JPS6051836A - Light collector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] "Unexploded" is, for example, written by Gukin Elmer (Perki).
Microline (Micrali) manufactured by n-J mer.
gn) Projection aligners such as the 100-300 series
Condensers suitable for use in
ser system).

Scanning type alignment alignment
proJccLion aligners) must meet the following requirements.

(1) Mask illumination
nation ) must be limited by a narrow annular arc with an angular spacing of approximately 90° and a radius specified by the aligner's projection optics (e.g., 5g, 7 (requires a nominal arc radius in millimeters).

(2) The annular arc image must have a width less than or equal to 1 millimeter and be in focus at all wavelengths for optimal performance.

(3) The brightness distribution along the length of the arc must provide constant exposure at the image plane.

(4) The brightness distribution along the arc must be constant regardless of changes over time or replacement of the light source.

(5) The light output of the condenser must be constant when scanning one wafer and when scanning several different wafers.

(6) The spectral content of the arc must be substantially constant regardless of lamp aging or replacement.

(7) The aperture of the concentrator should be between f/42 and f/6 for optimal performance with f/3 aligners.

(8) The arc images must be concentric so that the aperture of the condenser is imaged within the entrance of the projection optics of the aligner.

(9) Adjustment of the concentrator includes focusing and positioning of the arc and control of the radius of the arc, and
= Must be accommodating.

The UV radiation and resist sensitive portions of the flOJ output tract must be blocked to prevent any exposure of the wafer during alignment of the wafer to the mask.

Other requirements include the need for compatibility with setup tooling in and out of the light concentrator for center of curvature, parallelism, and focusing wedge tests typically required during aligner maintenance.

Existing light concentrator designs for nonoection aligners, such as those in the Microliner 1oO-300 series, have a number of drawbacks. For example, those existing designs have low optical efficiency. Are their existing designs usually bright enough to obtain acceptable wafer exposure times during mass production? 10 to yield an arc with
Although lamps rated between 1,000 and 2,000 watts are used, they generate a significant amount of heat that must be removed or reduced.

Because of the above-mentioned requirements for the light concentrator, more than 99% of the light output of the lamps is unusable4, since the aging and replacement of these lamps affects the uniformity of the brightness along the arc. Frequent adjustments to the concentrator are required. Capillary lamps are typically operated in AC mode producing a 12QHz output, resulting in exposure variations during high speed wafer scanning. At the lower end of the light spectrum, for example around 365 nanometers, capillary arc lamps exhibit significant squictole changes over time. With existing concentrator designs, the radius of the arc cannot be adjusted to accommodate changes in the aligner optics. Existing roles do not remove infrared and 0'' visible light from the light reaching the wafer;
The mask will be heated unnecessarily, thereby causing magnification distortion of the projected image. Center of curvature adjustments in existing concentrator designs are cumbersome and lack precision when making axial lens adjustments.

The light condensing device according to the present invention overcomes all the drawbacks of the conventional methods mentioned above and satisfies all the general requirements for high speed wafer exposure in mass production.

A condensing device according to the invention comprises means for focusing the light over a cross-sectional area small enough to accommodate the means for homogeneously focusing the focused light. In addition, this condensing device has a full cone angle (light
means for efficiently homogenizing the focused light without substantial change in cone angle and without substantial reflection loss of light; . The light coming out of the homogenizing means is shaped like a full cone (l
The light is divided equally with controlled variable brightness, radius and width of the light cone.
g) sent to a means for doing so;

The splitting means expands the width of the arc of the light spot, and at the same time converts the angle of the cone emitted from the arc in its width direction into an elliptical distribution, so as to produce a circular and symmetrical light beam at the entrance of the projection optical system. coupled to a means for obtaining brightness. The condensing device according to the invention also transfers the arc of the light spot to the image plane and focuses the circular arc on the image plane, the length of the arc being determined by VCf2 so that the light '#i/;J'11 It is also equipped with a means for changing the radius of the arc by adjusting the number of times while the arc image is in focus. .

In the light concentrator of the present invention, the preferred means for producing light is a compact arc lamp with a rating in the range of 100-200 watts. The small arc dimensions relative to the light output make such lamps much more efficient than existing concentrators such as capillary arc lamps. In one embodiment of the invention, the arc from such a lamp is typically within the range of 0.25 to 0.5 millimeters in length.

In order to collect and focus the light from the lamp, the device of the invention collects light in the range of about 80-90% of the total light emitted by the lamp and has a diameter of about 4-8.
Preferably, an elliptical reflector is provided which forms an image in the millimeter range. The apparatus of the present invention also includes a cold mirror (cold m1rror) to prevent unnecessary portions of the optical beam from reaching the image plane.
filter wheels
and other devices are preferably used. Such devices can remove up to 90 degrees of infrared and visible light from the lamp output. However, when aligning,
Sufficient light is obtained at 546 and 580 nanometers.

In a preferred embodiment, the homogenizing means according to the invention consist of a light pipe with a rectangular, square or rounded cross section. Such a light pipe has a light cone angle
Scramble the brightness distribution of the light entering the light while maintaining the brightness.

An example of the uniformity obtained with such a light guide is a square cross-section with a diameter of 6.4 mm (0.
A solid quartz light bulb with a length of 178 centimeters (25 inches) and a finch length improved the output uniformity of the light output by a factor of about 40 for an f/2.5 entrance cone.

A light condensing device according to a preferred embodiment of the invention includes a light
The light coming out of the light guide is put into a bundle of optical fibers, and this optical fiber bundle divides the light coming out of the light guide equally and positionally (channel
ing) is the preferred means for making the light spot into an arc. In one embodiment, the optical fiber bundle includes approximately 99 quartz fibers each having a core diameter of 0.6 milJ. The input face of this fiber optic bundle has an area of approximately 1.6 square centimeters (0.25 square inches). By efficiently bundling optical fibers, the energy transfer from the light pipe to the optical fiber bundle is approximately 65-7
High efficiencies in the 5-inch range are achieved. The bending radius of the optical fibers is approximately the same for all fibers, which has the effect of making the angular distribution of light emitted from each fiber constant. Each fiber is approximately the same length, which further improves the uniformity of the light from each fiber.

The optical fiber bundle in the preferred embodiment, when properly assembled and spliced into a light epsilon ino, maintains a variation in the uniformity of light from the fibers to less than about a factor of ±5. The light distribution along the arc of a light spot emerging from an optical fiber is a function of the spacing between each fiber end, and decreases linearly as the fiber spacing increases.

At the output end of the optical fiber bundle, the optical fibers form a light cone concentric with the optical axis of the concentrator. The angle of this light cone with respect to the optical axis is approximately 48.2°.

The end of the optical fiber is polished to form a cylindrical segment in concentric relation to the optical axis of the concentrator. In one embodiment, the end of the optical fiber is cut to form an ellipsoid of the same size and shape on a radius of about 40 millimeters. In other embodiments, the end of the optical fiber is cut perpendicular to the longitudinal axis of the optical fiber.

In a preferred embodiment, the width of the arc is increased, the light cone angle is proportionally decreased across its width, and the concentrator aperture is provided with a circularly symmetrical illumination pattern.
The means for generating on pattern) k is composed of a toroidal lens made of a semi-cylindrical lens whose plane side is bent to a radius of about 40 mm.

If optical fibers are cut to form ellipsoids of the same size and shape, the polished ends of the optical fibers cannot be cemented or their polished ends may be cut by other means. The center of curvature is joined to the toroidal lens. If the optical fibers are cut at right angles to their longitudinal axes to form the output ends, the optical fibers
The toroidal lenses are attached on the lens surfaces parallel to their end surfaces. By fixing the end of the optical fiber to the toroidal lens, contamination of the end is prevented, scattering due to polishing defects at the end of the optical fiber is reduced, and light uniformity and concentration are improved. The overall transmission to the optical aperture is improved.

The toroidal lens expands the light from the optical fin in only one direction, that is, only in the width direction of the arc image, and proportionally reduces the cone angle of the arc in the width direction. The annular light cone from the end of the optical fin emerges from the toroidal lens as an elliptical light cone that produces a circularly symmetrical illumination pattern within the collection aperture.

This symmetry/turn in the collection aperture maximizes the amount of light to the image plane and ensures very uniform printing characteristics.

Between the magnifying means and the means for transferring the arc of the light spot to the image plane and focusing there, there is a plane mirror for changing the direction of the arc coming out of the toroidal lens, and a focusing device if necessary. An aperture stop and a filter wheel may be provided which are arranged in the aperture plane of the optical device. The center of the aperture stop must lie approximately on the optical axis of the focusing device and on the sagittal focus of the means for relaying the arc and focusing it on the image plane. The center of the aperture stop is also located on the apex of the optical axis of the optical fiber. Therefore,
The optical axis of each optical fiber intersects the optical axis of the concentrator at the center of the aperture. Such a configuration ensures the same partial coherence within the illumination along the circular arc.

In a preferred embodiment, the means for transferring the arc of the light spot to the image plane and for focusing the arc there and for blurring the light along the length of the arc comprises a relay spherical mirror. If the arc radius of the optical fiber is about 40 millimeters, then to obtain a nominal arc radius of 59.7 millimeters, the radius of the spherical mirror must be about 146 millimeters. The focus of the arc image is defined on a plane passing through the center of curvature of the relay spherical mirror and perpendicular to the optical axis of the condenser, and coincides with the tangential focus of the relay mirror.

The chief ray at each point along the arc image is perpendicular to this plane,
Determine the concentricity of the irradiation.

The conjugate focal plane near the nominal position of the optical fiber arc can be approximated by a cylindrical segment concentric with the optical axis of the concentrator. This approximation holds true when the principal light on the aperture side of the spherical mirror is at an angle of about 482° with respect to the optical axis of the condenser. Therefore, a small axial excursion of the fiber optic arc changes the radius of the arc image, but its tangential focus is not affected. For example, a one millimeter axial displacement of the fiber optic arc changes the arc radius by approximately 0.7 millimeters.

Since the condensing device of the present invention has approximately the same conjugate focal length,
The spherical aberration of the relay spherical mirror is small, so the sharpness at the edge of the arc image is large. In contrast, in conventional devices, the conjugate focal lengths were not equal, so a relay aspherical mirror was required.

In the condensing device of the present invention, since the sagittal focal plane of the relay mirror is located on the other side of the arc image, the arc is considerably shaken in the sagittal direction, that is, along the arc. Therefore, in order to create a smooth distribution of light along the arc, the brightness of the light coming out of the optical fiber is averaged at the image plane. The degree of smoothing increases with the size of the aperture. For an aperture dimensioned f/4.2, the blur + turn extends over 10-12 optical fibers. In order to avoid errors in the irradiation intensity near the ends of the arc image, additional fibers beyond the specified arc length are required.

Since the end of the fiber is located at the center of curvature of the toroidal lens, the toroidal lens does not affect the image quality of the arc. The only action of this toroidal lens is to multiply the apparent upper dimension of the fine end by N times (where N is the refractive index of the toroidal lens). Therefore, if N is 1.5, a 0.6 mm diameter fiber will yield an arc 0.9 mm wide.

The concentrating device according to the invention has several advantages not available in the prior art. A preferred embodiment using an optical fiber, a quartz light bulb, a 100 watt rung, and an elliptical reflector collects approximately 25-30% of the lamp light in the spectral region of interest and produces an arc image 0.9 mm wide. arise. For an equivalent aperture of f/4.2 to f15, the overall efficiency is at least about a factor of 20, even with absorption losses.

Fully equipped with 1200 watt capillary arc lamp, aperture f/.

4.2 and an arc width of 1 millimeter, the existing concentrator design provides only 15-25% of the concentrator output as in accordance with the present invention. The light concentrating device according to the invention is 1% in the range 350-450 nanometers.
Although achieving a lamp-to-power pair light output conversion efficiency of
In the conventional device, the lamp-to-moi pair light output conversion efficiency is 0.03% or less in the same spectral range. For example, in the device of the present invention, if the total lamp output is about 8 watts in the spectral range of about 350 to 450 nanometers, about 0.8 to 1.5 watts of power will be delivered to the output of the concentrator.

Another great advantage of the concentrator according to the invention is that the measured energy distribution along the five projection arc images is kept within ±2 factors of the desired distribution, thus resulting in a uniform exposure of the wafer in the image plane. That's true. Projection・
Compensation of the geometric scanning characteristics by the aligner is programmed into the concentrator design through the fiber spacing in the fiber arc. In the present invention, lamp alignment and lamp aging do not substantially affect the uniformity of the arc image. In contrast, conventional devices using capillary arc lamps are used to obtain the desired brightness distribution in the arc (Zolislino)
(pre-s'lft'). The device of the present invention does not have full slits and does not require slit adjustment to accommodate changes in lamp output.

According to the present invention, the arc radius can be adjusted by simply displacing the fiber arc bundle in the direction of the arm. Normally, the entire radius of the arc image can be changed by ±50 mils from a predetermined value without refocusing. The conventional device is
Although it was not possible to easily change the arc radius, the device of the present invention has a fine adjustment mechanism that provides the final resolution.

The device of the present invention produces a sharply focused arc along its entire length and width regardless of aperture selection. Focus can be changed with a single adjustment that does not change either the radius of the arc or the alignment of the arc. These features allow for smooth and rapid focusing adjustment to accommodate different mask thicknesses. In order to obtain the target resolution, it is desirable that the arc image be appropriately focused in the same way as the arc radius.

Embodiments of the present invention will be described below with reference to the drawings.

In the drawing, light from a 100 watt mercury arc lamp 1 is focused by an elliptical reflector 2 and then focused into a quartz lamp 3. The mercury arc lamp 1 is preferably placed at the focal point of the reflector 2 or adjusted to position it there. Most of the infrared rays and visible rays in the light are removed when reflected by the cold mirror 4. This cold mirror 4 has a dielectric wave it suitable for this purpose. A filter selector 5 placed between the cold mirror 4 and the light beam 3 blocks ultraviolet rays during alignment, provides shading, and uses a neutral density filter when exposing to the high-speed light source. attenuates the light. During wafer exposure, filter selector 5 typically has a narrow aperture.

The light passing through the light/matrix 3 undergoes total internal reflection, which homogenizes the light and provides a uniform brightness distribution on the exit surface 9 of the light/matrix 3.

An input end of an optical fiber bundle 10 is fixed to the exit face 9. The fiber optic bundle 10 splits the light at its exit 12 into discrete light spots arranged in an arc.

The spacing between the fibers within the optical fiber bundle 10 determines the brightness distribution in the final arc image. The output ends of the fibers in fiber optic bundle 10 are concentric with the optical axis of the concentrator;
and is inclined by 48.2° from its optical axis.

The toroidal lens 11 is - a glass rod whose side surfaces are polished and flattened, the radius of the curved surface is within a range of about 5 to 10 mm, and whose curved surface matches the arc radius of the fiber; The toroidal lens 11 is fixed to the end of the fiber. The end of the fiber is polished parallel to the optical axis to form a cylindrical surface. The light coming out of the toroidal lens 11 is collected by the condensing aperture 1 by the folding mirror 13 which is a flat sort.
Sent to 2A. The condensing aperture 12A is concentric with the optical axis of the condensing device and is located at the sagittal focus of the spherical relay mirror 14. The l1li index center of the spherical relay mirror 14 is on the optical axis of the condenser. Spherical relay mirror 1
The radius of is selected to image an arcuate image on the image plane with a suitable radius to match the ring field of the projection optics. The inherent astigmatism of the spherical relay mirror 14 produces an arc image that is sharply focused along the arc width and significantly defocused along the arc length. The thus obtained blurred arc image converts the discontinuous output of the optical fiber bundle into a continuous light distribution along the arc image on the image plane.

In certain embodiments of the present invention, the light guide f (
The light pipe has a rectangular or square cross-section and can be composed of two or more sections with the same cross-sectional dimensions. These・zoino・
To join the sections to form a complete continuous light pipe passageway, two or more prisms can be used as connectors, as shown in FIG. 2. In FIG. 2, prisms 20 and 21 are fully connected to light and ino sections 22, 23 and 24. These 70 rhythms change the direction of light passing through the light P ino without changing the direction cosine of the ray.

To avoid light loss in the prisms, the refractive index of the fixed interface between the entrance and exit surfaces of each prism and the continuous line 4 iso must be small. Also, all five prism faces must be polished, and those prism faces and the joining light pipe sections must be matched in length, width, and flatness. The slopes of the prisms may need to be coated to prevent light from leaking through those surfaces.

In order for light to enter prism 20 from light pipe 22 without losses and angular distribution changes, the angle of incidence of the light beam exiting light pipe 22 and entering prism 20 must be close to the prism/light interface. must be smaller than the critical angle at . In order for light to exit the prism 20 and enter the RidePa 47'23, the angle of incidence of the light beam that exits the prism and enters the entrance surface of the Rite-P Ino 23 must be the critical angle at the prism/Light-Guino 0 interface. I have to listen to dogs more. The critical angle of the prism is given by the arckozaino value obtained by dividing the Ju4 refractive index of the fixing material by the refractive index of the prism.

If these conditions are met, Light Moino 2
The light beam exiting the prism 20, entering the prism 20, and reflecting off the slopes of the prism 20, otherwise passing the light beam back to the light pipe 22, is reflected within the prism 20 and enters the light pipe 23. . Light Noya Eve 2
The angle of the light beam entering the prism 20 from the prism 20 will be smaller than the critical angle, and the light beam reflected from the slope of the prism 20 will have an angle of incidence at the vertical wall of the prism that is larger than the critical angle. In this way, the light beam is directed to the prism 20
and enters the light pipe 23 with an angle of incidence smaller than the critical angle.

FIG. 6 shows the accurate and precise alignment of each component of the light condensing device according to the invention and the Perkin-Elmer (Perkin-Elmer)
1 shows a scheme for aligning a light collection device with the projection optics of an apparatus such as an in-Elmer photolithography apparatus. This alignment device 111'' is called an autocollimator, and includes a viewing screen 30, a beam sinter 31, a beam expander 39, a folding mirror 13 (FIG. 1), a focusing lens 35, and a relay mirror 14.
(Figure 1) Fully equipped. The folding mirror 13 and the relay mirror 111 are also components of the condensing device of the present invention.

The light projecting optics 36 are those found in photolithographic apparatus such as those manufactured by Nosekin Elmer, mentioned above.

In operation, beam 33 from helium/neon laser 32 enters beam cylinder 3LK and then passes through passage 40 to beam expander 39.

Beam expander 39 emits an expanded beam 41 which is incident on folding mirror 13 . A portion of the beam 41 is reflected from the surface of the folding mirror 1 onto the viewing screen 30 and forms a reference point on the viewing screen. The remainder of the beam 41 passes through the opening in the folding mirror 13 and onto the passage 42. Removing the lens 35 from the system and placing a test mask at the surface 38 in the path of the light beam 42, the light beam 42 is directed from the test mask to the path through the folding mirror 130. It is reflected along the screen and returned to the viewing screen 30.

Adjusting the test mask at step 38 until the reflected beam matches the reference point formed by the light reflected from the folding mirror 13, so that the test mask surface is parallel to the folding mirror 13. It is done. By this adjustment, the surface of the circular arc image emerging from the optical fiber bundle 10 is folded (parallel to the 7 mirror 13), so the focal plane of the circular arc image becomes parallel to the mask surface. This is the first step in accurately and precisely aligning each component in the image forming apparatus.

The second step requires placing the lens 35 into the autocollimator device shown in FIG. lens 35
For example, the beam 42 is fully focused at the intersection of the test mask surface 38 and the optical axis of the inventive focusing device. The optical axis of the condenser also coincides with the center of curvature of the relay mirror 14. A means for diffusing light is arranged at the focal point of the lens 35, and the light entering the surface of the relay mirror 14 from the light diffusing means is transmitted to the lens 35.
) middle group: mirror 1,
By adjusting the position of 1, the center of curvature of the relay mirror 10 can be aligned with the optical axis of the concentrator.

The autocollimating device shown in FIG. 6 also makes it possible to align the focusing device of the invention with the projection optics in a photolithographic device, such as the device manufactured by Ginn-Elmer & Co. . The first step in this method is
Photo of the folding mirror 1:3! J) Parallel to the actual mask surface in the graphing device. The method for achieving this result tq↓I is the same method used to bring the test mask surface parallel to the folding mirror 13, as described above.

The second step is to fully position the optical axis of the light condensing device together with the optical axis of the light projection optical system in the photolithography device V. This is achieved by aligning the center of curvature of the secondary mirror in the system with the focal point of the lens 35.

Third, the collimation device according to the present invention can be used to focus the light emerging from the lens 35 onto the actual mask surface 38 of the photolithographic device. When a proper focusing is achieved, the relay mirror, the folding mirror, the fiber arc body and the lens 35 can be moved to the optical axis.

Fourth, the radius of the circular arc in mask plane 38 may be adjusted as described above to obtain optimal resolution.

The autocollimator device according to the invention performs other important functions. That is, this device is designed to obtain the required separation between the centers of curvature of the primary and secondary mirrors in the projection optics of the photolithographic apparatus and to ensure that the center of curvature of the -order mirror is on the optical axis of the focusing device according to the invention. It is used to ensure the existence of These two objectives are accomplished by focusing the light emerging from lens 35 at the centers of curvature of the primary and secondary mirrors in the photolithographic device.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram (not shown) of an example of a light condensing device according to the present invention;
Figure 2 shows the light beams used in the device shown in Figure 1.
A schematic diagram illustrating means for bending in the above directions. In the figure, 1 is a mercury arc lamp, 2 is an elliptical reflector, 1 is a light pipe, 4 is a cold mirror, 5 is a filter selector, 10 is an optical fiber bundle, 11 is a toroidal lens, 1 :3 is a folding mirror, 1 and 1 are relay mirrors, 20 and 21 are Norism, 22° 2:3 and 24 are light pipes, 30 is a viewing screen IJ-7, :31 is an IJ beam to a beam snoritzer-132+1 /Neon Laser, 35
36 is a focusing lens, 36 is a projection optical system, and 39 is a beam expander. Patent JIB Person Ronald Niss - Shell agent Patent attorney Toshihito Yamamoto tA side j? ``I ki; no change to l stroke i) me; 4JI Display Patent No. 118675 of 1988 2 Name of Komei Light condensing device 3 Relationship with 811 persons who make corrections Patent applicant name Ronald Nis Vernonil 4, agent Postal address 105 5 Daily publication of Sleeve correction order Spontaneous Amendment (J Amendment 71 section of application for priority claim, full text of specification and drawings, and contents of amendment to power of attorney 7 fl) Hlj, power of attorney (original text and translation) are as attached.

Claims (1)

[Claims] 1. Slight and substantial (
(a means for homogenizing the light without previous absorption or reflection losses; and a predetermined means for dividing the light emerging from the homogenizing means into light spots of substantially equal brightness. means for forming an arc having a radius, width and direction;
means for enlarging the width of the arc and proportionally reducing the cone angle of the arc in the width direction thereof to produce a circularly symmetrical light distribution within the aperture of the concentrator; transferring the arc from the means to an image plane and focusing the arc on the image plane;
A condensing device comprising means for homogenizing the light along the length of an arc in the image plane. 2. The light collecting device according to claim 1, wherein the light homogenizing means comprises at least one light beam. 3. A condensing device according to claim 2, wherein the light guide is a solid quartz prism having a rounded, square or rectangular cross section. 4. The light condensing device according to claim 1, wherein the means for dividing the light emitted from the homogenizing means comprises an array of optical fibers. 5. The condensing device according to claim 4, wherein the luminance distribution along the arc image is a function of the spacing between the fiber ends. 6. In the condensing device according to claim 1, the means for enlarging the width of the arc of the light spot comprises a toroidal lens to which the dividing means is joined, and the toroidal lens is arranged within the aperture. said condensing device adapted to produce circularly symmetrical illumination; 7. In the light condensing device according to claim 1, the means for transferring the arc of the light spot and focusing the arc on the image plane comprises a spherical relay mirror, and the center of curvature of the relay mirror is The optics of i'llll are in a plane perpendicular to K, and the circular image power s jl j[',
The image is formed at a tangential focus of a mirror, and the focal plane of the mirror homogenizes the arc of the light spot in the sagittal direction along the arc, producing a smooth light distribution along the arc at the image plane. said concentrating device adapted to be displaced towards said image of said arc by a distance sufficient to . 8. A light condensing device according to claim 1, comprising a lamp/circular reflector combination for directing light to the homogenizing means, the lamp having a wattage of about 100 to 50 watts.
Said light concentrator in the range of 0 watts. 9. The light condensing device according to claim 1, further comprising means for bringing the image plane accurately and precisely parallel to a mask surface of a photolithography device. 10. In the light condensing device according to claim 1,
said light focusing device, comprising all means for focusing said arc on a mask surface of a photolithographic device; 11. In the light condensing device according to claim 1,
The light collecting device comprises means for aligning the optical axis of the light collecting device with the optical axis of the projection optical system in the lithographic apparatus 1. 12. In the light condensing device according to claim 1,
The light condensing device comprises means for accurately and precisely adjusting the spacing between the centers of curvature of the primary and secondary mirrors in a photolithographic apparatus. 13. Means for homogenizing light with little and substantially no absorption or reflection loss with a substantial change in the angle of the full cone, and for dividing and predetermining the light sound emerging from the homogenizing means. means for producing a circularly symmetrical illumination within the aperture of the concentrator in the form of an arc of light spots having a brightness, radius, width and direction of the light, and homogenizing said light along the length of said arc; means for transferring said circular arc to an image plane and focusing it on said image plane; the luminance distribution along said arc is within about 261) of the desired distribution, and the arc radius is within a predetermined range without refocusing. A light concentrator that is adjustable within approximately ±50 mils from the defined radius.