Study on quasi-orthogonal machining of elastomer pad by single-point diamond tool

Abstract

Chemical mechanical polishing (CMP) process has been a popular wafer and thin film planarization process for semiconductor fabrication. In CMP process, a diamond dresser with well-distributed diamond grits is usually applied for regenerating the pad surface topography to maintain the pad polishing capability. This paper describes the fundamentally quasi-orthogonal diamond dressing process by pyramid single-point diamond tools at different grit angles under the fixed down pressure and slow dressing speed for elastomer pad conditioning. Experiments of single-point diamond dressing by both face direction dressing (FDD) and edge direction dressing (EDD) have been performed to investigate the normal force profile and pad surface topography. Experimental results show that FDD generates a higher quality of pad surface with lesser plowing volume and relatively stable pad cutting rate (PCR). Moreover, diamond grit with grit angle of 90° has been found to be most suitable while shifting between EDD and FDD during actual diamond dressing process. Results of this study can be applied to diamond dresserv design and optimization of the pad surface topography uniformity in diamond dressing process for CMP of integrated circuit (IC) production.