Laser fabrication of micron-size apertures for electron beam microcolumns

For electron beam nanolithography and scanning electron microscopy applicat ions, an electrostatic electron lens system called a microcolumn must be as sembled. In order to reduce aberrations, laser drilling of the assembled mi crocolumn system should be highly beneficial. We have drilled micron-size a pertures on silicon substrates including molybdenum and tantalum using a 1. 064 mu m Nd:YAG laser. In this work, a layer-by-layer evaporation technique using multiple pulse treatment (MPT) is employed in order to minimize melt ing of the crater wall and maximize the evaporation of the bottom layer of the crater. The machining conditions of an Nd:YAG laser pulsed in the TEM00 mode for ceramic, silicon, and molybdenum diaphragms are optimized. We obt ain micron-size apertures for electron beam microcolumn applications such a s electron lenses.