Superlattice source and its application in Co/Pd multilayers for perpendicular magnetic recording

Abstract

This article reports a sputtering system, the Intevac Superlattice Source (SLS), designed to meet the needs of making perpendicular multilayers for hard disk manufacturing. The SLS is a two-sided sputtering station in which each side is capable of depositing multiple sequential bilayers of two different film materials. Each side of the source contains a magnetron (sharing the same centerline as the substrate) and a rotating cathode on which are mounted two semicircular targets. The two rotating cathodes (one on each side of the source) are synchronized to ensure matched elements sputtering simultaneously and to prevent cross contamination between target materials. The design easily integrates onto standard hard disk manufacturing systems and can deposit up to 5 bilayers per second. Using this source, a series of Co/Pd multilayers has been made. We investigated the effect of different seedlayers, Pd, Ti, and Ru, on the coercivity and microstructure of Co/Pd multilayers. We found that although the crystalline growth is very different for each of the three seed layers studied, all three lead to higher coercivity and unique squareness of Co/Pd multilayers as compared to multilayers made without any seedlayer. The coercivity achieved for a 300 Å thick seedlayer [Co 4 Å/Pd 10 Å]×15 multilayer is 6253, 6871, and 6920 Oe for Pd, Ti, and Ru seedlayers, respectively.