Effect of surface cleanness on the magnetic properties of CoNiCr and CoCrTa thin-film media fabricated using an ultraclean sputtering process

The correlation between the cleanness of the substrate surface and magnetic properties is discussed for thin-film media fabricated using an ultraclean (UC) sputtering process. Only slight dry-etching of the substrate surface (etched depth about a few Angstrom) just before film deposition results in an increase in H-c, especially in media with thin Cr and magnetic layers. The removal of the adsorbed oxygen impurities on the substrate surface by slight dry-etching in the UC process, was found to cause the increase in H-c. It is suggested that the re-adsorption of gas impurities makes it impossible to improve magnetic properties by dry-etching in the normal sputtering process. Furthermore, it is clarified that the inducement of uniaxial magnetic anisotropy due to the texture of the substrate surface is strongly connected with the adsorption of gas impurities on the substrate surface.