In Situ Atomic-Scale Investigation of Electromigration Behavior in Cu-Cu Joints at High Current Density

Area of Science:

• Materials Science
• Semiconductor Device Physics
• Reliability Engineering

Background:

• Electromigration (EM) is a major challenge for the reliability of miniaturized electronic devices, especially 3D integrated circuits (3DICs) under high current densities.
• EM involves atomic-scale mechanisms driven by electron momentum transfer, leading to material transport and potential device failure.

Purpose of the Study:

• To investigate the atomic-scale behavior of electromigration in copper-copper (Cu-Cu) joints using high-resolution transmission electron microscopy (HRTEM).
• To identify the critical factors influencing the reliability of 3DIC packaging due to EM.

Main Methods:

• High-resolution transmission electron microscopy (HRTEM) was utilized to observe atomic-scale phenomena.
• Analysis focused on the microstructural evolution and atomic transport mechanisms within Cu-Cu joints during EM.

Main Results:

• Electromigration initially induced slip along diverse crystallographic planes, transitioning to stable slip along specific orientations that dominated failure.
• Anisotropic atomic transport resulted in progressive interface degradation, including void formation and microstructural changes in Cu-Cu joints.
• Interface depletion was identified as a critical factor affecting 3DIC reliability.

Conclusions:

• The study highlights the anisotropic nature of atomic transport in Cu-Cu joints under electromigration.
• Optimizing interconnect and interface properties is crucial for mitigating EM-induced failures in high-power semiconductor technologies.
• Understanding interface depletion mechanisms is essential for enhancing the reliability of 3DICs.