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Fatigue life evaluation for single‐ and poly‐crystalline silicon films by pulsating‐tension cyclic loading test
Author(s) -
Nagai Yuji,
Namazu Takahiro,
Inoue Shozo
Publication year - 2008
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.2820
Subject(s) - materials science , scanning electron microscope , microscale chemistry , composite material , cyclic stress , tension (geology) , stress (linguistics) , ultimate tensile strength , silicon , fracture (geology) , fatigue limit , amplitude , crystalline silicon , optics , metallurgy , mathematics , physics , linguistics , philosophy , mathematics education , layer (electronics)
This paper describes the fatigue life of microscale single‐crystalline silicon (SCS) and poly‐crystalline silicon (PCS) used in microelectromechanical systems (MEMSs). The fabricated SCS and PCS specimens having nominal dimensions of 20 µm in width, 600 µm in length, and 2 µm in thickness at the gauge section were subjected to cyclic loading by means of pulsating‐tension fatigue test under a constant frequency from 1 to 10 Hz. The average fracture strengths of the SCS and PCS specimens measured by quasi‐static tensile test were 3.26 and 2.08 GPa, respectively, which were utilized as the reference stresses in the fatigue test. In the fatigue test, the peak stress and stress amplitude were maintained constant for both the specimens. The number of cycles to failure increased with a decrease in the peak stress. No manifest fatigue limit was observed in both the specimens. The stress ratio parameter, σ peak /σ f , gave a good correlation with the number of cycles to failure, and a large scatter of the lifetime data in the SCS specimens was found as compared with the PCS specimens. Scanning electron microscopy (SEM) suggested that a number of latent defects inside or on the surface of the specimen would have influenced the scatter of the fatigue life. Copyright © 2008 John Wiley & Sons, Ltd.