Gallium-Enhanced Aluminum and Copper Electromigration Performance for Flexible Electronics

Area of Science:

• Materials Science
• Solid State Physics
• Electrical Engineering

Background:

• Electromigration is a major failure mechanism in microelectronic interconnects.
• Developing materials with enhanced electromigration resistance is crucial for high-current and high-power electronics.
• Alloying is a common strategy to improve material properties for electronic applications.

Purpose of the Study:

• To screen binary and ternary thin film alloys of Al, Cu, and Ga for enhanced electromigration resistance.
• To identify specific alloy compositions suitable for replacing pure Al or Cu in electronic interconnects.
• To evaluate the performance of promising alloys on both rigid (SiO2) and flexible (PEN) substrates.

Main Methods:

• Fabrication of combinatorial thin film libraries using lithography and vacuum co-deposition.
• High-throughput screening via automated current-voltage measurements to determine electrical failure thresholds.
• Analysis of electromigration mechanisms, focusing on grain boundary dynamics influenced by electron flux and atomic concentration gradients.
• Characterization of film adhesion and electrical properties on various substrates.

Main Results:

• Al-8 at.% Ga and Cu-5 at.% Ga were identified as promising alloys for improved electromigration resistance.
• Alloying with Ga enhanced film adhesion to polyethylene naphthalate (PEN) flexible substrates.
• Al-8 at.% Ga demonstrated a nearly 50% increase in electromigration suppression compared to pure Al on PEN substrates.
• Cu-5 at.% Ga exhibited over 100% increase in maximum current density compared to pure Cu on both SiO2 and PEN substrates.

Conclusions:

• Al-8 at.% Ga and Cu-5 at.% Ga alloys offer superior electromigration resistance and current carrying capacity compared to pure Al and Cu.
• These alloys are suitable for interconnect applications in high-current/power electronics and flexible electronics.
• Gallium alloying provides a viable route to enhance the reliability and performance of metallic interconnects.