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

• Published in: Journal 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
• Language: English
• 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
• ISSN: 1674-4926
• DOI: 10.1088/1674-4926/35/9/096001

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.