Tungsten and Metal Liner Residues

During W CMP, if the WIWNU is poor, some areas may clear sooner than the others. This may leave tungsten and/or tungsten linear residues (Fig. 17.20). 

FIGURE 17.21 The W residue on this image is pattern dependent. The W structure is above the edge of some underneath arrays of structures. These arrays have different topography that still remains after PMD deposition and even after not 100% efficient PMD CMP. 

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