Dual pass electron beam writing of bit arrays with sub-100 nm bits on imprint lithography masters for patterned media production

A model and experimental results of a new method for exposing bit arrays with electron beam lithography are presented. The method allows the reduction of the amount of pattern data by orders of magnitude. The method utilises two overlapped exposures. In the first exposure a 1-D array of parallel stripes is written and in the second exposure another 1-D array of parallel stripes orthogonal to the first ones. Exposure dose is chosen so that after development only the areas where a positive resist have been subjected to overlapped exposure are fully developed. The bit size is determined by the widths of the stripes. In order to compensate for an approximately 50% loss of contrast a contrast enhancement scheme utilizing a trilayer resist was used.