An experimental variable shaped electron beam lithography system

Abstract

An experimental variable shaped electron beam lithography system has been built to verify the theoretical design considerations and fundamental control method. The electron beam column consists of four magnetic lenses, two square apertures, two aligners, an angular aperture, a set of blanking plates, and a position deflection yoke. The size of the beam spot is varied by a set of electrostatic deflection plates. In order to maintain the current density in the spot constant, as the size of the beam spot varies, the center of the shaped deflection plates is placed to coincide with the image of the gun crossover, and the shaped deflection plates position can be electrically adjusted. The acceleration voltage is 20 kV. The field size is 2.5 mm square. The maximum spot size is 10 μm2. The maximum current density is 1 A/cm2. The system is controlled by an EG 3003 computer. The beam blanking switching time is 50 nS.