Magnetic Duplication for Precise Servo Writing on Magnetic Disks

Abstract

A servo pattern of a 20 Gbit in 2 level was directly duplicated on hard disks by using a magnetic duplication method, and the accuracy of the signal and the following performance on the duplicated servo pattern were evaluated. The phase servo pattern was composed of straight lines and was lithographically formed on a mastering disk. The period accuracy of the readback signal was very high. The repeatable position error for adjacent tracks in a prototype drive was measured, and the difference between two adjacent RPE trajectories was sufficiently small. The magnetic duplication method showed the possibility of precise servo-track writing for high-density hard disk drives.Index Terms-Magnetic duplication, phase servo pattern, repeatable position error (RPE), servo-track writing.

Performance and Potential of High-Density Bit Recording Using Patterned Master Contact Duplication

“…A new type of magnetic duplication, called patterned master contact duplication, was proposed in 2000 [1,2] . Since the master does not need higher coercivity Hc , than that of the slave, it is possible to duplicate even to highrecording-density hard disks with high Hc This duplication is expected to resolve the problems of conventional servo-track writing (STW), such as STW time, writing cost, and precise writing [3,4]. Although many studies of the method have been conducted, most of them have involved micron-sized bits [5][6][7].…”

“…The master disks that we used were composed of a patterned Ni substrate covered with an Fe70Co30 magnetic layer. They were prepared by EB direct drawing and lithography for patterns, plating for the substrate, and sputtering for the magnetic layer [4]. Carbon layers with thicknesses from 5 to 40 nm were deposited on the masters as spacing between the master and slave disks.…”