Photocopying – Projection printing and copying cameras – With cathode ray tube for light source
Patent
1997-08-27
1999-08-03
Metjahic, Safet
Photocopying
Projection printing and copying cameras
With cathode ray tube for light source
2504922, G03B 2772, A61N 500
Patent
active
059332123
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a delineating method for illuminating an electron ray beam on an electron ray sensitive resist material on a substrate for delineating a pattern on the resist material. More particularly, it relates to a delineating method in which a pattern for delineation is divided into pre-set unitary domains and in which the exposure dose of the electron ray beam to be illuminated on each unitary area is corrected in view of the accumulated energy ascribable to backward scattering of electrons. The invention also relates to a proximity effect correcting method.
BACKGROUND ART
For delineating a pattern of a semiconductor integrated circuit on a resist material formed on a substrate formed by, for example, a silicon semiconductor substrate, an electron ray beam used for delineation is transmitted through the resist material to fall on the substrate. The electron ray is scattered in a broad range within the substrate. That is, the so-called backward scattering in electron ray lithography is produced. Part of the electron ray beams agin falls on the resist material. The result is that the resist material is sensitized over a range significantly wider than an area on which the electron ray beam has entered the resist material. If the delineation pattern is low in density, the light exposure of the resist material ascribable to backward scattering is negligible. However, if the delineation patterns are congested and lie close to one another, light exposure of the resist material ascribable to backward scattering occurs over an extremely wide range. This phenomenon, schematically shown in FIGS. 26A and 26B, is the proximity effect in the electron ray lithography. Up to now, various methods for correcting the proximity effect have been proposed.
The conventional method for correcting the proximity effect and the problems thereof will now be briefly explained.
Before proceeding to description of the method for correcting the proximity effect including that of the present invention using various equations, the variables used therein are first defined. The unitary domain is synonymous with mesh. A delineated figure is synonymous with a pattern to be delineated in the unitary domain, and means a pattern to be delineated using an electron ray beam present in the unitary domain. A pattern density A% means the percentage of the sum total of sub-areas occupied by patterns in the entire area. Meanwhile, a suffix `v` to a symbol `.DELTA.` means a vector. reflection coefficient) a side of a square-shaped delineated figure a delineated figure on a point (x, y) exerted by a delineated figure positioned at a unitary domain (p, q) on a point (x, y) all delineated figures on a point (x, y) all delineated figures on a unitary domain (i, j) to backward scattering, exerted by all delineated figures on a unitary domain (i, j) accumulated energy, ascribable to backward scattering, exerted by all delineated figures on a unitary domain (i, j) accumulated energy, ascribable to backward scattering, exerted by all delineated figures on a unitary domain (i, j) unitary domain (i, j) unitary domain (i, j) density in a unitary domain (i, j) an averaged pattern area density in a unitary domain (i, j) an averaged pattern area density in a unitary domain (i, j) (pre-set value) pattern in a pre-set pattern density (such as 50%) (.DELTA.Eb/Ds) at a pre-set pattern density, such as 50% (in other words, line width variation in a unitary domain) the y-axis direction accumulated energy ascribable to backward scattering at the center of a unitary domain (i, j) after N times of iterative calculations domain (i, j) after N times of iterative calculations density after N times of iterative calculations and pattern area density estimated from accumulated energy ascribable to backward scattering derived from the EID function an areal center of gravity in a pattern in a unitary domain (i, j) (total delineated figure) electron ray beam at the center of a divided pattern (x.sub.div--c, y.sub.div--c)
The method for sequential ca
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Metjahic Safet
Nguyen Hung Henry
Sony Corporation
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