This paper presents a basic structure combined with a film and a substrate to investigate the damage and deformation of thin films and to predict the life time of MEMS.The bifurcation and fracture of thin films under a tensive load were determined by an experiment where the film/substrate structure was used as the specimen.The substrate was a deposited aluminium film with different thicknesses of 100,150 and 200 nm.Then the experiment was initiated using our designed loading device.An OLYMPUS microscope was used to observe the change of the topography of the film surface.The destruction of the film and the corresponding sizes of the load and displacement were recorded.Finally,the effects of film thickness on bifurcation and fracture were obtained by comparing experimental results.These show that the relevant rupture strain increases with the film thickness and the crack density along the loading direction depends on the thickness of the film and the failure stain when there are cracks appear on the film surface.%将薄膜和基底作为一个基本结构来研究薄膜的变形和损坏可预测纳米薄膜器件的使用寿命.本文讨论和研究了薄膜基底结构在拉伸载荷下薄膜出现的分叉和断裂的过程.用在相同厚度的PET基底上沉积不同厚度铝膜的薄膜基底结构作为试件,分别对薄膜厚度为100,150和200 nm的3种不同试件进行了拉伸加载实验,并在OLYMPUS显微镜下观察了薄膜表面的变化情况.分析和对比结果表明:随着薄膜厚度的增加,薄膜出现分叉现象的失效应变也随着增大；当薄膜表面出现裂纹时,裂纹密度的大小取决于薄膜的厚度和加载应变的大小.
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