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We developed an electron beam recorder with a novel differential pumping head, which produces a local high-vacuum area for an electron beam by balancing nitrogen gas flow into and out of the head. Regarding recording speed, it was confirmed to be as high as 4.92 m/s while maintaining a 10-3 Pa vacuum condition. In order to achieve a high speed recording velocity, we introduced an electron gun with a low acceleration voltage (15 kV) and a chemically amplified resist to the mastering to make resist sensitivity very high. In addition, it takes only 2 min to exchange the Si substrate. As for the performance of the electron beam mastering, a bottom jitter value appropriate for mass production was obtained from a 25 GB/layer capacity disc. We also fabricated a 50 GB/layer capacity disc and confirmed the HF signal using a near-field optical pick up for the first time. Furthermore, we were able to fabricate a 100 GB/layer capacity disc using our electron beam recorder. more...

We improved the electron beam recorder with a differential pumping head for higher density discs and mass production. The beam diameters were improved by exchanging the aperture size of the objective lens and beam stability were also improved by adding a sound proof case. As for the performance of the improved electron beam recorder, we showed that a 104Gb/in 2 (150GB capacity/layer) density disc with EFM plus modulation codes can be fabricated. We also improved the pit shape uniformity and a margin of the process by introducing the appropriate write strategy that is simulated by the Monte Carlo simulation to the recording pulses. more...

We have demonstrated the capability of 100GB density recording by the electorn beam mastering and Si etching process optimization.

We demonstrate the capability of 100-GB density recording by electron beam mastering and readout by a near-field optical pickup with an effective NA of 2.05 and a blue LD of 405-nm wavelength. A silicon (Si) disk of 100-GB density is fabricated by an optimized Si etching process condition to form suitable pit pattern shapes for the near-field readout. more...

We developed an electron beam recorder (EBR) capable of recording master discs under atmospheric conditions using a novel differential pumping head. Using the EBR and optimized fabrication process for Si-etched discs with reactive ion etching (RIE), a bottom signal jitter of 9.6% was obtained from a 36 Gbit/inch2 density disc, readout using a near-field optical pickup with an effective numerical aperture (NA) of 1.85 and a wavelength of 405 nm. We also obtained the eye patterns from a 70 Gbit/inch2 density disc readout using an optical pickup with a 2.05 NA and the same wavelength, and showed almost the same modulation ratio as the simulation value. Moreover, the capability of producing pit patterns corresponding to a 104 Gbit/inch2 density is demonstrated. more...