Browsing by Author "Ho, WL"

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Continuous and precise work function adjustment for integratable dual metal gate CMOS technology using Hf-Mo binary alloys
(2005-06-01)
Li, TL
;
Hu, CH
;
Ho, WL
;
Wang, HCH
;
Chang, CY
We demonstrate for the first time a continuous and almost linear work function adjustment between 3.93 and 4.93 eV using HfxMo(1-x) binary alloys deposited by co-sputtering. In view of the process integration, dual work function metal gate technology using Mo and HfxMo(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.
Novel dual-metal gate technology using Mo-MoSix combination
(2006-06-01)
Li, TL
;
Ho, WL
;
Chen, HB
;
Wang, HCH
;
Chang, CY
A novel dual-metal gate technology that uses a combination of Mo-MoSix gate electrodes is proposed. An amorphous-Si/Mo stack was fabricated as a gate electrode for the n-channel device. It was thermally annealed to form MoSix. Pure Mo served as the gate electrode for the p-channel device. The work functions of MoSix and pure Mo gates on SiO2 are 4.38 and 4.94 eV, respectively, which are appropriate for devices with advanced transistor structures. The small increase in the work function (< 20 meV) and the negligible equivalent oxide thickness variation (< 0.08 nm) after rapid thermal annealing at 950 degrees C for 30 s also demonstrate the excellent thermal stabilities of Mo and MoSix on SiO2. Additional arsenic ion implantation prior to silicidation was demonstrated further to lower the work function of MoSix to 4.07 eV. This approach for modulating the work function makes the proposed combination of Mo-MoSix gate electrodes appropriate for conventional bulk devices. The developed dual-metal-gate technology on HfO2 gate dielectric was also evaluated. The effective work functions of pure Mo and undoped MoSix gates on HfO2 are 4.89 and 4.34 eV, respectively. A considerable work-function shift was observed on the high-k. gate dielectric. The effect of arsenic preimplantation upon the work function of the metal silicide on HfO2 was also demonstrated, even though the range of modulation was a little reduced.