蓄水池结构对Cu互连线电迁移寿命的影响

Effect of the Reservoir Structure on the Electromigration Lifetime of Cu Interconnects

集成电路特征尺寸的逐渐缩小带来了日益严峻的Cu互连线电迁移可靠性问题。为了改善40 nm和55 nm制程下Cu互连线的抗电迁移能力,基于加速寿命试验与失效分析的方法,研究了蓄水池结构对Cu互连线电迁移寿命的影响。研究结果表明,采用蓄水池配置方式的蓄水池结构,通过对通孔底部附近的空洞起着补充作用而在一定范围内提高了Cu互连线的电迁移寿命,改善了试验样品的双模对数正态失效分布现象,提高了试验样品电迁移寿命的一致性。此外,蓄水池结构的补充效果在蓄水池结构的长度达到一个临界值时效果最佳。以上研究结果对于Cu制程电迁移可靠性的改善具有一定的参考价值。

The gradual shortening of the integrated circuit feature size has brought increasingly serious problems with Cu interconnects electromigration reliability. In order to improve the anti-electromigration ability of Cu interconnects under 40 nm and 55 nm processes, the effect of the reservoir structure on the electromigration lifetime of Cu interconnects was studied based on the accelerated lifetime test and failure analysis methods. The research results show that the reservoir structure adopted the configuration of the reservoir improves the electromigration lifetime of the Cu interconnect to a certain extent by supplementing the void near the bottom of the through hole, and improves the Bi-mode log-normal failure distribution of the test samples and the consistency of the electromigration lifetime of the test samples. In addition, the supplementary effect of the reservoir structure is the best when the length of the reservoir structure reaches a critical value. The above research conclusions provide a certain reference for improving the electromigration reliability of Cu process.