The Material Interaction Behaviors in a Cu/Sn/Cu Interconnect Induced by Room Temperature Electromigration

  • 梁 鍵隴

Student thesis: Doctoral Thesis

Abstract

The aim of the present study is to clarify the fundamental athermal effects of electromigration on the material interaction behaviors in a Cu/Sn/Cu interconnect The electromigration experiment was conducted under a room temperature ambient condition approximately at 29 3oC through a thin film interconnect structure design to best reveal the athermal behaviors In addition an intermetallic compound (IMC)-free metallic interface was fabricated using a magneton sputtering technique to visualize the atomic-scale Cu/Sn interaction behavior The material interaction behaviors under room temperature electromigration were investigated using a spherical aberration corrected scanning transmission electron microscope (Cs-corrected STEM) The early stage room temperature electromigration at the IMC-free Cu/Sn interface within 1 h was found to trigger the Cu/Sn interaction and formed an amorphous CuSn interphase embedded with nano-scale Cu crystalline cells This amorphous interphase was derived from the original interfacial distortion zone across the as-annealed Cu/Sn interface The meta-stable amorphous CuSn interphase will further transform into a crystalline high-temperature η-Cu6Sn5 IMC as a relatively stable material reaction product under a long-term room temperature electromigration for up to 81 h Besides the IMC formation a particular athermal recrystallization behavior was found at the Cu/Sn interface and was proposed to be another stress relaxation mechanism that may occur within the meta-stable amorphous interphase to relief the accumulated high strain energy The recrystallized Sn interphase is considered as another stable material reaction product formed under room temperature electromigration The room temperature electromigration was also found to result in the accumulation of Cu atoms in the Sn matrix and thus the formation of a meta-stable Cu-in-Sn solid-solution revealing the occurrence of non-equilibrium supersaturation behavior The extent of supersaturation in the metal matrix was controlled by electromigration periods and geometrical (cathode/anode side) parameters The formation of the meta-stable amorphous CuSn interphase high-temperature η-Cu6Sn5 IMC recrystallized Sn interphase as well as the occurrence of the non-equilibrium supersaturation behavior resulted from the athermal behavior induced by electromigration rather than the thermal Joule heating effect The fundamental athermal behaviors induced by electromigration were established in the present study and their governing mechanisms were also disclosed
Date of Award2019
Original languageEnglish
SupervisorKwang-Lung Lin (Supervisor)

Cite this

The Material Interaction Behaviors in a Cu/Sn/Cu Interconnect Induced by Room Temperature Electromigration
鍵隴, 梁. (Author). 2019

Student thesis: Doctoral Thesis