Chen Ke-Xin, Gao Li-Yin, Li Zhe, Sun Rong, Liu Zhi-Quan
Shenzhen Institute of Advanced Electronic Materials, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
School of Material Science and Engineering, University of Science and Technology of China, Shenyang 110016, China.
Materials (Basel). 2023 Jun 26;16(13):4614. doi: 10.3390/ma16134614.
Copper is the most common interconnecting material in the field of microelectronic packaging, which is widely used in advanced electronic packaging technologies. However, with the trend of the miniaturization of electronic devices, the dimensions of interconnectors have decreased from hundreds of microns to tens of or even several microns, which has brought serious reliability issues. As a result, nanotwinned copper (nt-Cu) has been proposed as a potential candidate material and is being certified progressively. Firstly, the physical properties of nt-Cu have been widely studied. Notably, the higher thermal stability and oxidation resistance of the (111) texture causes nt-Cu to maintain excellent physical properties under high-temperature serving conditions. Secondly, recent works on the electrolyte and electroplating processes of nt-Cu on wafer substrates are summarized, focusing on how to reduce the thickness of the transition layer, improve the twin density, and achieve complicated pattern filling. Thirdly, nt-Cu can effectively eliminate Kirkendall voids when it serves as UBM or a CuP. Additionally, the high (111) texture can control the preferred orientation of interfacial intermetallic compounds (IMCs) at the Cu-Sn interface, which should be helpful to improve the reliability of solder joints. nt-Cu has superior electromigration resistance and antithermal cycling ability compared to ordinary copper RDLs and TSVs. Above all, nt-Cu has attracted much attention in the field of microelectronic packaging in recent years. The preparation-performance-reliability interrelationship of nt-Cu is summarized and displayed in this paper, which provides a solid theoretical basis for its practical applications.
铜是微电子封装领域中最常用的互连材料，广泛应用于先进的电子封装技术。然而，随着电子设备小型化的趋势，互连器的尺寸已从数百微米减小到几十甚至几微米，这带来了严重的可靠性问题。因此，纳米孪晶铜（nt-Cu）已被提出作为一种潜在的候选材料，并正在逐步得到验证。首先，nt-Cu的物理性能已得到广泛研究。值得注意的是，（111）织构具有较高的热稳定性和抗氧化性，使得nt-Cu在高温服役条件下仍能保持优异的物理性能。其次，总结了近期在晶圆衬底上制备nt-Cu的电解液和电镀工艺的相关工作，重点关注如何减小过渡层的厚度、提高孪晶密度以及实现复杂图案的填充。第三，当nt-Cu用作底部金属化层（UBM）或铜柱凸点（CuP）时，它可以有效地消除柯肯达尔空洞。此外，高（111）织构可以控制铜-锡（Cu-Sn）界面处界面金属间化合物（IMC）的择优取向，这有助于提高焊点的可靠性。与普通的铜再分布层（RDL）和硅通孔（TSV）相比，nt-Cu具有优异的抗电迁移性能和抗热循环能力。综上所述，近年来nt-Cu在微电子封装领域备受关注。本文总结并展示了nt-Cu的制备-性能-可靠性之间的相互关系，为其实际应用提供了坚实的理论基础。
