PERFORMANCE-MEASUREMENTS OF A 1-KEV ELECTRON-BEAM MICROCOLUMN

A complete 1-keV electron-beam microcolumn, measuring only 2.5 mm in length, has been assembled and tested. The microcolumn combines a scanning tunneling microscope aligned field-emission source with a miniaturized octupole scanner and a microfabricated einzel lens. Expected performance of this configuration, at a working distance of 1 mm and semiconvergent angle of 2.5 mrad, has been calculated to be a probe size of 8 nm with current density exceeding 10(4) A/cm2. The microcolumn has been successfully operated at 1 keV in scanning transmission mode using a 1-mum grid sample. Images were acquired with scan fields ranging from 10 to 100 mum and preliminary resolution measurements indicated Gaussian beam diameter of 200 nm. Significant improvements are expected in the near term.