Small d-Spacing and Internal Stress of Co-Cr Films Deposited by Kr Ion Sputtering

Abstract

AbstractIt is important to control the internal stress of the deposited film because the magnetic tape is becoming thinner for attaining higher recording density per volume. Kr gas was used as the working gas in the facing targets sputtering (FTS) system for depositing Co-Cr films. Kr gas has the larger ionization cross section and atomic mass than those of Ar, Co and Cr, so that Kr gas could make stable discharge at lower pressure and the recoiling of Kr atoms on the surface of the Co-Cr target was more effectively suppressed. Therefore, Kr ions seem to be more advantageous as working gas than Ar ions which are the most common working gas. The FTS method with Kr ions could deposit the stress-free Co-Cr films with good crystallinity. Actually, Δθ50 and (Mr/Ms) of Co79Cr21 films deposited on Si wafer by Kr ion sputtering in the pressure range of 10–4 ∼ 5×10−−5 Torr were as small as 4% and 0.1, respectively. The colpressive stress of 1500Å-thick Co79Cr21 films was as small as 108 dyne/cm2, of which the value was smaller than 10% of that by Ar ion sputtering. Therefore, the combination of the FTS method and Kr gas seems to be very convenient for solving the problem of the internal stress.