Impact of Cu contacts on front-end performance: a projection towards 22nm node

In this paper, we investigate the impact of replacing tungsten (W) by a Cu-based contact module. Our experiments show that a 50% reduction in contact resistance can be obtained. This is attributed to both the choice of barrier as well as filling material. An increased drive current is measured on narrow transistors with single contacts. The intrinsic gate oxide reliability is not compromised. Results on demonstrator ring oscillator structures show how the parasitic contribution to the transistor series resistance will increasingly impact circuit delay and power dissipation upon scaling. Cu is presented as a viable solution to postpone these effects by at least one node