High Density Optical Disk Mastering Research Articles

Thermal Recording for High-Density Optical Disc Mastering

Thermal recording using a dielectric as a recording material was examined to make a high-density optical disc master. We confirmed that a pit of 53 nm length was able to be recorded with a laser of 405 nm wavelength. As a result we could make a master with a 200 gigabyte (GB) data capacity with a conventional laser beam recorder (LBR). A 100 GB disc made by the same method was able to be read with a tester equipped with a solid immersion lens (SIL) and the measured jitter value was 9.9%.

Nanopattern Profile Control Technology Using Reactive Ion Etching for 100 GB Optical Disc Mastering

We had developed an electron beam recorder (EBR) and studied a process technology for high-density optical disc mastering. In this study, we aimed at controlling a nanopattern profile by adopting inductively coupled plasma reactive ion etching (ICP-RIE) under simple conditions. To control a pattern inclination angle, we introduced an etching power ratio of antenna to bias and investigated the relationship. From the results of our investigation, we confirmed that inclination angle depended on etching power ratio linearly. Furthermore, in the case of a 100 GB read-only memory (ROM) equivalent pattern, we formed two kinds of inclined pattern by adopting ICP-RIE. We evaluated line edge roughness (LER) to determine the difference in pit profile accurately. As the result, we confirmed that LER was improved at a steep inclination angle. In addition, we applied ICP-RIE to a 300 GB ROM pattern.

Improvements of Resolution and Surface Roughness using Alkaline Treatment of Photoresist Surface in High-Density Optical Disk Mastering

In the next-generation optical disk using blue laser diodes, the track pitch will be reduced to 0.3 µm, that is about half of the track pitch of digital versatile disks. To realize such high-density optical disks, it is important to develop a high-density optical disk mastering technique. In particular, in this mastering technique, two major improvements, resolution improvement and surface roughness reduction, are required. In this work, we fabricate grooves with track pitches of 0.28–0.40 µm land/groove using an ultraviolet laser beam recorder, and investigate the influences of an alkaline treatment of positive photoresist surface on the resolution and the surface roughness of the grooves. We confirm experimentally that the alkaline treatment is effective for the resolution improvement and the roughness reductions of the surface and sidewall. We also show that these effects are attributed to the contrast enhancement and the decrease of photoresist film thickness loss.

Performance of an Electron Beam Recorder for Disk Mastering

We have been developing an electron beam recorder (EBR) for high-density optical disk mastering, and use it for read-only memory (ROM) and rewritable (RW) substrate mastering. We confirmed a 4.4% jitter value at 25 GB ROM disk. The reproducing characteristics of the high-density optical disk were dominated by the signal-to-noise ratio and the cross-talk. We fabricated an RW substrate with a 320-nm track pitch and confirmed a 5.4% jitter value for a data bit length of 112 nm after 100 direct-over-write and crosswrite cycles.

Exposure Method Using Photoresist Mask for High-Density Optical Disk Mastering

A high-density digital versatile disk (HD-DVD) is being developed, aiming for high definition television. It is thought that the capacity of HD-DVD would be 15 GB, for example when its track pitch is 0.42 µm, its minimum mark length must be 0.22 µm. To fabricate such a high-density optical disk, we develop an exposure method using a photoresist mask. Super-resolution is also studied in order to make the exposure beam diameter smaller.

摩擦駆動を応用した光ディスク原盤露光装置用テーブル送り機構の開発

The purpose of this paper is to present a design outline and describe the characteristics of the table control system of a high density optical disk mastering machine. The table control system consists of a friction drive, a double guide air-pressurized slider, a laser interferometer and a controller. Friction drive makes it possible to position the table with 10 nm accuracy over 200 mm travel. The laser interferometer system is designed to measure the position of an optical head, exposure point, using the special laser optics configuration with two reflectors, between which the optical head is located. The table is positioned with a standard deviation of 2.9 nm (a) in a ramp command of 10 μm/s and the steady-state error and the settling time are better than 10 nm and 0.15 second, respectively, in 1 μm step response. The mastering machine has made pits and grooves with a track pitch of 0.65 μm and a pit width of 0.3 μm.