Space-charge effects in projection electron-beam lithography: Results from the SCALPEL proof-of-lithography system

Abstract

Articles you may be interested inPerformances by the electron optical system of low energy electron beam proximity projection lithography tool with a large scanning field J. Vac. Sci. Technol. B 23, 2754 (2005; 10.1116/1.2062435 Stochastic Coulomb interaction effect in ion-neutralized electron-beam projection opticsElectron optical image correction subsystem in electron beam projection lithography Scaled measurements of global space-charge induced image blur in electron beam projection systemIn projection electron-beam systems resolution and throughput are linked through electron-electron interactions collectively referred to as space-charge effects. Hence, a detailed understanding of these effects is essential to optimizing the lithographic performance of a projection electron-beam lithography system. Although many models have been developed to describe one or more of the various aspects of the Coulomb interactions that occur in the beam, there is minimal experimental data available. We have performed a series of experimental measurements in the scattering with angular limitation projection electron-beam lithography ͑SCALPEL͒ proof-of-lithography system to characterize the space-charge effects for such an optical configuration. The results of those measurements have been compared to a combination of computer simulations and analytical models. The agreement between the models and experiments was good, within the limits of experimental error. We determined the exponent in the dependence of blur on beam current to be 1.029Ϯ0.16 ͑1͒, consistent with more recent models. Additionally, we comment on the use of blur modeling for system optimization.

Lithography, metrology and nanomanufacturing

“…In an imaging system the pattern density varies and this can lead to non-uniformities across the beam. These effectively act as a highly aberrated electrostatic lens element and can cause timevarying, non-uniform blur and distortion across the field, 55,56 which can only be mitigated by careful optical design. It is interesting to speculate that part of the reason for the strong trend in throughput versus resolution originally observed for charged-particle systems 2 is a result of the optimization of optical design for a particular target resolution and the parametric dependence of space-charge effects on factors such as accelerating voltage, column length, beam current and numerical aperture.…”

Optimization of an electron beam lithography instrument for fast, large area writing at 10 kV acceleration voltage

“…This mode will approximately double the beam current. The ultimate resolution will decrease slightly due to space charge effects, 25 but the smaller, parallel beam will increase the depth of focus significantly. 24 We measured a beam current of 6.2 nA for the high current mode when the acceleration voltage was 10 kV and the 120 lm diameter collimating aperture was used.…”