利用X衍射技术测试了物理气相沉积Al2O3纳米薄膜的残余应力,分析了薄膜和基体间的应力测试原理,讨论了沉积温度、沉积速度和薄膜厚度等技术参数对残余应力的影响。实验结果表明,随着沉积温度升高,Al2O3薄膜残余应力值增大;当沉积速度增加时,Al2O3薄膜的残余应力增大,且从拉应力变为压应力;由于热膨胀系数的不同而产生热拉应力和温度不同产生马氏体相变的残余压应力,残余应力值先是随着晶化温度的升高而下降,然后随之而上升,在400℃进行晶化处理时,残余应力值表现为最小;残余应力随着薄膜厚度的增加而不断增大,当薄膜厚度较小时,薄膜残余应力的变化比较平缓,残余应力值较小,有利于提高薄膜界面结合强度。选择合理的薄膜制备参数,能精确地控制薄膜的残余应力,从而达到提高其结合强度的目的。
Residual stresses in Al2O3 nanostructured thin film made by PVD (physical vapor deposition) were measured with XRD (X-ray diffraction) technique. The measurement principle of residual stresses between the thin film and substrate was analyzed, and the technical parameters that effect residual stresses of the film, such as deposition temperature, deposition velocity, crystallization temperature, film thickness, and etc. , were discussed. Experimental results show that residual stresses of Al2O3 film increase with deposition temperature; and residual stresses also increase with deposition velocity and change from tensile stress into compressive stress. Because thermal expansion coefficient difference introduces residual thermal tensile stress, and temperature difference introduces residual compressive stress from martensite phase transition, the residual stresses decrease with crystallization temperature firstly, and then increase. The residual stress reaches its minimum under crystallization treatment at 400℃, which benefits improving the bonding strength of the film interface. Reasonably selecting the parameters for film preparation, the residual stress of the film is accurately controlled, which increases the bonding strength of the film.