High recording performance of Co-Cr medium sputter-deposited at high Ar pressure and high substrate temperature

Co-Cr films were prepared by sputter deposition at a high Ar pressure of 70 Pa with elevated substrate temperatures up to 400 degrees C. Films of 100 nm thickness were deposited using a 19 at.% Cr-Co target onto a well c-axis oriented Ti underlayer prepared on glass disk substrates, The perpendicular coercivity, H-c perpendicular to, of the films increased from 660 to 1940 Oe with increasing temperature. The films with high H-c perpendicular to exhibited a dense fine microstructure with distinct grain boundaries. The recording performance of the disk samples were measured by using a metal in gap type ring head, comparing with that of conventional Co-Cr films deposited at a low Ar pressure of 0.2 Pa. It was found that the high pressure deposited Co-Cr film exhibited higher output by more than 2 dB at the densities below 320 kFRPI (flux reversals per inch) compared with the conventional film with the same high coercivity. The D-50* of as high as 250 kFRPI and the highest recordable density of over 600 kFRPI were confirmed for the new type of Co-Cr film deposited at 70 Pa and at 400 degrees C. The noise level of the film, however, was slightly higher than that of conventional method films, disagreeing with the suggestion of the microstructure. (C) 1996 American Institute of Physics.