Servo patterns for self-assembled island arrays
View Patent ↗Servo patterns and associated methods of fabricating servo patterns are described. For patterned storage media, data sectors and servo sectors may be patterned using self-assembly. In one embodiment, self-assembly is used to form a first array of islands and a second array of islands in servo sectors that are track-wise offset. A servo writing process is then performed to write a desired servo pattern in the arrays, such as for burst fields, synchronization fields, etc.
1. A patterned storage media, comprising:
servo sectors that are patterned into discrete islands using self-assembly, the servo sectors comprising:
a first array of islands having hexagonal close packed (HCP) ordering that defines at least one burst field; and
a second array of islands having HCP ordering that defines at least one burst field that is track-wise offset from the first array of islands;
wherein the first array of islands define first and second burst fields and the second array of islands define third and fourth burst fields, the burst fields are comprised of a plurality of rows that are written with a servo writing process to have the repeating pattern of:
consecutive islands in a first row of the first array having uniform polarity in the first burst field, and having an alternating polarity in the second burst field, and consecutive islands in a second adjacent row of the first array having an alternating polarity in the first burst field, and having uniform polarity in the second burst field; and
consecutive islands in a first row of the second array having an alternating polarity in the third burst field, and having uniform polarity in the fourth burst field, and
consecutive islands in a second adjacent row of the second array having uniform polarity in the third burst field, and having an alternating polarity in the fourth burst field;
wherein the first and second rows in the first and second burst fields are track-wise offset from the first and second rows in the third and fourth burst fields.
2. The patterned storage media of claim 1 wherein the first and second rows in the first and second burst fields are track-wise offset from the first and second rows in the third and fourth burst fields by about a half track, with the first and second rows in the first and second burst fields between tracks and the first and second rows in the third and fourth burst fields center track.
3. The patterned storage media of claim 1 wherein the servo sectors further comprise a third array of islands having HCP ordering that defines a synchronization field, wherein the synchronization field is comprised of a plurality of rows that are written with a servo writing process so that consecutive islands in the rows have an alternating polarity.
4. A method of fabricating servo sectors of a patterned storage media, the method comprising:
forming a first array of islands having hexagonal close packed (HCP) ordering that defines at least one burst field;
forming a second array of islands having HCP ordering that defines at least one burst field that is track-wise offset from the first array of islands, wherein the first array of islands define first and second burst fields and the second array of islands define third and fourth burst fields; and
performing a servo writing process in the first array and the second array with the repeating pattern of:
writing to consecutive islands in a first row of the second array to have an alternating polarity in the third burst field, and to have uniform polarity in the fourth burst field;
writing to consecutive islands in a first row of the first array to have uniform polarity in the first burst field, and to have an alternating polarity in the second burst field;
writing to consecutive islands in a second adjacent row of the second array to have uniform polarity in the third burst field, and to have an alternating polarity in the fourth burst field; and
writing to consecutive islands in a second adjacent row of the first array to have an alternating polarity in the first burst field, and to have uniform polarity in the second burst field;
wherein the first and second rows in the first and second burst fields are track-wise offset from the first and second rows in the third and fourth burst fields.
5. The method of claim 4 wherein the first and second rows in the first and second burst fields are track-wise offset from the first and second rows in the third and fourth burst fields by about a half-track, with the first and second rows in the first and second burst fields between tracks and the first and second rows in the third and fourth burst fields center track.
6. The method of claim 4 wherein the first array of islands and the second array of islands form radial columns of islands that span multiple rows, and further comprising:
performing a servo writing process with a wide write element that writes to islands of alternating rows simultaneously.
7. The method of claim 6 wherein performing a servo writing process with a wide write element comprises:
performing the servo writing process in the first array and the second array with the repeating pattern of:
writing a first polarity in the islands of a first radial column;
writing a second polarity in the islands of the next three adjacent radial columns.
8. The method of claim 4 further comprising:
forming a third array of islands having HCP ordering that defines a synchronization region; and
performing a servo writing process in the third array with the repeating pattern of writing to consecutive islands in the rows to have an alternating polarity.