Interface identification in micro-LED repair applications via depth profiling using femtosecond laser-induced...

Area of Science:

• Materials Science
• Optoelectronics
• Spectroscopy

Background:

• Micro light-emitting diode (micro-LED) display commercialization requires efficient, high-precision chip transfer.
• High pixel densities in 4K/8K displays challenge defect-free transfer and necessitate effective repair strategies.
• Conventional laser repair lacks real-time monitoring, risking damage and imprecise ablation depth control.

Purpose of the Study:

• To introduce femtosecond laser-induced breakdown spectroscopy (fs-LIBS) as a novel tool for micro-LED repair.
• To evaluate fs-LIBS for simultaneous real-time elemental analysis and high spatial resolution during micro-LED repair.
• To demonstrate fs-LIBS's capability in identifying critical interfaces within multilayer micro-LED structures.

Main Methods:

• Custom-fabricated multilayer micro-LEDs were analyzed using fs-LIBS with varying laser pulse energies.
• Spectral emissions from constituent elements (e.g., Ga, Au) were detected and analyzed.
• Depth profiling and elemental mapping via scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) were used for validation.

Main Results:

• fs-LIBS successfully detected spectral emissions from key micro-LED elements.
• Variations in Gallium (Ga) and Gold (Au) signals accurately identified the p-pad/p-contact layer interface.
• Depth profiling confirmed the interface by monitoring normalized Ga and Au signal intensities.
• SEM-EDS elemental mapping validated the fs-LIBS findings of ablation crater composition.

Conclusions:

• fs-LIBS is a promising technique for real-time monitoring during micro-LED repair.
• The method enhances repair precision by minimizing unintended damage to adjacent structures.
• fs-LIBS contributes to the viability of micro-LED display production through improved defect repair.