Optical annealing and zirconium diboride barrier layers have been optimised for Ni, Au, Ge alloyed ohmic contacts ton-GaAs. Contact resistances of below 0.06 Ωmm with a standard deviation of 0.02 Ωmm were attained across a 50 mm diameter wafer. MESFETs produced using this new technology have shown very good characteristics and minimal degradation after temperature stressing at 300°C for 100 h. Fully-functional yields of 32% were obtained for high speed MSI circuits with 15 mm gate width. The very stable and low contact resistance of these optically annealed zirconium diboride contacts combined with the high yield and good circuit performance demonstrate the suitability of these contacts for use in GaAs high-speed circuits.