Photocopying – Projection printing and copying cameras – Focus or magnification control
Reexamination Certificate
1997-08-20
2001-08-07
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Focus or magnification control
C355S053000, C355S077000, C356S401000
Reexamination Certificate
active
06271910
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a projection exposure apparatus and method, and, more particularly, to an exposure apparatus (being a semiconductor producing apparatus) and method for precisely aligning a plate, such as a mask or reticle, and a substrate to be exposed, such as a semiconductor wafer or the like.
2. Description of the Related Art
Finer and more highly integrated semiconductor integrated circuits, large-scale integrated circuits, and the like have led to the production of more capable semiconductor exposure apparatuses that provide greater precision. There has particularly been a demand for a technique for superimposing a plate and a substrate on the order of a few tens of nanometers during alignment.
Steppers and step-and-scan apparatuses are known as such exposure apparatuses used in the production of semiconductors. They successively transfer a pattern formed on a plurality of locations of a plate (such as a reticle) onto a substrate (such as a semiconductor wafer), while the substrate is being moved in steps. Those which perform the transfer in one operation are called steppers, while those which perform the transfer while scanning the stage are called step-and-scan apparatuses. These two types of apparatuses differ in the manner of operation during exposure, but their basic operations are the same in that transfer is performed in a step-and-repeat fashion. In addition, these two types do not essentially differ in that the position of the entire region of the substrate (global) is previously determined.
In recent years, thermal expansion of the plate (reticle), during alignment of the plate and the substrate by means of a semiconductor exposure apparatus, can no longer be ignored. This problem of thermal expansion can be overcome by making corrections as a result of obtaining the thermal expansion amount from the thermal absorption rate and the exposure amount of the plate. The corrections, however, are strictly based on calculations, producing a large error from the actual expansion amount. The heat absorbed by the plate is dissipated by radiation and convection into the air, which cannot be easily and properly described by a single formula. However, the expansion amount of the plate can only be calculated from an accurate estimation of the heat absorbed by the plate and the heat dissipated from the plate.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide means for measuring the thermal expansion of the plate and making corrections in order to align the plate and the substrate to be exposed with high precision.
To this end, according to one aspect of the present invention, there is provided an exposure apparatus for projecting an image of a plate onto a substrate to be exposed through a projection optical system, which comprises means for measuring an elongation of the plate; and means for controlling a magnification of the projection optical system in accordance with the measured elongation.
The exposure apparatus may further comprise a reference mark fixed to a portion of the projection optical system, which is adjacent to the plate. The measuring means can measure the elongation of the plate with respect to the reference mark.
According to another aspect of the present invention, there is provided an exposure apparatus for projecting an image of a plate onto a substrate to be exposed through a projection optical system, which comprises means for measuring deformation of the plate; and means for controlling a magnification of the projection optical system and a position of the plate relative to a position of the substrate to be exposed in accordance with the measured deformation.
The exposure apparatus may further comprise a reference mark fixed to a portion of the projection optical system, which is adjacent to the plate. The measuring means can measure the deformation of the plate with respect to the reference mark.
In still another aspect of the present invention, there is provided an exposure apparatus for relatively scanning a plate and a substrate to be exposed, while projecting an image of the plate onto the substrate to be exposed through a projection optical system, the apparatus comprising means for measuring deformation of the plate; and means for controlling a magnification of the projection optical system and a relative scanning direction of the plate and the substrate to be exposed.
The exposure apparatus may further comprise a reference mark fixed to a portion of the projection optical system, which is adjacent to the plate. The measuring means can measure the elongation of the plate with respect to the reference mark.
In still another aspect of the present invention, there is provided an exposing method for projecting an image of a plate onto a substrate to be exposed through a projection optical system, which comprises the steps of measuring an elongation of the plate; and controlling a magnification of the projection optical system in accordance with the measured elongation.
The exposing method may further comprise the step of providing a reference mark fixed to a portion of the projection optical system, which is adjacent to the plate. In the measuring step, the elongation of the plate may be measured with respect to the reference mark.
In still another aspect of the present invention, there is provided an exposing method for projecting an image of a plate onto a substrate to be exposed through a projection optical system, which comprises the steps of measuring deformation of the plate; and controlling a magnification of the projection optical system and a position of the plate relative to a position of the substrate to be exposed in accordance with the measured deformation.
The exposing method may further comprise the step of providing a reference mark fixed to a portion of the projection optical system, which is adjacent to the plate. In the measuring step, the deformation of the plate may be measured with respect to the reference mark.
In still another aspect of the present invention, there is provided an exposing method for relatively scanning a plate and a substrate to be exposed, while projecting an image of the plate onto the substrate to be exposed through a projection optical system, the method comprising the steps of measuring deformation of the plate; and controlling a magnification of the projection optical system and a relative scanning direction of the plate and the substrate to be exposed in accordance with the measured deformation.
The exposing method may further comprise the step of providing a reference mark fixed to a portion of the projection optical system, which is adjacent to the plate. In the measuring step, the elongation of the plate may be measured with respect to the reference mark.
REFERENCES:
patent: 5008703 (1991-04-01), Kawakami et al.
patent: 5063582 (1991-11-01), Mori et al.
patent: 5112133 (1992-05-01), Kurosawa et al.
patent: 5131022 (1992-07-01), Terashima et al.
patent: 5142156 (1992-08-01), Ozawa et al.
patent: 5150391 (1992-09-01), Ebinuma et al.
patent: 5157700 (1992-10-01), Kurosawa et al.
patent: 5172402 (1992-12-01), Mizusawa et al.
patent: 5182615 (1993-01-01), Kurosawa et al.
patent: 5184176 (1993-02-01), Unno et al.
patent: 5231291 (1993-07-01), Amemiya et al.
patent: 5285488 (1994-02-01), Watanabe et al.
patent: 5317615 (1994-05-01), Ebinuma et al.
patent: 5377251 (1994-12-01), Mizusawa et al.
patent: 5499099 (1996-03-01), Sato et al.
patent: 5543921 (1996-08-01), Uzawa et al.
patent: 5581324 (1996-12-01), Miyai et al.
patent: 5585925 (1996-12-01), Sato et al.
patent: 5646413 (1997-07-01), Nishi
patent: 5695897 (1997-12-01), Mitome et al.
patent: 5781277 (1998-07-01), Iwamoto
Adams Russell
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Kim Peter B.
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