AVS 56th International Symposium & Exhibition
    Applied Surface Science Thursday Sessions
       Session AS1-ThM

Paper AS1-ThM12
The Workfunction Modulation of Al/TiN Bilayer Metal Gate Electrode/High-k Dielectric Gate Stack for NMOS Application

Thursday, November 12, 2009, 11:40 am, Room C2

Session: Advances in Surface Analysis
Presenter: E.J. Jung, Yonsei University, South Korea
Authors: E.J. Jung, Yonsei University, South Korea
C.J. Yim, Yonsei University, South Korea
W.S. Im, Yonsei University, South Korea
C.Y. Kim, Yonsei University, South Korea
D.-H. Ko, Yonsei University, South Korea
M.-H. Cho, Yonsei University, South Korea
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In the selection of metal gate electrode material, workfunction is one of the important properties. However, the workfunction tunning of metal gate is more difficult than that of poly-Si gate electrode. The workfunction of poly-Si gate can be tuned by changing dopants and doping concentration, but the workfunction of metal gate shows fixed value because the workfunction of metal is its own characteristic. Thus many research groups have studied bilayer metal stacking methods for tuning interface workfunction between gate dielectric and electrode. In this work, we studied bilayer metal gate stack using Al/TiN bilayer for NMOSFET application, because Al and TiN are commonly used in conventional CMOS process. The high-k dielectric layer(HfO2) and gate electrode stack is deposited by ALD and in-situ sputtering system, respectively. The thickness of Al/TiN bilayer was measured by TEM analysis. The workfunction of Al/TiN bilayer gate electrode/high-k dielectric gate stack is measured by backside XPS/UPS depth-profile method. This method is not influenced by gate dielectric type and oxide charge variation. The electrical properties are measured by C-V and I-V measurement methods.The workfunction value of Al/TiN bilayer gate stack was changed between workfunction of Al to workfunction of TiN depending on TiN layer thickness.