Control of Thin Film Media Microstructure by Using Very Thin Seedlayer Material with Different Affinity for Oxygen

Abstract

To reduce the grain size and the media noise in a typical CrMo/CoCrPtB longitudinal media, a sputtering process which includes the exposure of oxygen onto the surface of CrW<TEX>$_x$</TEX> (x=0, 25, 50, 75, 100 at.%) and CrTi<TEX>$_{15}$</TEX> seedlayers with the thickness of 0.5 nm have been utilized. The main results are: (1) the media grain size and the media noise are reduced when using CrW<TEX>$_x$</TEX> (x=0, 25, 50 at.%) seedlayers, and not reduced when using CrTils or CrW<TEX>$_x$</TEX> (x=75, 100 at.%) seedlayers, (2) AES and RHEED results suggest that W seedlayer, which has the highest melting point, forms layer-like film with very small and dense island grain, due to its high free surface energy and low mobility. On the other hand, CrW<TEX>$_{50}$</TEX> and Cr seedlayers, which have lower melting point than W seedlayer, form island film, (3) to effectively reduce the media grain size and improve the media signal to noise ratio, it is essential to utilize a very thin Cr-based seedlayer with high affinity for oxygen and which forms island-like structure, such as CrW<TEX>$_{50}$</TEX> seedlayer.