We report on the diffusion barrier properties of chemical-vapor-deposition grown graphene, graphene oxide, and reduced graphene oxide (rGO) for copper metallization in integrated circuits. Single-layer graphene shows the best diffusion barrier performance among the three but it has poor integration compatibility, displaying weak adhesion and poor nucleation for Cu deposition on top of it. Within the allowable thermal budget in the back-end-of-line process, rGO in a range of 1 nm thickness shows excellent thermal stability with suitable integration compatibility at 400 degrees C for 30 min. The diffusion barrier property was verified through optical, physical, and chemical analyses. The use of an extremely thin rGO layer as a Cu barrier material is expected to provide an alternative route for further scaling of copper interconnect technology.