The performance of each CMP Process depends on ability of tools and limitation of its consumables. Materials of CMP Process are roughly separated slurry, pad, conditioning disk, above all, it is a difficult problem to extend its life time of pad and conditioning disk for mass fabrication.
We were motivated to improve its change period. In this work, we focused on improvement of life time of pad and disk of W CMP Process in NAND FLASH Devices. Because that is less than half the change period to another CMP Processes, the improvement of efficiency of mass fabrication is greatly required. The W CMP Process consists of two step processes, the first step is polishing bulk W film and the second step is polishing oxide mold which was patterned by W film. In the first step for removing bulk W film, it is limited by increasing the polishing time according as accumulation processing wafer counts. On the other hand, in the last step for removing oxide mold which was patterned by w film, it is limited by decreasing the pad groove depth because the pad wear rate is extremely high than other CMP Process.
In this work, we studied characteristics of each step in W CMP Process to extend the life time. We focused on the ability improvement of diamond disk to keep the steady removal rate and to reduce the lower pad wear rate. We developed the novel diamond disk as controlling the shape and height of protrusion of diamonds.