Tribochemical Wear of Diamond-Like Carbon-Coated Atomic Force Microscope Tips

Area of Science:

• Materials Science
• Tribology
• Nanotechnology

Background:

• Nanoscale wear limits atomic force microscopy (AFM) applications in nanomanufacturing and nanometrology.
• Understanding AFM tip wear is essential for improving process reliability and precision.
• Current models inadequately explain the complex wear mechanisms involving evolving contact geometry.

Purpose of the Study:

• To systematically characterize the nanoscale wear behavior of diamond-like carbon (DLC) coated silicon AFM tips.
• To investigate the influence of external loading and sliding distance on DLC tip wear.
• To develop and validate a wear model that accurately describes wear across a range of contact stresses.

Main Methods:

• Experimental wear testing of commercial Si AFM tips with DLC coatings.
• Transmission electron microscopy (TEM) for post-wear analysis.
• AFM-based adhesion measurements and tip geometry estimation via inverse imaging.
• Quantitative analysis of wear rate as a function of contact stress.

Main Results:

• Observed gradual wear of DLC coatings with increasing sliding distance, leading to tip shape evolution from paraboloidal to flattened.
• Wear rate increases with average contact stress but deviates from Archard's classical wear law.
• Transition state theory model accurately describes wear at low stresses (<0.3 GPa) but fails at higher stresses.

Conclusions:

• A novel multibond wear model effectively describes the observed wear behavior across the entire range of stresses.
• The multibond model integrates Archard-like behavior at high stresses with transition state theory at lower stresses.
• This research provides a more comprehensive understanding of nanoscale wear mechanisms for AFM tips, crucial for advanced manufacturing and metrology.