Reverse optical mastering for data storage disks

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.

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.