Quality Improvement in Al2O3 and HfO2 Dielectrics in MOS Structures by Direct-Current Superimposed With Alternating-Current Anodization (DAC-ANO) Compensation Technique
Date Issued
2011
Date
2011
Author(s)
Chiang, Hsiang-Yao
Abstract
In this work, the improvements of electrical characteristics and reliability with the compensation of direct-current superimposed with alternating-current anodization (DAC-ANO) for the high-k dielectrics are investigated. And two high-k dielectrics are discussed in this work, which are Al2O3 and HfO2. First, Al2O3 is discussed. SiO2 layer was prepared by ANO as the buffer layer, and then Al2O3 was deposited by sputtering under room temperature. After this, the quality of the dielectric layer was compensated by DAC-ANO technique. Compare the samples with and without DAC-ANO compensation, it is easy to find out the sample with DAC-ANO compensation exhibits smaller EOT, i.e., the higher dielectric constant. The leakage current density of sample with DAC-ANO compensation is one order of magnitude smaller than the sample without. Patterned by various areas, it concludes that the leakage current is proportional to the device area, which indicates that the leakage current is uniformly distributed through the whole device instead of edges, and the quality is good. Besides, the reliability tests via TDDB under CVS, CCS, and TZDB are examined. All show that the sample with DAC-ANO compensation is more reliable and stable than the sample without. Secondly, HfO2 is discussed. The fabrication process of HfO2 is like that of Al2O3, so as the result. What’s more, the variations of C-V and J-V curves before and after CCS stress are examined. It shows that the variations of samples with DAC-ANO compensation are much smaller than those of samples without, indicating that the former samples are more stable.
Subjects
quality improvement in
Al2O3
HfO2
Dielectrics
DAC
Type
thesis
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