Electron beam recording with a novel differential pumping head realizing over 50 GB/layer capacity disc

High density mastering is the key technology to manufacture next generation optical disc recording with over 20 GB capacity for more than 2 hours of HDTV digital data. We developed a deep UV laser beam recorder (DUV-LBR) and the related mastering process to achieve such a high density (M. Takeda et al, Jpn. J. Appl. Phys. vol. 38, pp. 1837-1838, 1999), which is now to be introduced in the disc mastering process line of DVR-blue (I. Ichimura et al, Tech. Dig. ODS2001, pp. 139-141, 2001). Beyond DUV-LBR, an electron beam recorder (EBR) was proposed to produce further high density pit patterns (Y. Wada et al, Jpn. J. Appl. Phys. vol. 40, pp. 1653-1660, 2001). We have developed a new concept EBR with a novel differential pumping head attached to the bottom portion of the electron beam column. It has no vacuum chamber and an air-spindle motor with a translation stage under the electron beam column is installed in the atmosphere like a conventional LBR. The differential pumping head effectively separates the high vacuum region and the surrounding atmospheric pressure region. The high vacuum region, which is necessary for the electron beam emitted from the column and focused onto the resist coated silicon (Si) substrate, is confined within only a narrow gap between the head and the resist surface. As the spindle motor and the translation stage are operated not in a vacuum chamber but in the atmosphere, high speed recording with sufficient rotational and translational accuracy can be attained. Furthermore, the main body of the EBR can be very compact and cost effective due to the lack of a large and expensive vacuum chamber. In this paper, we report 25 GB density recording performance of our newly developed EBR and some experimental results of recording and reproducing even higher densities up to 50 GB.