由于集成电路领域的持续小型化和高载流需求,以及节省空间和提高计算能力的愿望,有一个不断的驱动,以减少集成电路的大小。然而,高度集成的电路也带来了诸如高电流密度和过度焦耳加热等挑战,导致了一系列由电迁移引起的可靠性问题。因此,集成电路的服务可靠性一直是人们关注的问题。锡基焊料由于其可用性而在行业中得到广泛认可,操作期间的最小技术问题,与传统焊料的兼容性好。然而,主要是基于锡的焊料,如SAC305和SnZn,具有复杂的电子电路高熔点。当添加Bi时,焊料的熔点降低,但也可能导致与电迁移可靠性相关的问题。本文回顾了电流在Cu衬底上SnBi焊点中的电迁移的一般原理,以及晶须形成的现象,空隙/裂缝,相分离,以及由于电迁移引起的原子迁移引起的电阻增加。此外,它探索了通过包括Fe在内的添加剂来提高焊点可靠性的方法,Ni,Ag,Zn,Co,RA(稀土元素),GNS(石墨烯纳米片),FNS(富勒烯)和Al2O3。此外,改变焊点内的晶体取向或向焊点引入应力也可以在不改变成分条件的情况下在一定程度上提高其可靠性。在文献中还对相应的可靠性增强机制进行了比较和讨论。
Due to the continuous miniaturization and high current-carrying demands in the field of integrated circuits, as well as the desire to save space and improve computational capabilities, there is a constant drive to reduce the size of integrated circuits. However, highly integrated circuits also bring about challenges such as high current density and excessive Joule heating, leading to a series of reliability issues caused by
electromigration. Therefore, the service reliability of integrated circuits has always been a concern. Sn-based solders are widely recognized in the industry due to their availability, minimal technical issues during operation, and good compatibility with traditional solders. However, solders that are mostly Sn-based, such as SAC305 and SnZn, have a high melting point for sophisticated electronic circuits. When Bi is added, the melting point of the solder decreases but may also lead to problems related to
electromigration reliability. This article reviews the general principles of
electromigration in SnBi solder joints on Cu substrates with current flow, as well as the phenomena of whisker formation, voids/cracks, phase separation, and resistance increase caused by atomic migration due to
electromigration. Furthermore, it explores methods to enhance the reliability of solder joint by additives including Fe, Ni, Ag, Zn, Co, RA (rare earth element), GNSs (graphene nanosheets), FNS (Fullerene) and Al2O3. Additionally, modifying the crystal orientation within the solder joint or introducing stress to the joint can also improve its reliability to some extent without changing the composition conditions. The corresponding mechanisms of reliability enhancement are also compared and discussed among the literature.