부산대학교 도서관

W seam is a common defect post WCMP at advanced technology node, which seriously affects the electrical performance of the device and the yield of the chip. The mainly suspected directions are the poor ability of the W gap fill with the CD shrink, or slurry corrosion during the WCMP process. In this paper, we focused the study on influences of WCMP process included oxide loss amount or corrosion caused by slurry soak time increase. First, the different oxide loss amount influence was studied, five wafers with the same incoming condition (gap fill) were processed with the same WCMP recipe body, and given different buffing polish time 20s, 30s, 40s, 50s and 65s for different oxide loss amount. Meanwhile, the five wafer were soaked different time with WCMP slurry. Then the defect was scanned by KLA. The results showed that the number of seam increased significantly when the polish time above 50s. The ILD film thickness of the 5 wafers decreased linearly with the increase of polish time, which proved that seam was buried in the middle of the W plug and gradually exposed on the film surface with the increase of oxide loss amount. By comparison, replace the polish step with slurry soaking step, the seam defect count shows no significant change with the increasing soaking time. The results show that seam is mainly strongly related to the WCMP oxide loss amount instead of WCMP slurry corrosion.