Study of Conditioner Abrasives in Chemical Mechanical Planarization

Abstract

Chemical Mechanical Planarization (CMP) has emerged as the central technology for polishing wafers in the semiconductor manufacturing industry to make integrated multi-level devices. Both chemical and mechanical processes work simultaneously to achieve local and global planarization. Although extensive research has been carried out to understand the various factors affecting the CMP process, many aspects remain unaddressed. One such aspect of CMP is the role of abrasives in the process of conditioning. Abrasives play an important role during conditioning to regenerate the clogged polishing pads. This research is focused on the study of abrasives in the process of conditioning with a focus on the size of abrasives. With diamond being widely used as an abrasive for conditioning the polishing pad, five different sizes of diamonds ranging from 0.25μm to 100μm were selected to condition the commercially available IC 1000 polishing pad. Properties like pad roughness and pad wear were measured to understand the effect of the abrasive size on the pad morphology and pad topography. In-situ ‘coefficient of friction’ was also monitored on the CETR bench top tester. The final impact was seen in the form of surface defects on the polished copper wafers using optical microscopy.