JPH04314321A - Aligner - Google Patents

Abstract

PURPOSE:To provide an aligner having the excellent uniformity of an exposure luminance and little luminous power loss by a method wherein a laser beam whose X-direction divergence angle and Y-direction divergence angle are different from each other is transmitted through an anamorphic optical system to make to make the divergence angles approximately zero degree. CONSTITUTION:An anamorphic optical system 2 which makes the divergence angles of a laser beam emitted from a laser beam source 1 approximately zero degree is provided between the laser beam source 1 and beam shaping/beam expander optical systems 3a and 3b.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus using a laser beam, particularly an excimer laser beam having a wavelength of 320 nm or less, as a light source.

0002

2. Description of the Related Art In recent years, with the miniaturization and increase in the degree of integration of circuit patterns of semiconductor devices such as LSIs, optical projection exposure apparatuses having high resolution performance have been widely used as pattern transfer means. Along with this, the wavelength of the light flux used in exposure apparatuses is progressing toward shorter wavelengths.

[0003] Recently, exposure apparatuses that use light beams in the ultraviolet wavelength range or even shorter wavelength excimer laser beams have been attracting particular attention. Excimer laser light has a short wavelength and can provide high output. However, due to the relationship between the electrodes of the laser beam oscillator, the cross section of the emitted excimer laser beam is usually not circular or square but rectangular. Furthermore, it is known that the divergence angle of excimer laser light is different between the longer and shorter sides of the rectangle, and the difference is several milliradians.

On the other hand, in an exposure apparatus using an excimer laser light oscillator as a light source, since the excimer laser light oscillator is quite large, the exposure apparatus main body and the excimer laser light source section are generally constructed separately and independently. It is true. In this case, the distance between the excimer laser light oscillator and the main body of the exposure apparatus becomes long, and the influence of the above-mentioned divergence angle of the laser light cannot be ignored.

[0005] To solve this problem, Japanese Patent Application Laid-Open No. 1983-1
As disclosed in Japanese Patent Application No. 33522, by disposing a beam shaping optical system in the excimer laser light oscillation section and disposing a beam expander optical system at the entrance of the illumination section of the main body of the exposure apparatus, the divergence of the excimer laser light can be improved. Negative measures have been taken to reduce the angle.

That is, as shown in FIG. 4, the laser light source section includes, on the optical axis 01, a laser light source 1 and a beam shaping optical section 3 consisting of two anamorphic lenses.
a and a beam expander 3b consisting of two spherical lenses.

Here, in FIG. 5, the position (
A) and (B), and further the cross section R of the laser light beam at the position (C) immediately after emission from the beam expander 3b.
are ideally shown in FIGS. 5(A), (B), and (C). However, in reality, the divergence angle of the laser beam is εx≒4mrd in the X direction, and εx in the Y direction.
y ≒ 2 mrd, and Fig. 6 (A), (B), (C)
It will be as shown below. Therefore, an exposure apparatus having a conventional laser light source will perform exposure that is significantly different from the designed value.

[0008]

[Problem to be solved by the invention]

The present invention has been made in view of the following problems of the above-mentioned prior art. In other words, in an exposure apparatus, it is desirable that the divergence angle of the laser beam be 0° in order to perform exposure of the designed area, but conventionally, a laser beam having such a divergence angle and a desired output is used. There is no laser light source.

Therefore, it is necessary to shape the laser beam. However, in conventional beam shaping, the length of either the long side or the short side of the beam is made to match the length of the other side, and then both the long side and short side are expanded by the same magnification using a beam expander. It is because
A problem arises in that the difference in divergence angles in each direction of the long side and the short side increases.

[0011] The present invention uses an anamorphic optical system to generate a laser beam with different divergence angles in the X direction and Y direction, so that the divergence angle of the laser beam is approximately 0°, and the uniformity of the exposure illuminance is excellent. An object of the present invention is to provide an exposure apparatus with low loss of light amount.

0012

[Means for Solving the Problems] The present invention provides a laser light source section that uses laser light having different divergence angles in the X direction and in the Y direction perpendicular to the X direction as an exposure illumination light source, and An illumination section that guides a light beam to a surface to be irradiated and projects an image of a pattern of the surface to be irradiated onto a photosensitive substrate is arranged in each independent device, and a light beam from the laser light source section is directed to the laser light source section. In an exposure apparatus having a beam shaping optical system that shapes the beam into a predetermined beam shape and a beam expander optical system that makes the beam a predetermined size,

0013
] An anamorphic optical system is arranged in the optical path between the laser light source and the beam shaping optical system and beam expander optical system so that the divergence angle of the emitted laser light is approximately 0°. It is an exposure device.

[0014]

[Operation] According to the above configuration, the anamorphic optical system independently corrects the different divergence angles of the laser beam itself in mutually orthogonal directions, and makes the divergence angle in any direction almost 0°. Can be done.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Exposure apparatuses according to embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the exposure apparatus includes a laser light source section 4 and an exposure section 5.

The laser light source section 4 includes a laser light source 1, an anamorphic optical system 2 for laser beam correction, and a beam shaping system 3 arranged on an optical axis 01. The beam shaping system 3 includes a beam shaping optical section 3a made up of two anamorphic lenses and a beam expander 3b made up of two spherical lenses. Note that the same configuration as the prior art light source device described above based on FIG. 4 is as follows.
The same reference numerals are given to the drawings, and the explanation thereof will be omitted.

As shown in FIG. 2, the anamorphic optical system 2 has power in the X plane, f1=1/ε
A y anamorphic lens 2b of y and an x anamorphic lens 2a of f2=1/εx having power in the Y plane are arranged at distances f1 and f2 from the emission part of the laser light source 1, respectively. do. εx≒4m
rd, εy≒2mrd, f1≒250m
m, f2≈500 mm.

In such an anamorphic optical system 2, the laser beam emitted from the laser beam source 1 has a cross section of a rectangle with sides x and y and a divergence angle, as shown in FIG. 5(A). It becomes 0°. Furthermore, the cross section of this laser beam is shaped by the beam shaping optical section 3a as shown in FIG.
As shown in FIG. 5C, it becomes a square with sides x and x, and by the beam expander 3b with magnification β and the beam shaping system 3, it becomes a square with sides βx as shown in FIG. 5C.

Note that although the anamorphic optical system 2 is formed of two lenses, anamorphic lenses 2a and 2b, having different predetermined focal lengths,
It may be formed by one anamorphic lens (toric lens) having a power of a predetermined focal length in the direction.

The exposure section 5 includes, on the optical axis 02, a first mirror 6 that receives the laser beam emitted from the laser beam optical section 4, an auxiliary lens 7 having an aperture σ, and second and third mirrors 8. , 9, a condenser lens 10, a transmission type diffraction grating 11 formed on a reticle 20, an imaging lens 12 with an aperture, and a reflection type diffraction grating 13 formed on a wafer 14.

In the exposure section 5, the transmission type diffraction grating 1 is exposed to the laser beam emitted from the laser beam optical section 4.
1 and the reflection type diffraction grating 13 is determined.

[0022]

As described above, according to the present invention, it is possible to obtain an exposure apparatus in which the divergence angle of the laser light beam is approximately 0°, the exposure illuminance is excellent in uniformity, and the loss of light amount is small.

[0023]

[Brief explanation of drawings]

FIG. 1 is an optical diagram of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of the anamorphic optical system of the present invention.

FIG. 3 is a front view of the anamorphic optical system of the present invention.

FIG. 4 is an optical diagram of a conventional laser light source section.

FIG. 5 is a cross-sectional view of an ideal laser light beam at positions (A), (B), and (C) in FIG. 4;

[Fig. 6] Position of Fig. 4 in a conventional laser light source (A)
, (B), and (C) are cross-sectional views of the laser light beams.

[Explanation of symbols]

1 Laser light source 2 Anamorphic optical system 2a x
Anamorphic lens 2b YAnamorphic lens 3 Beam shaping system 3a Beam shaping optical section 3b Beam expander 4 Laser light source section 5 Exposure section 7 Auxiliary lens 10 Condenser lens 11 Transmission type diffraction grating 12 Imaging lens 13 Reflection type diffraction lattice

Claims (4)

[Claims] 1. A laser light source section that uses laser light having different divergence angles in an X direction and a Y direction perpendicular to the X direction as an exposure illumination light source, and a laser light source section that guides a light flux from the laser light source to an irradiated surface. An illumination unit that projects an image of the pattern of the irradiated surface onto the photosensitive substrate is arranged in an independent device, and the laser light source unit emits a beam that shapes the light flux from the laser light source unit into a predetermined beam shape. In an exposure apparatus having a shaping optical system and a beam expander optical system for shaping the beam to a predetermined size, an emitted laser beam is provided in an optical path between the laser light source and the beam shaping optical system and the beam expander optical system. An exposure apparatus characterized in that an anamorphic optical system is arranged such that the angle of divergence of the angle of divergence is approximately 0°. 2. The anamorphic optical system according to claim 1, wherein the anamorphic optical system is formed by two anamorphic lenses, and the anamorphic lenses are arranged such that refractive surfaces perpendicular to the generatrix are orthogonal to each other. Exposure equipment. 3. The anamorphic lens has f1 determined by the divergence angles εx and εy of the beams.
=1/εx, f2 =1/εy, and is located at a position approximately f1, f2 from the divergence center of the beam. Exposure equipment. 4. The exposure apparatus according to claim 1, wherein the laser beam has a wavelength of 320 nm or less.