Gate Workfunction Optimization of a 32 nm Metal Gate MOSFET for Low Power Applications

Abstract

- The feasibility of a midgap metal gate is investigated for a 32 nm MOSFET for low powerapplications. The midgap metal gate MOSFET is found to deliver Ion as high as a bandedge gate if a the performance requirement given in the ITRS roadmap. A process simulation is also run to evaluate the feasibility of the necessary retrograde profile in manufacturing environments. Based on the simulated result, it is found that any subsequent thermal process should be tightly controlled to retain transistor performance, which is achieved using the retrograde doping profile. Also, the bandedge gate MOSFET is determined be more vulnerable to the subsequent thermal processes than the midgap gate MOSFET. A guideline for gate workfunction (Фm) is sugested for the 32 nm MOSFET. .