JPH05100095A - Lighting optics - Google Patents

Abstract

PURPOSE:To collect the synchrotron radiation light in parallel in two directions (X-direction and Y-direction) and increase the intake angle in the X-direction. CONSTITUTION:The synchrotron radiation light is collected in parallel in the parallel direction (X-direction) with the orbital plane of a synchrotron ring 1a and the vertical direction (Y-direction) respectively by the first mirror 5a and the second mirror 6a, and the mask pattern of a mask 3a is transferred on a wafer 4a. Since the light is collected in the X-direction by the first mirror 5a nearer to the luminescence point 2a of the synchrotron ring 1a, the intake angle in the X-direction is increased, and the wasteful synchrotron radiation light is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating optical device using a synchrotron radiation light generated by a charged particle storage ring (synchrotron ring) as a light source.

[0002]

2. Description of the Related Art Conventionally, there is an exposure apparatus described below, which uses the synchrotron radiation as a light source to transfer a fine mask pattern such as a VLSI to a wafer.

One of them is, as shown in FIG. 4, that the synchrotron radiation emitted from the light emitting point 12 of the synchrotron ring 11 is reflected by a mirror 15 which swings in the direction of the arrow shown in the figure, whereby the synchrotron is reflected. The ring 11 is enlarged in a direction perpendicular to the orbital surface of the ring 11 (hereinafter referred to as Y direction), and the mask 13 is illuminated to transfer the mask pattern onto the wafer 14 (referred to as a first conventional example).

In this first conventional example, for example, a light emitting point 12
Distance from the mirror 15 to the mirror 15 is 5 m, distance from the mirror 15 to the mask 13 is about 5 m, mask 13 to the wafer 1
Distance up to 4, so-called proximity gap 30μ
The transfer area is about 20 mm square.

In this case, the uptake angle in the direction parallel to the orbital surface of the synchrotron ring (hereinafter referred to as the X direction) is 2 m.
The maximum tilt of the synchrotron radiation emitted to the mask 13 is 1 mrad in the X direction and 2 in the Y direction.
It is mrad. Therefore, a so-called run-out error occurs in the mask pattern transferred to the wafer 14, and the maximum distortion is 0.06 μm in the Y direction.

An apparatus shown in FIG. 5 is conceivable as a synchrotron radiation exposure apparatus that solves the problem of the occurrence of the runout error as described above.

In the apparatus shown in FIG. 5, a beam emitted from a light emitting point 32 of a synchrotron ring 31 is reflected by a rotating hyperboloidal reflecting mirror 35, and is further rotated by a rotating parabolic reflecting mirror 36 in the X and Y directions. The mask pattern of the mask 33 is transferred to the wafer 34 in parallel.

[0008]

However, in the structure shown in FIG. 5, the X-direction and the Y-direction of the system composed of the reflecting mirrors 35 and 36.
Since the focal lengths in the directions are the same, X of the synchrotron radiation
The angles of uptake in the Y and Y directions are equal.

However, the synchrotron radiation is Y
Since the divergence angle in the X direction is larger than that in the direction, this system can capture only a part of the light in the X direction. That is,
Most of the light emitted from the synchrotron is wasted, and the utilization efficiency of the synchrotron radiation is low. Therefore, there is a problem that a long exposure time is required.

The present invention has been made in view of the above problems of the prior art, and it is possible to collimate synchrotron radiation in the X and Y directions,
In addition, it is another object of the present invention to realize an illumination optical device capable of taking in the synchrotron radiation at a large angle in the X direction.

[0011]

In order to achieve the above object, an illumination optical device of the present invention comprises a plurality of mirrors arranged between a light emitting point of a synchrotron ring and an object to be illuminated. A device for illuminating the irradiated object by making synchrotron radiation from a light emitting point substantially parallel to a direction parallel to the orbital plane of the synchrotron ring and a direction perpendicular to the orbital plane. The absolute value of the combined focal length in the direction parallel to the raceway surface is smaller than the absolute value of the combined focal length in the direction perpendicular to the raceway surface of the synchrotron ring.

Further, among the plurality of mirrors, a mirror for condensing the synchrotron radiation light in a direction parallel to the orbital plane of the synchrotron ring is arranged at a portion near the light emitting point, and is far from the light emitting point. A mirror for condensing the synchrotron radiation in the direction perpendicular to the orbital surface of the synchrotron ring may be arranged at the site.

[0013]

With the plurality of mirrors, the synchrotron radiation light is collected in a direction parallel to the orbital plane of the synchrotron ring that emits the light (X direction) and a direction perpendicular to the orbital plane of the synchrotron ring (Y direction). Glow. Since the synchrotron radiation has a divergence angle in the X direction larger than the divergence angle in the Y direction, the angle at which the synchrotron radiation in the X direction is taken in is increased to reduce wasted synchrotron radiation.

[0014]

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

FIG. 1 shows a first embodiment, (A) is a schematic elevation view and (B) is a schematic plan view.

In this embodiment, the synchrotron ring 1a
The synchrotron radiation generated in step 1 is emitted from the light emitting point 2a, is condensed and collimated by the first mirror 5a and the second mirror 6a, illuminates the mask 3a, and the mask pattern is applied to the resist coated on the wafer 4a. Transcribed.

Here, the first and second mirrors 5a and 6a
The reflecting surface is formed of a single layer film such as SiC or Pt or a multilayer film, and the first mirror 5a has a toroidal shape having a concave curvature in the X direction and a convex curvature in the Y direction. The second mirror 6a has a cylindrical shape with infinity in the X direction and concave curvature in the Y direction.

Therefore, the synchrotron radiation is
Since it is reflected by the mirror 5a and condensed in the X direction, it is taken in at a large angle and collimated, and then reflected by the second mirror 6a and collimated in the Y direction. The collimated synchrotron radiation illuminates the mask 3a and transfers the mask pattern onto the wafer 4a.

Table 1 shows specific examples of the first mirror and the second mirror of the first embodiment.

[0020]

[Table 1] In Table 1, a positive radius of curvature indicates a concave surface and a negative radius of curvature indicates a convex surface. The distance from the light emitting point to the first mirror is 4m,
The distance from the first mirror to the second mirror is 4 m, and the main incident angle of the synchrotron radiation to the mirror is 88 in both cases.
°. The combined focal length is 4 m in the X direction and 100 m in the Y direction.

When the size of the exposure area on the mask is 20 mm square, the angle of acceptance of the synchrotron radiation is 0.29 ° in the X direction and 0.011 ° in the Y direction. That is X
In this direction, the light is condensed 25 times as much as in the Y direction, so that the illuminance on the mask is improved and the exposure time can be shortened significantly.

FIG. 2 shows a second embodiment, (A) is a schematic elevational view, and (B) is a schematic plan view.

In this embodiment, the synchrotron ring 1b is used.
The synchrotron radiation light generated in 1 is emitted from the light emitting point 2b, is condensed and collimated by the first mirror 5b and the second mirror 6b and illuminates the mask 3b, and the mask pattern is applied to the resist coated on the wafer 4b. Transcribed.

Here, the first mirror 5b is concave in the X direction,
The toroidal shape has a concave curvature also in the Y direction, and the second mirror 6b has a toroidal shape having a concave curvature in the X direction and a concave curvature in the Y direction. Is different from.

Table 2 shows specific examples of the first mirror and the second mirror of the second embodiment.

[0026]

[Table 2] In Table 2, the distance from the light emitting point to the first mirror is 5
m, the distance from the first mirror to the second mirror is 5 m, and the main incident angle of the light ray on the mirror is 88.5 °. The combined focal length is 3 m in the X direction and 100 m in the Y direction.

When the size of the exposure area is 20 mm square, the angle of taking in the synchrotron radiation is 0.3 in the X direction.
8 ° and 0.011 ° in the Y direction. That is, 33 times more light is condensed in the X direction than in the Y direction, so that the illuminance on the mask is greatly improved.

The X-ray reflectivity largely depends on the incident angle.
In the case of a reflecting mirror using an ordinary metal or the like, a high reflectance is obtained when the incident angle is slightly smaller than 90 °, but the reflectance sharply decreases when the incident angle becomes small. Therefore, the light must be incident at an extremely oblique incidence angle. When the curved mirror is used at an oblique incidence, the focal length F is the curvature radius R of the mirror,
If the incident angle is θ, in the plane defined by the straight line parallel to the incident light and the projection of the mirror surface onto the tangent plane, F = (R × cos θ) / 2 A straight line perpendicular to the above plane and parallel to the incident light In the plane that includes F = R / (2 × cos θ) When a plurality of reflecting mirrors are used, the focal length of the first mirror is F1, the focal length of the second mirror is F2,
If the distance from the first mirror to the second mirror is L, the combined focal length FO of this system is given by FO = (F1 × F2) / (F1 + F2-L). By using these relationships, it is possible to design a collimating optical system having different combined focal lengths in the X and Y directions by using a plurality of oblique incidence reflecting mirrors as in the first and second embodiments.

FIG. 3 is a schematic elevational view showing the third embodiment.

The synchrotron radiation light is split into three beams in the X direction by the plane reflecting mirror 7c provided immediately after the light emitting point 2c. After that, the two mirrors 5c and 6c collect and collimate the light, and the light is guided to three exposure machines to transfer the mask pattern.

In such a system, it is possible to operate a plurality of exposure devices at the same time with one port, so that the utilization efficiency of synchrotron radiation is high. Also, the floor area of the entire device can be small.

The present invention is not limited to the above-mentioned three embodiments, but is a combination of mirrors for focusing in the X and Y directions, and the absolute value of the combined focal length in the X direction is the combined focal length in the Y direction. Any combination of mirrors can be used as long as it is smaller than the absolute value of.

As another application of the device of the present invention, X
Line microscope, photo CVD, photo etching, etc. are mentioned.

[0034]

Since the present invention is configured as described above, it has the following effects.

(1) Since the mask is illuminated with synchrotron radiation that is substantially collimated, the runout error is small or does not occur. Therefore, the positional accuracy of the transfer pattern is improved.

(2) Since the synchrotron radiation can be effectively taken in, the illumination intensity is increased, the exposure time is shortened, and the throughput is improved.

[Brief description of drawings]

FIG. 1 shows a first embodiment, (A) is a schematic elevation view,
(B) is a schematic plan view.

FIG. 2 shows a second embodiment, (A) is a schematic elevation view,
(B) is a schematic plan view.

FIG. 3 is a schematic plan view of a third embodiment.

FIG. 4 shows a first conventional example, (A) is a schematic elevation view,
(B) is a schematic plan view.

FIG. 5 shows a second conventional example, (A) is a schematic elevation view,
(B) is a schematic plan view.

[Explanation of symbols]

 1a, 1b, 1c Synchrotron ring 2a, 2b, 2c Light emitting point 5a, 5b, 5c First mirror 6a, 6b, 6c Second mirror 7c Plane reflecting mirror

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05H 13/04 U 9014-2G

Claims (2)

[Claims] 1. A plurality of mirrors are provided between a light emitting point of the synchrotron ring and an object to be irradiated, and synchrotron radiation from the light emitting point is directed in a direction parallel to an orbital surface of the synchrotron ring. And a device for illuminating the irradiation target substantially parallel to a direction perpendicular to the orbital plane, wherein an absolute value of a combined focal length in a direction parallel to the orbital plane of the synchrotron ring is an orbit of the synchrotron ring. An illuminating optical device characterized in that it is smaller than an absolute value of a combined focal length in a direction perpendicular to the plane. 2. A portion of the plurality of mirrors, which is near the light emitting point, is provided with a mirror for condensing synchrotron radiation in a direction parallel to the orbital plane of the synchrotron ring, and the portion is far from the light emitting point. The illumination optical device according to claim 1, further comprising a mirror for condensing the synchrotron radiation in a direction perpendicular to the orbital surface of the synchrotron ring.