| Summary: | 碩士 === 長庚大學 === 電子工程學系 === 98 === In this thesis, we added Ti to the Tb2O3、Y2O3、Gd2O3 film to form Ti-doped high-k dielectrics in place of traditional SiO2 insulator for applying in thin film transistor process. These high-k materials were deposited on polysilicon by RF sputtering and combined with the post-RTA treatment to remove defects and passivate the interface states between the high-κ materials and the bottom polysilicon in order to improve the characteristics of the poly-oxide dielectrics.
It’s well known that there are existed some drawbacks such as interface roughness, interface trap states and grain boundary trap states in polycrystalline silicon. Therefore, it’s necessary to improve polyoxide quality such as high gate leakage, low breakdown electric field, large charge trapping rate and low charge-to-breakdown. In our research, it can be found that doping Ti in the Tb2O3、Y2O3、Gd2O3 film can form Tb2Ti2O7、Y2Ti2O5 or Gd2Ti2O7 after rapid thermal annealing (RTA), which have higher dielectric constant and better electrical characteristics. After thermal annealing, it not only can passivate the trap defects and interface states between the high-k dielectric and polycrystalline silicon, but also the Ti-doped high-k dielectric can have high dielectric constant and suppress the generation of interfacial layer to reduce leakage current and form the stronger bonding to improve the characteristics of devices such as higher breakdown electric field, smaller gate voltage shift and larger charge-to-breakdown.
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