The effect of slurry viscosity on chemical–mechanical polishing of silicon wafers

The chemical–mechanical polishing (CMP) process planarises wafers with a high degree of success; however, many of the fundamental mechanisms of the process are yet to be fully understood and defined. Much of the theoretical analysis to date has focused on kinematics [J. Electrochem. Soc. 138 (6) (1991) 1778], von Mises stress distributions [CIRP Ann. Manuf. Technol. 48 (1) (1999) 143; Thin Solid Films 308–309 (1997) 533; J. Electrochem. Soc. 144 (3) (1997) 1121] and hydrodynamic aspects [J. Electrochem. Soc. 141 (6) (1994); J. Electrochem. Soc. 146 (2) (1999) 761]. This paper is concerned with the hydrodynamic aspect of CMP. It details, both experimentally and theoretically, how changes in slurry viscosity change removal rates and influence the contact mode between the wafer and the polishing pad.