Atomic surface achieved through a novel cross-scale model from macroscale to nanoscale.

Area of Science:

• Materials Science and Engineering
• Surface Science
• Chemical Engineering

Background:

• Chemical mechanical polishing (CMP) is crucial for achieving atomic-level surface smoothness in various applications.
• Traditional CMP methods often utilize hazardous slurries, posing environmental risks and limiting process sustainability.
• The intricate cross-scale mechanisms governing CMP, from macro to nano levels, remain poorly understood.

Purpose of the Study:

• To develop a novel green CMP process and an integrated cross-scale polishing model.
• To elucidate the fundamental mechanisms of material removal during CMP across different scales.
• To provide a foundation for designing environmentally friendly CMP slurries, pads, and equipment.

Main Methods:

• Development of a green CMP slurry using hydrogen peroxide, sodium carbonate, sodium hydroxycellulose, and silica.
• Integration of Eulerian and Lagrangian models with reactive force field-molecular dynamics for cross-scale modeling.
• Experimental validation of the proposed model using fused silica polished with a ceria slurry.

Main Results:

• The green CMP process achieved a surface roughness (Sa) of 0.126 nm, a material removal rate of 88.3 nm/min, and a damaged layer thickness of 8.8 nm.
• The cross-scale model accurately predicted experimental CMP outcomes, revealing stress distributions within the polishing pad fibers and abrasive-workpiece interface.
• Increased slurry viscosity was shown to enhance stress, facilitating material removal, while compressive stress influenced the material removal form from atomic to molecular chains.

Conclusions:

• The developed green CMP process and cross-scale model offer significant advancements in understanding and optimizing polishing mechanisms.
• The findings pave the way for the design of sustainable CMP technologies with improved efficiency and reduced environmental impact.
• This research provides critical insights for the future development of novel polishing materials and processes.