Title: Work function tunability of refractory metal nitrides by lanthanum or aluminum doping for advanced CMOS devices
Authors: Wang, Xin Peng
Lim, Andy Eu-Jin
Yu, Hong Yu
Li, Ming-Fu
Ren, Chi
Loh, WeiYip
Zhu, Chun Xiang
Chin, Albert
Trigg, Alastair David
Yeo, Yee-Chia
Biesemans, Serge
Lo, Guo-Qiang
Kwong, Dim-Lee
Department of Electronics Engineering and Institute of Electronics
Keywords: high-kappa gate dielectric;metal gate;MOSFET;work function tuning;(Hf(x)La(1-x))N(y);(ThAl(1-x))N(y)
Issue Date: 1-Nov-2007
Abstract: A lanthanum (La)-doped HfN is investigated as an n-type metal gate electrode on SiO(2) with tunable work function. The variation of La concentration in (Hf(x)La(1-x))N(y) modulates the gate work function from 4.6 to 3.9 eV and remains stable after high-temperature annealing (900 degrees C to 1000 degrees C, which makes it suitable for n-channel MOSFET application. An ultrathin high-k dielectric layer was formed at the metal/SiO(2) interface due to the (Hf(x)La(1-x))N(y) and SiO(2) interaction during annealing. This causes a slight reduction in the effective oxide thickness and improves the tunneling current of the gate dielectric by two to three orders. We also report the tunability of TaN with Al doping, which is suitable for a p-type metal gate work function. Based on our results, several dual-gate integration processes by incorporating lanthanum or aluminum into a refractory metal nitride for CMOS technology are proposed.
URI: http://dx.doi.org/10.1109/TED.2007.907130
ISSN: 0018-9383
DOI: 10.1109/TED.2007.907130
Volume: 54
Issue: 11
Begin Page: 2871
End Page: 2877
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