NANOSCALE SCRATCH RESISTANCE OF ULTRATHIN PROTECTIVE OVERCOATS ON HARD MAGNETIC DISKS

An atomic force microscope-based nanoscratch testing technique has bee n applied to evaluate scratch resistance of 100 Angstrom thick protect ive overcoats on hard magnetic disks. Among the overcoats prepared by de magnetron sputtering, an amorphous nitrogenated carbon (a-C:N) film showed the best performance in the tests, followed by an amorphous hy drogenated carbon (a-C:H) film and an undoped amorphous carbon (a-C) f ilm. Substrate temperature in the overcoat sputtering process was foun d to be an important factor affecting the film's scratch resistance. O vercoats sputtered at lower substrate temperature were more stable aga inst scratching. An ion beam deposition process was found to produce a n overcoat with superior scratch-resistant properties as compared to t he sputtered carbon overcoats. Nanoscale scratch testing results are c orrelated with the sp(3)-bonding character in the overcoats assessed b y Raman spectroscopy. (C) 1998 American Vacuum Society.