宽禁带功率器件键合缓冲技术的可靠性分析

Reliability Analysis of Bond Buffer Technologies for Wide Bandgap Power Devices

在电力电子应用中,性能优于硅功率器件的宽禁带功率器件得到广泛关注。然而,传统功率器件封装中的芯片顶部的电气互连结构现在已成为限制宽禁带功率器件寿命的主要因素。因此,有必要通过使用键合缓冲技术将铜键合线、焊带和引线框架来代替铝键合线作为芯片顶部的电气互联以满足宽禁带功率器件在高温工作条件下的要求。文章回顾了不同键合缓冲技术和金属键合材料在功率循环测试中的可靠性表现。其中,因瓦合金键合缓冲材料与铜键合线的结合在众多键合材料中显示出最强大的功率循环测试能力。失效分析显示,宽禁带功率器件封装的薄弱点已经从芯片顶部的键合材料变为氧化铝陶瓷衬底或芯片上表面的铝金属层。

Wide bandgap power devices with excellent performance over traditional silicon power devices have been introduced as the prime candidate for power electronics applications. However, interconnections on the chip topside in the traditional packaging are now limiting the lifetime of wide bandgap power devices. It is necessary to replace aluminum bond wires with copper bond wires, ribbons, and lead-frames with the help of bond buffer technologies to fulfill the requirements of wide bandgap power devices under high temperature operation conditions. The reliability performances of different bond buffer technologies and bonding materials under power cylcing tests were reviewed. The Cu-Invar-Cu bond buffer combined with Cu bonding material showed the most robust power cycling capability among all bonding materials. Failure analysus shows that the weak point of the packaging of wide bandgap power devices has been changed from the bonding material to the Al2O3 ceramic substrate or the aluminum metallization layer of the chip.