Electron optical design of an e-beam comb probe printer

Abstract

The electron optical design principles of a 50 keV comb probe printer with 1024 individually switchable 0.1 μm probes in a linear array are outlined. Theoretically the desired resolution of 25 nm and a current density of 50 A/cm 2 can be achieved by applying a LaB 6 linear source, a two lens condenser for forming a parallel ribbon beam and four imaging lenses operated telecentrically in couples for demagnifying the beam defining diaphragm array 100 times onto the water. A new designed source using a prismatically shaped LaB 6 crystal and an experimental imaging column are in operation showing promising results but also a number of practical difficulties which are expected to be governed by increased effort in optical adjustment elements. Particularly a third order compensation by an octopole is unavoidable to achieve the required degree of parallelism of the illumination beam.