薄膜厚度对HfO2薄膜残余应力的影响

HfO2薄膜是用电子束蒸发方法制备的，利用ZYGO干涉仪测量了基片镀膜前后曲率半径的变化，计算了薄膜应力。对样品进行了XRD测试，讨论了膜厚对薄膜残余应力的影响。结果发现不同厚度HfO2薄膜的残余应力均为张应力，应力值随薄膜厚度的增加而减小，当薄膜厚度达到一定值后，应力值趋于稳定。从微观结构变化对实验结果进行了分析，发现微结构演变引起的本征应力变化是引起薄膜残余应力改变的主要因素。

HfO2 thin films were prepared by electron beam evaporation. The residual stress was measured by viewing the substrate deflection using ZYGO interferometer. The microstructure of the HfO2 thin films was inspected by X-ray diffraction (XRD). The results show that the stress is tensile and the value of the residual stress decreases with the increase of the thin film thickness, and residual stress becomes stable when the film thickness reaches a certain value. The interplanar distance of the thin film increases with the increase of the thin film thickness, which is corresponding to the variation of the residual stress. The evolution of the residual stress may be due to the variation of the microstructure as the increasing of the thin film thickness.