AVS 52nd International Symposium
    Applied Surface Science Thursday Sessions
       Session AS+TF-ThA

Paper AS+TF-ThA2
An in situ Study on Amorphous Carbon Films and the Vapor Phase Lubrication in Magnetic Data Storage Media

Thursday, November 3, 2005, 2:20 pm, Room 206

Session: Thin Film Characterization II
Presenter: Y. Yun, Carnegie Mellon University
Authors: Y. Yun, Carnegie Mellon University
A.J. Gellman, Carnegie Mellon University
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Amorphous carbon films have been used as a protection for the magnetic layer in hard disks for years. Perfluoropolyalkylether (PFPE) has been applied on the amorphous carbon film surface as lubricant during the crashing of the read-write head on the amorphous carbon film. The fundamental understanding of the thermal stability and oxidation kinetics of amorphous carbon films and the adsorption of PFPE lubricants is essential to obtain the ultimate high performance protection and lubrication. Vapor phase lubrication integrates the amorphous carbon film deposition and lubrication in vacuum. The amorphous carbon film can be oxidized under controlled conditions immediately prior to lubricant adsorption. The kinetics of oxidation has been studied using x-ray photoelectron spectroscopy in an UHV apparatus that allows oxidation of freshly deposited amorphous carbon films. The dissociative sticking coefficient of oxygen is ~10-6 and the oxidation kinetics can be described by a Langmuir-Hinshelwood mechanism. The vapor phase lubrication of amorphous carbon film has been emulated by absorbing (CF3CF2)2O and CF3CH2OH that serve as models for the fluorinated ether backbone and hydroxyl endgroup of PFPE lubricants. No decomposition was observed. The desorption energy of the hydroxyl endgroup is sensitive to the oxidation of the amorphous carbon film by air or O2. The increase of the desorption energy is proportional to the oxygen content on the amorphous carbon film surface. This indicates that the interaction between PFPE lubricant and the amorphous carbon film can be tailored by controlled oxidation of the amorphous carbon film. Vapor phase lubrication not only helps to probe the bonding mechanism of PFPE lubricant with amorphous carbon film, but also proposes a lubrication method which allows people to design and tune the bonding of PFPE lubricants with amorphous carbon films by controlled oxidization.