Copper contact technology for sub-100nm contacts

This paper addresses the challenges associated with introducing a manufacturable, reliable and cost-effective Cu contact module. We show that Cu can potentially reduce the contact resistance by as much as 50% having a positive performance effect on selected devices and circuits without degrading the front-end reliability. Scalability of the PVD-based Ta(N) Cu barriers proves to be a major challenge upon implementing 65nm node compatible structures because of the need for a thick metal deposit on the contact bottom to prevent Cu silicidation. A hybrid barrier scheme with a PVD Ta bottom and ALD TaN top layer is presented as a possible route to scale Cu contact barriers beyond the 65nm technology node.