Cleaning and Hydrophilization of Atomic Force Microscopy Silicon Probes

The silicon surface of commercial atomic force microscopy (AFM) probes loses its hydrophilicity by adsorption of airborne or package-released hydrophobic contaminants. Cleaning of the probes by acid piranha solution or discharge plasma removes the contaminants and renders very hydrophilic probe surfaces. Time-of-flight secondary-ion mass spectroscopy and X-ray photoelectron spectroscopy investigations showed that the native silicon oxide films on the AFM probe surfaces are completely covered by contaminants for the as-received AFM probes, while the cleaning methods effectively remove much of the hydrocarbons to reveal the underlying oxidized silicon of the probes. Cleaning procedure drastically affect the results of adhesive force measurements in water and air. Thus, significant adhesive force values arise in deionized water due to the formation of a bridge of hydrophobic material at the AFM tip-sample contact. Cleaning of the AFM tip and sample surfaces results in a significant increase of the adhesive force in air. Presence of water soluble contaminants at the tip-sample contact lower the capillary pressure in the water bridge formed by capillary condensation at the AFM tip-sample contact, and this results in a smaller adhesive force between the contaminated surfaces of the AFM tip and sample.

SIRGHI Lucel;  KYLIAN Ondrej;  GILLILAND Douglas;  CECCONE Giacomo;  ROSSI Francois; 

2007-01-25

AMERICAN CHEMICAL SOCIETY

JRC33826

https://publications.jrc.ec.europa.eu/repository/handle/JRC33826,