Wear Phenomena in Abrasive-Free Copper CMP Process

The role of process parameters in wear mechanisms of abrasive-free copper chemical mechanical planarization (CMP) process has been investigated in this study. Qualitative analyses were performed to figure out the wear mechanisms by using scanning electron microscopy, atomic force microscopy, and energy-dispersive X-ray. Also, quantitative analysis was performed using the material removal rate model of abrasive-free CMP process. Chemical etching (corrosive wear), fatigue wear, particle adhesion, and abrasion wear have been found as the wear mechanisms in abrasive-free copper CMP, and sliding-induced chemical etching has been established as the dominant wear mechanism by both qualitative and quantitative analysis. However, increase of pressure and decrease of relative velocity and slurry flow rate give the dominance of chemical wear, and vice versa. In addition, some sort of incomplete growth and faceting of cupric layer have been observed on the wafer at some polishing conditions.