| 초록 |
Amorphous oxide channel layers with high mobility and stability can be deposited on these substrates at relatively low temperatures for the fabrication of thin-film-transistors (TFTs), as compared to the conventional polycrystal Si TFTs. Meanwhile, the amorphous Si layers grown at low temperatures exhibit uniform electrical characteristics on a large area, but their low field effect mobility and electrical instability under bias stress and different environmental gases hinder their use in commercial products. Low temperature polycrystalline Si TFTs exhibit a comparatively high field effect mobility and better electrical stability. However, there are still significant issues related to their poor uniformity over a large area and high process temperature. Surprisingly, amorphous oxide TFTs fabricated by relatively low-temperature growth and thermal annealing on glass substrates have been reported to show excellent TFT performance for transparent display. But area is larger than, driving power is increased. To reduce this power, high-K such as HfO2, Al2O3 and Si2N4 can be used. High-K materials have a low leakage current and at least equivalent capacitance, performance and reliability. This study demonstrated the effect of various growth temperature of Al2O3 by atomic layer deposition (ALD) on the TFT device performance. ALD is a deposition technique that is deposited high conformal, defect-free dielectric layers at low temperature comparison with other deposition equipment. This process has advantage of low-cost, compatible with variation in substrates made from different materials and with irregular shapes and very simple. After ITO with gate metal was cleaned acetone, alcohol, DI-water, ITO was wet chemical etching (HCl : HNO3 = 3:1). Al2O3 was deposited by ALD with various growth temperatures and lift-off. a-InGaZnO channel layer was deposited by rf magnetron sputtering, where RF power is 150W. And working pressure is 3m Torr, at O2/Ar (1/29 sccm) atmosphere. The electrodes were formed with electron-beam evaporated Ti (30 nm) and Au (70 nm) bilayer. TFT devices were heat-treated in a furnace at 300 oC and nitrogen atmosphere for 1hour by rapid thermal anneal treatment (RTA). The electrical properties of the TFTs were measured using a probe-station (4145B), and LCR meter. |
