Process integration of TDEAT-based MOCVD TiN as diffusion barrier for advanced metallization

摘要

Decreasing contact geometry imposes stringent requirements on barrier metals in providing good barrier against Al-Si interdiffusion. The challenge for the barrier metal technologies is to develop a process to give conformal and thermally stable barrier metal film at low enough temperature, so as to be applicable to multilevel interconnect metallization. Collimated Ti/TiN process results in overhanging at the top of the contact and conformality is no way possible. CVD (Chemical Vapor Deposition) process has been demonstrated to provide excellent conformality and is definitely an attractive option for sub-half micron technology. Process integration of Metalorganic CVD (MOCVD) TiN using TDEAT (Tetrakis(diethylamido) Titanium) precursor and NH$-3$/ as co-reactant, together with PVD Ti has been demonstrated as diffusion barrier at contact level for advanced metallization. Two process pressure and temperature regimes of deposition were evaluated. The 30 Torr, 300$DGR@C higher step coverage process and the 10 Torr, 425$DGR@C lower resistivity were under study. All barrier stacks went through vacuum break before CVD TiN deposition. RTP was carried out either right after PVD Ti deposition or after CVD TiN deposition. Its impact on contact resistances and junction leakages upon thermal stress were investigated. In addition, the impact of Ti wetting layer on electrical parameters and barrier integrity, which is essential for Al planarization on small geometry contacts, was also studied.