JPH07134232A - Projection optical system - Google Patents

Abstract

PURPOSE:To provide a projection optical system capable of easily/quickly attaching/detaching pupil filters to/from a pupil surface or its vicinity or exchanging the pupil filters. CONSTITUTION:A front group lens system 3 and an aperture diaphragm 5 are fixed in a front group lens barrel 2A, a rear group lens system 4 is fixed in a rear group lens barrel 2B and a rotary plate 41 is disposed in the vicinity of the pupil surface between the lens barrels 2A and 2B and freely rotatably supported centering an axis 41a parallel with an optical axis AX. Six pupil filters 43A-43F are arranged on the rotary plate 41 and an optimum pupil filter out of the pupil filters 43A-43F is installed in the vicinity of the pupil of the projection optical system 1B in accordance with an exposing pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection optical system mounted on, for example, a projection exposure apparatus for manufacturing semiconductor devices and used for transferring an image of a fine circuit pattern on a photomask or reticle onto a wafer. Regarding

[0002]

2. Description of the Related Art In a photolithography process for manufacturing a semiconductor device, a liquid crystal display device, a thin film magnetic head, etc., for example, a light source for generating illumination light and a photomask on which a transfer pattern is formed by the illumination light, Projection having an illumination optical system for illuminating a reticle (hereinafter, collectively referred to as "reticle") and a projection optical system for projecting a pattern image of the reticle onto a substrate (wafer or glass plate, etc.) coated with a photosensitive material. An exposure device is used.

FIG. 5 shows a conventional projection optical system 1, which is constructed by housing a front lens group system 3 and a rear lens group system 4 in a lens barrel 2. The front lens group 3 is composed of lenses 3 _{1 to} 3 _{n in} order from the uppermost part, and a pupil between the lowermost lens 3 _n of the front lens group 3 and the rear lens group 4 in the lens barrel 2. The aperture stop 5 is attached on a surface (Fourier transform surface) or a surface in the vicinity thereof. And conventionally,
No optical filter (including a light shielding plate) other than the aperture stop 5 was installed on the pupil plane or the surface in the vicinity thereof.

However, due to recent advances in optical design,
By disposing an optical filter such as a light-shielding plate (hereinafter referred to as “pupil filter”) near the pupil plane of the projection optical system, the resolution of an isolated pattern such as a contact hole pattern and the depth of focus can be improved. I understand. FIG. 6 shows a schematic configuration of a projection exposure apparatus according to a prior application (Japanese Patent Application No. 4-263521) of the present applicant that has not been publicly known and puts the pupil filter into and out of the projection optical system. In FIG. 6, the exposure light emitted from the mercury lamp 6 is reflected by an elliptic mirror 7, and then passes through an input lens 9 and a filter plate 10 that selectively passes light in a predetermined wavelength band and then fly-eye lens 11 Incident on. A shutter 8 for switching irradiation and blocking of exposure light is arranged near the second focal point of the elliptic mirror 7, and a main control system 22 for controlling the operation of the entire device opens and closes the shutter 8 via a drive device 23. .

An aperture stop for exposure light (hereinafter, "σ stop") is formed on the focal plane on the rear side (reticle side) of the fly-eye lens 11.
12 is arranged, and the exposure light from a large number of secondary light sources in the σ diaphragm 12 is reflected by the mirror 13, and then the first relay lens 14, the variable field diaphragm (reticle blind) 15, the second relay lens 14, The pattern area of the reticle R is illuminated with a uniform illuminance via the relay lens 16, the mirror 17 and the condenser lens 18. In this case, the arrangement surface of the variable field stop 15 is conjugate with the pattern formation surface of the reticle R, and the arrangement surface of the σ stop 12 is the pupil plane of the projection optical system 1A (Fourier transform surface of the pattern area of the reticle R) FTP. It is conjugate. The main control system 22 sets the shapes of the openings of the σ diaphragm 12 and the variable field diaphragm 15 to predetermined shapes via the driving device 24.

Also, the reticle R is a reticle stage RST.
The reticle reader 25 is held near the reticle stage RST and is arranged near the reticle stage RST. The reticle R is moved to the reticle stage RST by a reticle loader system (not shown).
When loaded on the reticle R, reticle information (bar code or the like) formed on the reticle R is read by the reticle reader 25, and the read reticle information is supplied to the main control system 22. This allows the main control system 22 to recognize the contents of the reticle R currently held on the reticle stage RST (type of pattern, minimum line width of pattern, etc.).

Under the exposure light IL emitted from the condenser lens 18, the pattern image of the reticle R is projected and exposed onto the wafer W coated with the photoresist through the projection optical system 1A. The wafer W is placed on the wafer stage WST, and the wafer stage WST aligns the wafer W in the XY plane perpendicular to the optical axis AX of the projection optical system 1A and the wafer W parallel to the optical axis AX. It is composed of a Z stage or the like that positions in the Z direction. The two-dimensional coordinates of wafer stage WST are constantly measured by laser interferometer 19, and the measurement result is supplied to wafer stage drive unit 20. Wafer stage drive unit 20 sets wafer stage WS to the target coordinates supplied from main control system 22.
Position T. As a result, the desired shot area of the wafer W is positioned within the exposure field of the projection optical system 1A. In addition, the wafer W may be placed near the projection optical system 1A.
A focus / leveling sensor 21 for detecting the focus position (position in the optical axis AX direction) and the tilt angle of the exposure surface of the is provided.
The measurement result of 1 is also supplied to the wafer stage drive device 20. Wafer stage drive device 20 performs auto-focusing and auto-leveling by matching the exposure surface of wafer W with the image plane of projection optical system 1A via a leveling stage in wafer stage WST.

Further, the main control system 22 disposes a pupil filter 26 on the pupil plane FTP of the projection optical system 1A or a surface in the vicinity thereof, as required, via the attachment / detachment device 27. Pupil filter 2
Reference numeral 6 is a combination of two polarizing plates, but a light shielding plate or the like is also used as the pupil filter 26. Further, depending on the type of reticle R to be transferred, the main control system 22 removes the pupil filter 26 from the projection optical system 1A via the attachment / detachment device 27. For example, when an isolated pattern such as a contact hole pattern is formed on the reticle R, the pupil filter 26 is installed on the pupil plane FTP of the projection optical system 1A or on a surface in the vicinity of the pupil plane FTP to project the projection optical system 1A. It has been found that the resolution and the depth of focus of the projected image can be improved.

FIG. 7 shows the configuration of the pupil filter 26. As shown in FIGS. 7 (a) and 7 (b), the pupil filter 26 is
Is outside the polarizing plate 28A for extracting linearly polarized light having a radius r ₁ and a thickness t, and a thickness t having an inner radius r ₁ and an outer radius r _2.
The ring-shaped polarizing plate 28B is fitted in, and the polarization directions of the linearly polarized light extracted by the polarizing plate 28A and the linearly polarized light extracted by the polarizing plate 28B are orthogonal to each other. Therefore, when the pupil filter 26 is arranged in the projection optical system 1A so that the center CC matches the optical axis of the projection optical system 1A in FIG.
The light that has passed through 8A and the light that has passed through the polarizing plate 28B are superimposed on the wafer W in an incoherent state.

As the pupil filter disposed in the projection optical system 1A, not only the pupil filter 26 shown in FIG. 7 but also the pupil filter 26A shown in FIG. 8 and the pupil filters 26B to 26B shown in FIGS. 26G, or the pupil filter 26H in FIG. 10 or the like can also be used. For example, the pupil filter 26A of FIG. 8 is formed by coating a light-shielding film 30 having a predetermined radius on a light-transmitting glass substrate 29, and the center CC of the light-shielding film 30 coincides with the optical axis AX of the projection optical system 1A. So that the pupil filter 26
A is installed in the projection optical system 1A. Even in this case, the resolution and the depth of focus can be improved when exposing an image of an isolated pattern such as a contact hole pattern.

Further, the pupil filter 26B shown in FIG.
A glass substrate 31 on which a light-transmissive substrate 32 having a thickness ta and a radius r ₁ is adhered, and a pupil filter 26D shown in FIG. 9C.
Is a glass substrate 33 in which a light transmissive substrate 33 having a depth of tc and a radius of r ₁ is embedded, and the pupil filter 26 of FIG.
E is a glass substrate 31 in which a layer 34 having a depth td and a radius r ₁ and a phase different from that of the glass substrate 31 is formed, and the thicknesses ta, tc, and td respectively pass within the radius r ₁ . The thickness is set so that the exposure light and the exposure light that passes through other regions become incoherent.

Further, the pupil filter 26C shown in FIG.
The glass substrate 31 having a radius r _{1 at} the center thereof is thickened by tb, and the pupil filter 26F of FIG.
Those fitting the glass substrate 35 having a thickness of tf at the inner radius r ₁ to the outside of the glass substrate 36 having a thickness of te _1, FIG. 9 (f)
The pupil filter 26G is formed by hollowing out the central portion of the radius r ₁ of the glass substrate 37 having the thickness tg, and the thickness tb, the difference in thickness (te-tf), and the thickness tg are respectively the radius r. _The thickness is set so that the exposure light passing through ₁ and the exposure light passing through the other regions are incoherent. Furthermore, the pupil filter 26H of Figure 10, the outside of the polarizing plate 38A of radius r _1, an inner radius r ₁ fit the annular polarizing plate 38B of the outer radius r _3, outside the polarizing plate 38B, the inner radius is constituted by fitting the annular polarizing plate 38C of the outer radius r ₂ at r _3, the linearly polarized light taken out by linearly polarized light and the polarization plate 38B to take out the polarizing plate 38A and 38C in which the polarization directions are orthogonal . As the pupil filter installed in the projection optical system as described above, various filters can be used.

[0013]

As described above, by installing the pupil filter on the pupil surface of the projection optical system or on the surface in the vicinity thereof, the resolution and the depth of focus when exposing a predetermined pattern can be improved. Do you get it. However, as an exposure pattern at the time of manufacturing a semiconductor element or the like, not only an isolated pattern such as a contact hole pattern but also other exposure patterns such as a line and space pattern are used. It is necessary to be able to easily and quickly put the pupil filter in and out.

In this regard, in the projection exposure apparatus of FIG.
Although an attachment / detachment device for attaching / detaching the pupil filter 26 to / from the projection optical system 1A is provided, the ease and speed of attachment / detachment have not been deeply considered. The present invention has been made in view of the above problems, and an object of the present invention is to provide a projection optical system capable of easily and quickly attaching or detaching a pupil filter to or from a pupil surface or a surface in the vicinity thereof.

[0015]

A first projection optical system according to the present invention is a projection optical system for projecting an image of a pattern on a first surface onto a second surface, as shown in FIG. 1, for example. ,
A front group optical system (3) for generating a Fourier transform image of the pattern on the first surface on a pupil plane in a space where no lens element exists, and a front group lens barrel (2) holding the front group optical system.
A), a rear group optical system (4) for generating an inverse Fourier transform image of the Fourier transform image on the pupil plane on the second surface, and a rear group lens barrel (2B) for holding the rear group optical system. And about an axis parallel to the optical axes of the front group optical system and the rear group optical system,
Light of the front group optical system and the rear group optical system is rotatably supported on the pupil plane between the front group lens barrel (2A) and the rear group lens barrel (2B) or on a surface in the vicinity of the pupil surface. A plurality of pupil filters (43A to 4A) different from each other around a plurality of positions passing through the axis.
3F) is arranged on the rotary plate (41).

The second projection optical system is, for example, as shown in FIG. 2, a front group optical system for generating a Fourier transform image of the pattern on the first surface on the pupil plane in the space where no lens element exists. (3) and a rear group optical system (4) for generating an inverse Fourier transform image of the Fourier transform image on the pupil plane on the second surface.
A lens barrel (2C) holding the front group optical system and the rear group optical system, and its pupil plane or a plane in the vicinity of the pupil plane,
Openings (45A, 45) formed on the side surface of the lens barrel (2C)
A slide plate (46) slidably supported through B) and having a plurality of pupil filters (43B to 43E) different from each other around a plurality of positions passing through the optical axes of the front group optical system and the rear group optical system. And have.

The third projection optical system is, for example, as shown in FIG. 3, a front group optical system for generating a Fourier transform image of the pattern on the first surface on the pupil plane in the space where no lens element exists. (3) and a rear group optical system (4) for generating an inverse Fourier transform image of the Fourier transform image on the pupil plane on the second surface.
A lens barrel (2D) holding the front group optical system and the rear group optical system, and its pupil plane or a surface in the vicinity of the pupil plane,
The front lens group optical system and the rear lens group optical system that can be freely inserted and removed through an opening (48) formed in the side surface of the lens barrel (2D) and are mounted on the pupil surface or a surface in the vicinity of the pupil surface. And a cassette member (50B) in which a pupil filter (51B) is arranged centering on a position that coincides with the optical axis of.

The fourth projection optical system is, for example, as shown in FIG. 4, a front group optical system for generating a Fourier transform image of a pattern on the first surface on a pupil plane in a space where no lens element exists. (3) and a rear group optical system (4) for generating an inverse Fourier transform image of the Fourier transform image on the pupil plane on the second surface.
A lens barrel (2E) for holding the front lens group optical system and the rear lens group optical system, and rotatably supported inside the lens barrel on its pupil surface or on a surface in the vicinity of the pupil surface. The rotary member (54, 55) is provided with a shading band (56) centered on a position that coincides with the optical axes of the group optical system and the rear group optical system.

In other words, the first projection optical system to the fourth projection optical system of the present invention are a revolver type, a slide type, a cassette exchange type, and an internal retraction type. A pupil filter (including a light shielding plate) is attached to and detached from the surface.

[0020]

According to the present invention, when the pattern exposed through the projection optical system is an isolated pattern such as a contact hole pattern, the revolver type, the slide type, the cassette exchange type, or the internal type, respectively. In the retract type, a pupil filter corresponding to the isolated pattern is installed near the pupil plane of the projection optical system, and then exposure is performed. Next, when the size or the like of the isolated pattern to be exposed is changed, the exposure is performed after exchanging with another pupil filter. This improves the resolution and depth of focus of the projected image.

If the pattern exposed through the projection optical system is a periodic pattern such as a line-and-space pattern, the currently installed pupil filter is placed near the pupil of the projection optical system. Take it out. Alternatively, a dummy glass substrate having the same optical thickness as the pupil filter is installed near the pupil. At this time, the pupil filter is easily attached / detached or replaced according to the pattern to be exposed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the projection optical system according to the present invention will be described below with reference to FIGS. The projection optical system of these examples can be used instead of the projection optical system 1A in the projection exposure apparatus of FIG. In the following examples, the optical axis of the projection optical system is the Z axis, and the orthogonal coordinates of the plane perpendicular to the Z axis are the X axis and the Y axis.

[First Embodiment] In the first embodiment, a revolver system is used to replace or remove the pupil filter. FIG. 1B is a front sectional view of the projection optical system 1B of the present embodiment, and FIG. 1A is a plan view of the projection optical system 1B. Parts corresponding to those in FIG. . As shown in FIG. 1B, the front group lens system 3 composed of lenses 3 _{1 to} 3 _n is fixed in the front group lens barrel 2A in order from the top, and the rear group lens system 4 is fixed to the rear group lens barrel 2B. Then, the lens barrels 2A and 2B are fixed to a support member (not shown) so that the optical axes AX of the front lens group system 3 and the rear lens group system 4 coincide with each other. At this time, the Fourier transform surface (pupil surface) of the front lens group system 3 is almost the same as the lens barrel 2A.
The lengths of the lens barrels 2A and 2B are set in advance so as to be located in the space between the lens barrel 2B and the lens barrel 2B, and the aperture stop 5 is attached near the lowermost pupil surface of the lens barrel 2A.

Further, a rotary plate 41 is arranged between the lens barrel 2A and the lens barrel 2B, and the rotary plate 41 has a shaft 41a parallel to the optical axis AX.
Is rotatably supported by a motor 42. The distance between the optical axis AX and the rotating shaft 41a is R1. Figure 1
As shown in (a), six pupil filters 43A to 43F are arranged on the rotary plate 41, and the pupil filters 43A to 43F are arranged.
Radius R around the axis 41a on the rotating plate 41
Position them on the circumference of 1 at substantially equal angular intervals. The pupil filters 43A, 43B, 43D to 43F respectively have light-shielding films 44A, 44B, 44 having different diameters on the glass substrate.
D to 44F are formed, and the pupil filter 43C is formed.
Is just a dummy glass substrate.

Pupil filters 43A, 43B, 43D-43
F is installed near the pupil plane of the projection optical system 1B when exposing contact hole patterns of different sizes,
The dummy pupil filter 43C is installed in the vicinity of the pupil plane of the projection optical system 1B when exposing a periodic pattern such as a line and space pattern, and when a contact hole pattern is exposed and when a line and space pattern is used. The optical characteristics of the projection optical system 1B are prevented from changing during the exposure. However, the pupil filter 43A,
As 43B and 43D to 43F, filters that simply support light-shielding plates having different diameters with thin columns can be used, and in this case, the pupil filter 43C becomes a mere space.

When this projection optical system 1B is mounted on the projection exposure apparatus shown in FIG. 6, the projection exposure system shown in FIG.
Of the pupil filter 43A by rotating the rotary plate 41 in the θ1 direction of
Of the optimal pupil filter center of the projection optical system 1
Position on the optical axis AX of B. As a result, exposure is performed with high resolution and a deep depth of focus according to the pattern to be exposed.

Further, as the rotating shaft of the rotating plate 41, a rotating shaft having a high precision with no runout or rattling is used, and the rotating angle is detected optically or electrically, whereby the rotating plate 4
The rotation angle of 1 can be switched or fixed with high accuracy. Since the rotary plate 41 is a simple mechanism that simply rotates and stops, the pupil filter can be replaced easily and in a short time.

[Second Embodiment] In the second embodiment, the pupil filter is replaced or replaced by a slide type. Figure 2
2B is a front sectional view of the projection optical system 1C of the present embodiment, FIG.
(A) is a plan view of the projection optical system 1C, and the portions corresponding to those in FIG. As shown in FIG. 2B, the front group lens system 3, the aperture stop 5, and the rear group lens system 4 are fixed in this order from the top in the lens barrel 2C, and the portion of the lens barrel 2C immediately below the aperture stop 5 is fixed. That is, the openings 45A and 45B are formed near the pupil plane of the projection optical system 1C. Then, a slide plate 46 is arranged in the X-axis direction that crosses the optical axis AX perpendicularly through the openings 45A and 45B, and the slide plate 46 is slidably supported in the X-direction by the feeding device 47. As shown in FIG. 2A, pupil filters 43B to 43E are arranged on the slide plate 46 so as to have their centers on the X axis.

In the present embodiment, the slide plate 46 is moved in the X-axis direction according to the pattern to be exposed, and the pupil filter 4 is moved.
The center of the optimum pupil filter of 3B to 43E is matched with the optical axis AX of the projection optical system. Thereby, exposure is performed with high resolution and a deep depth of focus according to the pattern to be exposed. Further, as the slide plate 46, a high-precision linear guide having no shake or backlash is used, and the slide position is detected optically or electrically, so that the pupil filters can be switched with sufficient accuracy. Since the slide plate 46 is a simple mechanism that simply slides and stops, the pupil filter can be replaced in a short time.

[Third Embodiment] In the third embodiment, the pupil filter is replaced or attached / detached by a cassette type. Figure 3
3B is a front sectional view of the projection optical system 1D of the present embodiment, FIG.
(A) is a plan view of the projection optical system 1D, and the portions corresponding to those in FIG. 1 are designated by the same reference numerals. As shown in FIG. 3B, the front group lens system 3, the aperture stop 5, and the rear group lens system 4 are fixed in this order from the inside in the lens barrel 2D, and the portion of the lens barrel 2D immediately below the aperture stop 5 is fixed. That is, the opening 48 is formed near the pupil plane of the projection optical system 1D. A stopper 49 for positioning and holding the cassette is provided in the lens barrel 2D near the opening 48.
A and a mounting portion 49B for holding the cassette are attached so as not to interfere with the image forming light flux.

Then, if necessary, the cassette 50A is placed on the stopper 49A and the mounting portion 49B through the opening 48.
Set up. The cassette 50A has a thin box shape, a circular pupil filter 51A is fixed inside, and the center of the pupil filter 51A coincides with the optical axis AX of the projection optical system 1D. As the pupil filter 51A, for example, any of the pupil filters 43A to 43F in FIG. 1 can be used.

Further, another cassette 50B is prepared outside the projection optical system 1D, and a pupil filter 51B different from the pupil filter 51A is held in the cassette 50B.
Further, openings 50Ba and 50Bb for passing exposure light are formed on the front surface and the back surface of the cassette 50B, respectively. The same applies to the cassette 50A. In this embodiment, the cassette 50 is changed according to the pattern to be exposed.
The optimum cassette of A, 50B, or another cassette is replaced near the pupil plane of the projection optical system 1D. This allows
The exposure is performed with a high resolution and a deep depth of focus according to the pattern to be exposed.

At this time, since the stopper 49A for positioning the cassette is provided near the pupil plane in the lens barrel 2D, the cassette can be replaced with sufficient positioning accuracy. Since the cassettes 50A and 50B have a simple mechanism that is simply pushed in, they can be replaced in a short time. In addition, when higher positioning accuracy is required, or when it is necessary to improve the efficiency of cassette replacement work, an auto-loading mechanism such as that provided in a VCR is used for the projection optical system 1D. The cassette may be attached and detached. In addition, an external transport robot is used to project an arbitrary cassette taken out from the cassette storage shelf into the projection optical system 1D.
It may be automatically replaced with the cassette inside. Also,
Although the cassettes 50A and 50B are used in this embodiment, the pupil filters 51A and 51B can be directly replaced without using the cassettes 50A and 50B.

[Fourth Embodiment] In the fourth embodiment, the pupil filter is replaced or attached / detached by an internal retracting method. Figure 4
4B is a front sectional view of the projection optical system 1E of the present embodiment, FIG.
4A is a plan sectional view near the pupil plane of FIG. 4B,
The parts corresponding to those in FIG. 1 are designated by the same reference numerals. Figure 4
As shown in (b), the front group lens system 3, the aperture stop 5, and the rear group lens system 4 are fixed in this order from the top in the lens barrel 2E, and the portion immediately below the aperture stop 5 of the lens barrel 2E, that is, the projection. Optical system 1E
An opening 52 is formed in the vicinity of the pupil plane. A rotation holding member 53 is attached to the inner surface of the lens barrel 2E in the vicinity of the opening 52 so as not to interfere with the image forming light flux, and a lever 54 is attached to the rotation holding member 53 rotatably around a shaft 53a. A light blocking plate 56 as a pupil filter is fixed to the tip through a thin column 55 (see FIG. 4A).

The other end of the lever 54 is connected to the external lever 5
4a is put out of the lens barrel 2E through the opening 52. Then, as shown in FIG. 4A, with the distance between the center of the light shielding plate 56 and the axis 53a being R2, the axis 53a is arranged at a position of a distance R2 from the optical axis AX of the projection optical system 1E. Accordingly, by rotating the external lever 54a in the θ2 direction, the center of the light shielding plate 56 can be installed on the optical axis AX via the lever 54 and the support 55. Further, when the light shielding plate 56 is unnecessary, the light shielding plate 56 can be retracted to a position in the lens barrel 2E that does not interfere with the image forming light beam by rotating the external lever 54a.

Further, although the light shield plate 56 is retracted in an arc shape in FIG. 4, the light shield plate 56 may be linearly retracted by, for example, pulling out the external lever 54a in the X direction. In addition, a plurality of pupil filters are arranged within the lens barrel 2E so that the optimum one can be selected within a range allowed by the pupil diameter of the projection optical system 1E (diameter of the aperture stop 5). Good.

In this embodiment, the rotation holding member 53 is provided with a highly accurate rotation shaft free from runout and rattling, and the internal retracted position and the installed position are detected optically, electrically, or mechanically to detect the pupil. The shading plate 56 as a filter can be set or retracted with sufficient accuracy. Since the switching of the pupil filter is performed by a simple mechanism that only rotates or reciprocates linearly, the replacement of the pupil filter is performed in a short time.

In the above-mentioned embodiment, the light shielding plates having different diameters or simple dummy glass substrates are used as the pupil filter, but various pupil filters shown in FIG. 7, FIG. 9 or FIG. 10 are used. It is possible to use a pupil filter, for example, a filter in which a polarizing plate is combined, a filter having a predetermined optical path length difference between the central portion and the peripheral portion, and the like. As described above, the present invention is not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

[0039]

According to the present invention, each is a revolver type, a slide type, a cassette exchange type, or an internal retraction type,
Since the pupil filter corresponding to the pattern to be projected is installed near the pupil plane of the projection optical system, the best resolving power and depth of focus of the projection optical system can be obtained according to the pattern to be exposed. Especially for an isolated pattern such as a contact hole pattern, the resolution and the depth of focus can be improved by installing a corresponding pupil filter. Moreover, there is an advantage that the pupil filter can be replaced or removed easily and quickly.

[Brief description of drawings]

FIG. 1A is a plan view showing a projection optical system according to a first embodiment of the present invention, and FIG. 1B is a front sectional view showing the internal structure of the projection optical system.

2A is a plan view showing a projection optical system according to a second embodiment of the present invention, and FIG. 2B is a front sectional view showing the internal structure and the like of the projection optical system.

FIG. 3A is a plan view showing a projection optical system according to a third embodiment of the present invention, and FIG. 3B is a front sectional view showing the internal structure and the like of the projection optical system.

FIG. 4A is a plan sectional view near a pupil plane of a projection optical system according to a fourth embodiment of the present invention, and FIG. 4B is a front sectional view showing an internal structure and the like of the projection optical system.

FIG. 5 is a sectional view showing a conventional projection optical system.

FIG. 6 is a configuration diagram showing a projection exposure apparatus in which a pupil filter is arranged near the pupil plane of the projection optical system.

FIG. 7A is a cross-sectional view of an example of a pupil filter seen from a side surface, and FIG. 7B is a plan view of the pupil filter.

FIG. 8A is a side view of another example of the pupil filter, and FIG.
Is a bottom view of the pupil filter.

FIG. 9 is a side sectional view showing various pupil filters.

FIG. 10A is a side sectional view of another example of the pupil filter, and FIG. 10B is a plan view of the pupil filter.

[Explanation of symbols]

 1B to 1E Projection optical system 2A Front lens barrel 2B Rear lens barrel 2C to 2E Lens barrel 3 Front group lens system 4 Rear group lens system 5 Aperture diaphragm 41 Rotating plate 43A to 43F, 51A, 51B Pupil filter 46 Slide plate 50A, 50B cassette 53 rotation support member 54 lever 56 light-shielding plate

Claims (4)

[Claims] 1. A projection optical system for image-projecting a pattern image on a first surface onto a second surface, wherein a Fourier transform image of the pattern on the first surface is formed on a pupil plane in a space where no lens element exists. A front group optical system generated above, a front group lens barrel holding the front group optical system, and a rear group optical system generating an inverse Fourier transform image of a Fourier transform image on the pupil plane on the second surface. A rear group lens barrel holding the rear group optical system, and a front group lens barrel and a rear group lens barrel having an axis parallel to the optical axes of the front group optical system and the rear group optical system as a center. A plurality of pupil filters, which are rotatably supported on the pupil plane between or in the vicinity of the pupil plane and are different from each other around a plurality of positions passing through the optical axes of the front group optical system and the rear group optical system, are arranged. A rotating optical plate, and a projection optical system. 2. A projection optical system for image-projecting a pattern image on a first surface onto a second surface, wherein a Fourier transform image of the pattern on the first surface is a pupil plane in a space where no lens element exists. A front group optical system generated above, a rear group optical system generating an inverse Fourier transform image of a Fourier transform image on the pupil plane on the second surface, the front group optical system and the rear group optical system. A lens barrel to be held, and an optical axis of the front group optical system and the rear group optical system, which is slidably supported on the pupil plane or on a surface in the vicinity of the pupil plane through an opening formed in a side surface of the lens barrel. And a slide plate having a plurality of pupil filters different from each other centered at a plurality of positions passing through the projection optical system. 3. A projection optical system for imaging and projecting an image of a pattern on a first surface onto a second surface, wherein a Fourier transform image of the pattern on the first surface is a pupil plane in a space where no lens element exists. A front group optical system generated above, a rear group optical system generating an inverse Fourier transform image of a Fourier transform image on the pupil plane on the second surface, the front group optical system and the rear group optical system. A lens barrel to be held, and on the pupil surface or on a surface in the vicinity of the pupil surface, insertable and removable through an opening formed in the side surface of the lens barrel, and on the pupil surface or on a surface in the vicinity of the pupil surface. A projection optical system, comprising: a cassette member having a pupil filter arranged around a position corresponding to the optical axes of the front group optical system and the rear group optical system when mounted. 4. A projection optical system for imaging and projecting an image of a pattern on a first surface onto a second surface, wherein a Fourier transform image of the pattern on the first surface is a pupil plane in a space where no lens element exists. A front group optical system generated above, a rear group optical system generating an inverse Fourier transform image of a Fourier transform image on the pupil plane on the second surface, the front group optical system and the rear group optical system. A lens barrel that holds the lens barrel, and a position that is rotatably supported inside the lens barrel on the pupil plane or on a surface in the vicinity of the pupil plane and that coincides with the optical axes of the front group optical system and the rear group optical system. And a rotating member on which a light-shielding band is arranged, as a projection optical system.