Work function modulation for TiN/Ta/TiN metal gate electrode

In this work, the metal gate effective work function (EWF) modulation for the TiN/Ta/TiN/SiO₂/p-Si(100) structure was investigated. Comparing with TiN/SiO₂/p-Si(100) structure, after annealing the introduction of Ta can effectively reduce the flat band voltage. It is also revealed that although as the thermal budget increases the flat band voltage obviously shifts toward the negative bias direction, the extracted EWF does not vary too much. An EWF of 4.4 eV is confirmed for TiN/Ta/TiN/SiO₂/p-Si(100) structure by C-V measurements, which is almost identical to Al/TiN metal gate electrode.