Mechanism Research and Improvement of AL Scratch Defect Based on MG CMP

In the High-K Last process, MG CMP(Metal Gate Chemical Mechanical Planarization) is required to precisely control the height of the gate and the surface flatness. Defects such as scratches and AL residue may cause short circuits between metals. AL residue can usually be checked through the process window to debug the appropriate process conditions to solve, and scratch defect formation mechanism and possible related factors are many, need to be analyzed according to the actual situation. In this paper, the mechanism of MG CMP scratch is discussed in detail, the source of scratch is investigated according to the characteristics of scratch defects. The defects are improved from many influencing factors, including: CMP recipe optimization; Selection of pad and Conditioner; Optimization of mixing mode of slurry; The influence of Glue Layer thickness combination; Wafer surface especially wafer edge health check and optimization (The optimal result is to add the Wet bevel etch step).