High current filtered arc deposition for ultra thin carbon overcoats on magnetic hard disks and read-write heads

Due to the lateral size reduction of stored bits on a hard disk, the head-to-med ia spacing has to be reduced as well as the thickness of the protecting carbon overcoats. In order to obtain a thickness in the 2 nm region a new process technology is needed. In the present paper, a high current pulsed arc (HCA) technique is presented as an innovative source for ultra thin carbon coating for industrial disk production. The hardness and scratching resistance of these films are remarkably higher than conventional magnetron sputtered films. With the HCA-Source we are able to produce pinhole-free carbon films with thicknesses down to 1.7 nm. The thickness profile and uniformity on disk is adjustable by a magnetic field array. The deposition rate is 0.070.3 nm per pulse, therefore the coating time is below 2 s per disk. The magnetic layer is left undamaged during the HCA depo sition process. These aspects are very important for industrial disk production efficiency. Strong particle reduction due to a magnetic filter tube is confirmed by repeatable glide tests. Particles are confined in the magnetic filter tube and do not reach the substrate. In several important tests, we showed that the HC A source is capable of producing carbon layers within a realistic disk production environment with a yield of approximately 93% which proved to be comparable to current magnetron sputtered overcoats.