Optical disk mastering using electron beam lithography

For the requirement of higher storage capacity of an optical disk, it is a good choice to shorten pit length and track pitch. However, the conventional laser beam mastering is more costly and difficult to supply smaller pit length than that of DVD because of the optical diffraction limit. In order to solve this problem, optical disk mastering using electron beam lithography is a better approach. The process parameters of the electron beam mastering such as beam current, constant linear velocity, develop time, and focus distance are discussed in this research. In our experiments, it is found focus distance is an important parameter to fabricate the pattern with small linewidth (FWHM). The experimental results reveal that the 10 um variance in focus distance causes about 12% variation in the 230 nm linewidth. In addition, a spiral groove with 110 nm linewidth and 80 nm depth is successfully fabricated for a stamper of about 50 Gbytes storage capacity.