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標題: 微力試驗下之銅奈米結晶薄膜尺度與不同平均應力之疲勞行為探討
Study on mean stress and thickness effects on fatigue behavior of nanocrystalline Cu thin films
作者: 陳俊宏
Chen, Chun-Hung
關鍵字: microtensile
Cu thin-film
出版社: 精密工程學系所
摘要: 本論文在探討薄膜材料中之銅薄膜受到一週期性外力之下,平均應力值對疲勞週期的影響,當材料受到一週期性反覆之應力,導致材料最終產生破壞的情形稱之為疲勞,因材料的疲勞行為發生時並無任何明顯的外觀改變,而是一種潛在的行為,若能了解材料之機械性質事先對其疲勞做估算,藉以預測元件之壽命,可防範因元件損傷造成傷害。 論文中所採用之試驗方式為單軸向微拉伸系統,藉由回授控制負載之平均應力,讓銅薄膜在承受相同平均應力之下直到破壞,再給予不同平均應力負載重複測試,觀察其疲勞週期變化,並描繪出銅薄膜材料之應力-週期數曲線圖,實驗中對三種銅薄膜厚度300奈米、500奈米及700奈米進行量測,並探討不同厚度對週期數的影響差異。 實驗結果顯示越高平均應力會越快導致材料疲勞破壞發生,而在不同厚度之間做比較發現,疲勞週期數會因薄膜越薄而有增加之趨勢。
Recently, microelectronics related industry such as semiconductor and MEMS has grown rapidly. As the size of microsystem devices continues to decrease, the reliability and lifetime of device would be affected, with a corresponding need to understand how length scales affect mechanical behavior, accurate knowledge on the mechanical behaviors of thin-film materials has become important for the design of MEMS device. Our study focuses on the fatigue property of copper thin-film, subjected to a periodic external force with a mean stress. The material subjected to a repeated cyclical stress, resulting in the damage of material is called fatigue. When the fatigue behavior occurs, there is no any significant change in appearance. When the mechanical properties of materials could be understood to estimate the fatigue cycles, the damages of components could be prevented. The method of Experimental used an uniaxial micro-tensile system, with a feedback controlled loading for a mean stress, so that the copper thin-film under the same mean stress until it damage, and then repeated to give different mean stress, observe the fatigue cycle, and describe the S-N curve of copper thin-films. The experiment measured three thickness copper thin-films that include 300 nm, 500 nm and 700 nm to study the effects with different thickness. As a result, the higher mean stress would lead to material fatigue occurs sooner. To compare with different thickness of copper thin films, the fatigue cycles would increase when the thin-film became thinker.
Appears in Collections:精密工程研究所



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