氧离子能量对离子束辅助沉积Al_2O_3薄膜的结构及光学性能的影响

Synthesis and Characterization of Al_2O_3 Films by Oxygen Ion Beam Assisted Reactive Pulsed Magnetron Sputtering

利用氧离子束辅助脉冲反应磁控溅射技术在聚酰亚胺基底上沉积Al2O3薄膜。这项技术在溅射高纯铝靶材的同时利用低能氧离子进行氧化来控制薄膜的化学配比。研究了薄膜沉积过程中离子束辅助的作用以及离子束放电电压对Al2O3薄膜的化学成分、结构、表面形貌、光学性能以及沉积速率的影响。结果发现,离子束放电电压对薄膜的化学成分具有显著影响,当电压增加到200 V,薄膜已基本达到完全化学计量比且薄膜为非晶结构;薄膜表面粗糙度随着离子束放电电压的增加而减小,当电压达到300V时,薄膜具有最小的表面粗糙度;通过对Al2O3薄膜透射谱的测量,分析薄膜的光学特性,获得了薄膜的光学常数随离子束放电电压的变化规律,发现氧离子束辅助沉积的薄膜具有较高的折射系数和较低的消光系数;另外,薄膜的沉积速率在电压增加到300V时达到最大值70 nm/min,是未采用离子束辅助时沉积速率的5倍。

The Al2O3 films were deposited by oxygen ion beam assisted reactive pulsed magnetron sputtering on polyimide substrate.In the newly-developed technique,the pulsed sputtering of Al was synchronized with irradiation of low energy oxygen ions to control the stoichiometry.The impacts of the growth conditions,including the ion beam assistance,ion beam discharge voltage,and deposition rate,on the microstructures and optical properties were evaluated.The films were characterized with X-ray diffraction,X-ray photoelectron spectroscopy,and atomic force microscopy.The results show that the discharge voltage strongly affects the stoichiometry.At 200 V,the amorphous Al2O3 films possess nearly stoichiometric contents.The surface roughness decreased with an increase of the discharge voltage,and minimized at 300 V.The Al2O3 films,grown with the ion beam assistance,outperform the control sample in many ways,such as a better transmittance,a higher refractive index,and a lower extinction coefficient.Besides,the maximized deposition rate,70 nm/min,was obtained at 300 V,5 times faster than that of the conventional technique without ion beam assistance.