Impact of Nanosecond Laser Anneal on PVD Ru Films

A novel nanosecond (ns) laser anneal (multiple laser shots at sub-melting low laser energy) was employed to reduce the blanket sheet resistance of Ru thin films deposited by physical vapor deposition (PVD). The laser anneal was conducted after PVD Ru deposition and then followed up with a standard 400°C anneal in a forming gas environment. Blanket sheet R decreased by 30% for the laser + furnace annealed Ru films, whereas the drop for just 400°C furnace annealed Ru films was only 18%. Multiple laser exposures at an optimized laser fluence was identified as a key factor in enabling this benefit at BEOL compatible thermal budget suitable for scaled-down Ru interconnects.