Ali Kamran, Choi Kyung-Hyun
Department of Mechatronics Engineering, Jeju National University , Jeju 690-756, Korea.
Langmuir. 2014 Dec 2;30(47):14195-203. doi: 10.1021/la503406v. Epub 2014 Nov 19.
The Al2O3 thin films deposition through conventional ALD systems is a well-established process. The process under low temperatures has been studied by few research groups. In this paper, we report on the detailed study of low-temperature Al2O3 thin films deposited via a unique in-house built system of roll-to-roll atmospheric atomic layer deposition (R2R-AALD) using a multiple-slit gas source head. Al2O3 thin films have been grown on polyethylene terephthalate substrates under a very low-temperature zone of room temperature to 50 °C and working pressure of 750 Torr, which is very near to atmospheric pressure (760 Torr). Al2O3 thin films with superior properties were achieved in the temperature range of the ALD window. An appreciable growth rate of 0.97 Å/cycle was observed for the films deposited at 40 °C. The films have good morphological features with a very low average arithmetic roughness (Ra) of 0.90 nm. The films also showed good chemical, electrical, and optical characteristics. It was observed that the film characteristics improve with the increase in deposition temperature to the range of the ALD window. The fabrication of Al2O3 films was confirmed by X-ray photoelectron spectroscopy (XPS) analysis with the appearance of Al 2p, Al 2s, and O 1s peaks at the binding energies of 74, 119, and 531 eV, respectively. The chemical composition was also supported by the Fourier transform infrared spectroscopy (FTIR). The fabricated Al2O3 films demonstrate good insulating properties and optical transmittance of more than 85% in the visible region. The results state that Al2O3 thin films can be effectively fabricated through the R2R-AALD system at temperatures as low as 40 °C.
通过传统的ALD系统沉积Al2O3薄膜是一个成熟的工艺。低温下的该工艺仅有少数研究小组进行过研究。在本文中，我们报告了通过一种独特的内部构建的卷对卷大气原子层沉积（R2R-AALD）系统，使用多缝气体源喷头对低温Al2O3薄膜进行的详细研究。Al2O3薄膜已在聚对苯二甲酸乙二酯基板上，在室温至50°C的极低温区域以及750托的工作压力下生长，该压力非常接近大气压（760托）。在ALD窗口温度范围内获得了具有优异性能的Al2O3薄膜。对于在40°C下沉积的薄膜，观察到可观的生长速率为0.97 Å/循环。这些薄膜具有良好的形态特征，平均算术粗糙度（Ra）非常低，为0.90 nm。薄膜还表现出良好的化学、电学和光学特性。观察到随着沉积温度升高到ALD窗口范围内，薄膜特性得到改善。通过X射线光电子能谱（XPS）分析，在结合能分别为74、119和531 eV处出现Al 2p、Al 2s和O 1s峰，证实了Al2O3薄膜的制备。傅里叶变换红外光谱（FTIR）也支持了其化学成分。制备的Al2O3薄膜表现出良好的绝缘性能，在可见光区域的光学透过率超过85%。结果表明，通过R2R-AALD系统可以在低至40°C的温度下有效地制备Al2O3薄膜。
