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

作　　者：马雪丽 杨红 王文武 殷华湘 朱慧珑 赵超 陈大鹏 叶甜春 

机构地区：[1]Institute of Microelectronics, Chinese Academy of Sciences

出　　处：《Journal of Semiconductors》2014年第9期162-165,共4页半导体学报（英文版）

基　　金：Project supported by the Important National Science & Technology Specific Projects(No.2009ZX02035);the National Natural Science Foundation of China(Nos.61176091,61306129)

摘　　要：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.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.

关 键 词：TAN TiA1 Ta-O dipole effective work function 

分 类 号：TN386[电子电信—物理电子学] TN383.1