Reverse optical mastering for data storage disks

• US 6,890,704 B2
• Filed: 12/05/2000
• Issued: 05/10/2005
• Est. Priority Date: 04/06/1998
• Status: Expired due to Term

• Current Assignee: Max Blu Technologies, LLC (IP Investments Group LLC)
• Original Assignee: Imation Corporation (Glassbridge Enterprises, Inc.)
• Inventors: Edwards, Jathan D.
• Primary Examiner(s): ANGEBRANNDT, MARTIN J
• Application Number:
  US09/730,246
• Publication Number:
  US 20010000746A1
• Time in Patent Office: 1,617 Days
• Field of Search: 430/320, 430/321, 430/945, 264/1.33, 264/1.31, 264/1.34, 369/275.4, 369/275.3, 369/238
• US Class Current: 430/321
• CPC Class Codes: G11B 23/0085 intermediate mediums using a photosensitive material, e.g. photo-resist
• CPC Class Codes: G11B 7/24 Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the arrangement of information on the carrier G11B7/007
• CPC Class Codes: G11B 7/24091 Combinations of pits and tracks with specific interrelation
• CPC Class Codes: G11B 7/261 Preparing a master, e.g. exposing photoresist, electroforming
• CPC Class Codes: G11B 7/263 Preparing and using a stamper, e.g. pressing or injection molding substrates production of optical record carriers, e.g. optical discs B29D17/005
• CPC Class Codes: Y10S 425/81 Sound record

Abstract

A data storage master disk and method of making a data storage master disk. The data storage disk master is for use in a data storage disk replication process. The data storage disk molding processes produces replica disks having a surface relief pattern with replica lands and replica grooves. The method includes providing a master substrate. The master substrate is at least partially covered with a layer of photosensitive material. A surface relief pattern having master lands and master grooves is recorded in the data storage disk master, including the steps of exposing and developing the photosensitive material. The exposing and developing of a specified thickness of photosensitive material is controlled to form master grooves extending down to a substrate interface between the master substrate and the layer of photosensitive material, such that the width of the master grooves at the substrate interface corresponds to a desired width of the replica lands.

Claims

1. A method of creating replica disks that define a desired replica pattern having flat coplanar land tops that define widths in a range of approximately 80-200 nanometers and groove depths in a range of approximately 20-120 nanometers comprising:

focusing light from a laser in a mastering system to form a focused laser spot on a photosensitive master, the focused law spot defining a laser spot size, wherein the laser spot size is defined by a full width at half maximum intensity;

laser etching the photosensitive master to form a master pattern that is inverse of the desired replica pattern, the desired replica pattern defining a track pitch less than 2 multiplied by the laser spot size associated with the laser used to perform the laser etching, wherein the track pitch is less than approximately 700 nanometers, and wherein the laser etching defines master groove bottom widths of the master pattern, which correspond to flat coplanar land tops of the desired replica pattern, substantially independently of a master groove depth of the master pattern;

creating a first generation stamper using the master, the first generation stamper having features that are inverted relative to the master such that the features of the first generation stamper correspond to the desired replica disk pattern;

creating a second generation stamper using the first generation stamper, the second generation stamper having features that correspond to the master pattern; and

creating replica disks using the second generation stamper, wherein the replica disks are formed with the desired replica pattern, which is inverted relative to the master pattern to define the flat coplanar land tops with widths in the range of 80-200 nanometers and the groove depths in the range of 20-120 nanometers.

2. The method of claim 1, wherein the desired replica pattern defines a track pitch less than 1.6 multiplied by the laser spot size.

3. The method of claim 1, further comprising laser etching the photosensitive master down to a substrate interface to define flat master groove bottoms that correspond to flat land tops of the desired replica pattern.

4. The method of claim 3, wherein the flat master groove bottoms define widths greater than 25 percent of the track pitch.

5. The method of claim 3, wherein the flat master groove bottoms define widths greater than 35 percent of the track pitch.

6. The method of claim 3, wherein the flat master groove bottoms define widths greater than 50 percent of the track pitch.

7. The method of claim 3, further comprising laser etching the photosensitive muster down to the substrate interface to define the flat master groove bottoms that correspond to flat coplanar land tops of the desired replica pattern, wherein the flat coplanar land tops define substantially sharp corners.

8. The method of claim 1, wherein the truck pitch is less than or equal to 400 nanometers.

9. The method of claim 8, wherein a groove depth in the master pattern is greater that 80 nanometers and a land width of the replica disk pattern is greater than 160 nanometers.

10. The method of claim 1, further comprising:

specifying a thickness of photosensitive material; and

coating a master substrate with the specified thickness of photosensitive material to form the photosensitive master;

wherein laser etching the photosensitive master comprises exposing the photosensitive material to a controlled amount of optical energy using the focused light from the laser; and

exposing the photosensitive material to developer solution, wherein the specified thickness of photosensitive material, the controlled amount of optical energy, and the exposure to developer solution collectively define on the photosensitive master the inverse of the desired replica pattern.

11. The method of claim 1, wherein the desired replica disk pattern defines lands and grooves.

12. The method of claim 1, wherein the desired replica disk pattern defines transducer-detectable surface variations.

13. The method of claim 1, wherein the replica disks comprise flyable media baying flat coplanar replica land tops.

14. A method of creating replica disks that define a desired replica pattern having flat coplanar land tops that define widths in a range of approximately 80-200 nanometers and groove depths in a range of approximately 20-120 nanometers comprising:

focusing light from a laser in a mastering system to form a focused laser spot on a photosensitive master, the focused laser spot defining a laser spot size, wherein the laser spot size is defined by a full width at half maximum intensity according to an equation (constant)(λ

)/(NA), where the constant is approximately equal to 0.57, λ

is a wavelength associated with the laser, and NA is a numerical aperture used in the mastering system; and

laser etching the photosensitive master down to a substrate interface to form a master pattern that is inverse of a desired replica pattern, the desired replica pattern defining a track pitch less than 2 multiplied by the laser spot size associated with the laser used to perform the laser etching, wherein the track pitch is less than approximately 700 nanometers, and wherein the laser etching defines master groove bottom widths of the master pattern, which correspond to flat coplanar land tops of the desired replica pattern, substantially independently of a master groove depth of the master pattern;

creating a first generation stamper using the master, the first generation stamper having features that are inverted relative to the master such that the features of the first generation stamper correspond to the desired replica disk pattern;

creating a second generation stamper using the first generation stamper, the second generation stamper having features that correspond to the master pattern; and

creating replica disks using the second generation stamper, wherein the replica disks are formed with the desired replica pattern, which is inverted relative to the master pattern to define the flat coplanar land tops with widths in the range of approximately 80-200 nanometers and the groove depths in the range of approximately 20-120 nanometers.

15. The method of claim 14, the desired replica pattern defining a track pitch less than by the laser spot size.

16. The method of claim 15, wherein master groove bottoms are flat and define widths greater than 50 percent of the track pitch.

17. The method of claim 16, wherein the track pitch is less than or equal to 400 nanometers.

18. A method of creating a master comprising:

specifying a thickness of photosensitive material;

coating a master substrate with the specified thickness of photosensitive material to form a photosensitive master;

focusing light from a laser in a mastering system to a focused laser spot on the photosensitive material of the photosensitive master, the focused laser spot defining a laser spot size, wherein the laser spot size is defined by a full width at half maximum intensity according to an equation (constant)(λ

)/(NA), where the constant is approximately equal to 0.57, λ

is a wavelength associated with the laser and NA is a numerical aperture used in the mastering system;

exposing the photosensitive material to a controlled amount of optical energy using the focused light from the laser; and

exposing the photosensitive material to developer solution, wherein the specified thickness of photosensitive material, the controlled amount of optical energy, and the exposure to developer solution collectively define on the photosensitive master an inverse of a desired replica pattern, the desired replica pattern defining a track pitch less than 2 multiplied by the laser spot size of the laser, and wherein the track pitch is less than approximately 700 nanometers, and wherein master groove bottom widths of the master pattern, which correspond to flat coplanar land tops of the desired replica pattern, are substantially independent of a master groove depth of the master pattern;

creating a first generation stamper using the master, the first generation stamper having features that are inverted relative to the master such that the features of the first generation stamper correspond to the desired replica disk pattern;

creating a second generation stamper using the first generation stamper, the second generation stamper having features that correspond to the master pattern; and

creating replica disks using the second generation stamper, wherein the replica disks are formed with the desired replica pattern, which is inverted relative to the master pattern to define the flat coplanar land tops with widths in the range of approximately 80-200 nanometers and the groove depths in the range of approximately 20-120 nanometers.

19. The method of claim 18, the desired replica pattern defining a track pitch less than 1.6 multiplied by the spot size of the laser.

20. The method of claim 18, wherein the photosensitive material comprises a positive photoresist material and wherein exposing the photosensitive material to developer solution comprises developing the positive photoresist material.