CEO2 Slurry Post Rinse Condition Research in STI CMP Technology

Chemical Mechanical Planarization(CMP) is a kind of removal technology, which combines chemical reaction and mechanical grinding to remove the film deposition and make the surface smooth. Shallow trench isolation(STI) layer is an important process in the CMP process which can affect the step height between STI and AA. Cerium dioxide(CEO2) slurry is widely used in the STI-CMP process for its high oxide to nitride selectivity. Different polish step settings lead to different thickness result. The post-rinse process is as important as main polish step for the cerium dioxide slurry. In this research, different post rinse condition of pressure and polish time is studied to reduce the OCD area variation. OCD pad trend up by ladder from pad rinse polish time trend up. Along with wafer rinse pressure and polish time increase, the OCD pad trend down obviously when the oxide and nitride pad keep stable. The results indicated that suitable STI-CMP post pad rinse and wafer rinse setting can be fixed.