Investigation on the bonding interface between AuAl2 and α-Al2O3 by oxidation heat treatment and first-principle

Abstract

The bonding interface is prone to fracture during high temperature service in integrated circuit of bonded gold wires, and the main cause of the fracture is the incompatibility of the brittle phase AuAl<inf>2</inf> with the substrate at the interface. In this paper, the oxidation stability and interface characteristics of AuAl<inf>2</inf> generated during the boding process of the gold boding wire were study in order to explore the performance of the brittle phase during high temperature. The AuAl<inf>2</inf> ingot was prepared by vacuum arc melting and subjected to oxidation heat treatment at 500 °C, then the phase change and interface character were analysed. The experimental and calculation results show that the Al atoms in the alloy were precipitated from the AuAl<inf>2</inf> grains during oxidation and formed Al<inf>2</inf>O<inf>3</inf> at the AuAl<inf>2</inf> grain boundaries and the (111) plane of AuAl<inf>2</inf> combined with this oxide layer and the potential diffusion direction of Al. In addition, the results of first-principles calculation demonstrate that the AuAl<inf>2</inf>/Al<inf>2</inf>O<inf>3</inf> interface tends to bond in the form of the Au-terminated (111) plane of AuAl<inf>2</inf> and the (0001) plane of α-Al<inf>2</inf>O<inf>3</inf>. This study is of great significance for elucidating the interfacial properties between the AuAl<inf>2</inf> substrate and the α-Al<inf>2</inf>O<inf>3</inf> oxide film, and provides a theoretical basis for investigating the role of intermetallic compounds in the fracture process of bonded gold wires, as well as for the design of high-reliability bonding materials.