MAGNETIC PROPERTY AND MICROSTRUCTURE DEPENDENCE OF COCRTA/CR MEDIA ON SUBSTRATE-TEMPERATURE AND BIAS

Thin CoCrTa/Cr films were deposited at different substrate temperature, T(s), and substrate biasing voltage, V(b). The in-plane coercivity increased significantly with T(s) and V(b). Coercive squareness and orientation ratio also increased with T(s) and V(b). TEM result indicated that at low T(s), the magnetic film had an isolated-grain structure, with smaller sub-grain structure within each grain. At high T(s), the magnetic film had a closely-packed-grain structure, probably due to the enhanced adatom mobility; the grain size was much larger and striations were observed in many grams. The application of a negative biasing voltage to the substrate also tended to reduce the grain isolation. At high T(s), it seems that biasing also reduced the number of grains with striations. SEM study indicated that with increasing T(s) and V(b), more high-frequency texture line appeared in the magnetic layer, which was likely related to the increase of orientation ratio and squareness with increasing T(s) and V(b).