Browse Prior Art Database

Servo Patterning of Magneto-Optical Disks

IP.com Disclosure Number: IPCOM000034632D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Marinero, EE: AUTHOR

Abstract

Servo-tracking in magneto-optical (MO) storage disks is currently achieved by monitoring the light diffracted from the edge of the grooves of a pre-stamped disk. The tracks are obtained by either mechanically molding a photo-polymerizable layer, a plastic substrate or direct etching of glass substrates. This article describes a novel approach which removes the need for photo-polymerizable layers and the processing steps needed to generate the servo pattern, thus eliminating defects inherent in the replication process and chemical and mechanical interfacial concerns. Grooves are considered indispensable in optical storage disks for achieving high recording densities and to permit accurate random access.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

Page 1 of 2

Servo Patterning of Magneto-Optical Disks

Servo-tracking in magneto-optical (MO) storage disks is currently achieved by monitoring the light diffracted from the edge of the grooves of a pre-stamped disk. The tracks are obtained by either mechanically molding a photo- polymerizable layer, a plastic substrate or direct etching of glass substrates. This article describes a novel approach which removes the need for photo- polymerizable layers and the processing steps needed to generate the servo pattern, thus eliminating defects inherent in the replication process and chemical and mechanical interfacial concerns. Grooves are considered indispensable in optical storage disks for achieving high recording densities and to permit accurate random access. Current fabrication of a grooved recording structure encompasses several complex processes including the optical beam recording a master disk, the electroplating process to generate stampers, the transfer of the groove pattern by compression or injection molding onto a suitable polymer layer and finally the deposition process of the recording structure. Besides the numerous processing steps involved, the means of grooving optical storage structures leads to the introduction of defects that may result in dropouts or bit errors. This is either a consequence of the replication process which ultimately leads to the degradation of the stamper or to environmental contamination between the grooving process and the active layer deposition. Additionally, the photopolymer layer can readily entrap water vapor, and subsequent outgassing can chemically impair the stability of the recording layer. A new means of accomplishing track formation and servoing eliminates the need for photo- polymerizable layers and the necessary steps required to generate and replicate the tracking grooves. The servo pattern is generated within the MO layer and can be produced following complete encapsulation of the recording structure. Thus, defects that are inherent in the conventional fabrication of grooves, interfacial delamination and undesirable chemical reactions through solid-state diffusion processes are all eliminated. The technique is based on the unique structural changes that ca...