Significant components of electron beam lithography systems are the electron source, the electro-optical system and the focusing system (deflection or respectively projection unit). Hot cathodes are used for equipment with lower resolution, devices with higher resolution, however, preferably need thermic field emission sources. In order to focus and concentrate the electron beams, special equipment is needed, which, analogical to optics, is refered to as lens systems. Both magnetic and electrostatic lenses are used for the direction of the electron beam, however, the latter ones are not suitable for fine focusing because they show greater aberration. For a very accurate focusing, electron beams with extremely narrow energy dispersion are prerequisite. Very little deflections of the electron beam are usually achieved by electrostatic systems, greater beam deflections by electromagnetic systems. Due to inaccuracies and the limited number of exposure steps, the exposure area is very small and only 100 to 1000 µm. For writing greater patterns, a moveable substrate plating is prerequisite and must fulfil particularly high requirements with regard to exact positioning for the pattern sequence.