Quality Improvement in Ultra-Thin Gate Oxides by Direct-Current Superimposed With Alternating-Current Anodization (DAC-ANO) Compensation Technique
Date Issued
2005
Date
2005
Author(s)
Lin, Yen-Ting
DOI
en-US
Abstract
The scale of the VLSI device has downsized in recent years. The studies of the ultra-thin gate oxide have progressed rapidly due to strict requirement of the gate dielectric. When gate oxide becomes thinner, it is important to lower the leakage current and improve the reliability. This work proposes room temperature anodic oxidation or anodization (ANO) to compensate the defects existed in the oxides grown by rapid thermal oxidation (RTO). By this method, we can get oxide with lower leakage current and better performance. First, we introduce the mechanism of the direct current ANO. Then, compensate the ultra-thin gate oxide with direct-current superimposed with alternating-current anodization (DAC-ANO) technique. We can find the quality of the oxide has been improved.
In the beginning of this work, we introduce study of the gate oxide and the motivation of this thesis. In chapter 1, the experimental setup and the measurement system are also briefly described. In chapter 2, basic theories about the mechanism of the constant voltage ANO of silicon are reviewed. These models suggest possible electrochemical reactions during the ANO. Besides, we utilize different DAC-ANO conditions to compensate the defects in RTO oxides. The conditions including 1. frequency effect, 2. duration effect, and 3. DC amplitude effect are inspected.
Next, in chapter 3, we compare the current densities in inversion region and accumulation region of the RTO oxides with and without ANO-DAC. We found that the leakage current in inversion region is smaller with ANO-DAC compensated, but the current density lowering is slower with time past. We also can get similar current scale with the world level in accumulation region. It confirms the contribution of DAC-ANO.
Subjects
陽極氧化
氧化層
二氧化矽
oxide
anodization
Type
thesis
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