• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.186-186
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• 2000

After LeComber et al. reported the first amorphous hydrogenated silicon (a-Si: H) TFT, many laboratories started the development of an active matrix LCDs using a-Si:H TFTs formed on glass substrate. With increasing the display area and pixel density of TFT-LCD, however, high mobility TFTs are required for pixel driver of TF-LCD in order to shorten the charging time of the pixel electrodes. The most important of these drawbacks is a-Si's electron mobiliy, which is the speed at which electrons can move through each transistor. The problem of low carier mobility for the a-Si:H TFTs can be overcome by introducing polycrystalline silicon (poly-Si) thin film instead of a-Si:H as a semiconductor layer of TFTs. Therefore, poly-Si has gained increasing interest and has been investigated by many researchers. Recnetly, fabrication of such poly-Si TFT-LCD panels with VGA pixel size and monolithic drivers has been reported, . Especially, fabricating poly-Si TFTs at a temperature mach lower than the strain point of glass is needed in order to have high mobility TFTs on large-size glass substrate, and the monolithic drivers will reduce the cost of TFT-LCDs. The conventional methods to fabricate poly-Si films are low pressure chemical vapor deposition (LPCVD0 as well as solid phase crystallization (SPC), pulsed rapid thermal annealing(PRTA), and eximer laser annealing (ELA). However, these methods have some disadvantages such as high deposition temperature over $600^{\circ}C$, small grain size (<50nm), poor crystallinity, and high grain boundary states. Therefore the low temperature and large area processes using a cheap glass substrate are impossible because of high temperature process. In this study, therefore, we have deposited poly-Si thin films on si(100) and glass substrates at growth temperature of below 40$0^{\circ}C$ using newly developed high rate magnetron sputtering method. To improve the sputtering yield and the growth rate, a high power (10~30 W/cm2) sputtering source with unbalanced magnetron and Si ion extraction grid was designed and constructed based on the results of computer simulation. The maximum deposition rate could be reached to be 0.35$\mu$m/min due to a high ion bombardment. This is 5 times higher than that of conventional sputtering method, and the sputtering yield was also increased up to 80%. The best film was obtained on Si(100) using Si ion extraction grid under 9.0$\times$10-3Torr of working pressure and 11 W/cm2 of the target power density. The electron mobility of the poly-si film grown on Si(100) at 40$0^{\circ}C$ with ion extraction grid shows 96 cm2/V sec. During sputtering, moreover, the characteristics of si source were also analyzed with in situ Langmuir probe method and optical emission spectroscopy.

• The Journal of the Petrological Society of Korea
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• v.11 no.3_4
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• pp.259-270
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• 2002

A small granodiorite-quartz monzonitic stock containing sericitic and propylitic alteration assemblages hosts a Cu-W breccia-pipe deposit in the southeastern Cyeongsang basin. The mineralized breccia-pipe contains angular to subangular brecciated fragments of granitic rocks showing clast-supported textures. An assemblage of quartz, tourmalines, sulfide minerals (mainly chalcopyrite, arsenopyrite and pyrrhotite) and calcite was precipitated as a hydrothermal cement between the brecciated fragments. A tourmaline aureole surrounds the breccia pipe. Extensive tourmalinization of the granitic rocks near and within the pipe and no tourmalinization in the sedimentary and volcanic rocks. The tourmalines are marked by Fe-rich, black charcoal-like schorl (80 mol% schorl relative) nearer the schorl-dravite solid solution. The chemical changes in the hydrothermal fluid are reflected by variations in compositional Boning from cores to rims. They generally contain cores with low values of Fe/(Fe+Mg) and high values of Na/(Na+ca) relative to rims. This is because of an increase Fe and Ca contents toward rims. The main trend of these variations is a combination of the exchange vectors Ca(Fe, Mg) $(NaAl)_{- }$ $_1$ and $Fe^{3}^{+}$ $Al_{[-10]}$ $_1$ It is thought that boiling causes the loss of $H_2$ into the vapor phase resulting in the oxidation of Fe in the aqueous phase. pH of the melt would be one of important controlling factors for the tourmaline stability. The tourmalines could be precipitated when the system evolved to the acidic hydrothermal regime as most hydrothermal brines and acidic gases exsolved from the magma. The Ilgwang tourmaline crystallization is products of hypogene orthomagmatic hydrothermal processes that were strongly pipe-controlled.