SEMICONDUCTOR ON GLASS PHOTOCATHODES AS HIGH-PERFORMANCE SOURCES FOR PARALLEL ELECTRON-BEAM LITHOGRAPHY

The throughput of electron beam lithography has historically been limi ted by electron-electron interactions that cause blurring at high curr ents. We present a system configuration for maskless parallel electron beam lithography using a new multiple primary source technology that, by employing widely spaced beams, significantly reduces this problem. The proposed source technology, a negative electron affinity (NEA) ph otocathode, allows us to generate an array of high brightness, low ene rgy spread, independently modulated beams over a large area. In order to assess the effects of electron-electron interactions in this system , Monte Carlo simulations have been performed. The results of these ca lculations indicate that this configuration enjoys significant advanta ges over existing maskless systems. By restricting the area of emissio n for the individual beamlets to submicron dimensions, the blurring du e to statistical electron-electron interactions can be significantly r educed for a given current at the wafer. For example, at 50 kV a total current of more than 2.5 mu A can be obtained with less than 10 nm be am blurring. Preliminary experimental results suggest that high bright ness emission can be maintained from a NEA photocathode in a demountab le vacuum system. (C) 1996 American Vacuum Society.