| Summary: | 博士 === 長庚大學 === 電子工程學系 === 99 === We investigated of the hafnium (Hf) base metal nitride (HfNx and HfxMoyNz) for metal gate electrode application in this dissertation. For HfNx gate electrode with SiO2 gate dielectric MOS capacitors, the effective work function (Φm,eff) of HfNx can be tuned from 4.1 to 4.55 eV by controlling N2 flow ratios. Moreover, the low effective work function (Φm,eff ~ 4.17 eV) and high effective work function (Φm,eff ~5.16 eV) can obtained for HfxMoyNz/SiO2 MOS capacitor with N2 flow ratios of 0 and 12%, respectively.
The threshold voltage (Vth) of HfxMoyNz/SiO2 pMOSFETs devices can be adjusted from -1.4 to -0.4 V by increasing nitrogen concentration in the HfxMoyNz metal gate. However, this adjustment degrades the negative bias temperature instability (NBTI) and the device electrical properties. Self-aligned fluorine ion implantation (SAFII) was introduced to improve NBTI reliability and electrical properties of HfxMoyNz/Gd2O3 pMOSFETs device. From the results, we observed that the improvement in the interface trapped charge densities (Nit) and the oxide trapped charge densities (Not). Base on the NBTI chemical reacting species model, the dominant mechanisms for NBTI degradation in the cases of low and high nitrogen percentage samples were oxide trapped charge densities (Not) and interface trapped charge densities (Nit), respectively.
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