Fatigue Life Prediction Criterion for Micro-Nanoscale Single-Crystal Silicon Structures
Fatigue Life Prediction Criterion for Micro-Nanoscale Single-Crystal Silicon Structures
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DOI：
10.1109/jmems.2008.2008583
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发表时间：
2009-02-01
影响因子：
2.7
通讯作者：
Isono, Yoshitada
中科院分区：
文献类型：
--
作者：
Namazu, Takahiro;Isono, Yoshitada
本文描述了微纳米级单晶硅（SCS）结构的疲劳损伤评估，以实现微机电系统在波动应力下的可靠性设计。利用原子力显微镜（AFM）、纳米压痕仪和自行研制的单轴拉伸试验机，在拉伸和弯曲变形模式下进行了疲劳试验，研究了试样尺寸、频率、温度和变形模式对SCS试样疲劳寿命的影响。无论频率和温度如何，疲劳寿命与试样尺寸相关。例如，与宽度为48 μ m、厚度为19 μ m的微尺度试样相比，宽度为200 nm、厚度为255 nm的纳米级SCS试样在相同应力水平下的失效循环次数要多10（5）倍。变形模式也影响寿命，但是，没有频率和温度依赖性已被观察到明确的S-N曲线。对应于峰值应力与平均断裂强度之比的应力比参数使我们能够估计每个变形模式的寿命。为了预测SCS结构的疲劳寿命，无论变形模式和试样尺寸如何，我们提出了一个经验参数，其中包括解析的剪切应力。从位错滑移、裂纹形核、扩展和失效的角度讨论了SCS结构的疲劳失效机理。[2008-0072]
This paper describes fatigue damage evaluation for micro-nanoscale single-crystal silicon (SCS) structures toward the reliable design of microelectromechanical systems subjected to fluctuating stresses. The fatigue tests, by using atomic force microscope (AFM), nanoindentation tester, and specially developed uniaxial tensile tester, have been conducted under tensile and bending deformation modes for investigating the effects of specimen size, frequency, temperature, and deformation mode on the fatigue life of SCS specimens. Regardless of frequency and temperature, the fatigue life has correlated with specimen size. For example, nanoscale SCS specimens with 200 nm in width and 255 nm in thickness have showed a larger number of cycles to failure, by a factor of 10(5), at the same stress level, as compared to microscale specimens with 48 mu m in width and 19 mu m in thickness. Deformation mode has also affected the lifetime; however, no frequency and temperature dependences have been observed unambiguously in the S-N curves. The stress ratio parameter corresponding to the ratio of peak stress to average fracture strength has enabled us to estimate the lifetime for each deformation mode. To predict the fatigue life of SCS structures regardless of deformation mode and specimen size, we have proposed an empirical parameter that includes the resolved shear stress. The mechanism of fatigue failure of SCS structures is discussed from the viewpoint of dislocation slip, crack nucleation, growth, and failure through observations using AFM and scanning electron microscope. [2008-0072]