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Dry Lithographic Method for Patterning Storage Media

IP.com Disclosure Number: IPCOM000042826D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Cuomo, JJ: AUTHOR [+4]

Abstract

This is a process for making servo patterns on a storage medium. It It uses a storage medium with a polymeric (organic) substrate carrying a markable thin (metallic) film or the equivalent. A third overcoat layer can be included if it is desired to increase the amount of energy absorbed by the markable film. The film is marked with an optical source of far ultraviolet (UV) radiation with wavelengths below about 220 nm which heats the polymeric material to ablate marks on that film. The film is thin so ultraviolet radiation passes through the polymeric material below, ablating the polymeric material. The film can be metallic, such as a bi-layer or a material with relatively high ultraviolet transmission characteristics providing good optical contrast with the radiation used for reading it.

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Dry Lithographic Method for Patterning Storage Media

This is a process for making servo patterns on a storage medium. It It uses a storage medium with a polymeric (organic) substrate carrying a markable thin (metallic) film or the equivalent. A third overcoat layer can be included if it is desired to increase the amount of energy absorbed by the markable film. The film is marked with an optical source of far ultraviolet (UV) radiation with wavelengths below about 220 nm which heats the polymeric material to ablate marks on that film. The film is thin so ultraviolet radiation passes through the polymeric material below, ablating the polymeric material. The film can be metallic, such as a bi-layer or a material with relatively high ultraviolet transmission characteristics providing good optical contrast with the radiation used for reading it. A metallic masking layer can be used with a material to be removed below it, or silicon dioxide can be used as the top layer. The pattern can be made by passing the laser through a single mask. Optical or capacitive transducers can detect a pattern printed on a storage medium to obtain servo information, such as radial position, track number, file number, etc., required for a read/write head to a data recording focus. A parallel replication process such as printing by contact lithography, projection lithography, or mechanical means, is fast. The UV light is able to penetrate thin layers of metal. Far UV radiation is absorbed in the first few tens of nanometers of the organic material. The metallic layer is thin and has a low complex index of refraction. Suitable metals are Ti, Mn, W, V, Ni, Pd, Mo, Cr, etc. The metallic film may be made more transmissive at the wavelength of the UV radiation by using a bi-layer structure or a tuned multilayer stack. One possible bi-layer is Ti overcoated with a thin flash of Si. The ablation process is shown schematically in Fig. 1, both before and after the ablation. Fig. 1A shows a recording medium 10 of metallic films 11 and 12 on...