Low resistivity and fully conformal ZrB2 thin films are deposited by remote plasma chemical vapor deposition using zirconium tetrahydroborate, Zr(BH4)4. The problems with thermal CVD using this precursor – excess B incorporation, oxygen contamination, and high resistivity – are eliminated by injecting atomic hydrogen from a remote microwave plasma source onto the substrate. Using this technique, the films are stoichiometric, have ∼ 40 μΩ-cm resistivity, < 4 at.% oxygen contamination, and are fully conformal in deep trenches and vias. We show that a 50 nm thick ZrB2 film on c-Si (100) prevents Cu in-diffusion after 1 hour annealing at 650°C.