High-density optical disk mastering using electron beam lithography with modified LIGA demolding mechanism

For the requirement of higher storage capacity of an optical disk, it is a good choice to shorten pit length and linewidth. In order to solve this problem, optical disk mastering using electron beam lithography is presented. The process parameters of the electron beam mastering such as beam current, constant linear stage velocity, developing time, and focus distance are discussed in this research. In these experiments, it is also found that focus distance is an important parameter to fabricate nano-linewidth. The experimental results reveal that the 10 μm variance in focus distance causes about 12% variation in linewidth. Modified LIGA process is applied to produce PMMA-based optical disk. The resist with nano-pattern is transferred into metal Ni-Co (Nickle-Cobalt) mold by electroplating. The technique of Ni-Co electroplating process with developed. Then, the Ni-Co mold is served as master for hot embossing process to replicate the nano-pattern onto PMMA sheet. Also, the study presents an innovative demolding mechanism to demold the master without damaging the patterns. In the study, a spiral nano-groove with 110 nm in linewidth and 80nm in depth has been successfully fabricated about 50 Gbytes storage capacity.