Microcolumn with variable axis lens for large scan fields and pixel numbers

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Abstract

A microcolumn is presented containing a variable axis lens optimized for large scan fields and pixel numbers with minimal probe sizes for the deflected beam. At beam energy of 1 keV and a working distance of 38 mm the magnifying column can address scan fields of more than 7 7mm2 employing dynamic correction. Simulations of the design predict a probe diameter of 75 nm on axis up to 1 lm for a beam being deflected 5 mm of axis, assuming a field emission source. Within a scan field of 3 3mm2 this microcolumn could address over 1 gigapixels of less than 100 nm in size. Tests of the column, using the 135 nm probe of a SEM as the source, resulted in a beam size of 720 nm on axis and up to 1.1 lm for a beam deflected 5 mm off axis, consistent with simulations.