A wire electronic discharge machine saddle-type deflector for electron beam lithography systems

Abstract

A new type of magnetic deflector [wire electron discharge machine (EDM) deflector] has been constructed for our gaussian round beam exposure system. To optimize the design of conventional saddle‐type deflection coils used for electron beam lithography systems (EBLS), one of the most important technical problems lies in the achievement of consistency between the computer aided design (CAD) calculated model and the actual structure of the windings. The present paper investigates the relation between the deflection aberration and winding width as well as winding distribution when the parameters of the deflector are optimized. The calculated results show that with 30° central angle of the winding and larger variance of the winding width the influence of third‐order aberration is negligible in micron‐EBLS and submicron‐EBLS. The design and experimental results are discussed for a new type of saddle coil used in EBLS and fabricated by the wire electron discharge machine (wire EDM) technology, this deflector indicates consistency between the CAD model and the actual structure of the winding. In our μm‐order EBLS using the wire EDM deflector, field stitching accuracy of <0.3 μm can be realized. The beam positioning accuracy is ∼0.2 μm.