The International Technology Roadmap for Semiconductors (2001 ITRS) and the Technology Roadmap for Nanoelectronics (TRN) favours the Extreme UV (EUV) approach for lithography at 45nm feature size and below. Nevertheless EBDW-techniques (E-Beam direct write) are still considered as potential candidates because sub 10 nm beam sizes are "easily" obtained. The drawback associated with this maskless method is the low throughput due to serial writing. To solve this problem, a relatively straightforward concept is to use an array of parallel electron beams. The feasibility of this approach has been demonstrated by Chang [1] and Muray [2] using an array of four miniature (2 * 2 cm) electron-beam columns. In order to further reduce the size of each column, Vu Thien Binh and co-workers have studied the concept of the microgun [3] which used a nanotip in tandem with electrostatic lenses fabricated on a single silicon substrate. The lenses included a 2-electrode lens having micron-size bores and a coplanar 4-pole deflector. Using this approach, the focussed spot-size could reach manometric dimensions with minimal aberrations [3] and the whole electron column size could be reduced to the sub-millimeter range. However, the uniformity constraints, with respect to the emitted currents and beam diameters, from column to column in a multiple electron beam system are very tight which makes designing such a system a challenging task.
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