Nanoindentation at loads from 100 to 750 mN was used to measure the interfacial adhesion energy of sputtered copper thin-films, for which the release of elastic strain energy drives delamination. The as-sputtered films were of four thicknesses, nominally 225 nm, 400 rn, 600 nm and 1000 nm, and were deposited onto Si/SiO2 wafers; one wafer of each two-wafer run was annealed at 600°C for 2 hrs in a nitrogen atmosphere. Subsequently, a nominally 700 nm thick sputtered superlayer of tungsten was deposited over all wafers. The tungsten overlayer was used to promote delamination at the copper-SiO2 interface. The energies for fracture ranged from 1 to 80 J/m2, increasing with increased indentation depth, and a trend of higher adhesion energy for annealed films. The large values of adhesion energy with respect to the thermodynamic work of adhesion are attributed primarily to plasticity and/or void nucleation within the copper film, which appears to be strongly influenced by the constraint of an overlayer.