Browsing by Author "Shen, Chih-Yen"

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An oxide-buffered BE-MANOS charge-trapping device and the role of Al2O3
(2008)
Lai, Sheng-Chih
;
Lue, Hang-Ting
;
Liao, Chien-Wei
;
Huang, Yu-Fong
;
Yang, Ming-Jui
The role of Al2O3 in MANOS device is critically examined, and we conclude that its primary function is to reduce gate injection during erase operation. By itself, Al2O3 cannot stop charge leakage from the charge-trapping nitride layer. Furthermore, Al2O3 provides no magic during the erase operation, and MANOS erases very slowly through charge de-trapping. BE-SONOS [1], with the band engineered ONO tunneling layers, provides efficient channel hole injection for erase. BE-MANOS [2] should be an ideal combination with fast erase and good reliability. However, it shows poor data retention. By inserting a SiO2 buffer layer between Al2O3 and the SiN storage layer, the oxide-buffered BE-MANOS shows good performance and good reliability. The EOT scalability is also investigated.
Electrical properties of low-temperature-compatible p-channel polycrystalline-silicon TFTs using high-kappa gate dielectrics
(2008-04-01)
Yang, Ming-Jui
;
Chien, Chao-Hsin
;
Lu, Yi-Hsien
;
Shen, Chih-Yen
;
Huang, Tiao-Yuan
In this paper, we describe a systematic study of the electrical properties of low-temperature-compatible p-channel polycrystalline-silicon thin-film transistors (poly-Si TFTs) using HfO2 and HfSiOx high-kappa gate dielectrics. Because of their larger gate capacitance density, the TFTs containing the high-kappa gate dielectrics exhibited superior device performance in terms of higher I-on/I-off current ratios, lower subthreshold swings (SSs), and lower threshold voltages (V-th), relative to conventional deposited-SiO2, albeit with slightly higher OFF-state currents. The TFTs incorporating HfSiOx as the gate dielectric had ca. 1.73 times the mobility (mu(FE)) relative to that of the deposited-SiO2 TFTs; in contrast, the HfO2 TFTs exhibited inferior mobility. We investigated the mechanism for the mobility degradation in these HfO2 TFTs. The immunity of the HfSiOx TFTs was better than that of the HfO2 TFTs-in terms of their V-th shift, SS degradation, mu(FE) degradation, and drive current deterioration-against negative bias temperature instability stressing. Thus, we believe that HfSiOx, rather than HfO2, is a potential candidate for use as a gate-dielectric material in future high-performance poly-Si TFTs.
Properties of Ge films grown through inductively coupled plasma chemical vapor deposition on SiO(2) substrates
(2008)
Yang, Ming-Jui
;
Chien, Chao-Hsin
;
Shen, Chih-Yen
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
In this study, we investigated the physical and electrical characteristics of Ge polycrystalline films deposited directly onto SiO(2)-covered substrates using inductively coupled plasma chemical vapor deposition (ICP-CVD). The pure Ge films that we deposited at a relatively low temperature of 300 degrees C exhibited the same cubic structure, with primarily (111), (220), and (311) orientations identified from X-ray diffraction patterns, as those deposited at 400 degrees C. The use of such a low temperature not only prevented the plasma window of the chamber from overheating but also allowed crack-free, thicker films to be deposited more easily. The ability to deposit Ge films on SiO(2) was closely linked to the hydrogen etching effect, as evidenced by the results obtained using X-ray photoelectron spectroscopy. Although the crystalline characteristics of the low-temperature as-deposited Ge films were somewhat poorer than those obtained at 400 degrees C, subsequent furnace annealing and rapid thermal annealing with a SiN(x) capping layer improved the crystalline quality significantly. These results, taken together with studies of the surface morphologies and dopant activation of the recrystallized Ge films, suggest that ICP-CVD might be a simple, powerful and reliable approach for the fabrication of polycrystalline Ge thin film transistors. (c) 2008 The Electrochemical Society.