HIGH-EMITTANCE ELECTRON SOURCE HAVING HIGH IRRADIATION UNIFORMITY

摘要

PROBLEM TO BE SOLVED: To form electron beams having uniform intensity in the large area and a large angle of beam divergence, applicable especially to an electron beam projection system and a lithography tool. SOLUTION: This electron source includes a negative electrode 10 having a planar main emission surface 10', a positive electrode 16 having an aperture and approximately parallel to the planar emission surface, and an arrangement 50 to uniformly heat the negative electrode in a comparatively large area by electron and photon impact on the surface of the negative electrode opposite to the planar main emission surface 10'. Both the direct heating by a large area filament and the indirect heating by the impact by the emission from an auxiliary negative electrode are provided in probably plural stages.