Submicron-scale film morphology effects on media noise of CoCrTa thin films on smooth substrates

The effect of submicron-scale morphology on media signal-to-noise ratio (SNR) has been evaluated for Cr/CoCrTa thin films deposited on super-smooth Al/NiP substrates. Two types of morphology and topography variations were studied. First, the underlayer X was made either smooth or rough in the submicron scale, and the subsequent Cr and magnetic layers deposition replicated the topography of layer X. For the second case, two different buffer layers were deposited with flat and smooth topography in the submicron scale. The subsequently deposited Cr/CoCrTa layers are either morphologically homogeneous or inhomogeneous. In both cases SNR measurements show a dramatic dependence on the morphology. It is concluded that the submicron-scale morphology variation was a profound contributor to the difference in media SNR. To make high-performance ultrahigh-density media, morphology homogeneity in the submicron-scale is essential.