Optical: systems and elements – Lens – With reflecting element
Reissue Patent
2001-01-19
2004-02-10
Schwartz, Jordan M. (Department: 2873)
Optical: systems and elements
Lens
With reflecting element
C359S727000
Reissue Patent
active
RE038421
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a catadioptric projection optical system suitable for applications to projection optical systems for 1:1 or demagnifying projection in projection exposure apparatus such as steppers used in fabricating, for example, semiconductor devices or liquid crystal display devices, etc., by photolithography process. More particularly, the invention relates to a catadiontric projection optical system of a magnification of ¼ to ⅕ with a resolution of submicron order in the ultraviolet wavelength region, using a reflecting system as an element in the optical system.
2. Related Background Art
In fabricating semiconductor devices or liquid crystal display devices, etc. by photolithography process, the projection exposure apparatus is used for demagnifying through a projection optical system a pattern image on a reticle (or photomask, etc.) for example at a ratio of about ¼ to ⅕ to effect exposure of the image on a wafer (or glass plate, etc.) coated with a photoresist or the like.
The projection exposure apparatus with a catadioptric projection optical system is disclosed, for example, in Japanese Laid-open Patent Application No. 2-66510, Japanese Laid-open Patent Application No. 3-282527, U.S. Pat. No. 5,089,913, Japanese Laid-open Patent Application No. 5-72478, or U.S. Pat. Nos. 5,052,763, 4,779,966, 4,65,77, 4,701,035.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an exposure apparatus having a catadioptric projection optical system which can use a beam splitting optical system smaller than the conventional polarizing beam splitter and which is excellent in image-forming performance, permitting a sufficiently long optical path of from the concave, reflective mirror to the image plane. Therefore, the catadioptric projection optical system has a space permitting an aperture stop to be set therein, based on a size reduction of the beam splitting optical system such as a polarizing beam splitter. The catadioptric projection optical system can be applied to the projection exposure apparatus of the scanning exposure method, based on use of a compact beam splitting optical system. Besides the projection exposure apparatus of the one-shot exposure method, the catadioptric projection optical system can be also applier to recent apparatus employing a scanning exposure method such as the slit scan method or the step-and-scan method, etc. for effecting exposure while relatively scanning the reticle and the wafer to the projection optical system.
To achieve the above object, as shown in
FIG. 1
, an exposure apparatus of the present invention comprises at least a wafer stage
3
allowing a photosensitive substrate W to be held on a main surface thereof, an illumination optical system
1
for emitting exposure light of a predetermined wavelength and transferring a predetermined pattern of a mask (reticle R) onto the substrate W, a catadioptric projection optical system
5
provided between a first surface P
1
on which the mask R is disposed and a second surface P
2
to which a surface of the substrate W is corresponded, for projecting an image of the pattern of the mask R onto the substrate W. The illumination optical system
1
includes an alignment optical system
110
for adjusting a relative positions between the mask R and the wafer W, and the mask R is disposed on a reticle stage
2
which is movable in parallel with respect to the main surface of the wafer stage
3
. The catadiodtric projection optical system has a space permitting an aperture stop
6
to be set therein. The sensitive substrate W comprises a wafer
8
such as a silicon wafer or a glass plate, etc., and a photosensitive material
7
such as a photoresist or the like coating a surface of the wafer
8
.
In particular, as shown in
FIGS. 2
,
17
, and
31
, the catadioptric projection optical system comprises a first image-forming optical system (G
1
(f
1
),G
2
(f
2
)) for forming an intermediate image
11
of the pattern of the mask R, and a second image-forming optical system (G
3
(f
3
)) for forming an image of the intermediate image
11
on the substrate W. The first image-forming optical system has a first group G
1
(f
1
) with a positive refractive power, comprising a refractive lens component, for converging a light beam from the pattern of the mask R, a second group G
2
(f
2
) with a positive a refractive power, comprising a concave, reflective mirror M
2
for reflecting a light beam from the first group G
1
(f
1
), for forming the intermediate image
11
of the pattern of the mask R, and a beam splitting optical system 10PBS (including
10
A,
10
B, and
10
C) or
an optical path changing mirror
12
as a beam splitting optical system for changing a traveling direction of one of a light beam from the first group G
1
(f
1
) and a reflected light from the concave, reflective mirror M
2
, and thereby a part of the light beam converged by the second group G
2
(f
2
) is guided to the second image-forming optical system G
3
(f
3
). The parameter f
1
means as a focus length of the first group G
1
in the first image-forming optical system, the parameter f
2
means as a focus length of the second group G
2
in the first image-forming optical system, and the parameter f
3
means as a focus length of a lens group G
3
in the second image-forming optical system.
The catadioptric projection optical system in
FIG. 2
is an optical system for projecting an image of a pattern of a first surface P
1
onto a second surface P
2
, which has a first image-forming optical system (G
1
, G
2
) for forming an intermediate image
11
of the pattern of the first surface P
1
and a second image-forming optical system (G
3
) for forming an image of the intermediate image
11
on the second surface P
2
.
The first image-forming optical system comprises a first group G
1
(f
1
) of a positive refractive power, comprising a refractive lens component, for converging a light beam from the pattern of the first surface P
1
, a prism type beam splitter 10PBS for separating a part of a light beam from the first group by a beam splitter surface 10PBSa arranged obliquely to the optical axis AX
1
of the first group, and a second group G
2
(f
2
) with a positive refractive power, comprising a concave, reflective mirror M
2
for reflecting the light beam separated by the prism type beam splitter 10PBS, for forming the intermediate image
11
of the pattern near the prism type beam splitter 10PBS, in which a part of the light beam converged by the second group G
2
(f
2
) is separated by the prism type beam splitter 10PBS to be guided to the second image-forming optical system G
3
(f
3
). The prism type beam splitter is disposed on the optical axis AX
1
of the first group G
1
(f
1
) and provided between the concave, reflective mirror M
2
and the second image-forming optical system.
In this case, it is desirable that the intermediate image
11
of the pattern be formed inside the prism type beam splitter 10PBS. Also, as shown in
FIG. 2
, it is desired that in order to prevent generation of flare due to repetitive reflections between the concave, reflective mirror M
2
and the second surface P
2
, a polarizing b spit-per be used as the beam splitter 10PBS and a quarter wave plate
9
be placed between the polarizing beam splitter and the concave, reflective mirror M
2
. Further, it is desired that the optical system be telecentric at least on the image plane P
2
side.
Next, the catadioptric projection optical system in
FIG. 17
is an optical system for projecting an image of a pattern P
10
on a first surface P
1
onto a second surface P
2
which has a first image-forming optical system (G
1
(f
1
), G
2
(f
2
)). for forming an intermediate image
11
of the pattern P
10
of the first surface P
1
, and a second image-forming optical system (G
3
(f
3
)) forming an image of the intermediate image
11
on the second surface P
2
.
The first image-forming optical system comprises a first group G
1
(f
1
) of a positive refrac
Nikon Corporation
Schwartz Jordan M.
LandOfFree
Exposure apparatus having catadioptric projection optical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Exposure apparatus having catadioptric projection optical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exposure apparatus having catadioptric projection optical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3353510