Mark Damage Phenomenon Caused by Superimposed CMP Dishing on Large-Area STI Regions

The phenomenon of mark damage observed at the large-area STI regions of scribe line will cause the overlay shift between different layers during the photo process, and it will further cause amount of residue/scratch defects on the wafer surface during the W CMP process. It has been confirmed that the decease of CMP dishing at the ILD0CMP1 process may be the root cause. The hard mask (SiN) residue on-top of the dummy poly will block the dummy poly remove process. Thus, only partial of the marks can be filled with HKMG and W, causing the mark damage. The partial filled mark will further be the peeling source of tungsten residue at W CMP process, and introduce the scratches on wafer surface.