Utilizing On-Chip Testing and Electron Microscopy to Study Fatigue and Wear in Polysilicon Structural Films
Utilizing On-Chip Testing and Electron Microscopy to Study Fatigue and Wear in Polysilicon Structural Films
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利用片上测试和电子显微镜研究多晶硅结构薄膜的疲劳和磨损
DOI：
10.1557/proc-821-p2.5
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
R. Ritchie
中科院分区：
文献类型：
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作者：
D. Alsem;E. Stach;C. Muhlstein;M. Dugger;R. Ritchie
磨损和疲劳是决定微电子机械系统可靠性的重要因素。虽然MEMS的可靠性受到了广泛的关注，但导致这些失效模式的物理机制尚未确定。在我们的工作中，我们使用了芯片测试方法和电子显微镜观察相结合的方法来研究这些机制。我们以前的研究表明，多晶硅结构薄膜中的疲劳是一个‘反应层’过程的结果，在这个过程中，高应力导致缺口悬臂梁根部的自然氧化物在室温下机械增厚，随后经历水分辅助开裂。最近一次制造过程中的器件在环境空气中疲劳，以表明我们在早期实验中观察到的释放后氧化层厚度不是特定批次多晶硅的人工制品。真空中的新数据表明，当释放后的氧化物由于缺乏氧气而被阻止生长时，这些硅膜不会表现出疲劳行为。此外，我们正在使用多晶硅MEMS侧壁摩擦试验样品在微观尺度上研究滑动磨损的活跃机制。特别是，我们在真空和扫描电子显微镜的现场实验中进行了开发，目的是最终确定导致磨损发展和碎片产生的机制。
Wear and fatigue are important factors in determining the reliability of microelectromechanical systems (MEMS). While the reliability of MEMS has received extensive attention, the physical mechanisms responsible for these failure modes have yet to be conclusively determined. In our work, we use a combination of on-chip testing methodologies and electron microscopy observations to investigate these mechanisms. Our previous studies have shown that fatigue in polysilicon structural thin films is a result of a ‘reaction-layer’ process, whereby high stresses induce a room-temperature mechanical thickening of the native oxide at the root of a notched cantilever beam, which subsequently undergoes moisture-assisted cracking. Devices from a more recent fabrication run are fatigued in ambient air to show that the post-release oxide layer thicknesses that were observed in our earlier experiments were not an artifact of that particular batch of polysilicon. New in vacuo data show that these silicon films do not display fatigue behavior when the post release oxide is prevented from growing, because of the absence of oxygen. Additionally, we are using polysilicon MEMS side-wall friction test specimens to study active mechanisms in sliding wear at the microscale. In particular, we have developed in vacuo and in situ experiments in the scanning electron microscope, with the objective of eventually determining the mechanisms causing both wear development and debris generation.