Brush cleaning effect on tugnsten voids defect in chemical mechanical polishing: CFM: Contamination free manufacturing

Abstract

Tungsten currently drives middle of line (MOL) metal interconnection for semiconductor manufacturing and chemical mechanical polishing (CMP) has become the process standard for controlling tungsten metal interconnection. Although tungsten CMP has brought a lot of advantages in metal interconnection over decades, tungsten void defect propagated by CMP is still an unsolved issue and its impact is further emphasized as device shrinks to sub 14nm nodes. Corrosion, chemically induced, is the leading mechanism of tungsten void associated with polishing slurry chemistry. Slurry induced corrosion has been further interpreted as oxidation and/or chemical dissolution. However, recent defect analysis reveals tungsten voids are strongly correlated with the CMP in-situ cleaning process. This paper provides a new mechanism for the tungsten void defect focused on the brush cleaning module. Experimental data supports that mechanically assisted tribo-corrosion is a dominant mechanism for the formation of tungsten void defect.