大气环境下多晶硅薄膜的疲劳性能

FATIGUE PROPERTY OF POLYSILICON THIN FILMS IN AMBIENT ENVIRONMENT

为评估多晶硅薄膜材料的加载可靠性,发展一种新型多晶硅薄膜疲劳性能测试实验系统,利用片外测试方法研究多晶硅薄膜在大气环境下的拉伸疲劳特性。实验试件采用MEMS(micro-electro-mechanical systems)工艺制造,具有相同的长度、厚度和不同的宽度。每个加载条件下重复10次实验,应用Weibull方法对疲劳实验数据进行处理,得到0.35GPa～0.70GPa应力幅值范围内5个应力水平下多晶硅薄膜拉伸疲劳的S—N曲线。研究表明,多晶硅薄膜的疲劳寿命随着交变载荷幅值的减小而增大,二者呈对数线性关系。该结果可以直接用于多晶硅薄膜材料MEMS器件的可靠性设计。

In order to evaluate the reliability of loaded polysilicon thin films, a novel experimental system was developed to measure the fatigue property of polysilicon thin films. Using out-chip test method, the fatigue property of polysilicon thin films in ambient environment was successfully measured. The tested specimens were fabricated in MEMS （micro-electro-mechanical systems） process, which were same in length and thickness, but were different in width. In each load condition, the same experiment was carried out for 10 times. Finally the experimental data were processed with Weibull method to obtain the S- N curve of polysilicon thin films on 5 different stress levels in the peak stress range of 0.35 GPa - 0.70 GPa. The results showed that the fatigue life of polysilicon thin films increased with the decrease in the peak stress of the alternating load, and they were logarithmically linear, which might be helpful to the reliability design of polysilicon MEMS devices.