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Patterning process for bipolar optical storage medium
| Details |
Inventors: Cheng, John C.; Hinsberg, III, William D.; Lynch, Jr., Robert T.; MacDonald, Scott A.; Pederson, Lester A.; Wong, James S.;
Assignee: International Business Machines Corporation (Armonk, NY)
Primary Examiner: Bowers, Jr.; Charles L.
Assistant Examiner: McPherson; John A.
Attorney, Agent or Firm: Millett; Douglas R., Saber; Paik
An optical data storage device having a substrate has guide ridges, or reverse grooves, in a concentric or spiral shape formed thereon, and disposed in a plane parallel to and disposed from the substrate surface. The device further has pits formed approximately midway between the guide ridges and disposed in the substrate and having bottoms below the plane of the substrate surface. A method for manufacturing the optical data storage device having both address pits and guide ridges is disclosed. A dual tone photosensitive material is applied to a substrate, exposed with a laser light source comprising two distinct wavelengths, and developed to provide a desired bipolar geometry thereon. |
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DETAILED DESCRIPTION OF THE INVENTION FIG.
1 illustrates a prior art optical storage device 1 having, for example, a plurality of concentric tracks 2, a few of which are shown.
Each track 2 is divided into a plurality of sectors 5.
Each sector comprises a data containing track portion 4, along which a user can record information or read-only information may be integrally formed during the manufacturing process.
Each sector further comprises a read-only header portion 3, which serves to identify the relative position of recorded data.
An alternative embodiment (not illustrated) utilizes a spiral track which is divided into a plurality of sectors.
FIG.
2 illustrates radially adjacent tracks 2 of the prior art optical storage device from FIG.
1.
Between successive concentric tracks 2, or successive turns of a spiral track, grooves 6 are formed in the surface of the substrate 8 and serve to differentiate between any radially adjacent tracks.
A film 9 may optionally be provided on the surface of the device substrate 8.
Further, pits 7 are integrally formed, approximately midway between adjacent device grooves 6, and disposed within the same direction as the device grooves 6.
That is, the device tracks 2, and the substrate 9 surface in general, define a plane.
The device grooves 6 and pits 7 are each downwardly disposed in a direction normal to the defined plane.
In an alternate embodiment, device pits and grooves are each disposed above the surface of the device track 2 (not shown).
In either embodiment the relative depth (height) of the device grooves 6 are shallower (shorter) than that of the device pits 7.
The above described features thereby defining a dual depth optical storage device.
FIG.
3(a)-(b) shows the result of a prior art process for manufacturing an optical storage device or stamper master with the dual depth feature.
That is, an optical disk or stamper master 1 having pits 7 and shallower grooves 6 each downwardly disposed within the device substrate 8.
In the dual depth process, a substrate 8 is first covered with a photoresist layer 11
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Manufacturing Materials 
