Influence of abrasive morphology and size dispersity of Cu barrier metal slurry on removal rates and wafer surface quality in chemical mechanical planarization

Abstract

Chemical mechanical planarization (CMP) is widely used in the fabrication of semiconductor devices to achieve global planarization. The overall CMP performance is affected by material removal rates. Defects and dishing generated on wafers during CMP increase device failure rate. In the present study, we examined the effect of silica abrasive morphology and size dispersity on removal rates and surface morphologies of wafers. The slurry composed of polydispersed irregular silica (PI) showed the highest overall removal rates (for interconnection, barrier, and dielectric materials), although the removal rate of the slurry consisting of polydispersed spheric silica for the interconnection material (Cu) was higher than that of PI. The overall removal rate increased with increasing silica concentration. The lowest surface roughness was achieved by polydispersed irregular abrasives. The surface roughness increased by increasing the concentration of abrasives. The polydispersed irregular abrasives also allowed for the lowest defects. Small dishing values were observed for the slurry systems manufactured in this study, indicating that the abrasive morphology seldom influenced the dishing behaviors. The understanding of morphology and size dispersity can be beneficial to CMP global planarization with high removal rates and low defects.