Optical: systems and elements – Lens – With reflecting element
Reexamination Certificate
2000-04-05
2002-04-30
Sugarman, Scott J. (Department: 2873)
Optical: systems and elements
Lens
With reflecting element
C355S053000
Reexamination Certificate
active
06381077
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scanning micro-lithographic apparatus and method for projecting a large field-of-view image on a substrate and, more particularly, to such apparatus that preferably employs a wide-field catadioptric projection system (e.g., a projection system incorporating a Wynne Dyson optical relay).
2. Description of the Prior Art
Some micro-lithographic applications, like flat display panel manufacturing, require a fast, seamless, high-resolution (e.g., 2-3 micrometers), large area exposure. This kind of exposure can be achieved effectively by scanning the substrate under a large exposure projection system with a field-of-view for exposure.
It is well known that micro-lithography can be done over a large area by combining two −1X projection systems having parallel object and image planes with a raster scanning system that moves the mask and substrate together so as to produce one strip of imagery at a time. The precision requirements on the scanning system are relaxed if adjacent strips of imagery are not butted together, but overlapped in a small area containing a linear variation in exposure intensity, such as can be obtained using a tapered illumination slit. A micro-lithography approach employing this principle is described in U.S. Pat. No. 5,298,939 and its division U.S. Pat. No. 5,835,195, both of which are entitled “Method and Apparatus for Transfer of a Reticle Pattern onto a Substrate by Scanning”. The drawback with this approach is that to obtain a +1X relay system it is either necessary to employ two −1X relays in series or to add an odd number of folds to the optical system which is often inconvenient or impossible. Also the requirements on the raster scanning system lead to substantial expense and complexity in the stage components.
An alternate approach, described in U.S. Pat. No. 5,585,972, entitled “Arbitrarily Wide Lens Array with an Image Field to Span the Width of a Substrate,” employs an array of +1X projection systems, which span the width of the substrate, to reduce the scanning requirement to a single linear scan. The drawback with this approach is that it requires a great many projection optical systems all of which have to be aligned very accurately and the illumination apertures are a staggered array of rectangles which is difficult to illuminate uniformly.
Therefore, there is a need for a scanning micro-lithographic apparatus and method that derives a high-resolution, large area exposure over a large area with a greatly simplified projection and illumination optical system, while not introducing too much complexity in the scanning system. In this regard, the teachings of U.S. Pat. No. 5,852,693, entitled “Low-loss Light Redirection Apparatus” which discloses a uniform illumination system employing light guiding technology using multiple light-pipes, is incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention is directed to a scanning micro-lithographic apparatus that employs a fixed −1X projection system (preferably, a wide-field catadioptric projection system) having a limited field of view in which image patterns located in its object plane can be imaged onto a substrate located in its image plane. These patterns, which are contained on a reticle or mask, are wider than the limited field size of the projection system. The mask is illuminated over the area corresponding to the field of the projection system and is moved in the object plane reticle in a direction parallel to that in which a vector in the object plane would be imaged parallel to its image in the object plane. Synchronous motion of the substrate in the same direction, scanning, copies the pattern from the reticle onto the substrate. In this fashion, a strip of imagery spanning the length of the pattern on the reticle may be copied onto the substrate. Other strips of imagery may be added in subsequent scans but, because the magnification is −1X, it is necessary to re-register the reticle and substrate by stepping them equally in opposite directions normal to the scanning direction. A second synchronous scan of the reticle and substrate then results in a pattern exposed on the substrate that is congruent with the reticle pattern. Subsequent stepping and scanning operations can be used to copy an arbitrarily large pattern on a reticle to a similarly sized substrate using a −1X relay having a smaller field size than the reticle pattern.
REFERENCES:
patent: 3951546 (1976-04-01), Markle
patent: 4011011 (1977-03-01), Hemstreet al al
patent: 4068947 (1978-01-01), Buckley et al.
patent: 5194893 (1993-03-01), Nishi
patent: 5281996 (1994-01-01), Bruning et al.
patent: 5298939 (1994-03-01), Swanson et al.
patent: 5585972 (1996-12-01), Markle
patent: 5815245 (1998-09-01), Thomas et al.
patent: 5835195 (1998-11-01), Gibson et al.
patent: 5852693 (1998-12-01), Jeong
patent: 6031597 (2000-02-01), Knirck et al.
David A. MarkleSubmicron 1:1 Optical Lithography, May 1986.
David A. Markle, A New Projection Printer, Jun. 1974, Solid State Technology, pp. 50-53
D. A. Markle, The future and Potential of Optical Scanning Systems, Sep. 1984, Solid State Technology, pp. 159-166.
Jeong Hwan J.
Markle David A.
Jones Allston L.
Sugarman Scott J.
Ultratech Stepper, Inc.
LandOfFree
Scanning microlithographic apparatus and method for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Scanning microlithographic apparatus and method for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Scanning microlithographic apparatus and method for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2849144