Effect of Sn Grain Orientation on the Formation of Cu6Sn5 Intermetallic Compounds during Electromigration

Abstract

Sn grain orientation that has highly anisotropic diffusivities plays a very important role on thermal-cycling test and electromigration failure. In this study, Cu/Sn-2.3Ag/Cu microbumps, assembled by thermal-compression bonding, after electromigration test are investigated grain orientation by electron-backscattering diffraction (EBSD). The condition of electromigration test is under the current density of 4x104 A/cm2 and 165 degrees C. In the results, The IMC growth at the interface of Cu/solder is very serious as the electron flow along a low alpha-angle grain as Very serious as that along a high alpha-angle grain. Therefore, we demonstrate IMC formations depend on the angle between c-axis and electron flow in Sn grains.