Cu diffusion barrier: Graphene benchmarked to TaN for ultimate interconnect scaling

Abstract

The advantages of graphene diffusion barrier are studied and benchmarked to the industry-standard barrier material TaN for the first time. Even when the wire width is scaled to 10 nm, the effective resistivity of the Cu interconnect is maintained near the intrinsic value of Cu using a 3 Å single layer graphene (SLG) barrier. In the time dependent dielectric breakdown (TDDB) test, 4 nm multi-layer graphene (MLG) gives 6.5X shorter mean time to fail (MTTF) than 4 nm TaN. However, when the barrier thickness is reduced, 3 Å single-layer graphene (SLG) gives 3.3X longer MTTF than 2 nm TaN, showing that SLG has better scaling potential. The influences of SLG grain size and various transfer methods are presented for further improving the SLG barrier performance.