退火温度对溅射氧化锌薄膜的影响

Effect of Annealing Temperature on Sputtered ZnO Thin Film

利用射频磁控溅射技术在玻璃基片上制备了高度C轴择优取向的纳米氧化锌(ZnO)薄膜,采用扫描电子显微镜和X射线衍射仪研究了退火热处理温度对ZnO薄膜形貌、结构和内应力的影响规律。结果表明:热处理可以明显改善薄膜的结晶质量,薄膜的晶粒变得致密,尺寸也变得均匀;(002)衍射面的晶面间距和内应力均低于未经热处理的样品;当温度高于450℃以后,薄膜的致密度反而下降,部分晶粒异常长大,随着退火温度的逐渐升高,ZnO薄膜(002)衍射面的晶面间距和内应力先减小,到450℃达到最小值,后又逐渐增大,可见450℃热处理后,薄膜的表面形貌、结构和内应力均得到很大的改善。

Highly C-axis oriented nano-ZnO thin fihn was manufactured by RF-magnetron sputtering technique on a normal glass base. The influence of the heat treatment temperature on the ZnO thin film＇s morphology, microstructure and the residual stress is studied by the Scanning Electron Microscope and X-ray diffraction apparatuses. During the sputtering process, due to various factors, there may be residual stresses in thin films, which are usually to be reduced by heat treatment. It is shown that the films＇ quality can be significantly improved by post-deposition heat treatment. With the heat treatment, the crystal grains become larger, more compact and better-proportioned. Therefore, the surface of the thin film becomes smoother as well as with distinctly fewer holes. The spacing of crystal plane （002） and the residual stress of all the samples are clearly reduced, as compared with those ZnO samples not heat treated. Firstly, the spacings of crystal plane （002） and residual stresses are reduced when the heat treatment temperature is raised and before it reaches the minimum at 450℃. Then, some of the crystal grains grow excessively and the smoothness and the compact level are reduced and the spacings of crystal plane （002） and the residual stress are increased when the annealing temperature rises higher than 450℃. It is concluded that ZnO thin film＇s surface morphology microstructure and residual stresses are significantly improved at the annealing temperature of 450℃, which is very effective in the removal of the residual stress in thin films. Therefore in the process of preparing ZnO thin films by magnetron sputtering technique, oxygen could be introduced into the film by postdeposition heat treatment in the ambient atmosphere.