Research on the highly reliable Cu multilevel interconnects employing the sustained self-sputtering

我们利用Cu的持续自溅射研究了一种高可靠的多级铜互连，防止电迁移。本研究的第一部分是自溅射的改进和机理研究。为此，我们比较了不同磁控管设计的溅射特性，并利用Langmuir探针进行了电子能量分布分析。最后，我们发现自溅射对磁场分布有微妙的依赖性，并指出通过控制靶与磁控管之间的距离可以大大延长靶的寿命。第二部分是将Cu薄膜填充到高长宽比的通孔和接触孔中，用于ulsi的应用。由于Cu原子的平均自由程较长，与传统准直或长射溅射相比，获得了很好的Cu填充，且长径比为3的空穴完全被Cu填充。

We have investigated a highly reliable multilevel Cu interconnections against electromigration by the use of the sustained self sputtering of Cu. The first part of this study is the improvement and mechanism studies of self-sputtering. For this purpose, we have compared sputtering characteristics of deferent magnetron designs, and carried out electron energy distribution analysis using Langmuir probe. Finally we have found that the self-sputtering is delicately dependent on the magnetic field distribution, and pointed out that the target life will be drastically prolonged by controlling the distance between target and magnetron. The second part is the filling of Cu films into a high aspect ratio via and contact holes for the application of the ULSIs. The very good Cu filling is obtained compared with conventional collimation or long-throw sputtering due to a long mean free path of Cu atoms, and holes of aspect ratio 3 were completely filled by Cu.