IMPROVEMENT OF ADHESION OF CO-CR LAYERS BY PLASMA SURFACE MODIFICATIONS OF THE PET SUBSTRATE

The influence of various plasma etching and ion beam etching pretreatm ents on the surface structure of PET [poly(ethylene terephthalate)] su bstrates and the properties of deposited Co-Cr layers used for magneti c recording has been investigated. The pretreatment had strong influen ce on the chemical composition, the topography, and the roughness of t he PET surface. The largest effects were observed after oxygen ion bea m etching. The adhesion of the Co-Cr layers was improved by all the pr etreatments, especially by oxygen ion beam etching. A clear correlatio n between the roughness of the PET substrate and the adhesion of the d eposited Co-Cr layer was found. The topographic changes on the PET sur face caused by the pretreatment methods largely influence the morpholo gy of the Co-Cr layer. By 1 min oxygen ion beam etching, stalk-like st ructure can be induced in the PET surface which result in a distinct c olumnar growth of the magnetic layer. Furthermore, the crack formation in the magnetic layer can be reduced by some pretreatment methods. A correlation exists between the adhesion of the Co-Cr layer and the red uction of cracks in the layer.