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Characterizing ultra-thin films by laser-acoustics

: Schneider, D.; Siemroth, P.

Verein Deutscher Ingenieure e.V. -VDI-, Kompetenzfeld Nanotechnik:
Nanofair 2003 - new ideas for industry : Tagung Dresden, 20. und 21. November 2003
Düsseldorf: VDI-Verlag, 2003 (VDI-Berichte 1803)
ISBN: 3-18-091803-9
Nanofair <2, 2003, Dresden>
Conference Paper
Fraunhofer IWS ()

The protecting against damage, computer hard disks have to be coated by hard films. The increasing data density requires reducing the film thickness down to few nano-meters due to the decreasing distance between the write-read head and the disk. This can only be realized using ultra-thin films of enhanced performance for wear and corrosion protecting. The excellent properties of amorphous carbon films termed diamond-like carbon (DLC) have turned to be suitable for this application. The mechanical testing of these ultra-thin and super-hard films is a challenge for the available test methods. Efforts have been done to adapt the laser-acoustic method yields the Youngs modulus, revealing the effect of varying bonding structure of the material, porosity and other micro-defects, including insufficient adhesion. For diamond-like carbon material, Youngs modulus correlates with the fraction of tetrahedral sp3-bonds causing its high hardness and excellent wear behavior. The films were deposited by high current pulsed vacuum arc discharges. The effects of the substrate temperature during the deposition and the film thickness were studied. The minimum film thickness was less than 3 nm.