Quantifying Joule Heating and Mass Transport in Metal Nanowires During Controlled Electromigration

Area of Science:

• Materials Science
• Nanotechnology
• Physics

Background:

• Nanoscale heat dissipation and mass transport during electromigration (EM) are critical for microelectronic reliability.
• Understanding electromigration in gold (Au) nanowires is essential for developing advanced electronic devices.

Purpose of the Study:

• To directly observe and quantify electromigration-driven void movement in gold nanowires of varying shapes.
• To investigate the influence of nanowire geometry on nanoscale heat dissipation (Joule heating) and mass transport during EM.
• To estimate local temperatures and junction voltages during EM and correlate them with power dissipation.

Main Methods:

• Direct observation of void movement in gold nanowires using atomic force microscopy.
• Measurement of mass transport rates and investigation of heat dissipation in L-shaped, straight-shaped, and bowtie-shaped nanowires.
• Estimation of local temperatures based on dissipated power and diffusive heat transport relationships.

Main Results:

• Average mass transport rates were determined to be 10⁵ to 10⁶ atoms/s.
• Bowtie-shaped nanowires exhibited lower maximum Joule heating power compared to straight-shaped ones, facilitating EM at lower power.
• Local temperatures and junction voltages increased with decreasing Joule heating power and current in both bowtie and straight nanowires, with current densities around 10⁸ A/cm².

Conclusions:

• Electromigration-driven mass transport in gold nanowires can be effectively controlled at temperatures significantly below the melting point of gold.
• Nanowire geometry plays a crucial role in modulating heat dissipation and electromigration behavior.
• The findings provide insights for designing more robust and reliable nanoscale interconnects.