Study of grain size and polishing performance of aluminum film as metal gate electrode

摘要

Aluminum (Al) film has been implemented in semiconductor manufacturing such as gap fill in the metal gate trench. Al-induced crystallization and layer exchange processes showed great impact on grain size, and Al grain size was varied by deposition rate and temperature. We investigated grain size of Al deposited on different substrates of p-Si, PEOX and thermal oxide by DC magnetron sputtering. Grain size and film roughness were characterized by SEM and AFM. The film polishing result was correlative with grain size, smoothness and continuous Al film showed better CMP performance, while larger grain size was easier to be pulled out by CMP.