EFFECTS OF SUBSTRATE BIAS ON CRYSTAL-STRUCTURES AND MAGNETIC-PROPERTIES OF COCRTA CR THIN-FILMS/

Effects of negative d.c. substrate bias on the film properties of CoCr Ta/Cr magnetic recording media have been investigated. When the substr ate bias was increased from zero to -250 V, the Ta content was found t o increase from 3.9 to 15.0 at. %, whereas the Cr content decreased an d the deposition rate was reduced. X-ray diffraction (XRD) analysis re vealed the replicate growth of Co (<11(2)over bar 0>) on the Cr (002) plane. The peak shift and line broadening of Co (<11(2)over bar 0>) di ffraction are attributed to the compositional change and presence of r esidual stress in the deposited film. The occurrence of maximum coerci vity at -150 V bias is correlated to the formation of structural defec ts. However, too high a bias (-250 V) induces formation of an excessiv e amount of weak magnetic phase, which causes the magnetic properties to deteriorate. The enhancement of the coercivity due to substrate bia s is primarily governed by hindrance of domain wall motion by structur e defects and/or residual stress.