Domain Studies of Electroplated High Moment CoFe and Ni45Fe55 on Test Structures

Magnetic properties of high moment magnetic materials for write head applications were measured for various geometries and anneal conditions. CoFe and Ni45Fe55 were electroplated on different test structures with 3--D topography as well as flat surfaces. Stripes of magnetic material with different width ranging from 5 mu m to 50 mu m are formed using a photo lithographic process. The resist thickness is 3 mu m and the seed layer was 800 Å Ni45Fe55 sputtered onto 47mmx47mm glass substrates. The thickness of the electroplated CoFe is between 0.8 mu m and 1.8 mu m and the electroplated Ni45Fe55 is approximately 1.2 mu m . Both B-H loops and domain imaging confirm that the easy axis of the films switches to a direction parallel to the stripes after plating although a magnetic field of 700-1200 Gauss was applied perpendicular to the stripe direction during plating. Another test structure design consists of two layers of photo resist stripes with 20 mu m width. These two layers of photo resist stripes are oriented perpendicular to each other. A Ni45Fe55 seed layer was sputtered between these layers to provide a conductive surface for electroplating. Domain studies reveal that the preferred transverse domain orientation can be achieved by optimizing the hard-bake conditions for the first layer of photo resist, and for different high moment materials, these conditions need to be optimized individually. This study has potential applications for the domain control in the yoke of write heads for high density and high data rate magnetic recording.