Joel W. Hoehn

Diamond-like carbon applications in high density hard disc recording heads

Between 1965 and 1993 areal bit density in hard disc recording heads grew at a rate of 45% per year. Subsequently the rate of growth increased to 65% through 1998. In the past 2 years, the density growth has increased yet again to an amazing 100% per year. Increasing areal density requires growth in both track and linear density. Products currently in production have areal density in the range of 10 to 15 Gbit/inch2. At a continuing density growth rate of 100% per year, 100 Gbit/inch2 production will become a reality in year 2003, less than 3 years hence. Reduction in head-to-media magnetic spacing follows areal density growth. Protective coatings on both the heads and the media contribute to spacing. One of the clear challenges going forward is reduction of the coating thickness while maintaining the functional properties of corrosion protection and tribology enhancement. Traditional direct ion beam DLC deposition coatings do not have the required properties at thickness below 30 A. New coating technology is required to meet the needs of the recording head industry. This paper will address the coating requirements as well as the test methods used to evaluate coatings.

Direct ion beam deposition of hard (> 30 GPa) diamond-like films from RF inductively coupled plasma source

Diamond-like carbon (DLC) films were deposited on Si substrates using highly reproducible direct ion beam deposition from a RF inductively coupled hydrocarbon plasma source. Combinations of gases, such as C 2 H 4 and C 2 H 4 -CH 4 , were used to form the plasma. The mechanical, electrical and optical properties of the films were examined as a function of the deposition conditions and CH 4 content in gas mixture. Hard DLC films with a hardness up to 40 GPa were obtained. By variation of the C 2 H 4 /CH 4 ratio, hardness of the films can be adjusted in the range 22-40 GPa. Highly reproducible deposition rates (< 5% from run to run for over several 100 h) have been achieved. The deposition uniformity was within 5% over 9-inches round. For investigation of the bulk and surface electrically active defects (density, activation energies and capture cross-sections), charge-based deep-level transient spectroscopy (Q-DLTS) was used.