Nanoindentation creep on Cu₃Sn, Cu₆Sn₅ and (Cu, Ni)₆Sn₅ intermetallic compounds grown in electrodeposited multilayered thin film

Abstract

Tin-based multilayered thin films were fabricated for application in three dimensional microelectronic packaging as joining materials. During device fabrication and application, interconnecting materials can be fully converted to intermetallic compounds (IMCs). As known, IMCs are generally brittle and associated with void formation which can make interconnection in the microelectronic devices vulnerable. In an effort to improve the reliability of the Sn–Cu based IMC, ultra thin layers of Ni (70 nm) were inserted into Cu/Sn system. Electrochemical deposition technique was used to fabricate the samples. Isothermal aging at 150 °C for 168 h was performed to grow the IMCs at required thickness for measuring creep by nanoindentation. Creep strain rate was calculated from experimental data. Creep resistance was significantly improved after adding the small amount of Ni in Cu/Sn multilayered thin film system.