Ta additive effect on RF magnetron sputtered CoCr films

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Abstract
Magnetic properties for sputtered CoCrTa films (18 at.% Cr and 2.0-3.0 at.% Ta), which were deposited under various background pressures P/sub i/, and argon sputtering pressures, P/sub Ar/, have been examined. The perpendicular anisotropy field H/sub k/ for CoCrTa films maintains high values of 5-6 kOe in a wide range of P/sub i/ and P/sub Ar/, as compared with that for CoCr films. In order to optimize Ta composition, magnetic properties and crystalline microstructures for Ta additive content (0-4.0 at.%) have been investigated. H/sub k/ and perpendicular coercivity H/sub c perpendicular to / increase with increasing Ta concentration above 2.0 at.% Ta. C-axis orientation is improved by adding Ta to CoCr films. However, above 3.0 at.% Ta, H/sub c perpendicular to / steeply decreases and domain wall motion is observed, owing to the increase in crystalline grain size. The appropriate Ta composition is 2.0-3.0 at.%.