DY-7 sub-0.1 micron EB lithography system

Abstract

A scanning electron beam lithography system with a field size of 1×1 mm has been built for the delineation of sub-0.1 μm patterns. The system comprises a 30-kV LaB6 electron gun with a zoom lens arrangement of a condenser doublet. To minimize the aberrations, a combined magnetic focusing and deflection system with prelens double deflection is adopted and optimized. To avoid the often-appearing problem with multi-variable optimization process, i.e. the ultimate results depend on the initial values, a practical way is suggested. Instead of the conventional coil-winding deflector, a saddle coil deflector consisted of electrodes fabricated by wire electron discharge machining (WEDM) is employed to gain higher geometrical accuracy and lower inductance. To increase writing speed and accuracy, we have developed a multi-function pattern generator to perform the writing of trapezoids, polygons, circles, rings as well as rectangles directly through hardware. In addition, a novel approach for linear and non-linear correction of patterns is introduced to improve the scan accuracy. The system has been used to delineate nanometer-scale patterns in both PMMA and ZEP 520 electronic resists on thick Si substrates over a field size of 1×1 mm. A lithographic example with the system is shown.