Erratum: ''Design of a high resolution focused ion beam system using liquid metal ion source'' [J.

Electron optical image correction subsystem in electron beam projection lithographyLie algebraic aberration theory and calculation method for combined electron beam focusing-deflection systems Electron and ion optical design software for integrated circuit manufacturing equipment This article investigates, with computer simulations, whether electron optical aberration correctors could be used to improve the performance of electron beam equipment for the semiconductor manufacturing industry. The simulations are performed using the differential algebraic method. Three types of aberration corrector are investigated: ͑1͒ a quadrupole-octopole corrector for critical dimension scanning electron microscopy for metrology and inspection ͑it is shown that this type of corrector, which corrects spherical and chromatic aberrations, can provide a smaller probe diameter with a larger numerical aperture, thereby improving resolving power and throughput͒, ͑2͒ a hexapole planator for projection electron beam lithography ͑it is demonstrated that field curvature, astigmatism, and spherical aberration can be corrected, thereby permitting a larger field size͒, and ͑3͒ a mirror corrector for reflective electron beam lithography ͑it is shown how field curvature and chromatic aberration in such systems can be corrected by using an electron mirror͒.

No abstract

No abstract

In SCALPEL, the maximum projected area of the electron optical sub-field, though large by electron optical standards, is limited by aberrations of the projection optics. The effective exposure region can be increased by electronically scanning the illumination off-axis, in a direction orthogonal to the mechanical motion of the mask and wafer stages.' Even though the aberrations associated with the scan are minimized by applying dynamic corrections, the residual aberrations may still increase with increasing off-axis scan distance. Thus the image quality may vary during dose accumulation in each pixel.Our previous simulation method has been extended to consider the writing strategy, including scanning the sub-field over a pixel, and eliminating the mask struts and the non-patterned regions (skirts) at the wafer plane. We have examined two variations of writing strategy, for a column with demagnification m: (1) The case where the mask stage velocity is exactly m times the wafer stage velocity, and (2) The case where the mask stage velocity is increased so that the mask and wafer pauerns remain in synchronism with each other, after removing the unpatterned areas of the mask from the image. In case (1), an additional deflection is required to eliminate the struts and skirts in the mask from the printed image. This deflection increases with time, as the mask and wafer patterns get progressively out of synchronism. Case (2) eliminates this effect. We compare these two cases, and show that case (2) provides significantly improved fabricated pattern quality.