Development of Control Method for Residual Stress in Thin Film by Ultrasonic Substrate Vibration

在这项研究中，一个优秀的和简单的方法来控制残余应力的建议。在此，使用与成膜条件无关的基板振动。在该工艺中，在沉积过程中仅通过PZT振动衬底。测试了TiN、Ti、Cu、Al、Si和C薄膜的残余应力变化。同时，还揭示了残余应力与材料磨损寿命、硬度、弹性系数等力学性能之间的关系。通过对薄膜微观结构的观察，探讨了薄膜残余应力变化的机理：1）薄膜残余应力随衬底振动而变化，衬底振动受偏压控制; 2）薄膜残余应力的变化与薄膜厚度和衬底晶体结构无关; 3）薄膜残余应力随衬底振动而变化当残余应力由压应力变为拉应力时，Ti和TiN薄膜的硬度值均降低。Ti和TiN薄膜的磨损寿命均随残余应力的降低而提高。5）随着振动振幅的增大，晶粒尺寸减小，相邻晶粒在聚并点处的差距增大。这是因为晶粒尺寸的减小刺激了由微晶聚结引起的拉伸应力的发展，而柱状结构中的间隙的增加导致膜中的收缩，从而增强了拉伸应力。6）将该方法应用于具有TiN中间层的CN膜。CN/TiN薄膜的残余应力降低，CN薄膜表现出较强的结合强度。

In this study, an excellent and simple method for controlling the residual stress is proposed. Here, substrate vibration that is independent of the deposition condition is used. In this process, only substrates are vibrated by PZT during the deposition. The changes of residual stress are tested on TiN,Ti,Cu,Al,Si and C films. Further more, the relationship between residual stress and the mechanical properties such as wear life hardness and elastic coefficient are clearly shown. The mechanism for change of residual stresses was also investigated by the observations of microstructures in films.1)The residual stresses of the crystalline films were changed upon the substrate vibration that was controlled by the bias voltage2)Changing residual stress was independent on film thickness and crystal stricture of the substrate3)The hardness values decreased when the residual stress was changed from compressive to tensile for both Ti and TiN films.4)The wear life was improved when the residual stress was decreased for both Ti and TiN films.5)The grain size decreased and the gap between adjacent crystals at the point of coalescence increased with an increase of vibration amplitude. This is because the decrease in grain size stimulates the development of tensile stress caused by crystallite coalescence while an increasing gap in the columnar structure causes contraction in the film enhancing tensile stress.6)This method was applied to CN films with TiN interlayer. The residual stress of CN/TiN film was decreased and the CN films showed strong adhesive strength.