Reliability of HfO2/ SiO2 Stacked Structure with Dielectrics Prepared by Nitric Acid Oxidation of Hafnium Metal
Date Issued
2012
Date
2012
Author(s)
Chang, Chin-Sheng
Abstract
In this work, the reliability of the HfO2/SiO2 stacked structure with dielectrics prepared by nitric acid oxidation(NAO) at low temperature is investigated and discussed. Two material dielectrics of HfO2 and SiO2 are compared in this work. First, a thin hafnium metal was deposited on the grown SiO2-IL on p-substrate and then the HfO2 were formed by NAO. In order to compare the characteristic of HfO2/SiO2, the conventional SiO2 dielectric was formed. It is found that the leakage current density of the HfO2/SiO2 is lower than SiO2 at same EOT. The fundamental characterization, such as capacitance characteristics, current-voltage characteristics and the interfacial properties of the HfO2/SiO2 and SiO2 will be discussed. It is found that the leakage current can be described by the negative bias region and positive bias region. The current at negative gate bias is proportional to the device area, but the saturation current at positive gate bias region is proportional to the edge perimeter. In addition, the reliability and non-ideal characteristics of the HfO2/SiO2 will are also discussed. We use CVS test to analyze the variations of leakage current and dielectric property, and it is found that the ability of charge trapping of HfO2/SiO2 is larger than SiO2. Moreover, the fringing field effect was considered to explain the variation of saturation current in more detail. It’s shown that the unstable factors of HfO2/SiO2 are of interest. The impact of the electron trapping phenomena observed in HfO2/SiO2 needs to be explored in detail. Finally, we proposed some suggestions for future work.
Subjects
High-k dielectrics
HfO2
Nitric acid oxidation
Fringing field effect
Constant voltage stress
Type
thesis
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