温度梯度对VLSI金属化布线电徙动特性的影响

设计了一种新型TiW膜自加热结构,产生沿金属化条长方向的温度梯度。文中采用独立的实验和测温金属条结构,利用电阻与温度间的线性关系精确测定金属条上的温度分布,用电阻测温法直接确定电迁徙失效在金属化条上的分布,SEM分析与测试结果一致。不同温度梯度和无温度梯度条件下的实验结果表明,逆向温度梯度能显著提高金属化电徙动失效时间,这可以从温度梯度驱动的热扩散离子流作用得到解释。理论分析和实验结果表明,逆向温度梯度能将金属化电徙动空洞失效位置“推向”阳极,在逆向温度梯度作用下,首次发现了电徙动电阻变化的“新平衡现象”。

Temperature Gradient Impact on Electromigration Characteristics in VLSI Metallization

In this paper,we proposed a novel TiW self-heating structure, which can generalize a temperature gradient along the metal stripe. The effectiveness of this design is confirmed by different experiments. A metal line resistance method was used to determine the temperature distribution of the metal line. A series of electromigration tests were performed at positive and negative temperature gradient. The results indicate that the negative temperature gradient greatly improved the failurc time of electromigration, changed the failure location distribution and caused a new tendency of resistance change, and we called it the "new balance phase ".