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

저전력 분야 응용을 위한 32nm 금속 게이트 전극 MOSFET 소자의 게이트 workfunction 의 최적화

The feasibility of a midgap metal gate is investigated for 32nm MOSFET low power applications. The midgap metal gate MOSFET is found to deliver a driving current as high as a bandedge gate one for the low power applications if a proper retrograde channel is used. An adequate design of the retrograde channel is essential to achieve the performance requirement given in ITRS roadmap. In addition, a process simulation is run using halo implants and thermal processes to evaluate the feasibility of the necessary retrograde profile in manufacturing environments. From the thermal budget point of view, the bandedge metal gate MOSFET is more vulnerable to the following thermal process than the midgap metal gate MOSFET since it requires a steeper retrograde doping profile. Based on the results, a guideline for the gate workfunction and the channel profile in the 32 nm MOSFET is proposed.