JP2001085307A - Light source system and aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to generate prescribed light having a simple constitution, while controlling the polarization state. SOLUTION: After a polarizationes-adjusting device 16D aligned the polarization state of several luminous fluxes emitted from several optical fibers, a polarization direction converting device 162 converts all the luminous fluxes through the several optical fibers into several linearly polarized luminous fluxes having the same polarization direction. In this case, the linearly polarized light is set to the polarization direction, in such a way that the wavelength conversion of a first-stage nonlinear optical crystal in the post-stage wavelength converting device 163 can be performed efficiently. By conducting wavelength conversion through inputting of the several straight polarized light flux in the same polarization direction in the wavelength converting device 163, a light of prescribed wavelength is obtained efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device and an exposure device, and more particularly, to a light source device which emits light of a desired wavelength while controlling the polarization of a plurality of light beams, and an exposure device having the light source device. Related to the device.

[0002]

2. Description of the Related Art Conventionally, in a lithography process for manufacturing a semiconductor device (integrated circuit), a liquid crystal display device and the like,
Various exposure apparatuses are used. In recent years, as this type of exposure apparatus, a fine circuit pattern formed on a photomask or a reticle is reduced and projected via a projection optical system onto a substrate such as a wafer or a glass plate having a surface coated with a photoresist. A reduction projection exposure apparatus such as a so-called stepper or a so-called scanning stepper for transferring and transferring data has become mainstream because of its high throughput.

However, an exposure apparatus such as a projection exposure apparatus is required to have high throughput and high resolution. Resolution R of projection exposure apparatus, DOF
Is the wavelength λ of the exposure illumination light, the numerical aperture N. of the projection optical system.
A. R = K · λ / N. A. (1) DOF = λ / 2 (NA) ² (2)

As is apparent from the above equation (1), in order to further reduce the resolution R, that is, the minimum pattern line width that can be resolved, the proportional constant K is reduced. A.
, The wavelength λ of the exposure illumination light is reduced,
The following three methods can be considered. Here, the proportionality constant K is a constant determined by the projection optical system and the process, and is usually 0.1.
It takes a value of about 5 to 0.8. The method of reducing the constant K is called super-resolution in a broad sense. Until now,
Improvements in projection optics, modified illumination, phase shift reticles, etc. have been proposed and studied. However, there are drawbacks such as limitations on applicable patterns.

On the other hand, the numerical aperture N. A. From equation (1), the larger the value, the smaller the resolution R can be made. This means that the depth of focus DOF becomes shallower as is clear from equation (2). For this reason, N.I. A. There is a limit in increasing the value, and usually about 0.5 is appropriate.

Accordingly, the simplest and most effective method for reducing the resolution R is to reduce the wavelength λ of the illumination light for exposure.

[0007] For this reason, as a stepper, a g-line stepper and an i-line stepper using an ultra-high pressure mercury lamp for outputting an ultraviolet bright line (g-line, i-line, etc.) as a light source for exposure have been mainly used. However, in recent years, shorter wavelength K
K that outputs rF excimer laser light (wavelength 248 nm)
KrF excimer laser steppers using an rF excimer laser as a light source are becoming mainstream. At present, an ArF excimer laser (wavelength 193n) is used as a light source of a shorter wavelength.
Exposure apparatuses using m) are being developed. However, the above-mentioned excimer laser is large,
Disadvantages as a light source for an exposure apparatus include the fact that optical components are easily damaged due to the large energy per pulse, and the use of toxic fluorine gas makes laser maintenance complicated and expensive. Exists.

Therefore, utilizing the nonlinear optical effect of the nonlinear optical crystal, long-wavelength light (infrared light, visible light) is converted into shorter-wavelength ultraviolet light, and the ultraviolet light thus obtained is used as exposure light. The methods used are of interest. An exposure light source employing such a method is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-334.
No. 803, one laser element that converts light from a laser light generator provided with a semiconductor laser into a wavelength by a nonlinear optical crystal provided in a wavelength converter and generates ultraviolet light. Multiple matrix (for example, 1
An example of an array laser which is bundled into 0 × 10) and used as one ultraviolet light source is disclosed.

[0009]

In an array laser as described above, by bundling a plurality of independent laser elements, the optical output of the entire apparatus is increased while the optical output of each laser element is kept low. Can be output. However, since the individual laser elements are independent, it is necessary to make fine adjustments and to adopt a very complicated configuration in order to match the oscillation spectra of the laser elements.

In view of this, a method is considered in which a single laser oscillation source is used, the laser light emitted from this laser oscillation source is branched, and each branched light is amplified and then wavelength-converted by a common nonlinear optical crystal. When employing this method, it is convenient to use an optical fiber for routing the laser light, and a configuration in which a plurality of light beams emitted from a plurality of bundled optical fibers are incident on the nonlinear optical crystal, It is optimal from the viewpoint of simplicity of the structure, miniaturization of the output beam diameter, and maintainability.

In order to efficiently generate the second harmonic and the like by the nonlinear optical effect using the nonlinear optical crystal, it is necessary to convert the linearly polarized light in a specific direction corresponding to the crystal direction of the nonlinear optical crystal to the nonlinear optical crystal. It is necessary to make the light incident on the optical crystal. However, it is generally difficult to align the directions of linearly polarized light emitted from a plurality of optical fibers. This is because even if a polarization maintaining fiber is used and linearly polarized light is guided, the optical fiber has a substantially circular cross-sectional shape. Because it is not possible to specify

The present invention has been made under the above circumstances, and a first object of the present invention is to provide a light source device capable of generating predetermined light while controlling the polarization state with a simple configuration. Is to do.

It is a second object of the present invention to provide an exposure apparatus capable of efficiently transferring a predetermined pattern onto a substrate.

[0014]

According to the present invention, there is provided a light source device comprising: a plurality of optical fibers; and a polarization adjusting device (1) for aligning the polarization states of a plurality of light beams having the same wavelength through the plurality of optical fibers.
6D); and a polarization direction conversion device (162) for converting all light beams passing through the plurality of optical fibers into a plurality of linearly polarized light beams having the same polarization direction.

According to this, after the polarization adjusting device aligns the polarization states of the plurality of light beams emitted from the plurality of optical fibers, the polarization direction conversion device converts all the light beams passing through the plurality of optical fibers into the same light beam. Since the light is converted into a plurality of linearly polarized light beams having a polarization direction, a plurality of linearly polarized light beams having the same polarization direction can be obtained with a simple configuration.

In the light source device according to the present invention, when the polarization adjusting device sets each of the plurality of light beams passing through each of the optical fibers to be substantially circularly polarized, the polarization direction conversion device may be configured as a １ ／ wavelength light. It can be configured to have a plate (162). In such a case, since each of the plurality of light beams passing through each optical fiber is substantially circularly polarized by the polarization adjusting device, all of the plurality of light beams are passed through the 波長 wavelength plate included in the polarization direction conversion device. Thereby, it can be converted into a plurality of linearly polarized light beams having the same polarization direction. Therefore, the polarization direction changing device is required to
It is possible to convert a plurality of light beams into a plurality of linearly polarized light beams having the same polarization direction while having a very simple configuration of a wave plate. The polarization direction of the linearly polarized light is 1 /
It is determined by the direction of the optical axis of the crystal material or the like forming the four-wave plate. Therefore, by adjusting the direction of the optical axis of the crystal material or the like forming the quarter-wave plate, it is possible to obtain a plurality of luminous fluxes having arbitrary identical linear polarization directions.

Here, when the optical fiber has a substantially cylindrically symmetric structure, the polarization adjusting device is configured so that the polarization state of each of the plurality of light beams incident on each of the optical fibers is substantially circularly polarized. be able to. This is because, when circularly polarized light is incident on an optical fiber having a cylindrically symmetric structure, circularly polarized light is emitted from the optical fiber. Since it is impossible to make the optical fiber completely cylindrically symmetric, it is preferable that the length of the optical fiber is short.

Further, in the light source device according to the present invention, when the plurality of light beams passing through the respective optical fibers are all in substantially the same polarization state and are in arbitrary polarization states, the polarization adjusting device may be configured such that: The converter rotates the plane of polarization 1
It can be configured to have a half-wave plate and a quarter-wave plate optically connected in series with the half-wave plate.
Here, when connecting the half-wave plate and the quarter-wave plate in series, either of them may be arranged on the upstream side in the optical path. For example, when a half-wave plate is arranged on the upstream side, the polarization planes of a plurality of light beams passing through the respective optical fibers are similarly rotated by passing through a common half-wave plate, and then further rotated. By passing through a common quarter-wave plate, all light beams become linearly polarized light having the same polarization direction. Also,
When the 波長 wavelength plate is arranged on the upstream side, all light beams can be linearly polarized light having the same polarization direction, similarly to the case where the 波長 wavelength plate is arranged on the upstream side. Therefore, the polarization direction changing device is composed of one half-wave plate and one half-wave plate.
A simple configuration of one quarter wavelength plate can be provided. In this case, by adjusting the direction of the optical axis of the crystal material or the like forming the half-wave plate and the quarter-wave plate, it is possible to obtain a plurality of luminous fluxes having any given linear polarization direction.

Further, in the light source device according to the present invention, each of the plurality of optical fibers constitutes an optical fiber amplifier (171) in which each of a plurality of light beams incident on the plurality of optical fibers is light to be amplified. It may be configured to be an optical fiber through which the target light is guided. In such a case, since the light incident on each optical fiber is amplified and emitted from each optical fiber, each of them has high intensity and has the same polarization direction as the light emitted from the polarization direction changing device. A plurality of linearly polarized light beams can be obtained. As a result, it is possible to increase the amount of emitted light as the light source device.

Further, in the light source device of the present invention, each of the plurality of light beams incident on the plurality of optical fibers can be a pulsed light train. In such a case, by adjusting the repetition period and pulse height of the light pulse in each pulse light train, the light amount of the emitted light as the light source device can be accurately controlled.

In the light source device of the present invention, each of the plurality of light beams incident on the plurality of optical fibers is amplified by one or more stages of optical fiber amplifiers (167) before being incident on the plurality of optical fibers. It is possible to adopt a configuration in which the luminous flux is applied. In such a case, by one or more stages of optical amplification by one or more stages of optical fiber amplifiers,
It is possible to increase the amount of emitted light as a light source device.

Further, in the light source device according to the present invention, the polarization adjusting device adjusts a mechanical stress or the like applied to each of the plurality of optical fibers disposed immediately before the polarization direction converting device, to thereby adjust the polarization direction changing device. Although it is also possible to adjust the polarization state of a plurality of light fluxes incident on the, the polarization adjusting device controls the optical characteristics of the optical components disposed upstream from the plurality of optical fibers to adjust the polarization. The configuration can be performed. In such a case, the plurality of optical fibers disposed immediately before the polarization direction conversion device have an optical amplifier,
Controls the optical characteristics of the optical component that is located on the more upstream side and is easier to adjust the polarization, even if the optical fiber through which the amplification target light is guided is not suitable for adjusting the polarization by applying stress. Thereby, the polarization states of a plurality of light beams incident on the polarization direction conversion device can be made uniform.

In the light source device according to the present invention, the plurality of optical fibers may be bundled substantially in parallel with each other. In such a case, the section occupied by the plurality of optical fibers can be reduced, and the light receiving area of the polarization direction conversion device can be reduced, so that the size of the light source device can be reduced.

Further, the light source device of the present invention further comprises a wavelength conversion device (163) for performing wavelength conversion by passing a light beam emitted from the polarization direction conversion device through at least one nonlinear optical crystal. It can be. In such a case, the polarization direction of the light beam emitted from the polarization direction conversion device should be set to the polarization direction of the incident light at which the wavelength conversion (generation of the second harmonic and generation of the sum frequency) is efficiently performed by the nonlinear optical crystal. As a result, the wavelength-converted light can be efficiently generated and emitted.

Here, the light emitted from the plurality of optical fibers has a wavelength in one of an infrared region and a visible region, and the light emitted from the wavelength converter has a wavelength in an ultraviolet region. be able to. In such a case, ultraviolet light suitable for transferring a fine pattern can be efficiently generated.

In this case, the light emitted from the plurality of optical fibers has a wavelength near 1547 nm, and the light emitted from the wavelength converter has a wavelength near 193.4 nm. it can. In such cases,
It is possible to efficiently obtain light having a wavelength obtained when an ArF excimer laser light source is used.

The exposure apparatus according to the present invention is an exposure apparatus for transferring a predetermined pattern onto a substrate by irradiating the substrate (W) with an exposure beam. An exposure apparatus comprising the light source device (16) of the present invention for generating light.

According to this, since a light source device for efficiently generating ultraviolet light suitable for transferring a fine pattern is used as a device for generating an exposure beam, a predetermined pattern can be efficiently transferred to a substrate. Can be.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG.

FIG. 1 shows a schematic configuration of an exposure apparatus 10 according to one embodiment including a light source device according to the present invention. The exposure apparatus 10 is a step-and-scan type scanning exposure apparatus.

The exposure apparatus 10 includes an illumination system including a light source device 16 and an illumination optical system 12, and a reticle R as a mask illuminated by exposure illumination light (hereinafter, referred to as "exposure light") IL from the illumination system. Stage RST for holding wafer W, projection optical system PL for projecting exposure light IL emitted from reticle R onto wafer W as a substrate, and Z tilt stage 5 as a substrate stage for holding wafer W
8 is provided with an XY stage 14 on which is mounted, and a control system for these.

The light source device 16 has a wavelength of 193, for example.
nm is (almost the same wavelength as the F ₂ laser beam) harmonic generator for outputting ultraviolet pulse light of ultraviolet pulse light, or wavelength 157nm of (almost the same wavelength as ArF excimer laser light). The light source device 16 includes an illumination optical system 12, a reticle stage RST, a projection optical system PL, a Z tilt stage 58, an XY stage 14, and an exposure apparatus main body including a main body column (not shown) on which these components are mounted. Environment chamber (hereinafter referred to as "chamber") whose pressure, humidity, etc. are adjusted with high precision
11.

FIG. 2 is a block diagram showing the internal configuration of the light source device 16 together with a main control device 50 that controls the entire device. As shown in FIG. 2, the light source device 16 includes a light source unit 16A, a laser control device 16B, a light amount control device 16C, a polarization adjustment device 16D, and the like.

The light source section 16A includes a pulse light generation section 160 as a light generation section, a light amplification section 161, a quarter wavelength plate 162 as a polarization direction changing device, a wavelength conversion section 163, a beam monitor mechanism 164, and an absorption cell. 165 and the like.

The pulse light generator 160 includes a laser light source 160A, optical couplers BS1, BS2, an optical isolator 160B, and an electro-optical modulator (hereinafter, referred to as an optical modulator).
160E). The elements between the laser light source 160A and the wavelength converter 163 are optically connected by an optical fiber.

As the laser light source 160A, here, a single wavelength oscillation laser, for example, an oscillation wavelength of 1.544
μm, continuous wave output (hereinafter referred to as “CW output”) 20 mW
InGaAsP and DFB semiconductor lasers are used. In the following, the laser light source 160A is appropriately referred to as “DF
B semiconductor laser 160A ".

Here, the DFB semiconductor laser is replaced with a Fabry-Perot resonator having low longitudinal mode selectivity,
A diffraction grating is built in a semiconductor laser, and is configured to oscillate in a single longitudinal mode under any circumstances. A distributed feedback (D)
FB) This is called a laser. Since such a laser basically oscillates in a single longitudinal mode, its oscillation spectrum line width can be suppressed to 0.01 pm or less.

The DFB semiconductor laser is usually provided on a heat sink, and these are housed in a housing. In the present embodiment, a temperature controller (for example, a Peltier element) is provided on a heat sink attached to the DFB semiconductor laser 160A, and the oscillation wavelength is controlled by the laser controller 16B controlling the temperature as described later. Are controllable (adjustable).

That is, the oscillation wavelength of the DFB semiconductor laser has a temperature dependency of about 0.1 nm / ° C. Therefore, for example, when the temperature of the DFB semiconductor laser is changed by 1 ° C.,
Since the wavelength of the fundamental wave (1544 nm) changes by 0.1 nm, the wavelength of the eighth harmonic (193 nm) changes by 0.0 nm.
The wavelength changes by 125 nm, and the wavelength changes by 0.01 nm at the tenth harmonic (157 nm).

In the exposure apparatus, it is sufficient if the wavelength of the exposure illumination light (pulse light) can be changed by about ± 20 pm with respect to the center wavelength. Therefore, the temperature of the DFB semiconductor laser 11 is set to about ± 1.6 °
In the case of the harmonic wave, it may be changed by about ± 2 ° C.

The laser light source 160A is a DFB
Not limited to semiconductor lasers such as semiconductor lasers, for example, ytterbium (Yb) -doped
A fiber laser or the like can also be used.

As the optical couplers BS1 and BS2,
Those having a transmittance of about 97% are used. Therefore, the laser beam from the DFB semiconductor laser 160A is split into two by the optical coupler BS1, about 97% of which travels toward the next-stage optical coupler BS2, and the remaining 3%
The degree is incident on the beam monitor mechanism 164. The laser light incident on the optical coupler BS2 is branched by the optical coupler BS2, and about 97% of the laser light travels toward the next-stage optical isolator 160B, and the remaining about 3% is absorbed by the absorption cell 1B.
65.

The beam monitor mechanism 164, absorption cell 165, etc. will be described later in further detail.

The optical isolator 160B is a device for passing only light in the direction from the optical coupler BS2 to the EOM 160C, and for blocking the light in the opposite direction. The optical isolator 160B prevents a change in the oscillation mode of the DFB semiconductor laser 160A and the generation of noise due to the reflected light (return light).

The EOM 160C is an optical isolator 1
This is for converting laser light (CW light (continuous light)) that has passed through 60B into pulsed light. As the EOM 160C, an electro-optic modulator (for example, a two-electrode type modulator) having an electrode structure in which chirp correction is performed so that the wavelength spread of the semiconductor laser output due to the chirp due to the time change of the refractive index is reduced. I have. The EOM 160C outputs pulse light modulated in synchronization with a voltage pulse applied from the light amount control device 16C. As an example, EOM1
The laser light oscillated by the DFB semiconductor laser 160A at 60C has a pulse width of 1 ns and a repetition frequency of 100 kHz.
Assuming that the pulse light is modulated into a pulse light of z (pulse period of about 10 μs), as a result of this light modulation, the peak output of the pulse light output from the EOM 160C is 20 mW and the average output is 2 μW. Here, it is assumed that there is no loss due to insertion of the EOM160C, but there is an insertion loss.
For example, when the loss is −3 dB, the peak output of the pulse light is 10 mW, and the average output is 1 μW.

When the repetition frequency is set to about 100 kHz or more, a decrease in the amplification factor due to the influence of ASE (Amplified Spontaneous Emission) noise can be prevented in a fiber amplifier described later. Is desirable.

If the extinction ratio is not sufficient even when the pulse light is turned off using only the EOM 160C, it is desirable to use the current control of the DFB semiconductor laser 160A together. That is, in the case of a semiconductor laser or the like, the output light can be pulse-oscillated by performing the current control. Therefore, it is desirable to generate the pulse light by using both the current control of the DFB semiconductor laser 160A and the EOM 160C. As an example, the DFB semiconductor laser 160
By the current control of A, a pulse light having a pulse width of, for example, about 10 to 20 ns is oscillated, and the EOM
At 160C, only a part of the pulse light is cut out from the pulse light, and the pulse light is modulated into a pulse light having a pulse width of 1 ns. This makes it possible to easily generate a pulse light having a narrow pulse width as compared with the case where only the EOM160C is used, and to easily perform the pulse light oscillation interval and the start and stop of the oscillation. It becomes possible to control.

Note that an acousto-optic light modulator (AOM) can be used instead of the EOM 160C.

The optical amplifying section 161 amplifies the pulse light from the EOM 160C, and here includes a plurality of fiber amplifiers. FIG. 3 shows an example of the configuration of the optical amplifier 161 together with the EOM 160C.

As shown in FIG. 3, the optical amplifier 16
Reference numeral 1 denotes a delay unit 167 having a total of 128 channels 0 to 127, and fiber amplifiers 168 ₁ to 168 ₁ connected to respective output stages of a total of 128 channels 0 to 127 of the delay unit 167.
68 ₁₂₈ and these fiber amplifiers 168 _{1 to} 168 _1
28 are provided with final-stage fiber amplifiers 171 _{1 to} 171 ₁₂₈ connected via narrow band filters 169 _{1 to} 169 ₁₂₈ and optical isolators 170 _{1 to} 170 ₁₂₈ , respectively. In this case, as is clear from FIG.
The fiber amplifier 168 _n , the narrow band filter 169 _n , the optical isolator 170 _n , and the fiber amplifier 171 _n (n
= 1, 2,..., 128) respectively.
72 _n (n = 1, 2,..., 128).

The components of the optical amplifying section 161 will be described in more detail. The delay section 167 has a total of 128 channels and provides a predetermined delay time (here, 3 ns) to the output of each channel. belongs to. In the present embodiment, the delay unit 167 includes an erbium (Er) -doped fiber amplifier (EDFA) that amplifies the pulse light output from the EOM 160C by 35 dB (3162 times), and an output of the EDFA to the channel 0. ~ 3
A splitter (a flat waveguide 1 × 4 splitter), which is an optical splitting means for splitting into four outputs in parallel, and four optical fibers having different lengths connected to respective output ends of channels 0 to 3 of the splitter. , Four splitters (flat waveguide 1 × 32 splitters) that divide the outputs of these four optical fibers into channels 0 to 31 respectively, and lengths connected to channels 1 to 31 except for channel 0 of each splitter. And 31 (total 124) optical fibers of different sizes. Hereinafter, the channels 0 to 31 of each of the splitters (flat waveguide 1 × 32 splitter) are collectively called a block.

This will be described in further detail.
The pulse light output from A has a peak output of about 63 W and an average output of about 6.3 mW. This pulsed light is split into channels 0 to 3 by a splitter (flat waveguide 1 × 4 splitter).
And the output light of each channel is given a delay corresponding to the length of the four optical fibers. For example, in the present embodiment, the propagation speed of light in an optical fiber is 2
× 10 ⁸ m / s, and the splitter (plate waveguide 1
.Times.4, splitter) channels 0, 1, 2, and 3 have optical fibers of 0.1 m, 19.3 m, 38.5 m, and 57.7 m length respectively (hereinafter, referred to as "first delay fiber").
Is connected. In this case, the optical delay between adjacent channels at the exit of each first delay fiber is 96 ns.

Also, optical fibers (hereinafter, referred to as “No. 1”) having a length of 0.6 × N meters (N is a channel number) are respectively provided to channels 1 to 31 of the four splitters (flat waveguide 1 × 32 splitter). 2 delay fibers). As a result, a delay of 3 ns is given between adjacent channels in each block, and the output of channel 31 is 3 × 31 = 9 with respect to the output of channel 0 of each block.
A 3 ns delay is provided.

On the other hand, between the first to fourth blocks, a delay of 96 ns is given by the first delay fiber at the time of input of each block as described above. Accordingly, the channel 0 output of the second block has a delay of 96 ns with respect to the channel 0 output of the first block, and the delay with the channel 31 of the first block is 3 ns. This is the same between the second and third blocks and the third and fourth blocks. As a result, a total output of 12
At the output terminals of the eight channels, pulse light having a delay of 3 ns between adjacent channels is obtained.

By the above-described branching and delay, a pulse light having a delay of 3 ns between adjacent channels can be obtained at the output terminals of a total of 128 channels. At this time, the optical pulse observed at each output terminal is EOM160C. 100 kHz (pulse period 10μ)
s). Therefore, looking at the entire laser beam generator, 9.62 after generating 128 pulses at 3 ns intervals.
The repetition that the next pulse train is generated at intervals of μs is performed at 100 kHz. That is, the total output is 12
8 × 100 × 10 ³ = 1.28 × 10 ⁷ pulses / sec.

In this embodiment, an example has been described in which the number of divisions is 128 and a short fiber is used as the delay fiber. 9.62 μs between each pulse train
Although the interval of non-emission occurred, increase the number of divisions or lengthen the delay fiber to an appropriate length,
Alternatively, by using these in combination, it is possible to make the pulse intervals completely equal.

The fiber amplifier 168 _n (n = 1,
2,..., 128) are erbium (Er) -doped with a mode field diameter (hereinafter referred to as “mode diameter”) of the optical fiber of 5 to 6 μm, similar to that used in normal communication. A fiber amplifier (EDFA) is used. The output light from each channel of the delay unit 167 is amplified by the fiber amplifier 168 _n according to a predetermined amplification gain. The pump light source of the fiber amplifier 168 _n will be described later.

The narrow band filter 169 _n (n = 1,
,..., 128) cut the ASE light generated by the fiber amplifier 168 _n and operate the DFB semiconductor laser 16.
By transmitting the output wavelength of 0 A (the wavelength width is about 1 pm or less), the wavelength width of the transmitted light is substantially narrowed. As a result, the ASE light is transmitted to the subsequent fiber amplifier 1.
It is possible to reduce the amplification gain of the laser beam by entering the laser beam 71 _n or prevent the laser beam from being scattered by the propagation of ASE noise. Here, the narrow band filter 1
69 _n preferably has a transmission wavelength width of about 1 pm, but the wavelength width of the ASE light is about several tens nm.
The ASE light can be cut to such an extent that there is no practical problem even if a narrow band filter having a transmission wavelength width of about 100 pm obtained at present is used.

In this embodiment, as will be described later, D
Since the output wavelength of the FB semiconductor laser 160A may be positively changed, the transmission wavelength width (about the same as the variable width) corresponding to the variable width of the output wavelength (for example, about ± 20 pm in the exposure apparatus of the present embodiment). It is preferable to use a narrow band filter having the above. In a laser device applied to an exposure apparatus, the wavelength width is set to about 1 pm or less.

The optical isolator 170 _n (n = 1,
2,..., 128) are the optical isolators 1 described above.
This is for reducing the influence of the return light as in the case of 60B.

The fiber amplifier 171 _n (n = 1,
2,..., 128), the mode diameter of the optical fiber used in normal communication (5 to 6 μm) to avoid an increase in the spectrum width of the amplified light due to the nonlinear effect in the optical fiber. Wider than, for example, 20-30
An EDFA having a large mode diameter of μm is used. The fiber amplifier 171 _n is the same as the fiber amplifier 16 described above.
The optical output from each channel of the delay unit 167 amplified by 8 _n is further amplified. As an example, assuming that the average output of each channel of 50 μW in the delay unit 167 and the average output of 6.3 mW in all the channels are amplified by a total of 46 dB (40600 times) by two-stage fiber amplifiers 168 _n and 171 _n . At the output end of the optical path 172 _n corresponding to each channel (the output end of the optical fiber constituting the fiber amplifier 171 _n ), the peak output is 20 kW, the pulse width is 1 ns, the pulse repetition is 100 kHz, the average output is 2 W, and the average of all channels is the total. An output of 256 W is obtained. The pump light source of the fiber amplifier 171 _n will be described later.

In this embodiment, the output end of the optical path 172 _n corresponding to each channel in the delay section 167, that is, the output end of each optical fiber constituting the fiber amplifier 171 _n is bundled in a bundle. A fiber bundle 173 having a cross-sectional shape as shown in FIG. At this time, the cladding diameter of each optical fiber is 125 μm.
m, the diameter of the bundle at the output end where the 128 bundles are bundled can be about 2 mm or less. In this embodiment, the fiber bundle 173 is an output end of the fiber amplifier 171 _n of the final stage is formed by using as it is, to bind the fiber of the non-doped fiber amplifier 171 _n of the final stage, at its output It is also possible to form bundle-fibers.

The connection between the previous-stage fiber amplifier 168 _n having the standard mode diameter and the last-stage fiber amplifier 171 _n having the wide mode diameter is made by using an optical fiber whose mode diameter increases in a tapered shape. Is being done.

Next, an excitation light source and the like of each fiber amplifier will be described with reference to FIG. FIG. 5 shows the optical amplifier 1
The fiber amplifier constituting 61 and its peripheral portion are schematically shown together with a part of the wavelength converter 163.

In FIG. 5, a semiconductor laser 178 for excitation is fiber-coupled to a first-stage fiber amplifier 168 _n, and the output of the semiconductor laser 178 is supplied to a wavelength division multiplexer (Wavelength Division Multiplexer).
(iplexer: WDM) 179 to enter the doped fiber for the fiber amplifier, thereby exciting the doped fiber.

On the other hand, a fiber amplifier 17 having a large mode diameter
In 1 _n, a semiconductor laser 174 as an excitation light source for exciting a large fiber amplifier for doped fiber mode diameter of the fiber coupled to large mode diameter fiber to match the diameter of a fiber amplifier for doped fiber The output of the semiconductor laser 174 is input to a doped fiber for an optical amplifier by using a WDM 176 to excite the doped fiber.

The laser light amplified by the large mode diameter fiber (fiber amplifier) 171 _n is
, Where the wavelength is converted to ultraviolet laser light. The configuration and the like of the wavelength converter 163 will be described later.

Large mode diameter fiber (fiber amplifier) 1
The laser light (signal) to be amplified propagating through 71 _n is
It is desirable that the fundamental mode is mainly used, and this can be realized by selectively exciting the fundamental mode mainly in a single mode or a multimode fiber having a low mode order.

In this embodiment, four high-power semiconductor lasers coupled to a large-mode diameter fiber are coupled from the front and four from the rear. Here, in order to efficiently couple the semiconductor laser light for excitation to the doped fiber for optical amplification, an optical fiber having a double clad structure having a double clad structure is used as the doped fiber for optical amplification. desirable. At this time, the semiconductor laser light for excitation is introduced into the inner clad of the double clad by the WDM 176.

The semiconductor lasers 178 and 174 are controlled by a light quantity control device 16C.

[0071] Further, in the present embodiment, the fiber amplifier 168 _n, 1 as optical fibers constituting the optical path 172 _n
Since 71 _n is provided, the difference between the gains of the fiber amplifiers causes variations in the optical output of each channel. For this reason, in the present embodiment, the fiber amplifier (1
68 _n , 171 _n ), a part of the output is branched and photoelectrically converted by photoelectric conversion elements 180, 181 provided at the respective branch ends. The output signals of these photoelectric conversion elements 180 and 181 are supplied to the light quantity control device 16C.

In the light amount control device 16C, each of the pumping semiconductor lasers (178, 178) is controlled so that the light output from each fiber amplifier becomes constant (ie, balanced) at each amplification stage.
The drive current of 174) is feedback-controlled.

Further, in this embodiment, as shown in FIG. 5, the light split by the beam splitter in the middle of the wavelength converter 163 is photoelectrically converted by the photoelectric conversion element 182, and the output signal of the photoelectric conversion element 182 is output. Is supplied to the light amount control device 16C. The light amount control device 16C monitors the light intensity in the wavelength conversion unit 163 based on the output signal of the photoelectric conversion element 182, and controls the excitation semiconductor laser so that the light output from the wavelength conversion unit 163 becomes a predetermined light output. At least one of the drive currents 178 and 174 is feedback-controlled.

With such a configuration, the amplification factor of the fiber amplifier of each channel is made constant for each amplification stage, so that there is no uneven load between the fiber amplifiers, and the light is uniformly uniform as a whole. Strength is obtained. Further, by monitoring the light intensity in the wavelength conversion unit 163, a predetermined predetermined light intensity is fed back to each amplification stage, and a desired ultraviolet light output can be stably obtained.

The light amount control device 16C will be described in further detail later.

The optical amplifier 16 constructed as described above
From 1 (the output end of each optical fiber forming the bundle-fiber 173), the pulsed light is all output into the circularly polarized light by the polarization adjusting device 16D described later. These circularly-polarized pulse lights are supplied to a quarter-wave plate 162 (FIG. 2).
), The light is converted into linearly polarized light having the same polarization direction, and is incident on the next-stage wavelength converter 163.

The wavelength conversion section 163 includes a plurality of nonlinear optical crystals, and the amplified pulse light (wavelength 1.54
(4 μm light) is wavelength-converted into its 8th harmonic or 10th harmonic, and the same output wavelength (19) as that of the ArF excimer laser.
3 nm).

FIG. 6 shows an example of the configuration of the wavelength converter 163. Here, a specific example of the wavelength conversion unit 163 will be described with reference to FIG. FIG. 6 shows that a fundamental wave having a wavelength of 1.544 μm emitted from the output end of the fiber bundle 173 is converted to a fundamental wave by using a nonlinear optical crystal.
A configuration example in which the wavelength is converted to a harmonic (harmonic) to generate 193 nm ultraviolet light having the same wavelength as that of the ArF excimer laser will be described.

In the wavelength converter 163 of FIG. 6, the fundamental wave (wavelength 1.544 μm) → the second harmonic wave (wavelength 772 nm) → the third harmonic wave (wavelength 515 nm) → the fourth harmonic wave (wavelength 386 nm) → 7
Wavelength conversion is performed in the order of harmonic (wavelength: 221 nm) → eighth harmonic (wavelength: 193 nm).

More specifically, the wavelength output from the output end of the fiber bundle 173 is 1.544 μm.
The fundamental wave of (frequency ω) is the first-stage nonlinear optical crystal 53
3 is incident. When the fundamental wave passes through the nonlinear optical crystal 533, the second harmonic generation causes the fundamental wave to have a frequency ω of 2
Double, ie, frequency 2ω (wavelength is ２ of 772 nm)
Is generated. In the case of FIG. 6A, the above-described linear polarization by the quarter-wave plate 162 is performed so that the nonlinear optical crystal 533 has a polarization direction in which the second harmonic is generated most efficiently. The setting of the polarization direction of the linearly polarized light is performed by adjusting the direction of the optical axis of the 波長 wavelength plate 162.

A LiB ₃ O ₅ (LBO) crystal is used as the first-stage nonlinear optical crystal
A method by temperature control of LBO crystal for phase matching for wavelength conversion to harmonic, NCPM (Non-Critical Phase Match)
ing) is used. The NCPM does not cause an angle shift (Walk-off) between the fundamental wave and the second harmonic in the nonlinear optical crystal, so that conversion into a second harmonic wave can be performed with high efficiency. This is advantageous because the beam is not deformed by -off.

The fundamental wave transmitted without wavelength conversion by the nonlinear optical crystal 533 and the second harmonic wave generated by the wavelength conversion are given a half-wavelength and a one-wavelength delay by the next-stage wavelength plate 534, respectively. Only the fundamental wave rotates its polarization direction by 90 degrees,
The light is incident on the nonlinear optical crystal 536 of the stage. An LBO crystal is used as the second-stage nonlinear optical crystal 536, and the LBO crystal is the first-stage nonlinear optical crystal (LBO crystal).
Crystal) 533 is used in NCPM at a different temperature.
In this nonlinear optical crystal 536, a third harmonic (wavelength: 515 nm) is generated from the second harmonic generated in the first-stage nonlinear optical crystal 533 and the fundamental wave transmitted through the nonlinear optical crystal 533 without wavelength conversion. Get)

Next, the 3D obtained by the nonlinear optical crystal 536
The harmonic, the fundamental wave and the second harmonic transmitted through the nonlinear optical crystal 536 without wavelength conversion are separated by a dichroic mirror 537, and the third harmonic reflected here is collected by a condenser lens 540 and a dichroic.・ Mirror 543
And enters the fourth-stage nonlinear optical crystal 545. On the other hand, the fundamental wave and the second harmonic transmitted through the dichroic mirror 537 pass through the condenser lens 538 and enter the third-stage nonlinear optical crystal 539.

As the nonlinear optical crystal 539 of the third stage, L
A BO crystal is used, and the fundamental wave is
While passing through the BO crystal, the second harmonic is 2
It is converted into a fourth harmonic (wavelength 386 nm) by generation of the second harmonic. The fourth harmonic obtained by the nonlinear optical crystal 539 and the fundamental wave transmitted therethrough are separated by the dichroic mirror 541, and the fundamental wave transmitted therethrough is collected by the condenser lens 54.
4 and is reflected by a dichroic mirror 546 to enter a fifth-stage nonlinear optical crystal 548. On the other hand, the fourth harmonic reflected by the dichroic mirror 541 reaches the dichroic mirror 543 through the condensing lens 542, where it is coaxially combined with the third harmonic reflected by the dichroic mirror 537 to form a fourth stage. The light enters the nonlinear optical crystal 545 of the eye.

The fourth-stage nonlinear optical crystal 545 includes:
β-BaB ₂ O ₄ (BBO) crystal is used,
Seventh harmonic (wavelength 221 nm) by sum frequency generation from harmonics
Get. The seventh harmonic obtained by the non-linear optical crystal 545 passes through the condenser lens 547 and is coaxially synthesized by the dichroic mirror 546 with the fundamental wave transmitted through the dichroic mirror 541.
8 is incident.

LB as the fifth-stage nonlinear optical crystal 548
An O crystal is used, and an eighth harmonic (wavelength 193 nm) is obtained from the fundamental wave and the seventh harmonic by generating a sum frequency. In the above configuration, instead of the seventh harmonic generation BBO crystal 545 and the eighth harmonic generation LBO crystal 548, CsLiB ₆ O ₁₀ (CL
BO) crystal or Li ₂ B ₄ O ₇ (LB4) crystal can also be used.

In the configuration example of FIG. 6, since the third harmonic and the fourth harmonic enter the fourth-stage nonlinear optical crystal 545 through different optical paths, a lens 540 for condensing the third harmonic.
And the lens 542 that collects the fourth harmonic can be placed in separate optical paths. The fourth harmonic generated by the third-stage nonlinear optical crystal 539 has an oval cross section due to the walk-off phenomenon. Therefore, the fourth-stage nonlinear optical crystal 54
In order to obtain good conversion efficiency in 5, it is desirable to perform beam shaping of its fourth harmonic. In this case, the condenser lens 5
Since the lenses 40 and 542 are arranged on different optical paths, for example, a pair of cylindrical lenses can be used as the lens 542, and the beam shaping of the fourth harmonic can be easily performed. For this reason, it is possible to improve the overlap with the third harmonic in the fourth-stage nonlinear optical crystal (BBO crystal) 545, and to increase the conversion efficiency.

Further, the lens 544 for condensing the fundamental wave incident on the fifth-stage nonlinear optical crystal 548 and the lens 547 for condensing the seventh harmonic can be placed in separate optical paths. The seventh harmonic generated by the fourth-stage nonlinear optical crystal 545 has an elliptical cross-sectional shape due to the walk-off phenomenon. Therefore, in order to obtain good conversion efficiency in the fifth-stage nonlinear optical crystal 548, it is preferable to perform beam shaping of the seventh harmonic thereof. In the present embodiment, the condenser lens 544,
Since the 547s can be arranged in separate optical paths, for example, a pair of cylindrical lenses can be used as the lens 547, and the beam shaping of the seventh harmonic can be easily performed. Therefore, the fifth-stage nonlinear optical crystal (LBO)
It is possible to make the overlap with the fundamental wave at (crystal) 548 good and increase the conversion efficiency.

The second-stage nonlinear optical crystals 536 and 4
The configuration between the nonlinear optical crystal 545 of the stage and the third harmonic wave generated from the nonlinear optical crystal 536 and reflected by the dichroic mirror 537 is not limited to FIG.
The two nonlinear optical crystals are arranged such that the second harmonic generated by the nonlinear optical crystal 536 and transmitted through the dichroic mirror 537 is wavelength-converted by the nonlinear optical crystal 539 and the fourth harmonic is simultaneously incident on the nonlinear optical crystal 545. 536, 5
Any configuration may be used as long as the two optical path lengths between 45 are equal. This is the same between the third-stage nonlinear optical crystal 539 and the fifth-stage nonlinear optical crystal 548.

According to the experiment conducted by the inventor, in the case of FIG. 6, the average output of the eighth harmonic (wavelength: 193 nm) per channel was 45.9 mW. Therefore, the average output from the bundle including all 128 channels is 5.9 W, and the wavelength 193 is sufficient for the light source for the exposure apparatus.
nm ultraviolet light can be provided.

In this case, for the generation of the eighth harmonic (193 nm), an LBO crystal which is readily available as a commercially available high-quality crystal is currently used. This LBO crystal has 19
This is advantageous in terms of durability because the absorption coefficient of 3 nm ultraviolet light is extremely small and light damage to the crystal does not matter.

Further, in the generation portion of the eighth harmonic (for example, the wavelength of 193 nm), the LBO crystal is used after being subjected to angular phase matching.
Due to the large phase matching angle, the effective nonlinear optical constant (d
eff) becomes smaller. Therefore, it is preferable to provide a temperature control mechanism for the LBO crystal and use the LBO crystal at a high temperature. Thereby, the phase matching angle can be reduced, that is, the above constant (deff) can be increased,
Eighth harmonic generation efficiency can be improved.

The wavelength conversion section 16 shown in FIG.
Reference numeral 3 is an example, and it goes without saying that the configuration of the wavelength conversion unit of the present invention is not limited to this. For example, a wavelength of 1.57 μm emitted from the output end of the fiber bundle 173
It is also possible to generate a 157 nm ultraviolet light having the same wavelength as that of the F ₂ laser by generating a 10th harmonic using the nonlinear optical crystal for the fundamental wave.

Returning to FIG. 2, the beam monitor mechanism 164
Here is the Fabry-Perot etalon
etalon: hereinafter, also referred to as an “etalon element” and an energy monitor (not shown) including a photoelectric conversion element such as a photodiode. Light incident on the etalon element constituting the beam monitor mechanism 164 is
The light is transmitted at a transmittance corresponding to the frequency difference between the resonance frequency of the etalon element and the frequency of the incident light, and an output signal of a photodiode or the like that detects the transmitted light intensity at this time is supplied to the laser control device 16B. The laser control device 16B performs predetermined signal processing on this signal to obtain information on the optical characteristics of the incident light with respect to the beam monitor mechanism 164, specifically, the etalon element (specifically, the center wavelength and the wavelength width of the incident light ( The information on the optical characteristics is obtained in real time by the main controller 5.
0 is notified.

The frequency characteristics of the transmitted light intensity generated by the etalon element are affected by the temperature and pressure of the atmosphere, and the resonance frequency (resonance wavelength) is temperature-dependent. Therefore, in order to accurately control the center wavelength and the spectral half width of the laser beam oscillated from the laser light source 160A based on the detection result of the etalon element, it is necessary to examine the temperature dependence of the resonance wavelength. is important. In the present embodiment, the temperature dependence of the resonance wavelength is measured in advance, and the measurement result is stored as a temperature dependence map in a memory 51 (see FIG. 1) as a storage device provided in the main control device 50. . Then, the main controller 50 performs, for example, when the absolute wavelength calibration of the beam monitor mechanism 164 is performed.
In order to make the resonance wavelength (detection reference wavelength) at which the transmittance of the etalon element becomes the maximum exactly coincide with the set wavelength, an instruction is given to the laser control device 16B so that the temperature of the etalon element in the beam monitor mechanism 164 is reduced. They are actively controlled.

The output of the energy monitor constituting the beam monitor mechanism 164 is supplied to the main controller 50. The main controller 50 detects the energy power of the laser beam based on the output of the energy monitor, and The amount of the laser light oscillated by the DFB semiconductor laser 160A via the control device 16B is controlled as necessary,
For example, the semiconductor laser 160A is turned off. However, in the present embodiment, as described later, normal light amount control (exposure amount control) is mainly performed by the light amount control device 16C by the EOM1.
This is performed by controlling the peak power or frequency of the output pulse light of 60C, or by controlling the on / off control of the output light of each fiber amplifier constituting the optical amplifying unit 161. Then, main controller 50 controls laser controller 16B as described above.

The absorption cell 165 performs absolute wavelength calibration of the oscillation wavelength of the DFB semiconductor laser 160A,
That is, it is an absolute wavelength source for absolute wavelength calibration of the beam monitor mechanism 164. In this embodiment,
Since the absorption cell 165 uses a DFB semiconductor laser 160A having an oscillation wavelength of 1.544 μm as a laser light source, an isotope of acetylene having an absorption line densely in a wavelength band near this wavelength is used. .

As will be described later, as the light for monitoring the wavelength of the laser light, the intermediate wave (second harmonic, third harmonic) of the above-described wavelength converter 163 is used together with or instead of the fundamental wave.
In the case of selecting a harmonic wave, a fourth harmonic wave or the like, or light after wavelength conversion, an absorption cell in which absorption lines exist densely in a wavelength band such as an intermediate wave thereof may be used. For example, when the third harmonic is selected as the wavelength monitoring light, the wavelength 503 is selected.
An iodine molecule having an absorption line densely in the vicinity of nm to 530 nm may be used as an absorption cell, an appropriate absorption line of the iodine molecule may be selected, and the wavelength may be used as an absolute wavelength.

Further, the absolute wavelength source is not limited to the absorption cell, and an absolute wavelength light source may be used.

The laser controller 16B detects the center wavelength and the wavelength width (spectral half width) of the laser beam based on the output of the beam monitor mechanism 164 so that the center wavelength becomes a desired value (set wavelength). DFB semiconductor laser 16
The temperature control (and current control) of 0 A is performed by feedback control. In this embodiment, the DFB semiconductor laser 160
The temperature of A can be controlled in 0.001 ° C. units.

The DFB semiconductor laser 1 is controlled by the laser controller 16B in response to an instruction from the main controller 50.
Switching between a pulse output of 60 A and continuous output, control of an output interval and a pulse width at the time of the pulse output, and control of the DF so as to compensate for output fluctuation of the pulsed light.
The oscillation of the B semiconductor laser 160A is controlled.

As described above, the laser control device 16B stabilizes the oscillation wavelength to control it at a constant wavelength, or finely adjusts the output wavelength. Conversely, the laser controller 16B responds to an instruction from the main controller 50 to
The output wavelength may be adjusted by positively changing the oscillation wavelength of the B semiconductor laser 160A.

For example, according to the former, the occurrence of the aberration (imaging characteristics) of the projection optical system PL due to the wavelength fluctuation or its fluctuation is prevented, and the image characteristics (optical characteristics such as image quality) during the pattern transfer are prevented. Will not change.

According to the latter, an altitude difference and a pressure difference between a manufacturing site where the exposure apparatus is assembled and adjusted and a location where the exposure apparatus is installed (delivery destination), and a difference in environment (atmosphere in a clean room), etc. Therefore, fluctuations in the imaging characteristics (such as aberration) of the projection optical system PL that occur in accordance with the above conditions can be offset, and the time required to start up the exposure apparatus at the delivery destination can be reduced. Furthermore, according to the latter, during the operation of the exposure apparatus, it is possible to cancel the variation of the aberration, projection magnification, and focal position of the projection optical system PL caused by the irradiation of the exposure illumination light and the change in the atmospheric pressure. Thus, the pattern image can always be transferred onto the substrate in the best image forming state.

As described above, the light quantity control device 16C controls the fiber amplifiers 168 _n , 17
Each excitation semiconductor laser (178, 17) is based on the output of the photoelectric conversion element 180, 181, which detects the 1 _n light output.
4) feedback control of the drive current to stabilize the amplification factor of the fiber amplifier of each channel for each amplification stage, and a photoelectric conversion element for detecting light split by the beam splitter in the wavelength conversion section 163 182, based on the output signal of the semiconductor laser 182,
A feedback control of at least one of the drive currents to feed back a predetermined light intensity to each amplification stage to stabilize a desired ultraviolet light output.

Further, in this embodiment, the light amount control device 16
C also has the following functions.

That is, in response to an instruction from the main controller 50, the light quantity controller 16C outputs the fiber output of each channel constituting the fiber bundle 173,
That is, a function of controlling the average light output of the entire bundle by individually turning on and off the output of each optical path 172 _n (hereinafter, referred to as a “first function” for convenience) and a main controller 50 EOM160 according to instructions from
By controlling the frequency of the pulsed light output from C, the average optical output (output energy) of each channel of the optical amplifier 161 per unit time, that is, the output light from each optical path 172 _n per unit time. A function for controlling the intensity (hereinafter, referred to as a “second function” for convenience) and an EOM 160 according to an instruction from main controller 50.
By controlling the peak power of the pulse light output from C, the average light output (output energy) of each channel of the optical amplifier 161 per unit time, that is, the output light from each optical path 172 _n per unit time. (Hereinafter, referred to as “third function” for convenience).

According to the first function of the light quantity control device 16C, the average light output (light quantity) of the entire bundle can be controlled at intervals of 1/128 of the maximum output light quantity (about every 1% or less). That is, the dynamic range is 1-1 / 12
It can be set to a wide range of eight. Each optical path 172 _n
Are configured using the same components, the optical output of each optical path 172 _n should be equal by design,
The above-mentioned light quantity control in 1/128 increments has good linearity.

In the present embodiment, the wavelength converter 163 for wavelength-converting the output of the optical amplifier 161, that is, the output of the fiber bundle 173 is provided. _Since the output of _n , that is, the number of fibers for which the output of the fiber amplifier 171 _n is ON, is proportional to the set light quantity, linear control (in steps of approximately 1%) of the maximum output light quantity in units of 1/128 is in principle. It should be possible.

[0110] However, in practice, due to errors of manufacture or variations in the output of each optical path 172 _n, it is likely that variations in the wavelength conversion efficiency is present on the output of each optical path 172 _n Therefore, the dispersion of the output of each optical fiber (optical path 172 _n ) and the dispersion of the output caused by the dispersion of the wavelength conversion efficiency with respect to the output of each optical fiber are measured in advance, and from each optical fiber based on the measurement result, A first output intensity map, which is a map of the intensity of the optical output from the wavelength conversion unit 163 corresponding to the on / off state of the optical output (a conversion table of the output intensity corresponding to the fiber groove to be turned on), is created. The first output intensity map is stored in the memory 51 attached to the main controller 50.

In the light quantity control device, when the light quantity control is performed by the first function, the light quantity control is performed based on the set light quantity given from the main controller 50 and the output intensity map. I have.

Further, the light quantity control device 16C controls the frequency of the pulse light output from the EOM 160C in the second function by changing the frequency of the rectangular wave (voltage pulse) applied to the EOM 160C. EOM16
The frequency of the pulse light output from 0C is EOM160C
In this case, the frequency of the output pulse light is controlled by controlling the applied voltage to match the frequency of the voltage pulse applied to.

In the case of the present embodiment, as described above, EOM1
The frequency of the rectangular wave applied to 60C is 100 kHz. For example, if this frequency is 110 kHz, EO
The number of optical pulses output from the M160C per unit time increases by 10%. As a result, the pulses are sequentially distributed by the delay unit 167 for each pulse to a total of 128 channels from channel 0 to channel 127 as described above. Looking at each channel, the pulse light per unit time is 1
0% increase, the light energy per light pulse is the same,
That is, if the peak power of the pulse light is constant, the output light intensity (light amount) of each optical path 172 _n per unit time also increases by 10%.

In this embodiment, the wavelength converter 163 performs wavelength conversion of output light of each channel of the optical amplifier 161.
However, the amount of output light per unit time of the wavelength conversion unit 163 is proportional to the frequency of the output pulse of each channel if the peak power is constant. As described above, the light amount control by the second function is a control excellent in linearity.

However, in general, since the amplification gain of the fiber amplifier depends on the input light intensity, if the frequency of the output light of the EOM 160C is changed, the fiber amplifier 168 _n ,
Since the input light intensity of the 171 _n changes, and as a result, the peak power of the pulse light output from the fiber amplifiers 168 _n and 171 _n may change, the linearity as described above is not always obtained in practice. Absent. Therefore, in the present embodiment, the input frequency intensity dependency of the fiber amplifier output is measured in advance, and the output intensity of (each channel of) the optical amplifier 161 corresponding to the frequency of the pulse light input to the optical amplifier 161 based on the measured intensity. Of the second output intensity map (the optical amplification unit 161 corresponding to the frequency of the output light of the EOM)
, And a second output intensity map is stored in the memory 51.

The light amount control device 16C uses the second
When the light amount control is performed by the function (1), the light amount control is performed based on the set light amount given from the main controller 50 and the second output intensity map.

The light quantity control device 16C controls the peak power of the pulse light output from the EOM 160C in the third function by controlling the peak intensity of the voltage pulse applied to the EOM 160C. EOM
This is because the peak power of the 160C output light depends on the peak intensity of the voltage pulse applied to the EOM 160C.

However, as described above, since the amplification gain of the fiber amplifier depends on the input light intensity, the EOM 160
When the peak intensity of the pulse light output from C is changed, the input light intensity of the fiber amplifiers 168 _n and 171 _n changes,
As a result, the peak power of the pulse light output from the fiber amplifiers 168 _n and 171 _n may change. By appropriately designing the fiber amplifiers 168 _n and 171 _n , it is possible to suppress this peak power change, but other performances such as the optical output efficiency of the optical fiber amplifier may be reduced.

Therefore, in the present embodiment, the input pulse peak intensity dependency of the fiber amplifier output is measured in advance, and based on the measured value, each of the optical amplifiers 161 (corresponding to the peak intensity of the pulse light input to the optical amplifier 161) is measured. A third output intensity map (a conversion table of the intensity of the output pulse light of the optical amplifying unit 161 corresponding to the peak intensity of the output light of the EOM), which is a map of the output intensity of the channel, is created. The map is stored in the memory 51. This third output intensity map may be an intensity map of the ultraviolet light that is the output of the wavelength converter.

In the light amount control device 16C, the third light
When the light amount control is performed by the function (1), the light amount control is performed based on the set light amount given from the main controller 50 and the third output intensity map.

An EOM for controlling transmittance is provided in the output stage of the DFB semiconductor laser 160A in addition to the EOM 160C, and the transmittance of the EOM is changed by changing the voltage applied to the EOM. It is also possible to change the energy emitted from the optical amplification unit and the wavelength conversion unit per unit time.

As is clear from the above description, the second and third functions of the light amount control device 16C can control the light amount of the output light of the light source device 16 more finely than the first function. is there. On the other hand, the first function can set a wider dynamic range than the second and third functions.

Therefore, in the present embodiment, at the time of exposure to be described later, coarse adjustment of the exposure amount is performed by the first function of the light amount control device 16C, and fine adjustment of the exposure amount is performed by using the second and third functions. It is supposed to do. This will be described later.

The light quantity control device 16C also controls the start and stop of pulse output based on an instruction from the main control device 50.

The polarization adjusting device 16D includes an optical fiber extension.
Width 171_nControl the polarization characteristics of optical components before
As a result, the optical fiber amplifier 171_nEjected from
Light is circularly polarized. The optical fiber amplifier 171_nof
The doped fiber has a substantially cylindrically symmetric structure,
In the case of a relatively short optical fiber amplifier 171 _n
Optical polarization can also be achieved by circularly polarizing the light
Amplifier 171_nCircularly polarized light emitted from
Can be.

Here, as an optical component upstream of the optical fiber amplifier 171 _n , there is a relay optical fiber (not shown) for optically coupling each element of the optical amplifier 161 described above. As a method of controlling the polarization characteristics of such a relay optical fiber, for example, there is a method of applying anisotropic mechanical stress to the relay optical fiber, and this method is also employed in the present embodiment.

In general, a relay optical fiber has a cylindrically symmetric refractive index distribution, but when an anisotropic mechanical stress is applied, an anisotropic stress is generated in the relay optical fiber.
This stress causes an anisotropic refractive index distribution. By controlling the amount of such anisotropic refractive index distribution, the polarization characteristics of the relay optical fiber can be controlled.

The amount of change in the refractive index distribution due to the stress of the relay optical fiber and the polarization characteristics of other optical components generally depend on temperature. For this reason, the polarization adjusting device 16D performs temperature control to keep the ambient temperature of the relay optical fiber or the like constant, and can maintain circular polarization once performed.

Note that, without performing the above-described temperature control, the polarization state of light is monitored at any position downstream of the relay optical fiber, and the polarization characteristics of the relay optical fiber, that is, The refractive index distribution may be controlled.

Returning to FIG. 1, the illumination optical system 12 includes a beam shaping optical system 18, a fly-eye lens system 22 as an optical integrator (homogenizer), an illumination system aperture stop plate 24, a beam splitter 26, and a first relay lens 28A. , A second relay lens 28B, a fixed reticle blind 30A, a movable reticle blind 30B, a mirror M for bending the optical path, a condenser lens 32, and the like.

The beam shaping optical system 18 includes the light source device 1
The cross-sectional shape of the ultraviolet light (hereinafter referred to as “laser beam”) LB generated by the wavelength conversion of the wavelength conversion unit 163 of FIG. 6 is converted to the fly-eye lens system 22 provided behind the optical path of the laser beam LB. The beam is shaped so as to be incident efficiently, and includes, for example, a cylinder lens and a beam expander (both not shown).

The fly-eye lens system 22 is arranged on the optical path of the laser beam LB emitted from the beam shaping optical system 18, and is a surface light source comprising a large number of light source images for illuminating the reticle R with a uniform illuminance distribution. That is, a secondary light source is formed.
The laser beam emitted from the secondary light source is also referred to as “exposure light IL” in this specification.

In the vicinity of the exit surface of the fly-eye lens system 22, an illumination system aperture stop plate 24 made of a disc-like member is arranged. The illumination system aperture stop plate 24 includes, at equal angular intervals, an aperture stop composed of, for example, a normal circular aperture, an aperture stop composed of a small circular aperture, for reducing the σ value, which is a coherence factor, and a ring for annular illumination. A band-shaped aperture stop, a modified aperture stop having a plurality of apertures eccentrically arranged for the modified light source method (only two types of aperture stops are shown in FIG. 1) and the like are arranged. . The illumination system aperture stop plate 24 is configured to be rotated by a driving device 40 such as a motor controlled by a main control device 50, so that one of the aperture stops responds to the exposure light IL according to the reticle pattern. It is selectively set on the optical path.

Exposure light IL emitted from illumination system aperture stop plate 24
A beam splitter 26 having a small reflectance and a large transmittance is disposed on the optical path of the first relay lens 28A, and the first relay lens 28A and the second relay A relay optical system including a lens 28B is provided.

The fixed reticle blind 30A is arranged on a plane slightly defocused from a conjugate plane with respect to the pattern plane of the reticle R, and has a rectangular opening defining an illumination area 42R on the reticle R. Further, a movable reticle blind 30B having an opening whose position and width in the scanning direction are variable near the fixed reticle blind 30A.
Is arranged, and at the start and end of the scanning exposure, the illumination area 42R is further restricted via the movable reticle blind 30B, so that exposure of an unnecessary portion is prevented.

On the optical path of the exposure light IL behind the second relay lens 28B constituting the relay optical system, a bending mirror M for reflecting the exposure light IL passing through the second relay lens 28B toward the reticle R is arranged. And this mirror M
A condenser lens 32 is arranged on the optical path of the rear exposure light IL.

Further, an integrator sensor 46 and a reflected light monitor 4 are provided on one of the optical paths which are vertically bent by the beam splitter 26 in the illumination optical system 12 and on the other optical path.
7 are arranged respectively. The integrator sensor 46 and the reflected light monitor 47 have a high sensitivity in the deep ultraviolet region and the vacuum ultraviolet region, and have a high response frequency for detecting the pulse light emission of the light source device 16.
Type photodiodes are used. Note that a semiconductor light receiving element having a GaN-based crystal can be used as the integrator sensor 46 and the reflected light monitor 47.

In the above configuration, the entrance surface of the fly-eye lens system 22, the arrangement surface of the movable reticle blind 30B, and the pattern surface of the reticle R are optically set to be conjugate with each other. The light source surface and the Fourier transform surface (exit pupil surface) of the projection optical system PL are optically set to be conjugate to each other to form a Koehler illumination system.

The operation of the illumination system 12 configured as described above will be briefly described. The laser beam LB pulse-emitted from the light source device 16 enters the beam shaping optical system 18, where the rear fly-eye is formed. After its cross-sectional shape is shaped so as to efficiently enter the lens system 22, the light enters the fly-eye lens system 22. As a result, a secondary light source is formed on the exit-side focal plane of the fly-eye lens system 22 (pupil plane of the illumination optical system 12). The exposure light IL emitted from the secondary light source passes through one of the aperture stops on the illumination system aperture stop plate 24, and then reaches a beam splitter 26 having a large transmittance and a small reflectance. The exposure light IL transmitted through the beam splitter 26 passes through the first relay lens 28A, passes through the rectangular opening of the fixed reticle blind 30A and the movable reticle blind 30B, passes through the second relay lens 28B, and is mirrored by the mirror M. After the optical path is bent vertically downward, the rectangular illumination area 42R on the reticle R held on the reticle stage RST is illuminated with a uniform illuminance distribution via the condenser lens 32.

On the other hand, the exposure light IL reflected by the beam splitter 26 is received by an integrator sensor 46 via a condenser lens 44, and a photoelectric conversion signal of the integrator sensor 46 is converted into a peak hold circuit (not shown) and an A / D converter.
It is supplied to the main controller 50 as an output DS (digit / pulse) via a converter. The correlation coefficient between the output DS of the integrator sensor 46 and the illuminance (exposure amount) of the exposure light IL on the surface of the wafer W is stored in a memory 51 provided as a storage device provided in the main controller 50. ing.

The illuminated area 42R on the reticle R illuminates the luminous flux reflected by the pattern surface (lower surface in FIG. 1) of the reticle, passes through the condenser lens 32 and the relay optical system in the opposite direction, and The light is reflected by the beam splitter 26 and received by a reflected light monitor 47 via a condenser lens 48. When the Z tilt stage 58 is below the projection optical system PL, the exposure light IL transmitted through the pattern surface of the reticle is applied to the projection optical system PL and the surface of the wafer W (or the surface of a reference mark plate FM described later). The reflected light flux passes through the projection optical system PL, the reticle R, the condenser lens 32, and the relay optical system sequentially in the opposite direction to the front, is reflected by the beam splitter 26, and is reflected by the condensing lens 48. The light is received by the monitor 47. Each optical element disposed between the beam splitter 26 and the wafer W has an anti-reflection film formed on the surface thereof, but the exposure light IL is slightly reflected on the surface, and the reflected light is also reflected light. The light is received by the monitor 47. The photoelectric conversion signal of the reflected light monitor 47 is supplied to the main controller 50 via a peak hold circuit and an A / D converter (not shown). In this embodiment, the reflected light monitor 47 is mainly used for measuring the reflectance of the wafer W and the like. Note that the reflected light monitor 47 may be used for the preliminary measurement of the transmittance of the reticle R.

As the fly-eye lens system 22, for example, JP-A-1-235289 (corresponding US Pat. No. 5,307,207) and JP-A-7-142354 (corresponding US Pat. No. 5,534,970) ) May be used to form a Koehler illumination system.

Further, together with the fly-eye lens system 22,
A diffractive optical element may be used. When such a diffractive optical element is used, the light source device 16 and the illumination optical system 12 may be connected via a diffractive optical element. That is, a diffractive optical element in which a diffractive element is formed corresponding to each fiber of the fiber bundle 173 is provided in the beam shaping optical system 18, and a laser beam output from each fiber is diffracted so as to be incident on the fly-eye lens system 22. You may make it superimpose on a surface. In this example, the output end of the fiber bundle 173 may be arranged on the pupil plane of the illumination optical system. In this case, the intensity distribution on the pupil plane (that is, the secondary light source) is performed by the first function (decimation). Of the reticle pattern may be different from the optimal shape and size for the reticle pattern. Therefore, it is desirable to superimpose the laser beam from each fiber on the pupil plane of the illumination optical system or the entrance plane of the optical integrator using the above-described diffractive optical element or the like.

In any case, in the present embodiment, even if the distribution of the light output portion of the fiber bundle 173 changes due to the first function of the light amount control device 16C described above, the pattern surface of the reticle R can be changed. The uniformity of the illuminance distribution can be sufficiently ensured on both the (object surface) and the surface (image surface) of the wafer W.

A reticle R is mounted on the reticle stage RST, and is held by suction via a vacuum chuck (not shown). The reticle stage RST is finely drivable in a horizontal plane (XY plane), and is scanned by a reticle stage driving unit 49 in a predetermined stroke range in a scanning direction (here, the Y direction which is the horizontal direction of the paper of FIG. 1). It has become so. The position and the rotation amount of the reticle stage RST during the scanning are measured by an external laser interferometer 54R via a movable mirror 52R fixed on the reticle stage RST, and the measured value of the laser interferometer 54R is used as a main controller. 50.

Note that the material used for the reticle R must be properly used depending on the wavelength of the exposure light IL. That is,
When using exposure light having a wavelength of 193 nm, synthetic quartz can be used. However, when using exposure light having a wavelength of 157 nm, it is necessary to use fluorite, synthetic quartz doped with fluorine, quartz, or the like.

The projection optical system PL is, for example, a double-sided telecentric reduction system, and includes a plurality of lens elements 70a, 70b,... Having a common optical axis in the Z-axis direction. As the projection optical system PL, one having a projection magnification β of, for example, １ ／, 、, 、, or the like is used. Therefore, as described above, when the illumination area 42R on the reticle R is illuminated by the exposure light IL, the image formed by reducing the pattern formed on the reticle R by the projection optical system PL at the projection magnification β is applied to the surface. Is projected onto a slit-shaped exposure region 42W on a wafer W on which a resist (photosensitive agent) is applied and transferred.

In the present embodiment, among the above lens elements, a plurality of lens elements can be independently moved. For example, the uppermost lens element 70a closest to the reticle stage RST is held by a ring-shaped support member 72.
Telescopic drive elements, for example, piezo elements 74a, 74
b, 74c (the drive element 74c on the far side of the drawing is not shown) is supported at three points and is connected to the lens barrel 76. The drive elements 74a, 74b, and 74c allow the three peripheral points of the lens element 70a to be independently moved in the optical axis AX direction of the projection optical system PL. That is, the lens element 70a can be translated along the optical axis AX according to the displacement of the driving elements 74a, 74b, 74c, and can be arbitrarily inclined with respect to a plane perpendicular to the optical axis AX. . Then, these drive elements 74a, 74b, 74
The voltage applied to c is controlled by the imaging characteristic correction controller 78 based on a command from the main controller 50, whereby the displacement of the driving elements 74a, 74b, 74c is controlled. In FIG. 1, the optical axis AX of the projection optical system PL refers to the optical axis of the lens element 70b fixed to the lens barrel 76 and other lens elements (not shown).

In the present embodiment, the relationship between the vertical amount of the lens element 70a and the change amount of the magnification (or distortion) is obtained in advance by experiments, and this is stored in the memory inside the main control device 50. The vertical amount of the lens element 70a is calculated from the magnification (or distortion) corrected by the main controller 50 at the time of correction, and an instruction is given to the imaging characteristic correction controller 78 to drive the drive elements 74a, 7a.
By driving the 4b and 74c, magnification (or distortion) correction is performed. The relationship between the vertical amount of the lens element 70a and the amount of change in magnification or the like may use an optically calculated value. In this case, an experiment is performed to determine the relationship between the vertical amount of the lens element 70a and the amount of change in magnification. Process can be omitted.

As described above, the lens element 70a closest to the reticle R is movable, but this element 70a is one of the elements whose influence on magnification and distortion characteristics is large and easy to control as compared with other lens elements. Is selected, and any lens element that satisfies the same condition may be configured to be movable to adjust the lens interval instead of the lens element 70a.

By moving at least one lens element other than the lens element 70a, other optical characteristics such as curvature of field, astigmatism, coma, and spherical aberration can be adjusted. In addition, by providing a sealed chamber between specific lens elements near the center of the projection optical system PL in the optical axis direction, and adjusting the pressure of gas in the sealed chamber by a pressure adjusting mechanism such as a bellows pump, An imaging characteristic correction mechanism for adjusting the magnification of the projection optical system PL may be provided. Alternatively, for example, an aspherical lens may be used as a part of the lens elements constituting the projection optical system PL, and the lens may be rotated. May be.
In this case, so-called rhombic distortion can be corrected. Alternatively, a parallel plane plate may be provided in the projection optical system PL, and the imaging characteristic correcting mechanism may be configured by a mechanism that tilts or rotates the parallel flat plate.

When a laser beam having a wavelength of 193 nm is used as the exposure light IL, synthetic quartz, fluorite, or the like can be used as each lens element (and the parallel plane plate) constituting the projection optical system PL. But the wavelength 15
When using a laser beam of 7 nm, the projection optical system P
Fluorite is used for all materials such as lenses used for L.

The XY stage 14 is two-dimensionally driven by a wafer stage drive unit 56 in the Y direction, which is the scanning direction, and the X direction, which is orthogonal to the scanning direction (the direction perpendicular to the plane of FIG. 1). A wafer W is held on a Z tilt stage 58 mounted on the XY stage 14 via a wafer holder 61 (not shown) by vacuum suction or the like. The Z tilt stage 58 adjusts the position (focus position) of the wafer W in the Z direction by, for example, three actuators (piezo elements or voice coil motors), and also adjusts the position of the wafer W with respect to the XY plane (the image plane of the projection optical system PL). It has the function of adjusting the inclination angle of. Also,
The position of the XY stage 14 is controlled by an external laser interferometer 5 via a movable mirror 52W fixed on a Z tilt stage 58.
4 W, and the measured value of the laser interferometer 54 W is supplied to the main controller 50.

Here, the moving mirrors actually include an X moving mirror having a reflecting surface perpendicular to the X axis and a Y moving mirror having a reflecting surface perpendicular to the Y axis. Interferometers for X-axis position measurement, Y-axis position measurement, and rotation (including yawing amount, pitching amount, and rolling amount) are provided, respectively. , A moving mirror 52W, and a laser interferometer 54W.

Further, on the Z tilt stage 58, a light receiving surface having the same height as the exposure surface of the wafer W is provided near the wafer W, and the amount of the exposure light IL passing through the projection optical system PL is detected. Dose monitor 59 is provided. The irradiation amount monitor 59 has a rectangular housing in plan view extending in the X direction, which is slightly larger than the exposure area 42W. A slit-shaped opening having substantially the same shape as the exposure area 42W is formed in the center of the housing. This opening is actually formed by removing a part of the light shielding film formed on the upper surface of the light receiving glass made of synthetic quartz or the like forming the ceiling surface of the housing. Si underneath the opening via a lens
An optical sensor having a light receiving element such as a system PIN type photodiode is arranged.

The irradiation amount monitor 59 is used for measuring the intensity of the exposure light IL applied to the exposure area 42W. A light amount signal corresponding to the amount of light received by the light receiving element constituting the irradiation amount monitor 59 is supplied to the main controller 50.

The optical sensor does not necessarily need to be provided inside the Z tilt stage 58. An optical sensor is provided outside the Z tilt stage 58, and the illumination light beam relayed by the relay optical system is used to transmit an optical fiber or the like. Needless to say, the light sensor may be guided to the optical sensor via the optical sensor.

On the Z-tilt stage 58, a reference mark plate FM used for performing reticle alignment described later is provided. The surface of the reference mark plate FM has substantially the same height as the surface of the wafer W. Reference marks such as a reticle alignment reference mark and a baseline measurement reference mark are formed on the surface of the reference mark plate FM.

Although not shown in FIG. 1 from the viewpoint of avoiding complicating the drawing, this exposure apparatus 10 actually has a reticle alignment system for performing reticle alignment.

When aligning reticle R, first, reticle stage RST and XY stage 14 are driven by main controller 50 via reticle stage drive unit 49 and wafer stage drive unit 56, and are exposed in rectangular exposure area 42W. A reticle alignment reference mark on the reference mark plate FM is set, and the relative position between the reticle R and the Z tilt stage 58 is set so that the reticle mark image on the reticle R substantially overlaps the reference mark. In this state, both marks are imaged by the main controller 50 using the reticle alignment system.
Then, the imaging signal is processed to calculate the amount of displacement in the X and Y directions of the projected image of the reticle mark with respect to the corresponding reference mark.

A detection signal (image signal) of the projected image of the reference mark obtained as a result of the alignment of the reticle.
It is also possible to obtain a focus offset and a leveling offset (the focal position of the projection optical system PL, the image plane inclination, and the like) based on the contrast information included in.

In this embodiment, at the time of the reticle alignment, the main controller 50 also measures the baseline amount of a wafer-side off-axis alignment sensor (not shown) provided on the side surface of the projection optical system PL. Done. That is, a reference mark for baseline measurement is formed on the reference mark plate FM in a predetermined positional relationship with respect to the reference mark for reticle alignment, and the amount of displacement of the reticle mark is measured via a reticle alignment system. At this time, by measuring the amount of displacement of the baseline measurement reference mark with respect to the detection center of the alignment sensor through the alignment sensor on the wafer side, the baseline amount of the alignment sensor, that is, the reticle projection position and the alignment sensor Are measured.

Further, as shown in FIG. 1, the exposure apparatus 10 of the present embodiment has a light source whose ON / OFF is controlled by the main controller 50, and is directed toward the image forming plane of the projection optical system PL. An irradiation optical system 60a for irradiating an image forming light beam for forming images of a large number of pinholes or slits obliquely with respect to the optical axis AX, and a wafer W of the image forming light beam
An obliquely incident light type multi-point focal position detection system (focus sensor) including a light receiving optical system 60b for receiving a light beam reflected on the surface is provided. The main controller 50 controls the inclination of the reflected light flux of the parallel plate (not shown) in the light receiving optical system 60b with respect to the optical axis, thereby offsetting the focus detection system (60a, 60b) in accordance with the focus fluctuation of the projection optical system PL. To perform the calibration. As a result, the image plane of the projection optical system PL and the surface of the wafer W coincide with each other within the range (width) of the depth of focus in the above-described exposure area 42W. The detailed configuration of the multipoint focus position detection system (focus sensor) similar to that of the present embodiment is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-283403.

At the time of scanning exposure or the like, the main controller 50 controls the Z tilt stage 58 so that the defocus becomes zero based on a defocus signal (defocus signal) from the light receiving optical system 60b, for example, an S-curve signal. By controlling the Z position via a drive system (not shown), auto focus (auto focus) and auto leveling are executed.

The reason why a parallel flat plate is provided in the light receiving optical system 60b to give an offset to the focus detection system (60a, 60b) is, for example, to move the lens element 70a up and down to correct magnification. Also, since the projection optical system PL absorbs the exposure light IL, the imaging characteristics change and the position of the imaging surface fluctuates. In such a case, an offset is given to the focus detection system, and the focus detection system This is because it is necessary to match the in-focus position with the position of the imaging plane of the projection optical system PL. For this reason, in the present embodiment, the relationship between the vertical amount of the lens element 70a and the focus change amount is also obtained by an experiment in advance and stored in the memory inside the main control device 50. The lens element 70
A calculated value may be used for the relationship between the vertical amount of a and the focus change amount. Further, the auto-leveling may not be performed in the scanning direction but may be performed only in the non-scanning direction orthogonal to the scanning direction.

The main controller 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory),
M (random access memory) or the like, and includes a so-called microcomputer (or workstation). In addition to performing the various controls described above, the reticle R is used to perform the exposure operation properly. , Scanning of the wafer W, stepping of the wafer W, exposure timing, and the like. Further, in the present embodiment, the main controller 50 controls the exposure amount at the time of scanning exposure as described later, calculates the amount of change in the imaging characteristics of the projection optical system PL by calculation, and On the basis of the result, an image forming characteristic of the projection optical system PL is adjusted via the image forming characteristic correcting controller 78, and the whole apparatus is controlled overall.

More specifically, main controller 50 synchronizes, for example, at the time of scanning exposure, when reticle R is scanned via reticle stage RST in the + Y direction (or -Y direction) at a speed V _R = V. Then, the wafer W is moved in the −Y direction (or + Y direction) with respect to the exposure area 42W via the XY stage 14.
The laser interferometer 54 is scanned at a speed V _W = β · V (β is a projection magnification from the reticle R to the wafer W).
The positions and speeds of the reticle stage RST and the XY stage 14 are controlled via the reticle stage driving unit 49 and the wafer stage driving unit 56 based on the measured values of R and 54W, respectively. Further, at the time of stepping, main controller 50 controls XY stage 14 via wafer stage driving unit 56 based on the measurement value of laser interferometer 54W.
Control the position of.

Next, an exposure sequence when a reticle pattern is exposed on a predetermined number (N) of wafers W in exposure apparatus 10 of the present embodiment will be described.
The following description focuses on the control operation.

First, main controller 50 loads reticle R to be exposed onto reticle stage RST using a reticle loader (not shown).

Next, as described above, while performing reticle alignment using the reticle alignment system,
Perform baseline measurement.

Next, main controller 50 instructs a wafer transfer system (not shown) to replace wafer W. As a result, the wafer is exchanged (mere wafer loading when there is no wafer on the stage) by the wafer transfer system and a wafer transfer mechanism (not shown) on the XY stage 14, and then so-called search alignment and fine alignment (such as EGA) Is performed in a series of alignment steps.
Since the wafer exchange and wafer alignment are performed in the same manner as in a known exposure apparatus, further detailed description is omitted here.

Next, based on the alignment result and the shot map data, the operation of moving the wafer W to the scanning start position for exposure of each shot area on the wafer W and the above-described scanning exposure operation are repeated. Then, the reticle pattern is transferred to a plurality of shot areas on the wafer W by a step-and-scan method. During this scanning exposure, the main controller 50 issues a command to the light amount controller 16C while monitoring the output of the integrator sensor 46 to give the target integrated exposure amount determined according to the exposure conditions and the resist sensitivity to the wafer W. give. Thus, in the light amount control device 16C, the coarse adjustment of the exposure amount is performed by the first function, and the second function and the third function are adjusted.
Controls the frequency and peak power of the laser beam (ultraviolet pulsed light) from the light source device 16 to perform fine adjustment of the exposure amount.

The main control device 50 controls the illumination system aperture stop plate 24 via the driving device 40 and further synchronizes with the operation information of the stage system to move the movable reticle blind 30B.
Control the opening and closing operations of

When exposure of the first wafer W is completed, main controller 50 instructs a wafer transfer system (not shown) to replace wafer W. As a result, the wafer is exchanged by the wafer transfer system and the wafer transfer mechanism (not shown) on the XY stage 14, and thereafter, search alignment and fine alignment are performed on the replaced wafer in the same manner as described above. In this case, the main controller 50 causes the integrator sensor 46 and the reflected light monitor 47 to change the irradiation variation of the imaging characteristics (including the focus variation) of the projection optical system PL from the start of the exposure on the first wafer W.
Is given to the imaging characteristic correction controller 78 and an offset is given to the light receiving optical system 60b. Further, main controller 50 also obtains the atmospheric pressure fluctuation of the imaging characteristic of projection optical system PL based on the measurement value of atmospheric pressure sensor 77, and issues a command value for correcting this irradiation fluctuation to the imaging characteristic. It is provided to the correction controller 78 and the light receiving optical system 6
0b is given an offset.

Then, as described above, the reticle pattern is transferred to a plurality of shot areas on wafer W by the step-and-scan method.

In this case, the above-described coarse adjustment of the exposure amount (light amount) may be performed by performing test emission before the actual exposure, and surely controlling the exposure amount set value with an accuracy of 1% or less. good.

Although the dynamic range of the coarse adjustment of the exposure amount in the present embodiment can be set within a range of 1 to 1/128, the dynamic range normally required is typically about 1 to 1/7. Therefore, the number of channels (the number of optical fibers) for which the optical output should be turned on may be controlled between 128 and 18. As described above, in the present embodiment, the coarse adjustment of the exposure amount according to the difference in the resist sensitivity or the like for each wafer can be accurately performed by controlling the exposure amount by individually turning on / off the optical output of each channel.

The light amount control by the second and third functions by the above-described light amount control device 16C is characterized by high control speed and high control accuracy. It is possible to surely satisfy the required control requirements.

Accordingly, in order to control the exposure amount, the light amount control device 16C only needs to perform at least one of the light amount control by the second and third functions.

Also, in the exposure apparatus 10 of this embodiment, the exposure amount may be controlled by combining any one of the light amount control by the second and third functions of the light amount control device 16C and the scanning speed. Well, of course.

The exposure condition of the wafer W is changed according to the reticle pattern to be transferred onto the wafer W. For example, the intensity distribution of the illumination light on the pupil plane of the illumination optical system (ie, the shape of the secondary light source) Or the size), or an optical filter that shields a circular area centered on the optical axis on almost the pupil plane of the projection optical system PL is inserted and removed. The illuminance on the wafer W changes due to the change in the exposure condition, but this also occurs due to the change in the reticle pattern. this is,
This is due to the difference in the occupied area of the light shielding portion (or the transmission portion) of the pattern. Therefore, when the illuminance changes due to a change in the exposure condition and / or the reticle pattern, it is desirable to control at least one of the above-described frequency and peak power so that an appropriate exposure amount is given to the wafer (resist). . At this time, in addition to at least one of the frequency and the peak power, the scanning speed of the reticle and the wafer may be adjusted.

[0182] As described above, according to the light source device according to the present embodiment, the polarization adjustment device 16D is aligned in polarization state of a light beam emitted from the optical fiber amplifier 171 _n respectively to circularly polarized light, of the light beam All are converted into linearly polarized light in the same direction by one quarter-wave plate 162 and emitted. Therefore, by appropriately setting the direction of the optical axis of the quarter-wave plate, it is possible to efficiently generate the wavelength-converted light in the subsequent wavelength converter 163. In addition, since the polarization direction conversion device has a very simple configuration of one quarter wavelength plate 162, the size of the light source device 16 as a whole can be reduced.

Further, according to the light source device 16 of the present embodiment, since the plurality of light beams emitted from the optical fiber amplifier 171 _n are linearly polarized in the same direction, the light emitted from the 波長 wavelength plate 162 To obtain a plurality of linearly polarized light beams each having high intensity and having the same polarization direction. As a result, it is possible to increase the amount of emitted light as the light source device 16.

[0184] Further, according to the light source device 16 according to this embodiment, since a plurality of light beams incident to the optical fiber amplifier 171 _n a pulsed light train, the repetition period and the pulse height of the optical pulses in each pulse light train Is adjusted, the light amount of the emitted light as the light source device 16 can be accurately controlled.

[0185] Further, according to the light source device 16 according to the present embodiment, each of the plurality of light beams incident to the optical fiber amplifier 171 _n is, before entering the optical fiber amplifier 171 _n, is amplified by the optical fiber amplifier 167 _n The multi-stage optical fiber amplifiers 167 _n and 171 _n
, The amount of emitted light as the light source device 16 can be increased.

[0186] Further, according to the light source device 16 according to the present embodiment, the relay optical fiber of the optical component that than the optical fiber amplifier 171 _n are disposed on the upstream side by the addition of anisotropic stress polarization characteristics Control and adjust the polarization,
Even when the doped fiber of the optical fiber amplifier 171 _n does not adapt to the polarization adjustment by applying stress or the like, the light enters the quarter-wave plate 162 without adversely affecting the performance and function of the light source device 16. The polarization state of the plurality of light beams can be adjusted to circularly polarized light.

[0187] Further, according to the light source device 16 according to the present embodiment, the doped fiber of an optical fiber amplifier 171 _n is, since the bundled almost in parallel, thereby reducing the space occupied, 1/4-wavelength Since the light receiving area of the plate can be reduced, the size of the light source device 16 can be reduced.

[0188] Further, according to the light source device 16 according to this embodiment, light emitted optical fiber amplifier 171 _n and the infrared region light (around the wavelength = 1547 nm), ultraviolet light emitted from the wavelength conversion unit 163 (Wavelength = around 193.4 nm), it is possible to efficiently generate ultraviolet light suitable for transferring a fine pattern.

The exposure apparatus 10 according to the present embodiment uses the above-described light source device 16 that efficiently generates ultraviolet light suitable for transfer of a fine pattern, so that the pattern is efficiently transferred to the wafer W. be able to.

Note that, in the above embodiment, the polarization adjusting device 1
6D adjusts the output light of the optical fiber amplifier 171 _n to circularly polarized light. However, when the polarization adjustment is limited to the same elliptically polarized light, the polarization plane is rotated instead of the quarter-wave plate 162. By using a combination of a 波長 wavelength plate and a 波長 wavelength plate optically connected in series with the 波長 wavelength plate, a plurality of light beams emitted from the optical fiber amplifier 171 _n can be made the same. Can be converted into linearly polarized light having a polarization direction of Here, in the series connection of the half-wave plate and the quarter-wave plate, either may be arranged on the upstream side.

In the above embodiment, the １ ／ wavelength plate 1
Although the light incident on 62 is the emission light of the optical fiber amplifier 171 _n , a plurality of light beams emitted from a plurality of optical waveguide optical fibers may be incident on the １ ／ wavelength plate 162.

In the above embodiment, the optical amplifying unit 161
Has been described in the case where the light source device has a 128-channel optical path. However, the number of optical paths may be arbitrary, and specifications required for a product to which the light source device according to the present invention is applied, for example, an exposure apparatus (illuminance on a wafer) And the optical performance, that is, the transmittance of the illumination optical system and the projection optical system, the conversion efficiency of the wavelength conversion unit, the output of each optical path, and the like, may be determined. Even in such a case, the control of the light amount and the exposure amount by the frequency control and the peak power control of the pulse light output from the light modulation device described above can be suitably applied.

Further, in the above embodiment, the wavelength of the ultraviolet light is set to be substantially the same as that of the ArF excimer laser. However, the setting wavelength may be arbitrary, and the wavelength of the laser light source 160A is set according to the wavelength to be set. What is necessary is just to determine the oscillation wavelength, the configuration of the wavelength conversion unit 163, the harmonic magnification, and the like. The set wavelength may be determined, for example, according to the design rule (line width, pitch, etc.) of the pattern to be transferred onto the wafer. (Phase shift type or not) may be considered.

In the above embodiment, the laser light source 16
In order to control the oscillation wavelength of 0A, the laser light is monitored by the beam monitor mechanism 164 immediately after the laser light source 160A. However, the present invention is not limited to this. For example, as shown by a dotted line in FIG. The light beam may be branched in the section 163 (or behind the wavelength conversion section 163) and monitored by a beam monitor mechanism 183 similar to the beam monitor mechanism 164. Then, based on the monitoring result by the beam monitoring mechanism 183, it is detected whether or not the wavelength conversion is performed accurately, and based on the detection result, the main controller 50 performs feedback control of the laser controller 16B. May be. Of course, the laser light source 160A is used by using the monitoring results of both beam monitoring mechanisms.
May be controlled.

In the above embodiment, the fly-eye lens system 22 is used as an optical integrator (homogenizer). However, a rod integrator may be used instead. In an illumination optical system using a rod integrator, the rod integrator is arranged so that its exit surface is substantially conjugate with the pattern surface of the reticle R. The blind 30A and the movable reticle blind 30B may be arranged.

Although not particularly described in the above embodiment, in the case of an apparatus for performing exposure with an exposure wavelength of 193 nm or less as in this embodiment, a light beam passing portion passes through a chemical filter. It is necessary to take measures such as filling or flowing clean air, dry air, N ₂ gas, or an inert gas such as helium, argon, or krypton, or evacuating the light passing portion.

The exposure apparatus of the above embodiment assembles various subsystems including the respective constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by. Before and after this assembly, adjustments to achieve optical accuracy for various optical systems, adjustments to achieve mechanical accuracy for various mechanical systems, and various electric systems to ensure these various accuracy Are adjusted to achieve electrical accuracy. The process of assembling the exposure apparatus from various subsystems includes mechanical connections, wiring connections of electric circuits, and piping connections of pneumatic circuits among the various subsystems. It goes without saying that there is an assembling process for each subsystem before the assembling process from these various subsystems to the exposure apparatus. When the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed, and various precisions of the entire exposure apparatus are secured. It is desirable that the manufacture of the exposure apparatus be performed in a clean room in which the temperature, cleanliness, and the like are controlled.

Further, in the above embodiment, the case where the light source device according to the present invention is applied to the step-and-scan type scanning exposure apparatus has been described. The light source device according to the present invention can also be applied to a laser repair device used for cutting a part (such as a fuse) of the formed circuit pattern. Further, the light source device according to the present invention can be applied to an inspection device using visible light or infrared light. In this case, it is not necessary to incorporate the above-mentioned wavelength converter into the light source device. That is, the present invention is effective not only for an ultraviolet laser device but also for a laser device that generates a fundamental wave in the visible or infrared region and has no wavelength conversion unit. Further, the present invention is not limited to the step-and-scan type scanning exposure apparatus, but can be suitably applied to a static exposure type, for example, an exposure apparatus (stepper or the like) of a step-and-repeat type. Further, the present invention can be applied to a step-and-stitch type exposure apparatus, a mirror projection aligner, and the like.

Note that the projection optical system and the illumination optical system shown in the above embodiments are merely examples, and it goes without saying that the present invention is not limited to these. For example, the projection optical system is not limited to the refractive optical system, but may be a reflective system including only a reflective optical element, or a catadioptric system having a reflective optical element and a refractive optical element (a catadioptric system). Vacuum ultraviolet light (VUV light) with a wavelength of about 200 nm or less
In an exposure apparatus using, a catadioptric system may be used as the projection optical system. As the catadioptric projection optical system, for example, a catadioptric system having a beam splitter and a concave mirror as a reflective optical element, or a catadioptric system disclosed in Japanese Patent Application Laid-Open Nos. A catadioptric system having a concave mirror or the like can be used as a reflective optical element without using a beam splitter as disclosed in Japanese Unexamined Patent Publication No. Hei 8-334695 and Japanese Unexamined Patent Publication No. Hei 10-3039.

In addition, US Pat. No. 5,488,229
And a plurality of refractive optical elements and two mirrors (a primary mirror which is a concave mirror and a reflective surface formed on the side opposite to the incident surface of the refractive element or the parallel flat plate) disclosed in Japanese Patent Application Laid-Open No. 10-104513. And a reflection mirror that re-images an intermediate image of the reticle pattern formed by the plurality of refractive optical elements on the wafer by the primary mirror and the secondary mirror. A refraction system may be used. In this catadioptric system, a primary mirror and a secondary mirror are arranged following a plurality of refractive optical elements, and illumination light is reflected through a part of the primary mirror in the order of a secondary mirror and a primary mirror. Part to reach the wafer.

Of course, not only an exposure apparatus used for manufacturing a semiconductor element, but also an exposure apparatus used for manufacturing a display including a liquid crystal display element for transferring a device pattern onto a glass plate, and manufacturing a thin film magnetic head The present invention can also be applied to an exposure apparatus used to transfer a device pattern onto a ceramic wafer, an exposure apparatus used to manufacture an imaging device (such as a CCD), and the like.

[0202]

As described in detail above, according to the light source device of the present invention, after the polarization adjusting device aligns the polarization states of the plurality of light beams emitted from the plurality of optical fibers, the polarization direction conversion device is changed. Since all light beams passing through a plurality of optical fibers are converted into a plurality of linearly polarized light beams having the same polarization direction, a plurality of light beams having the same polarization direction can be obtained with a simple configuration.

Further, according to the exposure apparatus of the present invention, since the light source apparatus of the present invention that efficiently generates ultraviolet light suitable for transferring a fine pattern is used as a device for generating an exposure beam, the exposure apparatus can be efficiently used. A predetermined pattern can be transferred to a substrate.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing an internal configuration of the light source device of FIG. 1 together with a main controller.

FIG. 3 is a diagram schematically illustrating a configuration of an optical amplifier of FIG. 2;

FIG. 4 is a diagram illustrating a cross-section of a bundle-fiber formed by bundling output ends of a final-stage fiber amplifier constituting an optical amplification unit.

FIG. 5 is a diagram schematically showing a fiber amplifier constituting the optical amplifying unit of FIG. 2 and a peripheral part thereof together with a part of a wavelength conversion unit.

FIG. 6 is a diagram illustrating a configuration of a wavelength conversion unit in FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Exposure apparatus, 16 ... Light source apparatus, 16D ... Polarization adjustment apparatus, 162 ... 1/4 wavelength plate (polarization direction conversion apparatus), 16
3. Wavelength conversion unit (wavelength conversion device), W: Wafer (substrate).

Continued on the front page F term (reference) 5F046 AA22 BA05 CA03 CA08 CB01 CB04 CB05 CB11 CB12 CB13 CB22 CB23 CB25 CC01 CC02 CC05 DA01 DA02 DA05 DA13 DA14 DA26 DA27 DB01 DB05 DC01 DC02 DC12 EB02 EB03 ED03

Claims (13)

[Claims] 1. A plurality of optical fibers; a polarization adjusting device for aligning the polarization states of a plurality of light beams of the same wavelength passing through the plurality of optical fibers; and the same polarization of all the light beams passing through the plurality of optical fibers. And a polarization direction conversion device for converting the light into a plurality of linearly polarized light beams having directions. 2. The polarization adjusting device according to claim 1, wherein the polarization state of each of the plurality of light beams passing through each of the optical fibers is substantially circularly polarized, and the polarization direction conversion device has a quarter-wave plate. Item 2. The light source device according to item 1. 3. The optical fiber according to claim 2, wherein the optical fiber has a substantially cylindrically symmetrical structure, and the polarization adjusting device sets the polarization state of each of the plurality of light beams incident on each of the optical fibers to substantially circular polarization. Item 3. The light source device according to item 2. 4. The polarization adjusting device sets the polarization state of each of the plurality of light beams passing through the optical fibers to substantially the same elliptically polarized light, and the polarization direction conversion device includes a half-wave plate that rotates a plane of polarization. , Which are optically connected in series with the half-wave plate
The light source device according to claim 1, further comprising a four-wavelength plate. 5. Each of the plurality of optical fibers is an optical fiber through which the amplification target light is guided, which constitutes an optical fiber amplifier that uses a plurality of light beams incident on the plurality of optical fibers as amplification target light. The light source device according to claim 1, wherein the light source device is provided. 6. The light source device according to claim 1, wherein each of the plurality of light beams incident on the plurality of optical fibers is a pulse light train. 7. Each of the plurality of light beams incident on the plurality of optical fibers is a light beam amplified by one or more optical fiber amplifiers before being incident on the plurality of optical fibers. The light source device according to claim 1. 8. The polarization adjusting device according to claim 1, wherein the polarization adjusting device controls the optical characteristics of an optical component disposed upstream of the plurality of optical fibers to adjust the polarization. The light source device according to claim 1. 9. The light source device according to claim 1, wherein the plurality of optical fibers are bundled substantially in parallel. 10. The apparatus according to claim 1, further comprising a wavelength conversion device for performing wavelength conversion by passing a light beam emitted from said polarization direction conversion device through at least one nonlinear optical crystal. The light source device according to claim 1. 11. The light emitted from the plurality of optical fibers has a wavelength in one of an infrared region and a visible region, and the light emitted from the wavelength conversion device has a wavelength in an ultraviolet region. The light source device according to claim 10. 12. The light emitted from the plurality of optical fibers has a wavelength around 1547 nm, and the light emitted from the wavelength conversion device has a wavelength around 193.4 nm. The light source device according to item 1. 13. An exposure apparatus for transferring a predetermined pattern onto a substrate by irradiating the substrate with an exposure beam, wherein the exposure beam generator is used as the exposure beam generator.
An exposure apparatus comprising: the light source device according to claim 1.