多結晶シリコン薄膜の面外曲げ共振振動を用いたメンブレンの信頼性試験

概要

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In this paper, we propose and demonstrate, for the first time, a testing method without applying the stress on the etched surface roughness of sidewalls to evaluate intrinsic material's reliability. The specimen is a square membrane constituting from polycrystalline silicon, silicon dioxide and silicon nitride, which has a cylindrical Si-weight at the center and is supported by Si-frame. The load to the membrane is applied by vibrating the specimen in out-of-plane direction near the resonant frequency. The initial fracture strength of 250 nm and 500 nm thick poly-Si film has been revealed as; 2.59 GPa and 2.28 GPa in average, 0.17 GPa (6.6 %) and 0.28 GPa (12.1 %) in standard deviation, 15.2 and 9.94 in Weibull modulus, respectively. The Weibull modulus was much higher than previous researches since smaller surface roughness increases the fracture strength and decreases the deviation. As a next step, fatigue lifetime will be also examined using the same setup with long-term constant cyclic loadings.
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