Miniature SEM with permanent-magnet lenses

A very compact low-voltage SEM has been designed, fabricated, and tested. The system is a two-lens column equipped with a Schottky emitter electron source. The lenses are energized by permanent magnets. The low aberration coefficients of magnetic lenses and the short column length allow high performance of the column. We have investigated imaging results obtained at electron beam currents of 18 nA and 220 nA at landing energies close to 1 keV. Predicted spot sizes were 13 nm and 90 nm, respectively. The measured spot sizes were 20 nm and 100 nm.