Multisource optimization of a column for electron lithography

The optimization of key parameters determining the performance of a multisource electron column is discussed. A 50 keV multisource test bed incorporating a photocathode and multiple modulated light beams has been developed and tested. The multisource test bed allows for a detailed evaluation of both the photocathode sources and the electron optics for sub-100 nm lithography applications and is designed to reduce electron–electron interactions. Results have been obtained using cesiated GaAs negative electron affinity and gold photocathodes at beam energies varying from 10 to 50 kV, allowing the experimental evaluation of key design parameters.