Microcolumn design for a large scan field and pixel number
A different approach in microcolumn design is presented, aiming at a large number of pixels at minimal probe size for the deflected beam. An optimization routine resulted in a seven times magnifying column featuring a more than 7×7 mm2 scan field at 40 mm working distance. Simulations for 1 keV electrons from a field emission source predict an increase in beam size from 85 nm on axis up to only about 200 nm for a beam deflected 3 mm off axis. Within a 1 mm scan field this microcolumn could address over 100 Mpixels of less than 100 nm in size. Tests of this design using the 130 nm electron probe of a scanning electron microscope as the electron source resulted in a beam size of 930 nm on axis up to 1000 nm for a beam deflected 3 mm off axis.