Achieving Low V t (≪-0.3V) and Thin EOT (~1.0nm) in Gate First Metal/High-k pMOSFET for High Performance CMOS Applications

A metal/high-k gate stack with P-type band edge effective work function (EWF) of 5.1-5.2 eV is achieved through optimization of a Ru-Al based metal electrode. The critical factors controlling the high EWF values are found to be Al incorporation at the high-k/SiO 2 interface and stabilization of the conductive RuO 2 layer at the electrode/high-k interface. A pMOSFET with a fully optimized RuAl metal electrode system demonstrates a long channel Vt of-0.29 V with EOT= 1.05 nm.