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We have made measurements with our Quadra raster shaped beam lithography system to evaluate the shot-noiseinduced critical dimension uniformity (CDU). We found that at the isofocal dose, the shot-noise-induced CDU is directly proportional to the edge blur, and is linear with the rate of CD change with dose. Here we propose a phenomenological model which permits an experimentalist to relate the CDU to controllable lithographic parameters. The model considers both the counting statistics of the incident electrons and the noise from the electron induced chemistry. The model suggested that the shot-noise induced CDU may be minimized by reducing the beam blur, forward scattering, through the optimization of the resist smoothing distance and maximizing the number of acid molecules created in the resist by an incident electron. With the proper parameters, this model matches the experimental observations well. It also predicts the limit of the improvements and suggests guides for future resist development. Shot-noise induced line edge roughness is also discussed.

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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