Anomalous growth of interfacial intermetallic compounds on (111)-oriented nanotwinned Cu substrate

摘要

The microstructural evolution in the micro-scale (111)-oriented nanotwinned Cu (nt-Cu)/Sn/polycrystalline Cu interconnect during the interfacial soldering reaction was in situ examined using synchrotron radiation imaging technology. The growth rate of interfacial intermetallic compounds (IMCs) was anomalously higher on the (111)-oriented nt-Cu (1.44 mu m/min) as compared with the polycrystalline Cu (0.25 mu m/min), while the consumption/dissolution rate of the (111)-oriented nt-Cu substrate (0.13 mu m/min) was significantly less than that of the polycrystalline Cu substrate (0.51 mu m/min). The abnormal interfacial reaction on the (111)-oriented Cu substrate is attributable to the particular crystal orientation and high-density nano twins of (111)-oriented nt-Cu films and can be well explained by the concentration gradient control (CGC) interfacial reaction model. These findings would provide a deeper understanding of micro-scale solder interconnects with (111)-oriented nt-Cu acting as under bump metallization (UBM). (C) 2020 Elsevier B.V. All rights reserved.