Microelectronic Engineering 67–68 (2003) 381–389 www.elsevier.com / locate / mee Dual pass electron beam writing of bit arrays with sub-100 nm bits on imprint lithography masters for patterned media production a, a b b * Alexei L. Bogdanov , Tommy Holmqvist , Piotr Jedrasik , Bengt Nilsson a ¨ OBDUCAT Technologies AB, Box 580, SE-201 25, Malmo, Sweden b ¨ MC2, Chalmers University of Technology, SE-412 96, Goteborg, Sweden Abstract 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.  2003 Elsevier Science B.V. All rights reserved. Keywords: Patterned media; Nanoimprint; Electron beam; Lithography 1. Introduction Electron beam lithography apparently is the most appropriate method for writing masters for nanoimprint lithography (NIL) with sub-100 nm features. Industrial applications of NIL in the very near future may need stampers of several inches in diameter. In the case of patterned media [1] (PM) such stampers most probably will contain circular arrays of identical dots of round or elongated shape (bits). Two kinds of electron beam mastering equipment can be employed—systems with polar coordinates ( r / f) stage [2,3]; and more common vector scan systems with Cartesian (X / Y) stage. The main advantage of the r / f systems in writing of polar arrays is their natural polar coordinate system data representation. This makes complex data transformations unnecessary and allows to avoid using extensive data volumes. However, an intrinsic rotary stage axel position run-outs and *Corresponding author. E-mail address: alexei.bogdanov@obducat.com (A.L. Bogdanov). 0167-9317 / 03 / $ – see front matter  2003 Elsevier Science B.V. All rights reserved. doi:10.1016 / S0167-9317(03)00093-5