JP2624193B2 - Illumination optical system and illumination method for semiconductor exposure apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical system of a semiconductor exposure apparatus, and more particularly, to an illumination optical system and an illumination method of a semiconductor exposure apparatus which enable uniform illumination when illuminating a fine processing pattern such as an electronic circuit. About.

[0002]

2. Description of the Related Art A recent semiconductor manufacturing technology requires a lithography technology capable of forming a finer circuit pattern as electronic circuits become more highly integrated.

Generally, the resolution line width of a circuit pattern is proportional to the wavelength of a light source. For this reason, the wavelength of the light source used tends to be shorter. As a short wavelength light source,
A light source having an oscillation wavelength in the deep UV region called an excimer laser has been developed, and various applications to lithography technology have been studied because of its high brightness, monochromaticity, directivity, and the like.

However, when using a short wavelength light source,
The types of glass materials that can be used are also limited. For a wavelength of 250 nm or less, practically usable glass materials are limited to synthetic quartz and fluorite, and it is difficult to achromatize the projection lens for a light source having a broad band spectral width. In the case of using such a glass material, it is necessary to use a light source whose wavelength spectrum width is narrowed. By narrowing the spectrum width, spatial and temporal coherence of light emitted from the light source is increased, and illumination unevenness occurs on the surface to be illuminated due to an interference pattern or a speckle pattern.

An illumination optical system and an illumination method of a conventional semiconductor exposure apparatus will be described with reference to the drawings. The illumination optical system of the semiconductor exposure apparatus shown in FIG.
1 shows the contents described in Japanese Patent Publication No. The illumination optical system of the semiconductor exposure apparatus includes an excimer laser light source 13 that is sequentially arranged along the optical axis, an integrator 15 that forms a plurality of images of the excimer laser light source 13, and a condenser lens 16. Further, the illumination optical system of the semiconductor exposure apparatus includes an image rotator 20 disposed between the excimer laser light source 13 and the integrator 15 and rotating the image rotator 20 about the optical axis during the exposure, so that the image rotator 20 is rotated. Is emitted and rotated about the optical axis of the light beam incident on the end face of the integrator 15 so that its illumination characteristics are rotationally symmetric with respect to the optical axis if a time average is taken.

In FIG. 10, 18 and 19 are total reflection prisms, 14 is a beam expander, 21 is a total reflection mirror, and 17 is a reticle.

[0007]

In the illumination optical system of this conventional semiconductor exposure apparatus, the secondary light source is not distributed outside the concentric circle of the optical axis even if the image rotator is rotated under any conditions. Since the number of secondary light sources cannot be increased, averaging of interference patterns, speckles, and the like is not sufficient, and there is a problem that these influences have a bad influence on the uniformity of illumination of the irradiated surface.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the adverse effect on the illumination uniformity due to an interference pattern and a spockle pattern generated on a surface to be illuminated when a light source having high spatial and temporal coherence is used. An object of the present invention is to provide an illumination method that enables uniform illumination.

Another object of the present invention is to uniformly illuminate a surface to be illuminated when a light source having high spatial and temporal coherence, such as an excimer laser, is used, thereby making it possible to increase the resolution of a circuit pattern image. It is an object of the present invention to provide a uniform illumination method suitable for an exposure apparatus for a semiconductor manufacturing apparatus.

It is still another object of the present invention to provide an illumination optical system for implementing the above-described illumination method.

[0011]

SUMMARY OF THE INVENTION An illumination optical system of a semiconductor exposure apparatus according to the present invention comprises a laser light source, a fly-eye lens for forming a plurality of secondary light sources by beam light based on the laser light source, and a fly-eye lens. A mechanism for raising an eye lens with respect to the optical axis of the beam light, and a condenser lens for irradiating the reticle with light from the secondary light source are provided.

The illumination optical system of the semiconductor exposure apparatus according to the present invention comprises a laser light source, a fly-eye lens for forming a plurality of secondary light sources by using a beam light based on the laser light source, and It is characterized by comprising a mechanism that rotates with respect to the optical axis of light, a mechanism that rotates around the optical axis, and a condenser lens that irradiates the reticle with light from the secondary light source.

An illumination method according to the present invention provides a laser light source, a fly-eye lens that forms a plurality of secondary light sources with a beam light based on the laser light source, and a condenser lens that irradiates light from the secondary light source to a reticle. In the illumination optical system of the semiconductor exposure apparatus provided with the above, the fly-eye lens vibrates with respect to the optical axis of the incident light beam.

The illumination method of the present invention is characterized in that the fly-eye lens is constituted by a plurality of lenses, and each or all of the fly-eye lenses vibrate two-dimensionally.

Further, in the illumination method according to the present invention, the fly-eye lens rotates around the optical axis simultaneously with the tilt vibration with respect to the optical axis.

[0016]

In the present invention, the secondary light source can be formed one-dimensionally or two-dimensionally by swinging the fly-eye lens one-dimensionally or two-dimensionally with respect to the optical axis. Further, by rotating while swinging one-dimensionally or two-dimensionally, a substantial secondary light source can be formed more finely and two-dimensionally, and the interference pattern and the speckle pattern generated on the irradiated surface can be formed. To reduce the adverse effects of illumination uniformity due to
Uniform illumination of the irradiated surface can be obtained.

[0017]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a view showing an embodiment of an illumination optical system according to the present invention. The illumination optical system includes an excimer laser light source 1 that emits a laser beam, a beam shaping optical system 2 that expands or contracts a beam as necessary, and converts the beam into a desired beam shape, and a laser from the beam shaping optical system 2. A total reflection mirror 3 for making light incident on a fly-eye lens system 4,
A fly-eye lens system 4 for splitting the incident light beam into a plurality of beams; and a condenser lens 5 for condensing a secondary light source formed by the fly-eye lens system 4 and irradiating a reticle 6
And a projection lens 7 for projecting a laser beam from a surface to be irradiated onto a wafer 8. The fly-eye lens system 4 has a tilt mechanism and a rotation mechanism.

In the illumination optical system having the above configuration, a case where the fly-eye lens system 4 vibrates one-dimensionally with respect to the optical axis will be described. 2 to 5 are diagrams showing a case where the fly-eye lens is one-dimensionally tilted and vibrated.

FIG. 2 shows the distribution of the secondary light sources 12 distributed on the secondary light source surface 10 when the tilt angle α of the fly-eye lens system 4 with respect to the optical axis 11 of the laser light 9 is 0.
The pitch of the secondary light source is formed at intervals between the elements constituting the fly-eye lens system 4 about the optical axis 11.

Next, FIG. 3 shows the distribution of the secondary light source 12 when the tilt angle α = α ₁ . 2 when tilt angle α = α ₁
The secondary light source 12 has a fly-eye lens system 4 around the optical axis 11.
Are formed at intervals of the elements constituting the fly-eye lens system 4 around a position shifted by ftan α ₁ as the focal length f of the lens.

FIG. 4 shows the distribution of the secondary light source 12 when the tilt angle α = α ₂ . As in the case of FIG. 3, the secondary light source 12 when the tilt angle α = α ₂ has a flywheel centered on a position shifted by ftanα _{2 which} is the focal length f of the fly-eye lens system 4 about the optical axis. It is formed at intervals between the elements constituting the eye lens system 4.

Secondary light source 1 with tilt angles α = 0, α ₁ , α ₂
When two are superimposed, an effective secondary light source 12 is shown in FIG. At this time, when the focal length f of the fly-eye lens system 4 is constant, the tilt angle α is changed so that the secondary light source 1
2 can be formed.

Next, a case where this principle is extended two-dimensionally, that is, a case where the fly-eye lens is vibrated two-dimensionally will be described with reference to FIGS.

In FIG. 6, the method of light propagation on the optical axis 11 is defined as the z-axis, and a plane perpendicular to the z-axis is defined as an xy plane. At this time, the tilt angles in the y-axis direction and the x-axis direction with respect to the optical axis 11 are α and β, respectively. FIG. 6 shows the case where the tilt angle is 0 degree for both α and β, that is, the fly-eye lens system 4.
And the optical axis 11 are parallel to each other, and the distribution of the secondary light sources 12 in this state is as shown in the figure. At this time, 2
The secondary light sources 12 are distributed around the optical axis in accordance with the intervals between elements constituting the fly-eye lens system 4.

Next, as shown in FIG. 7, the tilt angle α is α
When the value becomes ₁ , the secondary light source 12 is distributed according to the distance between the elements of the fly-eye lens system 4 in the y-axis direction around the position shifted from the optical axis 11 by ftan α ₁ in the y-axis direction. .

Similarly, as shown in FIG. 8, the tilt angle β is β
_When it becomes ₁ , the secondary light source 12 is distributed according to the distance between the elements of the fly-eye lens system 4 in the x-axis direction, centered on the position shifted from the optical axis 11 by ftan β ₁ in the x-axis direction. . In addition, the increment of the tilt angles α and β is reduced, and the fly-eye lens system 4 is vibrated at an appropriate speed, so that the fly-eye lens system 4 is arranged at intervals between the elements in the x- and y-axis directions. Distributed secondary light source 12
However, the secondary light source 12 is scanned two-dimensionally in the x- and y-axis directions on the secondary light source surface 10, and the secondary light source 12 can be effectively increased.

FIG. 9 shows an embodiment in which the fly-eye lens system 4 is rotated about the optical axis simultaneously with the tilting vibration with respect to the optical axis. As described with reference to FIGS. 2 to 5, the secondary light source 12 is distributed one-dimensionally by causing the fly-eye lens system 4 to vibrate one-dimensionally. As shown in FIG. 9, the secondary light source 12 is distributed two-dimensionally by rotating the fly-eye lens system 4 about the optical axis 11 while swinging the fly-eye lens system 4 with respect to the optical axis 11. 2
The secondary light source 12 is scanned in the rotation direction and the rotation vertical direction on the secondary light source surface 10, and the secondary light source 1 is effectively scanned.
2 can be increased.

As described with reference to FIGS. 6 to 8, the fly-eye lens system 4 is rotated two-dimensionally with respect to the optical axis 11 while being tilted and vibrated, so that the fly-eye lens system 4 is further finely divided.
The secondary light source 12 can be scanned on the secondary light source surface 10 in the rotational direction and the rotational vertical direction, and the secondary light source 12 can be effectively increased.

[0030]

As described above, according to the present invention, the secondary light source is distributed one-dimensionally or two-dimensionally by tilting the fly-eye lens one-dimensionally or two-dimensionally with respect to the optical axis. Can be formed. In addition, by rotating the fly-eye lens about the optical axis while swinging the fly-eye lens one-dimensionally or two-dimensionally with respect to the optical axis, a substantial secondary light source is more finely and two-dimensionally formed. This makes it possible to smooth the interference pattern and speckle pattern generated on the irradiated surface, reduce the adverse effect on the illumination uniformity due to the interference pattern and the speckle pattern, and obtain uniform illumination of the irradiated surface. There is.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of an illumination optical system of a semiconductor exposure apparatus of the present invention.

FIG. 2 is a diagram illustrating the principle of forming a secondary light source when a fly-eye lens is vibrated one-dimensionally.

FIG. 3 is a principle diagram of formation of a secondary light source when a fly-eye lens is one-dimensionally tilted and vibrated.

FIG. 4 is a diagram illustrating the principle of forming a secondary light source when a fly-eye lens is vibrated one-dimensionally.

FIG. 5 is a principle diagram of formation of a secondary light source when a fly-eye lens is one-dimensionally tilted and vibrated.

FIG. 6 is a principle diagram of formation of a secondary light source when a fly-eye lens is tilted and vibrated in two dimensions.

FIG. 7 is a principle diagram of formation of a secondary light source when a fly-eye lens is vibrated two-dimensionally.

FIG. 8 is a principle diagram of formation of a secondary light source when a fly-eye lens is two-dimensionally tilted and vibrated.

FIG. 9 is a principle diagram of formation of a secondary light source when the fly-eye lens is rotated while the fly-eye lens is vibrated in one dimension.

FIG. 10 is a diagram illustrating an example of an illumination optical system of a conventional semiconductor exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Excimer laser light source 2 Beam shaping optical system 3 Total reflection mirror 4 Fly-eye lens system 5 Condenser lens 6 Reticle 7 Projection lens 8 Wafer 9 Laser light 10 Secondary light source surface 11 Optical axis 12 Secondary light source distribution

Claims (5)

(57) [Claims] 1. A laser light source; a fly-eye lens for forming a plurality of secondary light sources using a beam light based on the laser light source; a mechanism for moving the fly-eye lens with respect to an optical axis of the beam light; A condenser lens for irradiating the reticle with light from the secondary light source. 2. A laser light source; a fly-eye lens for forming a plurality of secondary light sources by a beam light based on the laser light source; a mechanism for moving the fly-eye lens with respect to an optical axis of the beam light; An illumination optical system for a semiconductor exposure apparatus, comprising: a mechanism for rotating about an optical axis; and a condenser lens for irradiating light from the secondary light source to a reticle. 3. A semiconductor exposure apparatus comprising: a laser light source; a fly-eye lens that forms a plurality of secondary light sources using a beam light based on the laser light source; and a condenser lens that irradiates light from the secondary light source onto a reticle. The illumination optical system according to claim 1, wherein the fly-eye lens vibrates up and down with respect to an optical axis of the light beam incident thereon. 4. The semiconductor exposure apparatus according to claim 3, wherein said fly-eye lens comprises a plurality of lenses, and each or all of said fly-eye lenses vibrate two-dimensionally. Lighting method. 5. An illumination method for a semiconductor exposure apparatus according to claim 3, wherein said fly-eye lens rotates about the optical axis simultaneously with the tilt vibration with respect to said optical axis.