Dual-Metal-Gate Work Function by Controlling Metal Gate Thickness and Composition

Abstract

A dual-metal-gate stack with an interfacial layer of aluminum nitride and a top layer of iridium was investigated. By controlling the thickness and composition of aluminum nitride, we can effectively control the work function of the metal gate stack. The aluminum-rich aluminum nitride is useful for a lower work function, whereas the top layer of indium is useful for higher work function. Work functions of 5.2 and 4.3 eV can be obtained by controlling the process parameters. The metal stack has good thermal stability up to 950°C for the conventional transistor integration process.