Patent ID: 6492647
Filing Date: 2002-12-10
Classification: H01J

Abstract:
Method for the manufacture of semiconductor integrated circuits comprising at least one lithographic step in which a patterned electron beam is projected onto the surface of a resist coated semiconductor wafer using a lens system, the method comprising the steps of:(a) projecting a beam of electrons onto said resist coated semiconductor wafer sequentially through: (i) a lithographic mask, and (ii) a back focal plane filter, said back focal plane filter being essentially opaque to electrons in said electron beam, the method characterized in that said electron beam is produced by an electron gun and said electron gun is operated by(b) establishing a bias between an electron emitter, a Wehnelt aperture, and an anode so that said electron beam flows from said electron emitter through said Wehnelt aperture to said anode the method further characterized in that said Wehnelt aperture is biased positively with respect to said anode.