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Indexed by:期刊论文

Date of Publication:2014-12-01

Journal:JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY

Included Journals:SCIE、EI、ISTIC、CSCD

Volume:30

Issue:12

Page Number:1235-1242

ISSN No.:1005-0302

Key Words:Cu/Sn/Ni; Electromigration; Cross-solder interaction; Interfacial reaction; Diffusion

Abstract:The diffusion behavior of Cu and Ni atoms undergoing liquid solid electromigration (L-S EM) was investigated using Cu/Sn/Ni interconnects under a current density of 5.0 x 10(3) A/cm(2) at 250 degrees C. The flowing direction of electrons significantly influences the cross-solder interaction of Cu and Ni atoms, i.e., under downwind diffusion, both Cu and Ni atoms can diffuse to the opposite interfaces; while under upwind diffusion, Cu atoms but not Ni atoms can diffuse to the opposite interface. When electrons flow from the Cu to the Ni, only Cu atoms diffuse to the opposite anode Ni interface, resulting in the transformation of interfacial intermetallic compound (IMC) from Ni3Sn4 into (Cu,Ni)(6)Sn-5 and further into [(Cu,Ni)(6)Sn-5 + Cu6Sn5], while no Ni atoms diffuse to the opposite cathode Cu interface and thus the interfacial Cu6Sn5 remained. When electrons flow from the Ni to the Cu, both Cu and Ni atoms diffuse to the opposite interfaces, resulting in the interfacial IMC transformation from initial Cu6Sn5 into (Cu,Ni)(6)Sn-5 and further into [(Cu,Ni)(6)Sn-5 + (Ni,Cu)(3)Sn-4] at the anode Cu interface while that from initial Ni3Sn4 into (Cu,Ni)(6)Sn-5 and further into (Ni,Cu)(3)Sn-4 at the cathode Ni interface. It is more damaging with electrons flowing from the Cu to the Ni than the other way.