Articles you may be interested inHigh-current electron optical design for reflective electron beam lithography direct write lithography J. Vac. Sci. Technol. B 28, C6C1 (2010); 10.1116/1.3505130 REBL: A novel approach to high speed maskless electron beam direct write lithography

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Some systematic errors of the mebes raster scan lithography system are examined and how significant accuracy improvements can be achieved is demonstrated. The accuracy improvements result from error compensation hardware and software applying corrections that are either a function of time (write scan position) or of position on the substrate. Error analysis shows the following correctable errors to be among the largest error sources in the mebes iv: electronic noise, stage z runout, deflection alignment drift, mask flatness, and clamping distortion, and scan nonlinearity. These errors contribute to placement/overlay accuracy and to butting accuracy. The dynamic corrections implemented are automatic write scan correction, which reduces deflection alignment errors, scan linearity measurement and correction, grid correction, and height detection and correction, which reduce cassette height and mask flatness errors. With these corrections implemented, system performance improves dramatically.

To support device generations below 250 nm mask writing systems must improve productivity for smaller design address grids and simultaneously provide higher dose to support high resolution processes. Combining multipass writing techniques with higher pixel rate provides improved productivity and increased dose; however, many high resolution processes require even higher dose delivery. The optimization of field-emission systems for maximum effective brightness has been discussed previously, but the inclusion of electron-electron ͑e-e͒ interactions in the optimization process is a significant complication. There is little discussion in the general literature, except for Brodie and Meisburger ͓A. D. Brodie and W. D. Meisburger, Microelectron. Eng. 17, 399 ͑1992͔͒ about the impact of e-e interactions on the design of columns for electron-beam lithography systems. This article discusses several formulations of the problem and the solutions. Closed-form solutions for particular special cases ͑sphericaland chromatic-aberration limited systems͒ have been derived using the computer algebra code Mathematica and will be presented. The design of an improved field-emission gun and column is described, based on these general considerations, and on an acceleration-mode gun lens with particularly low chromatic aberration. Several improvements in the column design are discussed. These include optimization of the gun and the column for highest dose (800 A/cm 2 ) without increasing the beam energy of 10 keV.