Details

Autor(en) / Beteiligte

• Kadoshima, M.
• Matsuki, T.
• Miyazaki, S.
• Shiraishi, K.
• Chikyo, T.
• Yamada, K.
• Aoyama, T.
• Nara, Y.
• Ohji, Y.

Titel

Effective-Work-Function Control by Varying the TiN Thickness in Poly-Si/TiN Gate Electrodes for Scaled High- k CMOSFETs

Ist Teil von

• IEEE electron device letters, 2009-05, Vol.30 (5), p.466-468

Ort / Verlag

New York, NY: IEEE

Erscheinungsjahr

2009

Quelle

IEEE Xplore

Beschreibungen/Notizen

• We have investigated the controllability of the effective work function (phi m,eff ) of TiN as a work-function-determining metal (WFM) for various gate-electrode structures in HfSiON MOSFETs. phi m,eff was controllable from 4.7 to 4.44 eV by changing the TiN thickness from 30 to 2 nm in poly-Si/TiN gate electrodes, without any distinct increase in EOT. Therefore, thin-TiN and thick-TiN WFMs are preferred for the reduction in threshold voltage in nMOSFETs and pMOSFETs with poly-Si/TiN gate electrodes, respectively. A similar controllability was not observed with W/TiN gate electrodes but was evident with W/TaSiN/TiN gate electrodes. This means that controllability is a characteristic of metal gate electrodes with a structure including a Si-rich layer (such as poly-Si and TaSiN)/TiN. It is considered that Ti suboxides, which increase phi m,eff as a thin insulator with negative fixed charges, or interface dipoles in the TiN/HfSiON interface, are reduced by oxidation of the Si-rich layer, producing the required result of phi m,eff decrease when the TiN thickness becomes as thin as 2 nm.