本文研究了交流电致循环热应变作用下200 nm厚Au薄膜的失效行为. 结合实验结果和理论计算, 确定了交流电作用下6 μm宽Au薄膜导线上的温度分布, 并由此确定了Au互连线在交流电作用下达到稳定状态后的循环热应变范围. 结果表明, 应变范围Δε≦0.35%, 经过5×106 cyc热循环后, Au互连线中的晶粒出现不同程度的增长, 晶界损伤导致Au互连线的最终失效. 对Au薄膜热疲劳、机械疲劳失效行为及其机制进行了分析.
Metallization interconnects in microelectronic integrated circuits usually fail during fabrication and long-term service under electrical, mechanical, or thermal field and coupled multi-field of them, such as electromigration (EM) failure induced by direct current, stress-induced voiding (SIV) damage and thermal fatigue under thermal cyclic strain, which affect the reliability of the interconnects. Although EM and SIV have been actively investigated for several decades, there is limited work on thermal cyclic strain-induced thermal fatigue behaviors of thin metal films, which are becoming a more and more important reliability issue. In this work, the failure behavior of the 200 nm-thick Au thin films was studied through applying thermal cyclic strain generated by alternating current. The total thermal cyclic strain was determined from the temperature distribution along the Au line with a width of 6 μm according to the experiment measurement and theoretical calculation. It was found that the grain size in the Au thin films increased inhomogenously and the damage along grain boundaries resulted in the fatal failure of the Au line in the condition of Δε≦0.35% after 5$\times$10$^{6}$ cyc. Based on the experimental observations, thermal fatigue and mechanical fatigue failure behaviors were analyzed comparatively, and the basic mechanisms were discussed.
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