Colloid aspects of chemical-mechanical planarization.

Area of Science:

• Colloid and surface science
• Materials science
• Chemical engineering

Background:

• Semiconductor interconnects require precise planarization for logic and memory devices.
• Chemical-mechanical planarization (CMP) is crucial for removing excess metal and achieving flat surfaces.
• CMP slurries involve abrasive particles and chemicals interacting with metal and dielectric surfaces.

Purpose of the Study:

• To apply colloid science principles to optimize CMP materials and processes.
• To achieve desirable polish rates and defect-free planarized wafer surfaces.
• To understand the influence of abrasive properties and surface interactions on CMP.

Main Methods:

• Detailed analysis of abrasive particle composition, size, shape, and charge effects.
• Investigation of metal (copper) surface interactions with slurry chemicals (oxidizing, chelating agents).
• Evaluation of abrasive adhesion phenomena on metal and oxide surfaces using packed column technique.

Main Results:

• Established a correlation between abrasive particle characteristics and polish process outcomes.
• Illustrated how slurry chemistry influences metal surface dissolution and modification.
• Demonstrated a link between abrasive attachment/detachment and experimentally determined polish rates.

Conclusions:

• Colloid science provides a framework for optimizing CMP slurries and processes.
• Controlling abrasive properties and surface chemistry is key to achieving high-quality semiconductor planarization.
• Understanding interfacial phenomena is critical for defect-free wafer surfaces.