Demagnifying immersion magnetic lenses used for projection electron beam lithography without crossoversScaled measurements of global space-charge induced image blur in electron beam projection system Lie algebraic aberration theory and calculation method for combined electron beam focusing-deflection systemsThe 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.

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The ALTA  4300 system has been used to successfully write many advanced design layers previously only feasible with 50kV vector shaped beam tools. In order to further enlarge the application space of this high productivity an aerial image enhancement technique has been developed to deliver mask patterns that more closely match pattern data for corners and jogs. This image enhancement is done in real time in the ALTA systemís rasterizer by modifying the gray level mapping of pixels near the corner vertexes. SEM measurements of corner rounding with standard rasterization and the enhanced rasterization show an improvement of corner rounding radius from ~205 to ~132 nm. A direct comparison of SEM micrographs show no qualitative difference between vector scan mask features and those written with aerial image enhancement. This convincingly demonstrates that the ALTA  4300 system with the new image enhancement can write many layers requiring vector scan corner acuity.

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