Effect of mechanical process parameters on chemical mechanical polishing of al thin films

The effects of polishing pressure and abrasive on the chemical mechanical polishing of blanket and patterned aluminum thin films were investigated. The CMP process experiments were conducted using a soft pad and slurry mainly composed of acid solution and Al2O3 abrasive. The result of the blanket film showed that, as the concentration of abrasive in the slurry increased, surface roughness deteriorated but waviness improved. The planarity of the patterned Al films was slowly improved by the CMP when the widths of the gaps between the patterns were relatively small. An attempt was made to find the optimum CMP process conditions by which the patterned Al thin film could be planarized with a fine surface. The most satisfactory film surface was obtained when the applied pressure was low (10 kPa) and the abrasive concentration was relatively high (5 wt.%).