Process for forming a master mold for optical storage disks

• US 4,724,043 A
• Filed: 12/24/1986
• Issued: 02/09/1988
• Est. Priority Date: 09/04/1984
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Bergendahl, Albert S., Cade, Paul E., Petersen, Kurt E., Luecke, Francis S., Gonnella, Norman T.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US06/943,845
• Time in Patent Office: 412 Days
• Field of Search: 156/633, 156/643, 156/646, 156/657, 156/659.1, 156/662, 204/192.37, 430/320, 430/321, 430/323, 430/326, 430/329, 346/76 L
• US Class Current: 216/2
• CPC Class Codes: G11B 23/0057 Intermediate mediums, i.e. mediums provided with an information structure not specific to the method of reproducing or duplication such as matrixes for mechanical pressing of an information structure for record carriers with directly readable mechanical information G11B3/685; record carriers having a relief information structure provided with or included in layers not specific for a single reproducing method; apparatus or processes specially adapted for their manufacture
• CPC Class Codes: G11B 7/261 Preparing a master, e.g. exposing photoresist, electroforming

Abstract

A method for forming a master mold for optical storage disks includes thermally growing an oxide or nitride layer on a semiconductor wafer. The thermally grown layer is then coated with a photoresist. The photoresist is exposed to a laser beam to form a data pattern and developed. The oxide or nitride under the developed pattern is etched and the photoresist stripped to provide a semiconductor master mold for optical disks.

Claims

1. A process for forming a master mold for insertion in a molding jig used for making optical storage disks having data pits of a predetermined depth, the steps including:

thermally creating a layer of etchable material on a surface of a single-crystalline semiconductor substrate, said substrate and said etchable layer forming a monolithic structure with the thickness of said etchable layer corresponding to the predetermined depth of data pits to be molded in an optical storage disk,

applying a photoresist layer on said layer of etchable material,

exposing said photoresist layer to generate a data pattern in the photoresist layer,

developing and removing portions of the exposed photoresist to produce a data pattern mask,

etching said layer of etchable material, through said mask, down to the semiconductor substrate effectively forming pits in the monolithic structure, said pits having a depth corresponding to the predetermined depth of data pits to be molded in an optical disk, and

removing the remaining photoresist to form a master mold for insertion in the optical disk molding jig.

2. A process according to claim 1 wherein said single crystalline semiconductor substrate is selected from a group including silicon and germanium.

3. A process according to claim 1 wherein said semiconductor substrate is silicon and said layer of etchable material is silicon oxide and is thermally grown on said substrate.

4. A process according to claim 1 wherein the photoresist layer in said applying step is a positive photoresist.

5. A process according to claim 1 wherein said applying step is accomplished by spin coating.

6. A process according to claim 1 wherein the photoresist layer is exposed to a laser beam modulated according to the data to be stored.

7. A process according to claim 4 wherein the exposed photoresist is developed using a method allowing removal to occur at the portions of the photoresist layer not exposed to the laser beam.

8. A process according to claim 5 wherein said thermally created layer is etched by reactive ion etching.

9. A process according to claim 5 wherein said thermally created layer is etched by sputter etching.

10. A process according to claim 5 wherein said thermally created layer is etched by aqueous chemical etching.

11. A process according to claim 1 wherein said semiconductor substrate is silicon and said layer of etchable material is selected from a group including silicon oxide and silicon nitride and is chemical-vapor deposited on said substrate.