HRTEM and X-ray diffraction analysis of Au wire bonding interface in microelectronics packaging

Interfacial microstructures of thermosonic Au wire bonding to an Al pad of die were investigated firstly by high-resolution transmission electron microscopy (HRTEM) and X-ray micro-diffractometer. The equal-thickness interference structures were observed by HRTEM due to diffusion and reaction activated by ultrasonic and thermal at the Au/Al bond interface. And X-ray diffraction results showed that three different interplanar crystal spacings ('d' value) of the interfacial microstructures were 2.2257 angstrom, 2.2645 angstrom, and 2.1806 angstrom respectively from the high intensity of diffraction to the low intensity of diffraction. These indicated that the intermetallic phase AlAu(2) formed within a very short time. It would be helpful to further research wire bonding technology. Crown Copyright (C) 2010 Published by Elsevier Masson SAS. All rights reserved.