Continuous and precise work function adjustment for integratable dual metal gate CMOS technology using Hf-Mo binary alloys

We demonstrate for the first time a continuous and almost linear work function adjustment between 3.93 and 4.93eV using Hf_xMo_(1-x) binary alloys deposited by co-sputtering. In view of the process integration, dual work function metal gate technology using Mo and Hf_xMo_(1-x) formed by metal intermixing was proposed. Work function values were verified to be a function of the thickness ratio and accurate work function adjustment can be possible. Furthermore, one can be allowed to get around the thermal stability issue by choosing an appropriate total metal thickness corresponding to the thermal budget subsequent to gate deposition, since the thermal budget required for metal intermixing depends on the total metal thickness.