JP2000124105A - Aligner and illuminating optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illuminating optical device which is capable of preventing an illuminated surface from lowering in illuminance, without increasing the illuminating optical device in size. SOLUTION: An illuminating optical device is so structured that a light flux emitted from a light source is guided to an irradiated surface to light an illuminated region on the irradiated plane. In this case, the illuminating optical device is equipped with an optical element 20 arranged in an optical path between the light source and the irradiated plane, where the optical element 20 is equipped with gas passing parts 20b, which are provided to a region of the element 20 different from its region 20a where a light flux that reaches the illuminated region is made to pass through and enables space on a light source side to be connected with another space on an irradiated plane side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure device used for transferring a mask pattern onto a substrate in a lithography process for manufacturing a device such as a semiconductor device, a liquid crystal display device, an image pickup device and a thin film magnetic head. The present invention relates to an illumination optical device suitable for an apparatus.

[0002]

2. Description of the Related Art Generally, an exposure apparatus used for manufacturing a semiconductor device or a liquid crystal display device or the like uses a reticle or a mask called a mask on which a predetermined pattern is formed with illumination light (exposure light) having uniform illuminance. It has a function of illuminating and transferring the pattern of the original onto a wafer (or a glass plate or the like) coated with a photoresist. for that reason,
In an exposure apparatus, it is important to supply illumination light having a wavelength characteristic that matches the photosensitive characteristic of a photoresist that excels at high luminance. As an exposure light source, a short arc type (ultra high pressure) mercury lamp (Hg lamp, Xe -Hg lamp, etc.), an excimer laser light source and the like.

As a light source applied to an exposure apparatus as such an exposure light source, a light source having a shorter wavelength is used as the pattern of a device such as a semiconductor element or a liquid crystal display element becomes finer. . With the shortening of the wavelength of the exposure light, a decrease in illuminance due to substances attached to the surface of the optical element has become a problem. When such a decrease in illuminance occurs, the optical element causing the decrease in illuminance has been replaced.

[0004]

In order to prevent the illuminance from lowering without replacing the optical element, it is conceivable to replace the gas around the optical element to prevent substances from adhering to the surface of the optical element. For this purpose, a method of providing piping around the optical element in the apparatus or giving a margin to the lens barrel itself holding the optical element can be considered, but any of these methods may cause an increase in the size of the apparatus itself.

Accordingly, an object of the present invention is to prevent a decrease in illuminance without increasing the size of the device itself.

[0006]

In order to achieve the above-mentioned object, an illumination optical apparatus according to claim 1 of the present invention receives a light beam from a light source (1) as shown in FIGS. An illumination optical device for guiding to an irradiation surface (8) and illuminating an illumination area on the irradiation surface, wherein an optical element (2A to 2D) disposed in an optical path between the light source and the irradiation surface The optical element is provided in an area different from the area where the light flux reaching the illumination area passes through the optical element,
The optical element has a gas passage for connecting the space on the light source side and the space on the irradiated surface side of the optical element.

Further, in the illumination optical device according to claim 2 of the present invention, as shown in FIG. 4A, for example, the gas passage portion (20b) is provided in the optical element (20) in claim 1. One or more holes. Further, the illumination optical device according to claim 3 of the present invention, as shown in FIG.
c) is one or a plurality of grooves provided on the periphery of the optical element (20).

According to a fourth aspect of the present invention, there is provided an illumination optical device according to any one of the first to third aspects, wherein an optical element is provided in an optical path between a light source and a surface to be illuminated. 21) further comprising another optical element (22) arranged adjacent to the area (22a) in which the luminous flux reaching the illumination area passes through another optical element.
A gas passage portion (22b) provided in a region different from the above, for connecting a space on the light source side of another optical element and a space on the irradiated surface side, and a gas passage portion (21b) of the optical element
The gas passage portion (22b) of another optical element is provided at another position in a plane perpendicular to the optical axis Ax of the illumination optical device.

According to a fifth aspect of the present invention, there is provided the illumination optical device according to the fourth aspect, wherein the optical element and the other optical element are provided with marks for indicating the directions of the optical element and the other optical element. It is what is being done. Further, in the illumination optical device according to claim 6 of the present invention, as shown in FIG. 6, for example, in claim 4, the optical element (23) and the another optical element (24) have shapes in the direction perpendicular to the optical axis. The shape is different from the axisymmetric shape.

According to a seventh aspect of the present invention, there is provided an exposure apparatus which illuminates a pattern provided on a projection original (8) and illuminates the illuminated pattern with a photosensitive substrate (10) as shown in FIG. An exposure apparatus for transferring the light onto the pattern, comprising: an illumination optical device according to claim 1 for illuminating the pattern on the projection original; and a light source (1) in the illumination optical device includes: , 200 nm or less.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a projection exposure apparatus provided with an illumination optical device according to an embodiment of the present invention. In FIG. 1, a laser light source 1 has a wavelength of 193.
An exposure light from the laser light source 1 is provided with relay optical systems 2A and 2B, a bending mirror 3, and relay optical systems 2C and 2C.
After passing through D, the light enters a fly-eye integrator 4 as an optical element for generating multiple light beams. The fly-eye integrator 4 is formed by integrating a plurality of lens elements, and forms a plurality of light source images as secondary light sources on an exit end face thereof.

At the position where the secondary light source is formed, an illumination aperture stop 5 capable of changing the shape and size of the secondary light source is arranged. The light from the illumination aperture stop 5 passes through the bending mirror 6 and then illuminates the reticle 8 in a superimposed manner through a condenser lens system 7 having a front focal point near the secondary light source formation position. A predetermined circuit pattern is formed on the reticle 8, and this circuit pattern is transferred by a projection optical system 9 into a predetermined shot area on a wafer 10 as a photosensitive substrate. The incident side surface of the fly-eye integrator 4 is at a position conjugate with the pattern forming surface of the reticle 8 and the wafer 10.

As the laser light source 1, instead of an ArF excimer laser, a KrF excimer laser for supplying a laser light having a wavelength of 248 nm, an F2 excimer laser for supplying a laser light having a wavelength of 157 nm, and a laser light having a wavelength of 147 nm are supplied. Kr2 excimer laser, wavelength 126n
Ar2 excimer laser that supplies laser light of m
A harmonic of a G laser can be applied.

In the above example, a fly-eye integrator is used as an optical integrator. Alternatively, a rod-type integrator having an internal reflection surface may be used. When this rod-type integrator is applied, laser light from a laser light source is incident on the rod-type integrator in a state of being condensed near the incident side. The incident light is reflected by the internal reflection surface of the rod-type integrator, and then forms a uniform light amount distribution on the emission side. At this time, virtual images of a plurality of light sources are formed near the incident side of the rod-type integrator, and this position and a position conjugate with this position are the positions of the secondary light sources. Then, the uniform light amount distribution formed on the emission side of the rod-type integrator is re-imaged on the reticle 8 by the relay optical system.

In the embodiment shown in FIG. 1, among the plurality of optical elements constituting the illumination optical device, the relay optical systems 2A to 2A are used.
The 2D, the bending mirror 3 and the fly-eye integrator 4 are housed in a lens barrel 11. This lens barrel 11
Is shut off from the outside air. At this time, the interior of the lens barrel 11 is a space 11a between the laser light source 1 and the lens 2A, and a space 11a between the lens 2A and the lens 2B.
b, a space 11c between the lens 2B and the lens 2C, a space 11d between the lens 2C and the lens 2D, and a lens 2
Space 11 e between D and fly-eye integrator 4
Is divided into spaces.

In the present embodiment, each of the spaces 11a to 11
In order to connect e, a gas passage portion is provided outside the effective diameter of each of the lenses 2A to 2D. Hereinafter, this will be described in detail with reference to FIGS. FIG. 2 is a cross-sectional view for explaining the position where the gas passage section is provided. In FIG. 2, the lens 20 is held by a lens barrel 110. The luminous flux passing through the lens 20 reaches the illumination area on the illuminated surface. All the luminous fluxes reaching the entire illuminated area on the illuminated surface have the effective diameter 20a when passing through the lens 20. Decide. In other words, of the light beams passing through the lens 20, the peripheral envelope of the light beam (effective light beam) that reaches the illumination area on the irradiation surface determines the area 20a within the effective diameter.

The area 20 within the effective diameter of the lens 20
A hole 20b as a gas passage is provided in a region outside a. Since the region outside the effective diameter is a portion through which the effective light flux does not pass, the provision of the hole 20b does not cause deterioration of the optical performance of the illumination optical device. The space 110a on the front side (left side in the figure) of the lens 20 and the space 110b on the rear side (right side in the figure) are connected by the hole 20b as a gas passage portion. Therefore, for example, by providing a pipe for allowing gas to flow into the space 110a and providing a pipe for discharging gas to the space 11ab, the gas reaches the space 110b from the space 110a through the hole 20b as a gas passage.

The gas passage is not limited to the hole 20b. For example, instead of the hole 20b shown in FIG. 3A, a configuration in which a groove 20c is provided in a peripheral portion outside the area 20a within the effective diameter of the lens 20 as shown in FIG. A configuration in which a notch 20d is provided in a peripheral portion outside a region 20a within the effective diameter of the lens 20 as shown in FIG. At this time, a gap is formed by the hardware holding the lens 20, the hole 20b, the groove 20c, and the notch 20d.
The gas can be moved between the spaces 110a and 110b before and after zero. The number of the holes 20b, the grooves 20c, and the notches 20d is not limited to three. A configuration in which a plurality of these holes 20b, grooves 20c, and notches 20d are combined may be used.

Next, advantages of this embodiment over a comparative example will be described. FIG. 4 is a diagram showing a schematic configuration of a projection exposure apparatus as a comparative example. In the comparative example of FIG.
The difference from the first embodiment is that the lenses 2A to 2D constituting the relay optical system are not provided with the gas passages themselves,
The point is that a gas passage portion is provided in the lens barrel 12 itself holding the lenses 2a to 2d constituting the relay optical system. in this case,
Since it is necessary to provide a hole or the like in a holding portion for holding the periphery of the lenses 2a to 2d, it is necessary to allow a margin in the size of the lens barrel itself, which causes an increase in the size of the illumination optical device. Further, spaces adjacent to each of the lenses 2a to 2d can be connected by a pipe, but in this case, it is necessary to secure a space for the pipe, so that the size of the illumination optical device is increased.

In contrast to the comparative example shown in FIG. 4, in the embodiment shown in FIG. 1, there is no need to provide a new pipe or allow the lens barrel to have a margin, which may lead to an increase in the size of the apparatus itself. Is less. FIGS. 3A to 3C show the case where the shape of the region 20a within the effective diameter is circular. However, there are cases where the shape is not circular depending on the shape of the illumination region on the irradiated surface. is there. For example, in the projection exposure apparatus shown in FIG.
In many cases, the shape of the illumination area is rectangular, and the lens 7
In the short direction of the rectangular illumination area,
The area through which the effective light beam passes is smaller than the effective diameter of the circumscribed circle. In this case, holes and grooves may be formed using this region. Thereby, the size of the entire apparatus can be reduced.

Further, the position of the gas passage portion in a plane perpendicular to the optical axis Ax can be freely set as long as the position is outside the region 20a through which the effective light beam passes. In the case where a gas passage is provided, the position of each gas passage can be different in a plane perpendicular to the optical axis. Hereinafter, description will be made with reference to FIG. FIG.
FIG. 3 is a diagram schematically illustrating a part of the illumination optical device. In FIG. 5, a lens 21 and a lens 22 are arranged along a common optical axis Ax.
It is held by a lens barrel 110. Here, the lens 21
Outside the area 21a through which the effective light beam passes,
Two gas passage portions 21b are provided, and two gas passage portions 22b are provided outside a region 22a of the lens 22 through which the effective light flux passes. The gas passage portion 21b of the lens 21 and the gas passage portion 22b of the lens 22
They are positioned at different positions in a plane perpendicular to the optical axis (different by 90 degrees in the example of FIG. 5).

In this case, for example, considering a case where a gas flows from the space in front of the lens 21 (the side opposite to the lens 22) to the space behind the lens 22 (the side opposite to the lens 21), this gas is After passing through the gas passage portion 21b, the gas flows through the space between the lens 21 and the lens 22, and passes through the gas passage portion 22b of the lens 22. At this time, since the positions of the gas passage portions 21b and 22b are different in the plane perpendicular to the optical axis, gas stagnation can be reduced in the space between the lens 21 and the lens 22. This allows gas to spread throughout the optical element, thereby preventing illuminance reduction and illuminance unevenness on the surface to be irradiated. Here, if gas stagnates in the space between the lenses, gas replacement cannot be performed in this stagnant part, and it becomes impossible to prevent the substance from adhering to this part, and as a result, the surface to be illuminated This causes undesired reduction in illuminance and uneven illuminance.

As described above, when the positions of the gas passage portions of the plurality of optical elements are set to be shifted from each other, in order to facilitate the work of incorporating the plurality of optical elements into the lens barrel, a mark is provided on each optical member. Is preferably provided. As the mark, for example, a notch or an engraved mark around the optical member can be applied. The mark may be shared with the gas passage section itself.

As shown in FIG. 6, if the sectional shape of the lens barrel 111 is not a cylinder and the lenses 23 and 24 are shaped so that they cannot be inserted unless their directions coincide with the lens barrel, the work at the time of assembly is possible. Mistakes can be prevented. In the above-described embodiment, the present invention is applied to the optical path from the light source 1 to the fly-eye integrator 4. However, the present invention is not limited to the application only at this location. The optical path up to the reticle 8 can also be applied.

[0025]

As described above, according to the present invention, the gas can be replaced in a plurality of spaces between the optical elements without increasing the size of the lens barrel holding the optical elements. Illuminance and uneven illuminance can be prevented.
If the present invention is applied to a projection exposure apparatus, a fine pattern is transferred with a high throughput without variation in line width while reducing the size of the projection exposure apparatus body which tends to be large due to a large numerical aperture of a projection system. be able to.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a projection exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing the principle of the present invention.

FIG. 3 is a diagram showing a modification of the embodiment of the present invention.

FIG. 4 is a diagram schematically showing a projection exposure apparatus as a comparative example.

FIG. 5 is a diagram showing a modification of the embodiment of the present invention.

FIG. 6 is a diagram showing a modification of the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 excimer laser 2 a to 2 d relay optical system 3 folding mirror 4 optical integrator 5 illumination aperture stop 6 folding mirror 7 condenser lens 8 reticle 9 projection optical system 10 wafer 11 lens barrel 12 lens barrel

Claims (7)

[Claims] An illumination optical device for guiding a light beam from a light source to a surface to be illuminated and illuminating an illumination area on the surface to be illuminated, wherein the optical device is arranged in an optical path between the light source and the surface to be illuminated. The optical element is provided in a region different from a region where the light beam reaching the illumination region passes through the optical device, and the space on the light source side of the optical element and the light-irradiated region are provided. An illumination optical device, comprising: a gas passage portion for connecting a space on a surface side. 2. The illumination optical device according to claim 1, wherein said gas passage is one or more holes provided in said optical element. 3. The illumination optical device according to claim 1, wherein the gas passage portion is one or a plurality of grooves provided in a peripheral portion of the optical element. 4. The optical device according to claim 1, further comprising another optical element disposed adjacent to said optical element in an optical path between said light source and said illuminated surface, said another optical element reaching said illumination area. A light beam to be provided is provided in a region different from a region where the another optical element passes, and a gas passage portion for connecting the space on the light source side and the space on the irradiation surface side of the another optical element. Wherein the gas passage of the optical element and the gas passage of the another optical element are provided at different positions in a plane perpendicular to the optical axis of the illumination optical device. The illumination optical device according to claim 1. 5. The optical element and the another optical element,
5. A mark for indicating a direction of said optical element and said another optical element is provided.
The illumination optical device according to claim 1. 6. The illumination optical device according to claim 4, wherein the shapes of the optical element and the another optical element in the direction perpendicular to the optical axis are different from the axially symmetric shape. 7. An exposure apparatus for illuminating a pattern provided on a projection original and transferring the illuminated pattern onto a photosensitive substrate, for illuminating the pattern on the projection original. An exposure apparatus, comprising: the illumination optical device according to any one of Claims 6 to 6, wherein the light source in the illumination optical device supplies light having a wavelength of 200 nm or less.