Patterned media technologies involve a photolithographic patterning of the recording media. This patterning allows the head placement during operation to be physically pre-printed on each disk, reducing drive manufacturing costs. Traditionally, the magnetic servo pattern in a drive has to be recorded on the disks in that drive after the drive is assembled. Each data location will contain a single bit and provide isolation of each bit that reduces read-back noise, ultimately increasing SNR and storage density.
A key challenge of fabricating sub-20nm features on the entire media surface is doing so with very close tolerances and tightly controlled magnetic properties. Today, only electron beam lithography can produce imprint masters with these dimensions.
Manufacturing Process Flow
- Electron-beam lithography on a silicon wafer produces a master resist pattern
- Hundreds to thousands of imprint stamps are produced using this same master resist pattern
- Low-cost nano-imprint lithography transfers the pattern onto the magnetic disk surface
Rising to the Challenge
Moving to nano-patterned media will involve more layers of ultra-thin films with new alloys, thinner and denser carbon structures, improved lubrication materials and lower defects. To enable next-generation patterned media designs, with the 10 sputtered layers that are typical and the need for heating and sputter-etching, a manufacturing system with more sputtering stations is required.
The 200 Lean® system can handle up to 28 vacuum stations in a small footprint configuration, making it ideal for patterned media fabrication. The modular nature of the 200 Lean platform allows the development of a fully integrated, continuous media patterning and planarization process. Intevac’s patented Halo etch source can effectively etch cured photoresist as well as metal layers to fully define any particular pattern across the entire surface of the disk. Additional chambers are used for the pattern fill and etchback processes necessary to planarize the finished disk surface as well as deposit the final protective overcoat. The result is the production of fully patterned disks at throughput rates that are comparable to those achieved with planar media, a significant manufacturing advantage.
There are two methods to pattern disks:
- Pattern the substrate before deposition of the magnetic film structure
- Pattern the media after the magnetic layers have been deposited
The film thicknesses required for PMR make the second approach more practical and the method of choice. The pattern is then developed by ultra-violet (UV) curing and the magnetic islands – or tracks – are formed by etching the stamped resist pattern into the magnetic film. A non-magnetic material is then deposited into the subtracted areas and the media surface is planarized to help with head flyability over the media. Finally, the patterned, planarized disk will need a protective overcoat, lubrication and final testing.