Evaluation Method for Metal Line Failure Induced by High Current Density in Order to Ensure ULSI Reliability

1.通过将应力对原子扩散的影响加入到已经为未钝化线开发的控制参数中，新制定了钝化竹线中的电迁移损伤的控制参数。利用该参数，建立了一种简便、准确的薄膜特性常数的推导方法。2.对亚微米级钝化铝竹线进行了一定时间的高密度电流作用下的电迁移损伤加速比试验。将获得的速度输入到利用第1项中描述的控制参数的推导方法中，获得了膜特性常数，并且该常数被认为是有效的。由此验证了新提出的电迁移损伤的控制参数。3.在通孔连接线中存在电迁移损伤的阈值电流密度。利用电迁移损伤的控制参量，对原子密度分布的建立过程进行了数值模拟，从而建立了阈值电流密度的评价方法。该方法不仅适用于直线，也适用于二维形状的直线，如折线。4.对于直线，得到了阈值与直线长度成反比的评价结果，对于折线，得到了阈值大于直线的评价结果。从实验结果中得到与评价结果相同的趋势，从而验证了评价方法。研究发现，线的二维形状对阈值电流密度有影响，为保证ULSI的可靠性提供了有价值的知识。

1.The parameter governing electromigration damage in the passivated bamboo line was newly formulated by adding the effect of stress on atomic diffusion to the governing parameter which has already been developed for unpassivated line. Using the parameter the simple and accurate method for derivation of film characteristic constants was developed.2.Acceleration ration tests of electromigration damage were performed where high-density electric current was supplied to the passivated aluminum bamboo line of submicron width for a certain period of time. Inputting the obtained velocity into the derivation method utilizing the governing parameter described in item 1 the film characteristic constants were obtained and the constants were concluded to be valid. From this fact, the governing parameter for electromigration damage newly developed was verified.3.It is known that there is a threshold current density of the electromigration damage in the via-connected line. Utilizing the governing parameter for electromigration damage a numerical simulation of the building-up process of the atomic density distribution was developed and thus we achieved the construction of the evaluation method of the threshold current density. This method is applicable to not only straight shape line but also the two-dimensionally shaped line such as angled line.4.Concerning the straight lines, the evaluation result that the threshold was in inverse proportion to the line length was obtained, and regarding an angled line the evaluation result that threshold of the angled line was greater than that of straight line was obtained. From experimental results the same tendency was obtained as the evaluation results, and thus the evaluation method was verified. It was found out that two-dimensional shape of the line affected threshold current density, and valuable knowledge for ensuring ULSI reliability was obtained.