The properties comparison between Au and Cu wires bond in DRAM component

Abstract

Although Au wires is a popular bonding material in IC package. But the trend to replace Au wire with Cu in wire bonding process has become an important trend in semiconductor package. To explore properties variation for these two wires bond. We focused on mechanical, electrical, physical related properties comparison between Au and Cu wires bond in DRAM component. The test vehicles with both Au and 4N purity (99.99 wt%) Cu wires and then diameter size were 25um. To investigate mechanical properties of IMC formation on Au and Cu wires bond-ability on Al pad, both ball shear and wire pull tests were performed on test samples. In electrical related evolution result displayed that Cu wire was lower than Au wire bond in resistance increase rate up to thermal aging 500hr. SEM cross-sectioned was performed to identify IMC growth rate of Cu-Al pad is slower than that of Au-Al pad due to two raw materials with variation chemical property. Moreover, IMC growth behavior is different between Cu and Au wires bond. From this study result, we obtained Cu with advantages than Au in properties of wires bond.