Effects of O 2 Gas Addition on Diamond-Like Carbon Film Deposition
- PDF / 703,213 Bytes
- 5 Pages / 417.6 x 639 pts Page_size
- 33 Downloads / 229 Views
ABSTRACT The role of 02 gas addition on the deposition of Diamond-like Carbon (DLC) film was studied for hard disk drive (HDD) media application. The influence of 02 gas mixing ratio on DLC film quality was investigated using the dc magnetron sputtering method with a solid graphite target and Ar, CH 4 and 02 mixing gases. The 02 mixing ratio was varied between 0% and 50%. Film quality was evaluated using Raman spectroscopy and XPS. When 02 gas mixing ratio increased the peak in Raman spectra shifted gradually to higher wavenumbers and its bandwidth became narrower. This indicates graphite component increased in the DLC film. In addition, the lubricant coverage on oxygen-containing DLC was improved. Because adding oxygen increases the terminations of carbonyl group on DLC surface, this result suggests that the polar surface causes higher affinity for the lubricant. INTRODUCTION Diamond-like carbon (DLC) thin films are widely used as protective coatings on magnetic media in hard disk drive (HDD) because of their interesting characteristics, such as a high degree of hardness, high resistance to wear, and chemical inertness. Usually, the surface of DLC is coated with a thin film of lubricant. Since the lubricant has an extremely low coefficient
of friction, this combination remarkably improves the tribological performance. Hence, the strong interaction between DLC and the lubricant is essential to the durability of a magnetic media in addition to each characteristic. Commonly, perfluoropolyether (PFPE) is used as the lubricant for magnetic media. The lubricant molecule consists of two components, hydrophobic main chains and polar end groups. Because the polar groups have the tendency to orient towards the DLC, several research groups attempted to increase polarity of polar groups in order to achieve high lubricant coverage [1,2]. Indeed, it suggests that the polar groups having high adsorption energy also show strong bonding resulting in high lubricant coverage on the DLC [2]. In contrast, the adsorption site on the DLC side is not clear yet. Recently, Yanagisawa [3] investigated the adsorption sites on the DLC surface by XPS and ESR and concluded that dangling bonds and functional groups are plausible sites on the DLC side and polar functional groups increase the adsorption energy. We also believe that a high polar DLC surface will be suitable for the lubricant. Furthermore. Wu and co-workers [4] studied the effects of the deposition parameters, and observed that the wear rates of oxygen-contained DLC film improved over that of conventional DLC film. However, the role of 02 gas addition on the deposition of DLC has been less studied more than the deposition of diamond [5,6]. Because oxygen has a high electonegativity, an efficient polarization effect is expected. From this point of view, we carried out 02 gas addition on the deposition of DLC film and investigated the film properties of oxygen-containing DLC. 415 Mat. Res. Soc. Symp. Proc. Vol. 593 © 2000 Materials Research Society
EXPERIMENTAL DLC films were depos
Data Loading...
