An effective work-function tuning method of nMOSCAP with high-k/metal gate by TiN/TaN double-layer stack thickness

We evaluated the TiN/TaN/TiA1 triple-layer to modulate the effective work function （EWF） of a metal gate stack for the n-type metal-oxide-semiconductor （NMOS） devices application by varying the TiN/TaN thickness. In this paper, the effective work function of EWF ranges from 4.22 to 4.56 eV with diff...

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Published inJournal of semiconductors Vol. 35; no. 9; pp. 162 - 165
Main Author 马雪丽 杨红 王文武 殷华湘 朱慧珑 赵超 陈大鹏 叶甜春
Format Journal Article
LanguageEnglish
Published 01.09.2014
Subjects
Devices
Gates
Intermetallic compounds
Intermetallics
Semiconductors
Solvents
Tin
Tuning
Work functions
功函数
厚度
场效应晶体管
堆叠
氮化钽
调节方法
金属栅极
金属氧化物半导体
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ISSN1674-4926
DOI10.1088/1674-4926/35/9/096001

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Summary:We evaluated the TiN/TaN/TiA1 triple-layer to modulate the effective work function （EWF） of a metal gate stack for the n-type metal-oxide-semiconductor （NMOS） devices application by varying the TiN/TaN thickness. In this paper, the effective work function of EWF ranges from 4.22 to 4.56 eV with different thicknesses of TiN and TaN. The thinner TiN and/or thinner in situ TaN capping, the closer to conduction band of silicon the EWF is, which is appropriate for 2-D planar NMOS. Mid-gap work function behavior is observed with thicker TiN, thicker in situ TaN capping, indicating a strong potential candidate of metal gate material for replacement gate processed three-dimensional devices such as FIN shaped field effect transistors. The physical understandings of the sensitivity of EWF to TiN and TaN thickness are proposed. The thicker TiN prevents the A1 diffusion then induces the EWF to shift to mid-gap. However, the TaN plays a different role in effective work function tuning from TiN, due to the Ta-O dipoles formed at the interface between the metal gate and the high-k layer.
Bibliography:Ma Xueli, Yang Hong, Wang Wenwu, Yin Huaxiang, Zhu Huilong, Zhao Chao, Chen Dapeng, Ye Yianchun（Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China）
TaN; TiA1; Ta-O dipole; effective work function
We evaluated the TiN/TaN/TiA1 triple-layer to modulate the effective work function （EWF） of a metal gate stack for the n-type metal-oxide-semiconductor （NMOS） devices application by varying the TiN/TaN thickness. In this paper, the effective work function of EWF ranges from 4.22 to 4.56 eV with different thicknesses of TiN and TaN. The thinner TiN and/or thinner in situ TaN capping, the closer to conduction band of silicon the EWF is, which is appropriate for 2-D planar NMOS. Mid-gap work function behavior is observed with thicker TiN, thicker in situ TaN capping, indicating a strong potential candidate of metal gate material for replacement gate processed three-dimensional devices such as FIN shaped field effect transistors. The physical understandings of the sensitivity of EWF to TiN and TaN thickness are proposed. The thicker TiN prevents the A1 diffusion then induces the EWF to shift to mid-gap. However, the TaN plays a different role in effective work function tuning from TiN, due to the Ta-O dipoles formed at the interface between the metal gate and the high-k layer.
11-5781/TN
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ISSN:1674-4926
DOI:10.1088/1674-4926/35/9/096001