Method for making a master disk for nanoimprinting patterned magnetic recording disks, master disk made by the method, and disk imprinted by the master disk
View Patent ↗A method for making a master disk to be used for nanoimprinting patterned-media magnetic recording disks uses sidewall lithography. In one implementation, the master disk substrate has a first pattern of concentric rings formed on it by sidewall lithography, followed by a second pattern of generally radially-directed pairs of parallel lines, also formed by sidewall lithography, with the pairs of parallel lines intersecting the rings. An etching process is then performed, using the upper pattern as an etch mask, to remove unprotected portions of the underlying concentric rings. This leaves a pattern of pillars on the substrate, which then serve as an etch mask for an etching process that etches unprotected portions of the master disk substrate. The resulting master disk then has pillars of substrate material arranged in a pattern of concentric rings and generally radially-directed pairs of parallel lines.
1. A patterned-media magnetic recording disk comprising:
a substrate having a plurality of magnetic islands arranged about a center, the islands being arranged into a plurality of annular bands of concentric circular tracks about said center, the islands in each band being arranged into a plurality of generally radially-directed non-parallel pairs of parallel lines wherein the islands in the parallel lines in each pair are equally circumferentially spaced in all tracks of a band, the pairs of lines being generally equally angularly spaced about said center.
2. The disk of claim 1 wherein the islands in a circular track generally at the middle of each band are generally equally angularly spaced about said track.
3. The disk of claim 1 wherein the radially inner ends of the pairs of lines have the same equal angular spacing about said center as the radially outer ends of the pairs of lines.
4. The disk of claim 1 wherein each pair of lines is aligned along a radius from said center.
5. The disk of claim 4 wherein each pair of lines has a generally arcuate shape.
6. The disk of claim 1 wherein each pair of lines is oriented at an acute angle with a radius from said center.
7. The disk of claim 6 wherein the islands in alternate tracks are aligned to form generally radially-directed arcuate-shaped lines.
8. The disk of claim 7 wherein the islands are shaped as generally non-rectangular parallelograms having acute interior angles generally equal to the complement of said acute angle of orientation.