Work function (phi(m)) of metal transistor gates was controlled by using Al-Ni and Ni-Ta alloys made through an interdiffusion process, in which stacks of different metals were annealed. In addition to conventional capacitance-voltage measurements for phi(m) evaluation phi(m) uniformity was also measured microscopically. The average phi(m) of the Al-Ni alloy was successfully changed compared to that of pure Al by interdiffusion at 500 degrees C. The, nonuniformity of Al-Ni, however, was problematic. Though Ni-Ta alloys required interdiffusion at a higher temperature of 700 degrees C, the Ni-Ta alloys had better phi(m) uniformity. Thus, the Ni-Ta alloy is a more suitable candidate for use in metal gates of high-integrity transistors.