Impact of Bevel Condition on STI CMP Scratch

Shallow trench isolation chemical mechanical polishing (STI CMP) technology has been widely applied in the fabrication of ultra large scale integrated (ULSI). In STI CMP, the defect, topography control, thickness uniformity and so on are all so critical, especially, scratch defect is the major problem. Pad, disk, agglomerated slurry particles and incoming particles are the main sources of the tiny scratch. In this paper, we conducted a detailed study on the influence of one-step AA pull back process on the bevel region of wafer, which led to the introduction of incoming particles and ultimately led to the increase of STI CMP scratch. It was find that by adding a brush bevel process before STI CMP can reduce the scratch by 66%.