The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 29, 2004
Filed:
Jun. 11, 2002
Sumito Shimizu, Tokyo, JP;
Kazuaki Suzuki, Tokyo, JP;
Nikon Corporation, Tokyo, JP;
Abstract
Methods are disclosed for performing charged-particle-beam (CPB, e.g., electron-beam) microlithography with reduced Coulomb effects being manifest in pattern images as formed on the surface of a sensitive substrate. The pattern is defined on a segmented reticle, which can be a scattering-stencil reticle or scattering-membrane reticle. In an embodiment, the beam current actually reaching the substrate, as a proportion of beam current actually passing through the reticle, is reduced to 50% or less during exposure of the pattern. To achieve this reduction, the pattern as defined on the reticle can be normal or inverted in tone as required, and the resist on the substrate can be positive or negative in tone as required. In an example embodiment, the beam current reaching the substrate is reduced by establishing an opening ratio of 50% or less for the pattern as a whole as defined on the reticle. The opening ratio is expressed as 100[A /(A +A )], wherein A is a total area of the reticle occupied by both the weakly scattering reticle membrane and the highly scattering layer, and A is a total area of the reticle occupied by only the weakly scattering reticle membrane.