Effect of nucleation layers on the growth and magnetic properties of CoCr and CoCr-X films

Abstract

The initial growth region in CoCr thin films is discussed with regard to its effect on the magnetic and microstructural properties of perpendicular recording media. Various nucleation films have been evaluated by interposing the nucleation layer between the substrate and the CoCr film. In some instances, the nucleation layer significantly improved the oaxis texture and perpendicular anisotropy of the CoCr film. The results are reviewed and trends are evaluated to clarify the physical mechanism by which the phase and texture of polycrystalline CoCr films can be modified by sublayer nucleation films. Ternary CoCr-X films have also been considered for perpendicular recording media applications. Experiments have shown that initial growth layers of randomly oriented grains can degrade the magnetic and structural properties of the ternary CoCr-X alloys by the same mechanism. This paper describes a detailed evaluation of various nucleation layers for CoCr(W) and CoCr(Ta) magnetic films. Amorphous (microcrystalline) nucleation layers and polycrystalline films as thin as 300 A were used as seed layers for the controlled growth of magnetic films such as (CoH0Cr20)90W10and (CoK2Cr,K)9()TaJ0. The ternary alloy films were deposited as thin as 1000 A and exhibited excellent c-axis texture with no evidence of an initial growth region. The excellent magnetic properties of the CoCr(Ta) and CoCr(W)thin films were attributed to various properties of the nucleation layer, i.e., oriented nuclei, microcrystallinity, and low misfit between the nucleation layer and the magnetic film. © 1986, American Vacuum Society. All right reserved.