical process in advanced node semiconductor device manufacturing that enables metal interconnection. It is essential for device performance, and any defects caused by the tungsten CMP process have a direct effect on product yield. Among these defects, the highest yield killer is microscratches. Microscratches are a well-studied CMP produced defect; however, this paper provides a new look at controlling microscratches in a manufacturing environment. Specifically, the bulk tungsten slurry is the cause for nearly all scratches at tungsten contact CMP. This paper studies the effects of abrasive size on defect performance and suggests causes for variation in size of slurry particles outside of manufacturing variability. While tungsten removal rate is not affected by abrasive size, the defectivity performance relies heavily on the ability to remove large particles from suspension. Current filtration solutions are not completely effective in preventing large particles from contacting the wafer, so the burden falls on preventing their formation. Factors such as age of material, storage temperature and agitation induced agglomeration will be studied to characterize the effects on particle size. Volume manufacturing data will be used to support the claims made in this paper.