JP2001148345A - Illuminating optical system, method and apparatus for exposing by using the system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To illuminate a reticle in an equivalent illumination distribution even when a laser beam emitted from an optical fiber bundle is used as an exposure light beam. SOLUTION: The laser beam (beam bundle) LB5 radiated from an optical fiber bundle in an exposure source 161 is used as an exposure light beam IL. This beam IL is passed through a DOE (Diffraction Optical Element) 32A as a first optical integrator constituted of a plurality of basic elements 32a of the size included in individual beam section included in the bundle. Thereafter, the beam IL is reduced in a spatial coherence by a vibration mirror 34, and is illuminated to the reticle 163 through a relay lens 35, a fly eye lens 36 as a second optical integrator (homogenizer), a relay lens 37, a mirror 38 and a condenser lens system 39.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical device for illuminating a surface to be illuminated with a uniform illuminance distribution, and more particularly to a semiconductor device, an imaging device (such as a CCD), a liquid crystal display device, a plasma display device, and a thin film. It is suitable for use in an exposure apparatus used in a photolithography process for manufacturing a micro device such as a magnetic head.

[0002]

2. Description of the Related Art For example, an exposure apparatus used in a photolithography process for manufacturing a semiconductor integrated circuit uses a circuit pattern precisely drawn on a reticle (photomask) as a mask and a photoresist as a substrate. The coated wafer is optically reduced and projected and exposed. Minimum pattern size (resolution) on the wafer during this exposure
Is one of the simplest and most effective methods for reducing the wavelength of the exposure light (exposure wavelength). Here, a description will be given of some conditions to be provided for configuring an exposure light source, together with the realization of a shorter wavelength of exposure light.

First, a strong light output of, for example, several watts is required. This is necessary to shorten the time required for exposing and transferring the integrated circuit pattern and to increase the throughput. Second, when the exposure light is ultraviolet light having a wavelength of 300 nm or less, optical materials that can be used as a refraction member (lens) of the projection optical system are limited, and it becomes difficult to correct chromatic aberration. Therefore, monochromaticity of the exposure light is required, and the spectral line width of the exposure light is required to be about 1 pm or less.

Third, coherence (coherence) increases with the narrowing of the spectral line width. Therefore, if light having a narrow line width is directly irradiated, an unnecessary interference pattern called speckle occurs. Therefore, in order to suppress the occurrence of this speckle, it is necessary to reduce coherence in the exposure light source. One of the conventional short-wavelength light sources that satisfies these conditions is a light source that uses an excimer laser whose oscillation wavelength itself is a short wavelength, and the other is the generation of harmonics of an infrared or visible laser. It is a light source utilizing the above.

Among them, the former short wavelength light source is K
An rF excimer laser (wavelength: 248 nm) is used, and an exposure apparatus using an ArF excimer laser (wavelength: 193 nm) having a shorter wavelength is currently being developed. Furthermore, it has been proposed the use of F ₂ laser is a fellow excimer laser (wavelength 157 nm). However, these excimer lasers are large in size and the oscillation frequency is about several kHz at present, so that it is necessary to increase the energy per pulse in order to increase the irradiation energy per unit time. There have been various problems such as the fact that the transmittance of the optical component tends to fluctuate due to so-called compaction, etc., and that the maintenance is complicated and the cost is high.

As the latter method, there is a method of converting long-wavelength light (infrared light or visible light) into shorter-wavelength ultraviolet light by utilizing the second-order nonlinear optical effect of a nonlinear optical crystal. . For example, in the document “Longitudinally diode pumped cont
inuous wave 3.5W green laser ”, LY Liu, M. Oka,
W. Wiechmann and S. Kubota; Optics Letters, vol.1
9, p189 (1994) "discloses a laser light source for converting the wavelength of light from a solid-state laser excited by semiconductor laser light. In this conventional example, a method is described in which a 1064 nm laser beam emitted from an Nd: YAG laser is wavelength-converted using a nonlinear optical crystal to generate 266 nm light of a fourth harmonic. Note that a solid-state laser is a general term for a laser whose laser medium is solid.

[0007] For example, in Japanese Patent Application Laid-Open No. 8-334803, a laser light generator provided with a semiconductor laser and a wavelength converter for converting light from the laser light generator into ultraviolet light by a nonlinear optical crystal are used. There has been proposed an array laser in which a plurality of laser elements are bundled in a matrix (for example, 10 × 10).

[0008]

In the conventional array laser having such a configuration, the optical output of the entire apparatus can be increased while the optical output of each laser element is suppressed low. The burden on the user can be reduced. However, on the other hand, since the individual laser elements are independent, it is necessary to match the oscillation spectrum of the entire laser element to about 1 pm or less in the entire width in consideration of application to an exposure apparatus.

For this reason, for example, in order for each laser element to autonomously oscillate in a single longitudinal mode having the same wavelength, the resonator length of each laser element is adjusted, or a wavelength selection element is provided in the resonator. Or had to be inserted. But,
These methods have problems such as that the adjustment is delicate, and that the more laser elements that compose, the more complicated the configuration is required to oscillate the whole at the same wavelength.

On the other hand, an injection seed method is well known as a method for actively converting a plurality of lasers to a single wavelength (for example, “Walter Koechner; Solid-stadium”).
te Laser Engineering, 3rd Edition, Springer Series
in Optical Science, Vol.1, Springer-Verlag, ISBN
0-387-53756-2, p246-249 "). This is because the light from a single laser light source with a narrow oscillation spectrum line width is split into a plurality of laser elements, and this laser light is used as a guided wave to tune the oscillation wavelength of each laser element, and This is a method of narrowing the width. However, this method has a problem that the structure is complicated because an optical system for branching the seed light to each laser element and a tuning control unit for the oscillation wavelength are required.

Further, such an array laser can significantly reduce the size of the entire device as compared with a conventional excimer laser, but it is still difficult to reduce the output beam diameter of the entire array to several cm or less. Was. In addition, the array laser configured as described above is expensive because a wavelength conversion unit is required for each array, and it is expensive when a part of the laser elements forming the array is misaligned or when the optical element is configured. In the event that damage occurs to the laser element, there are issues such as the need to disassemble the entire array, take out the laser element once, adjust it, and reassemble the array in order to adjust this laser element. Was.

Further, a method of using laser light from an optical fiber bundle in which a plurality of optical fibers are bundled as exposure light has been attempted. In this case, the diameter of the optical fiber is about 125 μm, and the fly-eye lens is Since it is smaller than a lens element (usually about 2 mm square), there is a problem that the illuminance distribution cannot be sufficiently uniformized. In addition, since the laser light from the optical fiber bundle is a bundle of narrow beams and is not a continuous distribution like an excimer laser, even if a double fly-eye system is applied to make the illuminance distribution uniform, integration The effect, that is, the uniformity of the illuminance distribution is reduced.

The present invention has been made in view of the above points, and
It is a first object of the present invention to provide an illumination optical device capable of achieving a uniform illuminance distribution even when laser light emitted from a bundle is used as exposure light. A second object of the present invention is to provide an illumination optical device which can be used as a light source of an exposure apparatus, can be downsized, and can be easily maintained.

It is a third object of the present invention to provide an illumination optical apparatus capable of increasing the oscillation frequency and narrowing the overall oscillation spectrum line width with a simple configuration. Another object of the present invention is to provide an exposure method using such an illumination optical device, and a compact and highly flexible exposure device.

[0015]

SUMMARY OF THE INVENTION An illumination optical device according to the present invention is a laser device (16) for generating ultraviolet light of a single wavelength.
1) and an illumination optical system (162) for illuminating a surface to be illuminated with laser light from the laser device, wherein the laser device has a single wavelength within a wavelength range from an infrared region to a visible region. A laser light generator (11) for generating laser light of a wavelength, an optical fiber bundle (19) in which optical fibers for transmitting the laser light generated from the laser light generator are bundled, and laser light from the optical fiber bundle And a wavelength conversion unit (20) for converting the wavelength into ultraviolet light using a nonlinear optical crystal. The illumination optical system includes a plurality of basic elements (32a) for diverging the laser light.
A first optical element comprising a diffusion element formed from
An integrator (32A) and a second optical integrator (3A) that forms a plurality of light source images from the laser light passing through the first optical integrator.
6).

According to the illumination optical apparatus of the present invention, for example, a DOE (Diffractive Optical Element) is used as a diffusing element as a first optical integrator, and a second optical integrator is used as a second optical integrator. For example, a fly-eye lens is used. A fly-eye lens is usually composed of a lens element of about 2 mm square, and the basic element constituting the DOE is 100 μm
It can be as small as an angle. Thus, for example, 125 μm in diameter
Even when laser light from an optical fiber bundle composed of a plurality of optical fibers of about m is used as exposure light, the uniformity of the illuminance distribution can be improved.

Note that the basic element constituting the DOE indicates a necessary and sufficient minimum unit for generating a desired far-field light distribution. For example, when a fly-eye lens is used as the first optical integrator, each element lens element included in the fly-eye lens corresponds to a basic element. As the laser light generating unit, for example, a DFB (Dist
ributed feedback) A small light source having a narrow oscillation spectrum such as a semiconductor laser or a fiber laser can be used. Then, by amplifying the single-wavelength laser light from the laser light generation unit with a plurality of stages of optical fiber amplifiers, and converting it to ultraviolet light with a nonlinear optical crystal,
It is possible to obtain a high-output, single-wavelength, narrow-spectrum ultraviolet light. Therefore, it is possible to provide an illumination optical device having a laser device that is small and easy to maintain.

In this case, as the optical fiber amplifier,
For example, erbium (Er) -doped optical fiber amplifier (EDFA), ytterbium (Yb) -doped optical fiber amplifier (Y
DFA), praseodymium (Pr) -doped optical fiber amplifier (PDFA), thulium (Tm) -doped optical fiber amplifier (TDFA), or the like can be used.

As an optical fiber amplifier, for example, an erbium-doped optical fiber amplifier (EDFA)
Is used, the excitation light is 980 nm and 148 nm.
0 nm light can be used. However, as the excitation wavelength,
When 980 nm is used, the gain per unit length is larger than when 1480 nm is used. Therefore, the fiber length required to obtain a desired gain can be shortened, and ASE (Amplif
ied Spontaneous Emission) can be reduced. For this reason, the 980 nm excitation, compared to the 1480 nm excitation,
The noise of the optical fiber amplifier can be reduced. Also, since each laser beam is generated from a common laser beam generator,
The spectral line width of the finally obtained ultraviolet light is narrow.

Further, the laser light can be easily modulated at a high frequency of, for example, about 100 kHz by an optical modulator or the like. Therefore, compared with the case of using excimer laser light (frequency is about several kHz), the pulse energy can be reduced to about 1/10 to 1/100 to obtain the same illuminance. Fluctuation of transmittance of optical members due to compaction etc. is almost eliminated,
Exposure can be performed stably and with high accuracy.

Next, regarding the configuration of the wavelength conversion section of the present invention, the second harmonic generation (SHG) of a plurality of nonlinear optical crystals will be described.
And the sum frequency generation (SFG), the frequency of which is an integral multiple of the fundamental wave (the wavelength is 1 / integer)
Can be easily output. Then, for example, the wavelength is 1.5 μm in the laser light generating section.
m, in particular, a laser beam limited to 1.544 to 1.552 μm, and the wavelength converter generates an eighth harmonic of the fundamental wave, so that a wavelength of 193 is substantially the same as that of the ArF excimer laser. UV light of １９194 nm is obtained. In addition, the laser light generating section emits laser light having a wavelength of about 1.5 μm, particularly 1.57 to 1.58 μm, and the wavelength conversion section generates a tenth harmonic of the fundamental wave. , ultraviolet light 157~158nm of F ₂ laser and substantially the same wavelength can be obtained. Similarly, for example, a laser beam generator emits a laser beam having a wavelength around 1.1 μm, particularly 1.099 to 1.106 μm, and a wavelength converter generates a seventh harmonic of the fundamental wave. Depending on the configuration, ultraviolet light having substantially the same wavelength as the F ₂ laser can be obtained.

In the present invention, it is desirable that the size of one of the basic elements is a size included in each beam cross section included in a beam bundle incident on the basic element. Next, the exposure method according to the present invention is an exposure method using the ultraviolet light from the illumination optical device (161, 162) of the present invention, and irradiates the ultraviolet light to the mask (163) to form a pattern on the mask. The substrate (166) is exposed with ultraviolet light passed through the substrate. Also,
The exposure apparatus according to the present invention includes the illumination optical apparatus (16) according to the present invention.
1, 162) and a projection optical system (165) for projecting an image of the pattern of the mask (163) onto the substrate, and irradiating the mask with ultraviolet light from the illumination optical device, and changing the pattern of the mask. The substrate is passed by the ultraviolet light (166).
Is exposed. By using the illumination optical device of the present invention, the entire device can be reduced in size and maintenance can be facilitated.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this example, the present invention is applied to an exposure apparatus of a step-and-scan method. FIG. 1A shows an ultraviolet light generation device (a laser device that generates ultraviolet light) used in the exposure apparatus of the present embodiment,
In FIG. 1A, a laser beam LB1 having a wavelength of 1.544 μm, which is a single-wavelength continuous wave (CW) having a narrow spectrum width, is generated from a single-wavelength oscillation laser 11 as a laser light generation unit. The laser light LB1 is incident on an optical modulation element 12 as an optical modulator via an isolator IS1 for blocking light in the opposite direction, where it is converted into a pulsed laser light LB2, Incident on.

The laser beam LB2 incident on the optical branching amplifier 4
First, an optical fiber amplifier 1 as an optical amplification unit in the previous stage
After being amplified by passing through the splitter 3, the light enters the planar waveguide type splitter 14 as the first optical splitter via the isolator IS2, and is split into m laser beams having substantially the same intensity. m is an integer of 2 or more, and in this example, m = 4. The optical fiber amplifier 13 is an erbium-doped optical fiber amplifier (Erbium) in order to amplify light in the same wavelength range (around 1.544 μm in this example) as the laser beam LB1 generated from the single-wavelength oscillation laser 11.
-Doped Fiber Amplifier (EDFA) is used. The optical fiber amplifier 13 is supplied with pumping light having a wavelength of 980 nm from a pumping semiconductor laser (not shown) via a coupling wavelength division multiplexing device (not shown). Erbium-doped optical fiber amplifier (E
For DFA), 980 nm or 1480 nm excitation light can be used. However, in order to prevent the wavelength from spreading due to the non-linear effect, it is desirable to use a laser beam having a wavelength of 980 nm as the excitation light and to shorten the fiber length. As a result, the ASE (Amplified Spontaneous Emulation) is compared with the case where the light of 1480 nm is used as the excitation light.
The noise of the optical fiber amplifier 13 due to ission can be reduced. This is the same for the optical fiber amplifier at the subsequent stage.

The m laser beams emitted from the splitter 14 are coupled to optical fibers 15-1 and 15-1 having different lengths.
5-2,..., 15-m, the planar waveguide type splitters 16-1 and 16- as the second optical branching elements, respectively.
, 16-m, and is branched into n laser beams having substantially the same intensity. n is an integer of 2 or more, and in this example, n = 32. As a result, the laser beam LB1 emitted from the single-wavelength oscillation laser 11 is divided into nm (m in this example, 128) laser beams as a whole.

The n laser beams LB3 emitted from the splitter 16-1 are respectively provided as optical amplifiers at the subsequent stage via optical fibers 17-1, 17-2,..., 17-n having different lengths. Optical amplification unit 18-1,
, 18-n and amplified. The optical amplification units 18-1 to 18-n are single-wavelength oscillation lasers 1
Amplify the light in the same wavelength range (around 1.544 μm in this example) as the laser light LB1 generated from No. 1. Similarly, the n laser beams emitted from the other splitters 16-2 to 16-m also have optical fibers 17 having different lengths from each other.
The light enters the optical amplification units 18-1 to 18-n as optical amplification units at the subsequent stage via -1 to 17-n and is amplified.

M sets of optical amplification units 18-1 to 18-n
The laser light amplified by the optical amplifier unit 18
A predetermined substance in -1 to 18-n propagates through an extension of an exit end of an optical fiber (described later) doped with a predetermined substance, and these extensions constitute an optical fiber bundle 19. The lengths of the extension parts of the m sets of n optical fibers constituting the optical fiber bundle 19 are substantially the same. However, the optical fiber bundle 19 is formed by bundling m · n undoped optical fibers having the same length, and irradiating the laser light amplified by the optical amplification units 18-1 to 18-n with the corresponding undoped optical fibers. Optical fiber. The optical branching amplifier 4 is composed of members from the optical fiber amplifier 13 to the optical fiber bundle 19.

The laser beam LB4 emitted from the optical fiber bundle 19 enters a wavelength converter 20 having a non-linear optical element and is converted into a laser beam LB5 made of ultraviolet light. The laser beam LB5 is used as an exposure light and an alignment light. ,
Alternatively, the light is emitted to the outside as inspection light. As shown in FIG. 1 (b), the output end 19a of the optical fiber bundle 19 bundles mn (128 in this example) optical fibers in close contact with each other and in a circular outer shape. ing. Actually, the shape of the output end 19a and the number of bundled optical fibers are determined by the configuration of the wavelength conversion unit 20 in the subsequent stage,
And it is determined according to the usage conditions of the ultraviolet light generation device of this example. Since the clad diameter of each optical fiber constituting the optical fiber bundle 19 is about 125 μm, the diameter d1 of the output end 19a of the optical fiber bundle 19 when 128 fibers are bundled in a circle can be set to about 2 mm or less. .

In the wavelength converter 20 of this embodiment, the incident laser beam LB4 is converted into a laser beam LB composed of an eighth harmonic (wavelength is 1/8) or a tenth harmonic (wavelength is 1/10).
Convert to 5. Since the wavelength of the laser beam LB1 emitted from the single-wavelength oscillation laser 11 is 1.544 μm,
The wavelength of the second harmonic is 193n which is the same as that of the ArF excimer laser.
m, and the wavelength of the 10th harmonic is 154 nm, which is almost the same as the wavelength (157 nm) of the F ₂ laser (fluorine laser). To make the wavelength of the laser beam LB5 closer to the wavelength of the F ₂ laser beam, the wavelength converter 20 generates the 10th harmonic and the single-wavelength oscillation laser 11 emits a 1.57 μm laser beam. Should be generated.

In practice, the oscillation wavelength of the single-wavelength oscillation laser 11 is specified to be about 1.544 to 1.552 μm,
By converting to an eighth harmonic, ultraviolet light having substantially the same wavelength (193 to 194 nm) as the ArF excimer laser can be obtained. Then, the oscillation wavelength of the single-wavelength oscillation laser 11 is specified to be about 1.57 to 1.58 μm, and is converted into a tenth harmonic, thereby substantially the same wavelength (1) as the F ₂ laser.
57 to 158 nm). Therefore, it is possible to use these ultraviolet light generator as easy sources of each ArF excimer laser light source, and maintenance at low cost alternative to the F ₂ laser light source.

Incidentally, instead of finally obtaining ultraviolet light in a wavelength range close to ArF excimer laser or F ₂ laser, etc.,
For example, an optimum exposure wavelength (for example, 160 nm) is determined from a pattern rule of a semiconductor device or the like to be manufactured. The harmonic magnification in the unit 20 may be determined.

Single wavelength oscillation laser 1 oscillating at a single wavelength
For example, a DFB (Distributed feedback: InGaAsP structure) having an oscillation wavelength of 1.544 μm, a continuous wave output (hereinafter, also referred to as “CW output”), and an output of 20 mW.
(Distributed feedback type) semiconductor laser is used. Here, a DFB semiconductor laser is one in which a diffraction grating is formed in a semiconductor laser instead of a Fabry-Perot resonator having low longitudinal mode selectivity, and a single longitudinal mode oscillation can be performed under any circumstances. Is configured to do so. Since a DFB semiconductor laser basically oscillates in a single longitudinal mode, its oscillation spectrum line width can be suppressed to 0.01 pm or less. As the single-wavelength oscillation laser 11, a light source that generates laser light having a narrow band in the same wavelength region, for example, an erbium (Er) -doped fiber laser or the like can be used.

Further, it is desirable that the output wavelength of the ultraviolet light generator of this embodiment is fixed to a specific wavelength depending on the application. Therefore, an oscillation wavelength control device for controlling the oscillation wavelength of the single-wavelength oscillation laser 11 as a master oscillator (Master Oscillator) to a constant wavelength is provided. Usually, a DFB semiconductor laser or the like is provided on a heat sink, and these are housed in a housing. Therefore, in this example, a temperature adjustment unit 5 (for example, a heating element such as a heater, a heat absorbing element such as a Peltier element, and a temperature detecting element such as a thermistor) is attached to a heat sink attached to the single-wavelength oscillation laser 11 (such as a DFB semiconductor laser). ) Is fixed, and the operation of the temperature adjusting unit 5 is controlled by the control unit 1 composed of a computer, so that the temperature of the heat sink and thus the temperature of the single-wavelength oscillation laser 11 are controlled with high accuracy. The control unit 1 controls the driving power (for example, the driving current) of the single-wavelength oscillation laser 11 with high accuracy via the driver 2 and drives the light modulation element 12 via the driver 3.

As the monitor wavelength for feedback control when controlling the oscillation wavelength to a predetermined wavelength,
The oscillation wavelength of the DFB semiconductor laser, or the harmonic output (2nd harmonic, 3rd harmonic) after wavelength conversion in the wavelength converter 20 described later.
It is sufficient to select a wavelength that gives the sensitivity required for performing the desired wavelength control from among the harmonics, the fourth harmonic and the like, and is the most easily monitored.

In a semiconductor laser or the like, the output light can be pulse-oscillated by controlling the current. For this reason, in this example, the single-wavelength oscillation laser 11 (DF
It is preferable to generate pulsed light by using both the power control of a B semiconductor laser and the light modulation element 12 together. The pulsed light output obtained in this way is connected to the first-stage erbium-doped optical fiber amplifier 13 to obtain 35 dB (31
(62 times). At this time, the pulse light has a peak output of about 63 W and an average output of about 6.3 mW. Note that a plurality of optical fiber amplifiers may be used instead of the optical fiber amplifier 13.

The output of the first stage optical fiber amplifier 13
Are first output from the splitter 14 by four outputs of channels 0 to 3.
(M = 4 in this example). This channel 0
3 are connected to optical fibers 15-1 having different lengths.
~ 15-4 from each optical fiber
Output light has a delay time corresponding to the optical fiber length.
available. For example, in the present embodiment, the light in the optical fiber
Propagation speed of 2 × 10 ⁸m / s and the channel
0.1m, 19.3m, 3 for 0, 1, 2, 3 respectively
8.5m, 57.7m long optical fiber 15-1
15-4 is connected. In this case, the exit of each optical fiber
The optical delay between adjacent channels in the above is 96 ns.

FIG. 2 shows the optical amplifying unit 18 of this embodiment. In FIG. 2, the optical amplifying unit 18 is basically composed of two stages of erbium-doped fiber amplifiers (EDFAs). The optical fiber amplifiers 22 and 25 are connected. Wavelength division multiplexing (WDM) elements (hereinafter, referred to as "WDM elements") 21A and 21B for coupling pump light are connected to both ends of the first-stage optical fiber amplifier 22. Light EL from a semiconductor laser 23A as a pump light source by the WDM elements 21A and 21B, respectively.
1 and the excitation light from the semiconductor laser 23B (the excitation light EL1
) Are supplied to the optical fiber amplifier 22 from before and after. Similarly, the second-stage optical fiber amplifier 2
Coupling WDM elements 21C and 21D are also connected to both ends of 5, and pump light from semiconductor lasers 23C and 23D is supplied to optical fiber amplifier 25 from front and rear by WDM elements 21C and 21D, respectively. The pumping lights of the semiconductor lasers 23C and 23D have the same wavelength as each other, but may have the same wavelength as the first-stage pumping light EL1 or may have a different wavelength. That is, the optical fiber amplifiers 22 and 25 are both of a bidirectional pump type.

By the way, as described above, the output wavelength of the optical fiber amplifier having the cladding having the double structure is 1.51.
When using 1.59 μm, ytterbium (Y) in addition to erbium (Er) is added as ions to be doped.
Preferably, b) is co-doped. This is because there is an effect of improving the pumping efficiency by the semiconductor laser.

Next, some examples of the configuration of the wavelength converter 20 in the ultraviolet light generator of the embodiment shown in FIG. 1 will be described. FIG. 3A shows a wavelength conversion unit 20 that can obtain an eighth harmonic by repeating the generation of the second harmonic.
In (a), the wavelength output from the output end 19a of the optical fiber bundle 19 is 1.544 μm (the frequency is ω
) Of the laser light LB4 is incident on the first-stage nonlinear optical crystal 502, where the second harmonic is generated, and the frequency 2ω (the wavelength is ２), which is twice the frequency ω of the fundamental wave.
(772 nm). The second harmonic wave enters the second-stage nonlinear optical crystal 503 through the lens 505, where the second harmonic is again generated, and the frequency is twice the frequency 2ω of the incident wave, ie, four times the fundamental wave. A fourth harmonic having 4ω (the wavelength is ４ of 386 nm) is generated. The generated fourth harmonic further proceeds to the third-stage nonlinear optical crystal 504 via the lens 506, where the second harmonic generation again causes the frequency to be twice the frequency 4ω of the incident wave, ie, eight times the fundamental wave. An eighth harmonic having a frequency of 8ω (the wavelength is 1/8
3 nm). This eighth harmonic is an ultraviolet laser beam LB
Injected as 5. That is, in this configuration example, the fundamental wave (wavelength: 1.544 μm) → the second harmonic wave (wavelength: 772 nm) →
4th harmonic (wavelength 386 nm) → 8th harmonic (wavelength 193 nm)
Are performed in this order.

As the nonlinear optical crystal used for the wavelength conversion, for example, a LiB ₃ O ₅ (LBO) crystal is used for the nonlinear optical crystal 502 for converting a fundamental wave to a second harmonic.
LiB ₃ O ₅ (LBO) crystal is used for the nonlinear optical crystal 503 for converting the harmonic wave to the fourth harmonic, and Sr ₂ Be ₂ B for the nonlinear optical crystal 504 for converting the fourth harmonic to the eighth harmonic.
₂ O ₇ (SBBO) crystal is used. Here, in the conversion from the fundamental wave to the second harmonic using the LBO crystal, a non-critical phase matching (NCPM) by adjusting the temperature of the LBO crystal is used for phase matching for wavelength conversion. The NCPM enables conversion to the second harmonic wave with high efficiency and generates the "Walk-off", which is an angle shift between the fundamental wave and the second harmonic wave in the nonlinear optical crystal, and does not occur. The second harmonic is advantageous because it does not suffer from beam deformation due to walk-off.

In FIG. 3A, it is desirable to provide a condenser lens between the optical fiber bundle 19 and the nonlinear optical crystal 502 in order to increase the incidence efficiency of the laser beam LB4. At this time, the mode diameter (core diameter) of each optical fiber constituting the optical fiber bundle 19 is, for example, about 20 μm, and the size of the region having high conversion efficiency in the nonlinear optical crystal is, for example, about 200 μm. A microlens with a magnification of about 10 may be provided for each time, and the laser light emitted from each optical fiber may be focused on the nonlinear optical crystal 502. This is the same in the following configuration examples.

Next, FIG. 3B shows a wavelength converter 20A capable of obtaining an eighth harmonic by combining the generation of the second harmonic and the generation of the sum frequency. In FIG. The fundamental wave of the laser light LB4 having a wavelength of 1.544 μm emitted from the output end 19a of the bundle 19 is LBO
The light enters the first-stage nonlinear optical crystal 507 made of crystal and controlled by the NCPM, and a second harmonic (wavelength: 722 nm) is generated by the generation of the second harmonic. Furthermore,
A part of the fundamental wave passes through the nonlinear optical crystal 507 as it is. Both the fundamental wave and the second harmonic wave pass through a wave plate (for example, a half-wave plate) 508 in a state of linear polarization, and only the fundamental wave is emitted with the polarization direction rotated by 90 degrees. The fundamental wave and the second harmonic wave pass through the lens 509 and pass through the lens 509, respectively.
The light is incident on the nonlinear optical crystal 510 of the stage.

In the nonlinear optical crystal 510, a third harmonic (wavelength 511) is generated from the second harmonic generated in the first-stage nonlinear optical crystal 507 and the fundamental wave transmitted without being converted.
5 nm). As the nonlinear optical crystal 510, LBO
A crystal is used, but the first-stage nonlinear optical crystal 507 is used.
It is used in the NCPM having a different temperature from (LBO crystal). The third harmonic obtained by the non-linear optical crystal 510 and the second harmonic transmitted without wavelength conversion are separated by the dichroic mirror 511, and the dichroic mirror 5
The third harmonic reflected by 11 is reflected by mirror M1, passes through lens 513, and the third stage β-BaB ₂ O ₄ (BBO)
The light enters a nonlinear optical crystal 514 made of a crystal. Here, the third harmonic becomes the sixth harmonic (wavelength 257n) due to the generation of the second harmonic.
m).

On the other hand, the second harmonic transmitted through the dichroic mirror enters the dichroic mirror 516 via the lens 512 and the mirror M2, and the sixth harmonic obtained by the nonlinear optical crystal 514 also passes through the lens 515 to the dichroic mirror.
The light enters the mirror 516, where the second harmonic and the sixth harmonic are combined coaxially and incident on the nonlinear optical crystal 517 made of the fourth stage BBO crystal. In the nonlinear optical crystal 517,
Eighth harmonic (wavelength 1) by sum frequency generation from sixth harmonic and second harmonic
93 nm). This eighth harmonic is generated by the ultraviolet laser beam LB5.
Injected as The fourth-stage nonlinear optical crystal 51
As CsLiB ₆ O ₁₀ (C
It is also possible to use (LBO) crystals. In the wavelength conversion unit 20A, the wavelength is changed in the order of fundamental wave (wavelength 1.544 μm) → second harmonic wave (wavelength 772 nm) → third harmonic wave (wavelength 515 nm) → sixth harmonic wave (wavelength 257 nm) → eighth harmonic wave (wavelength 193 nm). A conversion has been made.

As described above, in the configuration in which one of the sixth harmonic and the second harmonic enters the fourth-stage nonlinear optical crystal 517 through the branch optical path, the sixth harmonic and the second harmonic are respectively transmitted to the fourth stage. Lenses 515 and 5 for condensing and entering the nonlinear optical crystal 517
12 can be arranged in different optical paths. In this case, since the sixth harmonic generated in the third-stage nonlinear optical crystal 514 has an elliptical cross-sectional shape due to the Walk-off phenomenon, good conversion efficiency is obtained by the fourth-stage nonlinear optical crystal 517. For this purpose, it is desirable to perform beam shaping of the sixth harmonic. Therefore, as in this example, the lenses 515, 51
2 are arranged in separate optical paths, for example, the lens 5
For example, a cylindrical lens pair 15 can be used, and the beam shaping of the sixth harmonic can be easily performed. Therefore, the fourth-stage nonlinear optical crystal (BBO crystal)
It is possible to increase the overlap with the second harmonic at 517 to increase the conversion efficiency.

The second-stage nonlinear optical crystals 510 and 4
FIG. 3B shows the configuration between the non-linear optical crystal 517 at the stage.
However, the present invention is not limited to this.
Any configuration is possible as long as the optical path lengths of the sixth harmonic and the second harmonic are equal so that the sixth harmonic and the second harmonic enter the 7 at the same time. Further, for example, the third-stage and fourth-stage nonlinear optical crystals 514 and 517 are arranged on the same optical axis as the second-stage nonlinear optical crystal 510, and the third-stage nonlinear optical crystal 514 applies only the third harmonic wave to the second stage. It may be converted into a sixth harmonic by the generation of the second harmonic, and may be incident on the fourth-stage nonlinear optical crystal 517 together with the second harmonic that is not wavelength-converted. This eliminates the need to use the dichroic mirrors 511 and 516.

The average output of the eighth harmonic (wavelength: 193 nm) per channel for each of the wavelength converters 20 and 20A shown in FIGS. 3A and 3B was experimentally obtained. As described in the above embodiment, the output of the fundamental wave is the output terminal of each channel, and has a peak power of 20 kW, a pulse width of 1 ns, a pulse repetition frequency of 100 kHz, and an average output of 2 W. As a result, 8 per channel
The average output of the harmonic is 2 in the wavelength conversion unit 20 in FIG.
29 mW, 38.3 in the wavelength converter 20A of FIG.
mW. Therefore, the average output from the bundle including all 128 channels is 29 W in the wavelength converter 20,
The wavelength converter 20A has a power of 4.9 W, and any of the wavelength converters 20 and 20A can provide ultraviolet light having a wavelength of 193 nm, which has a sufficient output as a light source for an exposure apparatus.

Note that, with the same configuration as the wavelength converters 20 and 20A, the fundamental wave (wavelength 1.544 μm) → the second harmonic wave (wavelength 772 nm) → the fourth harmonic wave (wavelength 386 nm) → the sixth harmonic wave (wavelength 257 nm) → It is also possible to perform wavelength conversion in the order of the eighth harmonic (wavelength 193 nm). Furthermore, fundamental wave (wavelength 1.544 μm) → second harmonic wave (wavelength 772 nm) → third harmonic wave (wavelength 515 nm) → fourth harmonic wave (wavelength 386 nm) → seventh harmonic wave (wavelength 221 nm) → eighth harmonic wave (wavelength 193 nm) Can be converted in the order of the fundamental wave (wavelength 1.5).
44 μm) → 2nd harmonic (wavelength 772 nm) → 3rd harmonic (wavelength 515 nm) → 4th harmonic (wavelength 386 nm) → 6th harmonic (wavelength 257 nm) → 7th harmonic (wavelength 221 nm) → 8th harmonic (wavelength 193 nm) The eighth harmonic can also be obtained by wavelength conversion in the following order. Of these, it is desirable to use one having a high conversion efficiency and a simplified configuration.

Next, a description will be given of a configuration example of a wavelength converter for obtaining ultraviolet light having substantially the same wavelength as that of the F ₂ laser (wavelength 157 nm). In this case, the wavelength of the fundamental wave generated in the single-wavelength oscillation laser 11 of FIG.
At 7 μm, a wavelength converter that generates a 10th harmonic may be used as the wavelength converter 20. FIG. 4 shows a wavelength conversion unit 20B that can obtain a 10th harmonic by combining the second harmonic generation and the sum frequency generation.
The fundamental wave of the 1.57 μm wavelength laser light LB4 emitted from the output end 19a of the optical fiber bundle 19 is L
The light enters the first-stage nonlinear optical crystal 602 made of a BO crystal, and is converted into a second harmonic by generation of a second harmonic. This 2
The harmonic enters the second nonlinear optical crystal 604 made of LBO via the lens 603, is converted into a fourth harmonic by generation of a second harmonic, and a part of the harmonic is transmitted as it is.

The fourth and second harmonics transmitted through the nonlinear optical crystal 604 travel to the dichroic mirror 605,
The fourth harmonic reflected by the dichroic mirror 605 is
The light reflected by the mirror M1 passes through the lens 608 and the third stage S
The light enters a nonlinear optical crystal 609 made of r ₂ Be ₂ B ₂ O ₇ (SBBO) crystal and is converted into an eighth harmonic by generation of a second harmonic. On the other hand, the second harmonic transmitted through the dichroic mirror enters the dichroic mirror 607 via the lens 606 and the mirror M2,
Is also incident on the dichroic mirror 607 via the lens 610, where the second harmonic and the eighth harmonic are synthesized coaxially to form the fourth stage SBBO crystal nonlinear optical crystal 611. Then, a 10th harmonic (wavelength: 157 nm) is obtained by generating a sum frequency from the 8th harmonic and the 2nd harmonic. This tenth harmonic is emitted as ultraviolet laser light LB5. That is, in the wavelength converter 20B, the fundamental wave (wavelength 1.57 μm) → the second harmonic wave (wavelength 785 nm) → the fourth harmonic wave (wavelength 392.5 nm) → the eighth harmonic wave (wavelength 196.25 n)
m) → the tenth harmonic (wavelength: 157 nm) in this order.

In the above embodiment, FIG.
As can be seen, m sets of n optical amplification units 18-1
The wavelengths of the combined lights having outputs of 〜18-n are converted by one wavelength converter 20. However, instead, for example, m ′ (m ′ is an integer of 2 or more) wavelength conversion units are prepared,
Outputs of the m sets of optical amplification units 18-1 to 18-n are n ′
Each group is divided into m ′ groups, wavelength conversion is performed by one wavelength converter for each group, and the obtained m ′ (eg, m ′ = 4 or 5 in this example) ultraviolet light is synthesized. You may make it.

According to the ultraviolet light generator of the above-described embodiment, the diameter of the output end of the optical fiber bundle 19 of FIG. It is possible to perform wavelength conversion of all channels by several wavelength converters 20. Moreover, since the output end uses a flexible optical fiber, it is possible to arrange components such as a wavelength converter, a single-wavelength oscillation laser, and a splitter separately, and the degree of freedom in arrangement is extremely high. . Therefore, according to the ultraviolet light generator of this example,
It is possible to provide an inexpensive and compact ultraviolet laser device having a single wavelength and low spatial coherence.

The wavelength converters 20, 20 as described above
Needless to say, A and 20B are configured such that the beam waist of the laser light is located in each nonlinear optical crystal. The state of the light from the individual fibers of the fiber bundle 19 incident on the wavelength conversion unit 20 is substantially maintained even after passing through the wavelength conversion unit 20, and the cross-sectional shape of the light at the exit end of the fiber bundle 19 is maintained. Is stored also in the laser beam LB5 emitted from the wavelength converter 20. For this reason, when the above-described laser device is used, it is effective to devise a later-described device in the subsequent illumination optical system.

Next, a description will be given of a step-and-scan type exposure apparatus using a laser device for generating ultraviolet light as shown in FIG. FIG. 5 shows an exposure apparatus of the present embodiment. In FIG.
It is possible to use a device in which the wavelength of the laser light output from the ultraviolet light generating device (a) is 193 nm, 157 nm, or another ultraviolet region. The laser beam LB5 emitted from the exposure light source 161 is used as the exposure light IL as the illumination system 162.
Incident on. The exposure light IL that has entered the illumination system 162 has its beam bundle shaped by the beam shaping system 30 and passes through the first optical integrator via the depolarizing prism 31 including the first prism 31a and the second prism 31b. (Diffractive Optical Element) as DOE
32A.

The DOE 32A is composed of a plurality of basic elements 32a for diverging the exposure light IL, and is set on the rotating plate 41. This DOE 32A is a DOE for ordinary circular illumination, and is provided on a far field, that is, a pupil plane as shown in FIG.
Illuminate a circular area as shown in FIG. Rotating plate 41
In addition to the DOE 32A for normal illumination, FIG.
(D) D for annular illumination that generates a light distribution indicated by oblique lines
An OE 32B and a four-pole illumination DOE (not shown) for generating a light distribution indicated by oblique lines in FIG. 8B are installed, and a desired DOE is selected by rotating the rotary plate 41 by the drive system 42. I can do it. Also,
It is desirable that the drive system 42 minutely drives or tilts the DOE through exposure to reduce illumination non-uniformity.

Exposure light I of the basic element 32a of the DOE 32A
The size of the cross section perpendicular to the optical axis of L can be designed to be about 100 μm square. In this example, in order to increase the uniformity of the illuminance distribution, the basic element 32a (ie, the DOE 32A) is configured such that the basic element 32a is smaller than the beam diameter of each beam included in the bundle of the exposure light IL at the position of the DOE 32A. We are designing. The exposure apparatus of this example is a step-and-scan type exposure apparatus. In the scanning direction between the reticle 163 and the wafer 166, which will be described later, an averaging effect is obtained and the illuminance uniformity is improved. For the non-scanning direction perpendicular to the scanning direction,
Since the averaging effect cannot be obtained, in the direction corresponding to the non-scanning direction of the basic element 32a, the basic element 32a is included in the beam diameter of each beam included in the bundle of the exposure light IL in the focused direction. It is desirable to set the size of the basic element 32a so that at least one element is included.

The individual laser beams in the bundle that are emitted from the optical fiber bundle and converted into higher harmonics by the nonlinear crystal may have an oval shape due to the walk-off phenomenon. In this case, the basic element of the DOE may have a rectangular shape so as to fit inside an oval. In the beam shaping system 30, the beam bundle system is
The size of each beam in the bundle is increased to about 1.25 mm by enlarging the element by about twice, and the basic element of the DOE is set to 500 μm.
It is also possible to design as about m square. Above is D
The basic element 32a of the OE 32A has been described, but the basic element of the DOE 32B for annular illumination and the DOE for quadrupole illumination have been described.
It is desirable to design the basic element (not shown) in the same manner as described above.

FIG. 6A shows that the diameter of each optical fiber is D.
FIG. 6 shows one optical fiber bundle 19A.
In (a), laser light is emitted from each optical fiber at a divergence angle φ1. FIG. 6B shows an optical fiber bundle 19B in which the diameter of each optical fiber is D2. In FIG. 6B, the diameter D of each optical fiber is shown.
2 is smaller than the diameter D1 of each optical fiber of the optical fiber bundle 19A, and the divergence angle φ2 of the laser light emitted from each optical fiber is
The divergence angle φ1 of the laser light emitted from each optical fiber of the bundle 19A is larger. in this way,
The divergence angle of the laser light emitted from the optical fiber increases as the optical fiber becomes thinner. In order to reduce the coherence of the exposure light, it is desirable that the optical fiber is thin,
If the optical fiber is made too thin, the divergence angle becomes too large, and it becomes difficult to route the exposure light.

Therefore, in order to reduce the speckle and facilitate the routing of the exposure light, the diameter of the laser beam LB5 in the short axis direction of the bundle cross section is Dx [mm], and the divergence angle in the short axis direction is φx [Mrad], the diameter in the major axis direction is Dy [m
m], the divergence angle in the long axis direction is φy [mrad], and the product of the diameter Dx in the short axis direction and the divergence angle φx is Kx [mrad · m
m] and the product of the major axis diameter Dy and the divergence angle φy is Ky [m
rad · mm], it is desirable to satisfy the following relationship. Here, Dx and D
y is a value related to the corresponding direction of d shown in FIG. Further, φx and φy are respectively φφ and φy shown in FIG.
1 (or φ2) for the corresponding direction. 0.5 <Kx <50 (1) 3 <Ky <300 (2)

In this regard, the product of the diameter in the short axis direction and the divergence angle of the laser beam emitted from the KrF excimer laser light source (the same applies to the ArF excimer laser light source) is about 5 [mrad · mm], and the long axis is Since the product of the diameter in the direction and the divergence angle is about 30 [mrad · mm], the products Kx and K of the laser beams LB5 in the above equations (1) and (2) are obtained.
y is the product of the KrF and ArF excimer lasers, respectively.
It means that it is larger than about / 10 and smaller than about 10 times. By satisfying the conditions of the expressions (1) and (2), even when the laser beam LB5 of the above embodiment is used, the speckle is reduced to the same degree as when the KrF excimer laser or the ArF excimer laser is used. Above,
The exposure light can be easily routed.

Returning to FIG. 5, the exposure light IL that has passed through the DOE 32A is reflected by the vibrating mirror 34 via the relay lens 33. A predetermined vibration is given to the vibration mirror 34 by a driving system 34a, so that the spatial coherence of the exposure light IL can be reduced. The exposure light IL reflected by the vibration mirror 34 is transmitted to the relay lens 35, the second optical
The slit-shaped illumination area on the pattern surface of the reticle 163 as a mask is illuminated with a uniform illuminance distribution via a fly-eye lens 36, a relay lens 37, a mirror 38, and a condenser lens system 39 as an integrator (homogenizer). Although not shown, the illumination system 1
62 also includes a field stop (reticle blind) and the like. As an example, an arrangement in which a field stop (reticle blind) and an imaging type relay lens are arranged between the lens 39 and the reticle 163, and the field stop is imaged on the reticle 163 by the relay lens can be used. .

Reticle 163 is a reticle stage 164
The exposure light IL, which is mounted on the reticle 163 and passes through the reticle 163, passes through a projection optical system 165 onto a wafer (wafer) 166 as a substrate to be exposed and reduces the reduced image of the pattern in the illumination area to a magnification M _RW ( (For example, 1/4, 1/5, 1/6, etc.). As the projection optical system 165, a refraction system, a reflection system,
Alternatively, a catadioptric system can be used. However, when the exposure light IL is vacuum ultraviolet light having a wavelength of about 200 nm or less, the material having a high transmittance is limited.
In addition, a catadioptric system may be used to enhance the imaging performance. A photoresist is applied to the wafer 166, and the wafer 166 is a disk-shaped substrate such as a semiconductor (silicon or the like) or an SOI (silicon on insulator).

The wafer 166 is held on a wafer stage 167, and the three-dimensional position of the wafer 166 is
The wafer stage 167 is driven by the wafer stage 167. At the time of exposure, the wafer stage 16
7, the reticle 163 is scanned in a predetermined direction through the reticle stage 164 with respect to the illumination area, and the wafer 166 is moved.
_Is scanned through a wafer stage 167 using a magnification M _RW as a speed ratio,
An image of the pattern of reticle 163 is transferred to each shot area on wafer 166. As described above, the exposure apparatus of this embodiment is of the scanning exposure type, but it is apparent that the present invention can be applied to a batch exposure type exposure apparatus such as a stepper.

Further, since the exposure light source 161 of this embodiment is small, it may be fixed together to a gantry supporting the illumination system 162. Alternatively, the exposure light source 161 may be independently fixed to the gantry. However, it is preferable that a power supply and the like connected to the exposure light source 161 are separately provided. As described above, the exposure apparatus using the ultraviolet light generator of this example is smaller than other conventional systems (exposure apparatus using an excimer laser or an array laser), and each element is connected by an optical fiber. Because of this, there is an advantage that the degree of freedom of arrangement of each unit constituting the apparatus is high.

The first optical integrator (diffusion element) of the present invention is not limited to the DOE, but uses a lemon skin plate (diffusion plate) 40 as shown in FIG. 7 instead of the DOE 32A. You may. In this case, using the average diameter Dm of the lemon skin plate 40 as a basic unit, the design of the lemon skin plate 40 and the adjustment of the beam diameter of each laser beam emitted from the optical fiber bundle are performed.

Here, the average diameter Dm of the lemon skin plate 40
For example, the local particle size at each point of the cross section (each cross section in two directions perpendicular to the optical axis) of the lemon skin plate 40 shown in FIG. It can be defined as the average value of the diameter data sequence. The local grain diameter can be defined by the distance from valley to valley when the step changes from valley to peak to valley in the cross-sectional direction.

Further, as the first optical integrator (diffusion element) of the present invention, a refraction type such as an element in which a large number of micro prisms are integrated on a single substrate, a micro lens array in which a large number of micro lenses are integrated, or the like. It is also possible to use the integrated optical element of the above. Further, the second optical integrator is not limited to a fly-eye lens, and it is also possible to use the above-described micro lens array, a rod-type integrator, or the like.

Incidentally, in the exposure amount control at the time of the scanning exposure, the pulse repetition frequency f defined by the light modulation element 12 in FIG. 1A and the delay elements (optical fibers 15-1 to 15-m, 17-) are used. 1 to 17-n), a plurality of pulsed lights may be oscillated at equal time intervals from the fundamental wave generator during scanning exposure by adjusting at least one of the delay times between the channels defined by 1-17-n). Further, depending on the sensitivity characteristics of the photoresist, the wafer 166 may be used.
By adjusting at least one of the intensity of the pulse light above, the scanning speed of the wafer 166, the oscillation interval (frequency) of the pulse light, and the width of the pulse light (that is, the irradiation area) in the scanning direction of the wafer 166, The integrated light quantity of the plurality of pulsed lights emitted while each of the points traverses the irradiation area is controlled to an appropriate exposure amount. At this time, in consideration of the throughput, at least the other control parameters, that is, the intensity of the pulse light, the oscillation frequency, and the width of the irradiation area are set so that the scanning speed of the wafer 166 is almost maintained at the maximum speed of the wafer stage 167. It is preferable to adjust one.

It is preferable that the surface of the optical fiber (including the optical fiber amplifier and the like) used in the above-described embodiment is covered with Teflon (registered trademark). This is to prevent the generation of such contaminants since foreign matter (including fibers and the like) generated from the optical fiber can become a substance that contaminates the exposure apparatus. However, instead of coating with Teflon, optical fibers arranged in the chamber may be collectively housed in a stainless steel housing.

It should be noted that the present invention is not limited to the above-described embodiment, but can take various configurations without departing from the gist of the present invention.

[0071]

According to the present invention, since a DOE composed of, for example, a basic element of about 100 μm square is used as a first optical integrator, for example, an optical fiber composed of a plurality of optical fibers having a diameter of about 125 μm is used. Even when the laser light from the bundle is used as the exposure light, the uniformity of the illuminance distribution can be improved.

Further, since the optical fiber amplifier is used, it is possible to provide an illumination optical device having a laser device which is small in size and easy to maintain. This illumination optical device includes an exposure light source of an exposure device, a light source for inspection, and the like. Can be used for Further, the oscillation frequency of the output light can be increased, and the oscillation spectrum line width as a whole can be reduced with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an ultraviolet light generating device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating optical amplification units 18-1 to 18-n in FIG.
FIG. 3 is a diagram showing an example of the configuration.

3A is a diagram illustrating a first configuration example of the wavelength conversion unit 20 in FIG. 1, and FIG. 3B is a diagram illustrating a second configuration example of the wavelength conversion unit 20.

FIG. 4 is a diagram illustrating a third configuration example of the wavelength conversion unit 20;

FIG. 5 is a configuration diagram illustrating an example of an exposure apparatus to which the ultraviolet light generation device according to the above embodiment is applied.

FIG. 6 is a diagram for explaining the relationship between the diameter of an optical fiber and the divergence angle of laser light emitted from the optical fiber.

FIG. 7 is a diagram showing a lemon skin plate 40 as an example of the first optical integrator of the present invention.

FIG. 8 is a diagram illustrating a far-field intensity distribution pattern generated by a modified illumination DOE and a normal illumination DOE.

[Explanation of symbols]

11: single wavelength oscillation laser, IS1 to IS3: isolator, 12: optical modulator, 13: optical fiber amplifier,
14 splitter, 15-1 to 15-m, 17-1 to 1
7-n: Optical fiber (delay element), 16-1 to 16-
m: Splitter, 18-1 to 18-n: Optical amplification unit, 18, 18A to 18D: Optical amplification unit, 19: Optical fiber bundle, 20: Wavelength conversion unit, 20A to 2
0C: wavelength conversion unit, 22, 25: optical fiber amplifier,
24A: narrow band filter, 31: depolarizing prism, 3
2A: DOE, 34: vibrating mirror, 36: fly-eye lens

Claims (5)

[Claims] 1. An illumination optical device comprising: a laser device that generates ultraviolet light of a single wavelength; and an illumination optical system that illuminates a surface to be illuminated with laser light from the laser device. A laser light generator for generating a laser light of a single wavelength within a wavelength range from the outer region to the visible region, an optical fiber bundle which bundles optical fibers for transmitting the laser light generated from the laser light generator, and the optical fiber A wavelength conversion unit that converts the wavelength of the laser light from the bundle into ultraviolet light using a nonlinear optical crystal, wherein the illumination optical system includes a diffusion element formed from a plurality of basic elements that diverge the laser light. A first optical integrator, and a second optical integrator for forming a plurality of light source images from the laser light passing through the first optical integrator. An illumination optical system which comprises a integrators. 2. The illumination optical apparatus according to claim 1, wherein the size of the one elementary element is included in individual beam cross sections included in a beam bundle incident on the elementary element. . 3. The overall cross-sectional shape of a beam bundle emitted from the laser device is oval or rectangular,
The diameter of the cross section of the entire beam bundle in the minor axis direction is Dx [m
m], the divergence angle in the short axis direction of each beam in the beam bundle is φx [mrad], the diameter of the entire beam bundle in the long axis direction is Dy [mm], and the long axis direction of each beam in the beam bundle is Is the divergence angle of φy [mrad], and the product of the diameter Dx in the minor axis direction and the divergence angle φx is Kx [mra].
3. The illumination according to claim 1, wherein the following relationship is satisfied when Ky [mrad · mm] is the product of the diameter Dy in the major axis direction and the divergence angle φy. Optical device. 0.5 <Kx <503 3 <Ky <300 4. An exposure method using ultraviolet light from the illumination optical device according to claim 1, 2, or 3, wherein the ultraviolet light is applied to a mask, and the ultraviolet light having passed through the pattern of the mask is used. An exposure method comprising exposing a substrate. 5. An illumination optical device according to claim 1, further comprising: a projection optical system configured to project an image of a pattern of a mask onto a substrate, wherein the ultraviolet light from the illumination optical device is applied to a mask. An exposure apparatus, comprising: irradiating the substrate with the ultraviolet light having passed through the pattern of the mask.