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High moment CoFe films on thin NiFe underlayers Disclosure Number: IPCOM000031485D
Publication Date: 2004-Sep-27
Document File: 6 page(s) / 82K

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High moment CoFe films on thin NiFe underlayers N.X. Sun, J. Jarratt, and R. Hsiao In this work, we disclose high saturation magnetization soft magnetic films, the NiFe seeded CoFe films with Co in the range of 30~40at%. The NiFe seeded CoFe films have a high saturation magnetization, low coercivity, decent corrosion resistance and thermal stability, and are adopted as the process record for our new products as the Pole cap (P1cap) layer of films.

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SJO820020140 Ron Feece/San Jose/IBM Nian Sun, Richard Hsiao, James Jarratt

High moment CoFe films on thin NiFe underlayers

  High magnetic moment films are a necessity for applications in write heads for magnetic data storage systems. Cobalt-iron based films with a Co composition in the range of 30~40at% are known to have the highest saturation magnetization, and are the best candidate materials. However, the FeCo magnetic films usually have no anisotropy field, and a large coercivity which can range up to 50~100 Oe [N.X. Sun, Dissertation, Stanford University, 2001], both of which are detrimental. Nitrogen doping into the FeCo30at% films by reactive diode sputtering is shown to be effective in inducing in-plane anisotropy and lowering the coercivity, but the adverse effect is a loss of magnetic moment by
0.05~0.1Tesla. This amount of moment loss, albeit small, corresponds to 1~2dB or overwrite for write heads. It is also shown that by putting a thin NiFe (80/20 permalloy) underlayer for the CoFeN films, excellent soft magnetic properties (<1 Oe coercivities) are achieved in the high moment FeCoN alloy films with the NiFe seed [N.X. Sun, Dissertation, Stanford University, 2001].

In this work, we disclose a NiFe seeded CoFe films with coercivities at the range of 5~20Oe, and a high Bs of 2.4~2.45T (or 4PiMs of 24~24.5kG). This NiFe seed CoFe films will be great for potential applications in write heads. In fact, the NiFe seeded CoFe films have been taken as the process of record (POR) for the P1cap for many new products. Other potential applications for this NiFe seeded CoFe films include the pole 2 seed layer for plating, and the perpendicular recording write pole film.

The table 1 below show how the easy and hard axis coercivities (Hce and Hch) are reduced with the presence of the thin NiFe underlayer and the optimal table bias voltage during the CoFe deposit...