Application Technique of Stacking High-k Dielectric Materials on MOS Device
Date Issued
2012
Date
2012
Author(s)
Yang, Che-Yu
Abstract
The result of this dissertation was divided into two parts. In the first part, it includes anodic oxidation (anodization) process，alternating-current anodization compensation technique and tandem structure to improve high-k dielectrics materials on Si substrate. In the second part, the capacitance- voltage deep depletion phenomenon of HfO2/SiO2 stacks was studied. Firstly, we propose a method that ultra-thin SiO2 was grown on p-type Si substrate by anodization in ambient temperature, then thin Al was deposited on top of SiO2 by thermal evaporation. Thin Al was oxidized to Al2O3 as high-k dielectrics by HNO3 oxidation. In addition, anodization compensation technique was adopted to improve the interface property between Al2O3 and SiO2 and also to compensate the trap. On the other hand, we propose a tandem structure in order to make Al oxidize completely and improve interfacial property thoroughly. Finally, the characteristics of dielectric were analyzed further by using transmission electron microscope (TEM) and energy dispersive X-ray (EDX) spectrometer to know the composition of material. It also provides the information of the physical thickness and related properties of material.
Secondly, we study the capacitance-voltage deep-depletion phenomenon of MOS structure with HfO2/SiO2. It was found that much possibility and larger amount of tunneling current would pass through the deep depletion region. Besides, we observed that the characteristics of charge collection were enhanced under the edge fringing field effect. Carriers of the photoluminescence were largely absorbed at the edge of device especially under illumination. In addition, responsivity R and photosensitivity Ps which were evaluative figure for photo-electrical applications were examined and discussed. The slope κ of photocurrent versus irradiance curves reaches to 1.59 which is feasible for image sensor. These results are attributed to the enhanced edge deep depletion absorption of light due to edge fringing field effect. Further analysis of photoelectrical characteristics was carried out and the energy band diagrams were also given to explain the mechanism of device physics.
Subjects
deep depletion
enhanced fringing field effect
Type
thesis
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