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Temperature control to stabilize the microscale contact surface between the pad and wafer, especially to prevent pad surface degradation, plays an important role in chemical mechanical polishing (CMP) processing of sub-50-nm devices. In this work, we investigated the phenomenon of pad surface hardening for various process temperatures and developed an effective method to minimize changes of the mechanical properties of the pad surface using diamond conditioner. The pad hardening characteristics were measured based on the force-distance (F-D) curve obtained by atomic force microscopy (AFM), and thermogravimetric analysis (TGA). F-D curve data showed that the increase of the elastic modulus with pad usage time at high process temperature was $1.5 times higher than at low process temperature. Also, TGA of a used polishing pad revealed a link between the endothermic peak intensity at 600°C and pad surface hardening. To prevent surface glazing or hardening throughout the lifetime of a pad at high process temperature, the optimum diamond size was investigated. Pad wear was investigated for various diamond conditioners with diamond grit size ranging from 100 lm to 270 lm. The results of pad surface analysis using scanning electron microscopy (SEM) and three-dimensional optical profiling showed that the 210 lm grit size was best for removing deformed layers, with the pad surface remaining consistent during the lifetime of the pad as verified by TGA and the F-D curve. The results of pad surface analysis are important for the design of conditioners that can produce pads with stable dynamic mechanical properties and prolonged lifetime at high process temperature.

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Chemical Mechanical Polishing (CMP) is the most effective planarization process in the integrated circuit fabrication. CMP Process has been applied in various purposes. Different types of surfaces are polished for each object, including oxides, Cu, W and others.  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.