Highly conductive metal gate fill integration solution for extremely scaled RMG stack for 5 nm & beyond

This paper describes replacement-metal-gate (RMG) fill integration solutions with a cobalt-reflow process combined with a thin barrier layer for future node FinFET and gate-all-around technology. As CMOS scaling continues, the conventional tungsten CVD for RMG runs out of room to fill in a scaled gate trench. The lack of low resistivity W fill causes gate conductance degradation and negatively impacts CMOS performance. A unique Co-fill process combined with scaled barrier thickness is proposed as a new RMG solution. The Co fill significantly improves gate conductance at sub-15nm CD by seam-free gap fill and low resistivity, while achieving target threshold voltage.