Low Stress TiN as Metal Hard Mask for Advance Cu-Interconnect

Abstract

As VLSI technology scaled down to 65nm-node and beyond, BD (Black Diamond) and BD II are widely used as the dielectric. The BD and BD II are porous and soft, the CD (Critical Dimension) will distort and change after etch and line slant without enough support. Metal Hard Mask is an effective solution. And TiN is a good candidate as metal hard mask materials for its high hardness. With traditional PVD (Physical Vapor Deposition) TiN stress is very high. It will cause CD distortion and Cu line void, too. In this paper, new PVD TiN process was developed and the film formation mechanism is studied based on TiN MD diagram. Experiment results show chamber pressure, process Ar flow, sputter power and deposition rate during processing can affect TiN film stress. Low stress TiN film with these new process used as Metal Hard Mask can avoid BD materials distortion and overcome Cu metal void formation due to Metal Hard mask process introduction.