JP2003163393A - Light source unit and irradiation unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source unit which can efficiently obtain light of high luminance in a simple configuration. <P>SOLUTION: An optical amplifier medium 171 is arranged on the optical path of light of stimulation light wavelength of an optical resonator 135 relating to the light of the stimulation light wavelength different from the wavelength of amplified light that a laser oscillator 130 has. Consequently, the optical amplifier medium 171 is supplied with very intense stimulation light. Light having the wavelength of the amplified light can, therefore, be amplified with a high gain and amplified light with high luminance can be emitted. <P>COPYRIGHT: (C)2003,JPO

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 a light irradiation device, and more particularly to a light source device including an optical amplifier that amplifies light, and a light irradiation device including the light source device.

[0002]

2. Description of the Related Art Conventionally, a light irradiation device has been used for inspecting a fine structure of an object, fine processing of the object, and treatment for correction of visual acuity. For example, in a lithography process for manufacturing a semiconductor device or the like, a mask or a reticle (hereinafter,
A pattern formed on a “reticle” is transferred onto a substrate such as a wafer or a glass plate (hereinafter, appropriately referred to as “substrate” or “wafer”) coated with a resist or the like via a projection optical system. Therefore, an exposure device, which is a kind of light irradiation device, is used. As such an exposure apparatus, a static exposure type projection exposure apparatus adopting a step-and-repeat method and a scanning exposure type projection exposure apparatus adopting a step-and-scan method are mainly used. In addition, a corneal surface ablation (PRK: Photorefractive Keratectom) is used to correct vision.
y) or ablation inside the cornea (LASIK: L
Laser treatment equipment, which is a type of light irradiation equipment, is used to treat myopia and astigmatism by performing aser Intrastromal Keratomileusis).

For such a light irradiation device, many developments have been made on a light source that emits light of a short wavelength. The direction of development of such a short wavelength light source is mainly classified into the following two types. One is the development of an excimer laser light source in which the oscillation wavelength itself of the laser is a short wavelength, and the other is the development of a short wavelength light source using the generation of harmonics of an infrared or visible light laser.

Of these, along the former direction, KrF
A light source device using an excimer laser (wavelength 248 nm) was developed, and now ArF is used as a light source with a shorter wavelength.
Development of a light source device using an excimer laser (wavelength 193 nm) or the like is in progress. However, these excimer lasers have disadvantages as a light source device, such as large size and complicated maintenance of the laser due to the use of poisonous fluorine gas and high cost.

Therefore, the nonlinear optical effect of a nonlinear optical crystal, which is a method of shortening the wavelength along the latter direction, is utilized.
A method of converting long-wavelength light (infrared light, visible light) into shorter-wavelength ultraviolet light has attracted attention. As a light source device using such a method, for example, International Publication WO99 /
There is one disclosed in 46835 (hereinafter, simply referred to as "conventional example").

[0006]

In the method of shortening the wavelength using the nonlinear optical crystal as described above, the generation efficiency of the short wavelength light is determined by the generation efficiency of the nonlinear optical effect in the nonlinear optical crystal. The generation efficiency of the effect becomes higher as the luminance (including the meaning of “peak power”) of the incident target light for wavelength conversion is higher. Therefore, in order to efficiently obtain ultraviolet light, it is necessary to make high-intensity infrared light or visible light incident on the nonlinear optical crystal. Therefore, in the above-mentioned conventional example, the infrared light or the visible light having a single wavelength generated by the semiconductor laser or the like is emitted from the erbium (E
r) and other rare earth elements are added to an optical fiber amplifier having an optical fiber for amplification, and the amplified optical fiber is made incident on a nonlinear optical crystal. In such an optical fiber amplifier, pumping light is supplied to the amplification optical fiber,
By exciting the added rare earth element, an inversion distribution is formed with respect to the energy level of the outer shell electrons of the rare earth element, thereby imparting an optical amplification function to the amplification optical fiber.

However, when light of high peak power is generated by using an amplification optical fiber doped with a rare earth element,
Stimulated Raman scattering (St
imulated Raman Scattering (SRS) and four-wave mixing (F
Noise light is generated by a nonlinear optical effect such as our-Wave Mixing (FWM). The occurrence of such a nonlinear optical effect becomes more remarkable as the amplification optical fiber becomes longer. Therefore, in order to obtain the signal light with a desired peak power, the length of the amplification optical fiber cannot be increased beyond a certain length.

On the other hand, in the optical amplification by the amplification optical fiber, the saturation of the gain G per unit length as given by the equation (1) occurs in the high repetition (high average power) operation of the signal light pulse.

G = G ₀ / (1+ (I _S / I _P )) (1) where G ₀ : small signal gain I _S : signal light output power I _P : pumping light power

Therefore, in order to suppress the occurrence of the above-mentioned nonlinear optical effect, the length is limited (shortened).
When using an amplification optical fiber, it is necessary to increase the pumping light power I _p in order to obtain a desired high peak power.

That is, when the pumping light intensity that can be input to the amplification optical fiber and the desired peak power are determined, the obtained signal light output power has an upper limit. For example, when the erbium-doped optical fiber was used as the amplification optical fiber, the signal light output power was about 1/10 of the pumping light power.

Therefore, in order to obtain a signal light of high peak power while avoiding the problem of the decrease in amplification gain due to the saturation as described above while using the shortened amplification optical fiber, a high intensity pump light is used. It has been exclusively performed to keep the amplification optical fiber at a high gain by preparing a laser light source for generating the laser light and supplying a strong pumping light to the amplification optical fiber through a single mode fiber. However, there is a limit to obtaining the output of the single-mode pumping light source with a simple configuration.

The present invention has been made under the circumstances described above, and a first object thereof is to provide a light source device capable of generating high-luminance light with a simple structure.

A second object of the present invention is to provide a light irradiating device capable of irradiating an object with high brightness light.

[0015]

A light source device of the present invention comprises a laser light generator (160) for generating light of a first wavelength,
A light source device comprising: an optical amplification unit (161) for amplifying light generated by the laser light generation unit, wherein the optical amplification unit is an optical resonator (135) for a second wavelength different from the first wavelength. A laser oscillator (130) having: a laser oscillator (130) disposed on the optical path of the light of the second wavelength in the optical resonator, the light of the second wavelength being incident as excitation light, and the incident first light. A light source device comprising: an optical amplification medium (171) for amplifying light of a wavelength.

According to this, on the optical path of the light of the second wavelength in the optical resonator related to the second wavelength of the laser oscillator, the intensity of the light of the second wavelength becomes extremely high. Is used as the excitation light, and an optical amplification medium that amplifies the light of the first wavelength is arranged. As a result, very strong pumping light is supplied to the optical amplification medium. Therefore, with a simple configuration, the first
The high-gain amplification of light of wavelength
Can generate light of different wavelengths

In the light source device of the present invention, the optical amplification medium may be an amplification optical fiber in which an element excited by light to the second wavelength is added to the core portion.

Here, the first wavelength may be a wavelength in the 1.55 μm band, and the element added to the amplification optical fiber may be erbium (Er).

Further, in the light source device of the present invention, the laser medium in the laser oscillator is an optical fiber type laser medium (131) in which an element excited by the light of the fourth wavelength is added to the core portion, The reflection element for the light of the second wavelength in the optical resonator may be a fiber type Bragg diffraction grating (133 _6A , 133 _6B ).

Here, the laser oscillator may be a Raman laser oscillator.

Further, the light source device of the present invention further comprises a wavelength converter (163) for converting the light of the first wavelength amplified by the optical amplifier into the light of the third wavelength. be able to.

Here, the first wavelength is a wavelength at which the light of the third wavelength is different from the absorption peak wavelength of the medium component of the optical path of the third wavelength, and according to the International Telecommunication Union. It can be one wavelength among a plurality of wavelengths that are standardly defined.

The light irradiating device of the present invention is a light irradiating device for irradiating an object with light, and includes the first or second light source device (16) of the present invention; and the light emitted from the light source device. A light irradiation device comprising: an irradiation optical system (12) for emitting the light toward the object.

According to this, since the light emitted from the first or second light source device of the present invention is applied to the object through the irradiation optical system, the efficiently generated light is applied to the object. be able to.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a schematic structure of an exposure apparatus 10 which is a light irradiation apparatus according to an embodiment, which is configured to include a light source device according to the present invention. This exposure apparatus 10 is
This 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 exposure illumination light (hereinafter referred to as "illumination light" or "exposure light") IL from the illumination system.
XY having a reticle stage RST holding a reticle R illuminated by a projection optical system PL for projecting the exposure light IL via the reticle R onto a wafer W as a substrate, and a Z tilt stage 58 holding the wafer W. The stage 14 and a control system for these are provided.

The light source device 16 has, for example, a wavelength of 19
It is a harmonic generation device that outputs an ultraviolet pulse light of 3.36 nm (substantially the same wavelength as the ArF excimer laser light).
The light source device 16 includes the illumination optical system 12, the reticle stage RST, the projection optical system PL, and the Z tilt stage 5.
8, an XY stage 14 and an exposure apparatus main body including a main body column and the like (not shown) on which each of these parts is mounted, together with an environmental chamber (hereinafter referred to as “chamber”) in which temperature, pressure, humidity, etc. are adjusted with high precision. ) 11 is stored. In the present embodiment, the light source device 1
Although all 6 are arranged in the chamber 11, only a part of the light source device 16, for example, a wavelength conversion unit 163 described later is provided in the chamber 11, especially on the same pedestal as the illumination optical system 12, and the wavelength conversion unit 163 is provided. 163 and the main body of the light source device 16 may be connected by an optical fiber or the like.

FIG. 2 is a block diagram showing the internal structure of the light source device 16 together with a main controller 50 for controlling 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, and the like.

The light source section 16A is a pulsed light generation section 16
0, an optical amplifier 161, a wavelength converter 163, and a beam monitor mechanism 164.

The pulsed light generator 160 includes a laser light source 160A, an optical coupler BS, an optical isolator 160B, and an electro-optic modulator (hereinafter referred to as "EOM") 160C.
And so on.

As the laser light source 160A, in the present embodiment, a single wavelength oscillation laser, for example, International Telecommunication Union (IT) is used.
U) is a wavelength of 1546.92 nm (hereinafter, referred to as “ITU-Grid standard wavelength”), which is one of the wavelengths (hereinafter referred to as “ITU-Grid standard wavelength”) that are standardized at intervals of approximately 0.8 nm for a wavelength in the range of 1530 nm to 1600 nm. A continuous wave output (hereinafter referred to as “CW output”) DFB semiconductor laser is used with an oscillation wavelength of “wavelength λ _S ”). In the following description, the laser light source 160A will also be appropriately referred to as "DFB semiconductor laser 160A".

Oscillation wavelength 1 of DFB semiconductor laser 160A
546.92 nm is the 8th harmonic (wavelength: 193.
(36 nm) is close to the oscillation wavelength of the ArF excimer laser and is a wavelength that can avoid the peak of the absorption spectrum of oxygen molecules as shown by the solid line in FIG. 3 as much as possible. Has been done. Note that in FIG. 3, the ITU-Grid standard wavelength is indicated by {circle around (1)}, and the wavelength of 1546.92 nm adopted in the present embodiment is indicated by {circle around ()}.

The DFB semiconductor laser 160A is usually provided on a heat sink, and these are housed in a housing. In this embodiment, the DFB semiconductor laser 1
A temperature adjuster (for example, a Peltier element) is provided on a heat sink attached to 60A, and the oscillation wavelength can be controlled (adjusted) by controlling the temperature by the laser control device 16B.

The optical coupler BS has a transmittance of 9
About 7% is used. Therefore, the laser light from the DFB semiconductor laser 160A is transmitted by the optical coupler BS.
The light is branched into two, about 97% of which is directed toward the optical isolator 160B in the next stage, and the remaining about 3% is incident on the beam monitor mechanism 164.

The beam monitor mechanism 164 includes an energy monitor (not shown) composed of a photoelectric conversion element such as a photodiode. The output of this energy monitor is
It is supplied to the main controller 50 via the laser controller 16B. The main controller 50 detects the energy power of the laser light based on the output of the energy monitor, and the DFB semiconductor laser 160A detects the energy power of the laser light via the laser controller 16B. The light amount of the oscillated laser light is controlled as necessary.

The optical isolator 160B allows only light in the direction from the optical coupler BS to the EOM 160C to pass therethrough, and blocks light in the opposite direction from passing therethrough. With this optical isolator 160B, the DF caused by the reflected light (return light)
The change of the oscillation mode of the B semiconductor laser 160A and the generation of noise are prevented.

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 modulator) having an electrode structure that is chirp-corrected so that the wavelength spread of the semiconductor laser output with the change of the refractive index with time is reduced is used. EOM160C is a light quantity control device 16
The pulsed light modulated in synchronization with the voltage pulse applied from C is output. For example, DFB with EOM160C
Laser light oscillated by the semiconductor laser 160A has a pulse width of 1 ns and a repetition frequency of 100 kHz (pulse cycle of about 1
0 μs) pulse light is modulated. The repetition frequency is the spontaneous emission (ASE: Am) in the optical fiber amplifier.
A value that can suppress the effect of noise caused by plified Spontaneous Emission) is selected.

The voltage applied to the EOM160C and the DF
It is desirable that the output light be pulsed in combination with the control of the supply current to the B semiconductor laser 160A. In such a case, the extinction ratio can be improved. By doing so, it becomes possible to easily generate pulsed light having a narrow pulse width while improving the extinction ratio as compared with the case where only the EOM160C is used, and the oscillation interval of the pulsed light and the start of oscillation It is possible to control the stop and the like more easily. An acousto-optic modulator (AOM) can be used instead of the EOM 160C.

The optical amplifying section 161 amplifies the pulsed light from the EOM 160C, and as shown in FIG. 4, periodically distributes the pulsed light from the EOM 160C in time order and branches (for example, 128 branches). Optical splitter 1
66 and a plurality of optical fiber amplifiers 167.

The optical fiber amplifier 167 is, as shown in FIG. 5, (a) cascade Raman laser device 13
0, and (b) an amplification optical fiber 171 for light of wavelength λ _S arranged in the resonator 135 for light of wavelength 1480 nm in the cascade Raman laser device 130.
And (c) a wavelength division multiplexer (1) having a wavelength of 1480 nm in the resonator 135 and a light (amplified light) having a wavelength λ _S from the optical branching device 166 and supplying the multiplexed light to the amplification optical fiber 171 ( WDM) 172, (d) optical coupler 134, (e)
And a photoelectric conversion element 138. Here, the optical coupler 134 is configured similarly to the above-mentioned optical coupler BS.

The cascade Raman laser device 130
Is (i) Ytterbium (Yb) is added and has an optical fiber 131 as a laser medium having a double clad structure (hereinafter, also referred to as “laser medium 131”).
(B) Excitation light for the laser medium 131 (hereinafter,
An excitation light source 132 for generating light having a wavelength of 965 nm, which is “laser excitation light”, and (c) fiber Bragg diffraction gratings 133 _{1A to} 133 _6A and 133 _{1B to} 133 _6B are provided.

Here, the fiber Bragg diffraction grating 13
3 _1A and 133 _1B have almost 100 wavelengths of light of 1117 nm.
%, And forms both ends of the Fabry-Perot resonator for light with a wavelength of 1117 nm. In addition, the fiber Bragg diffraction grating 133 _2A , 1
33 _2B is configured to reflect substantially 100% of light having a wavelength of 1175 nm, are formed at both ends of the Fabry-Perot resonator for light having a wavelength of 1175 nm. The fiber Bragg diffraction gratings 133 _3A and 133 _3B are configured so as to reflect almost 100% of light having a wavelength of 1240 nm, and form both ends of a Fabry-Perot resonator for light having a wavelength of 1240 nm.

Further, the fiber type Bragg diffraction grating 13
Three_4A, 133_4BIs almost 100% of the light of wavelength 1315nm
Light with a wavelength of 1315 nm that is configured to reflect light
About forming the two ends of a Fabry-Perot resonator
It In addition, the fiber Bragg diffraction grating 133_5A, 13
Three_5BReflects almost 100% of light with a wavelength of 1395 nm
It is configured as follows.
It forms both ends of the Fabry-Perot resonator. Also,
Fiber Bragg grating 133_6A, 133 _6BIs the wavelength
It is configured to reflect almost 100% of 1480 nm light.
And the Fabry for light with a wavelength of 1480 nm.
It forms both ends of the Perot resonator.

In the cascade Raman laser device 130,
Fiber Bragg grating 133 _1AIs the excitation light source 13
2 and the optical fiber 131, that is, the optical fiber 13
1 is arranged on the incident end side of the laser excitation light.
In addition, the fiber Bragg diffraction grating 133_2A~ 133_6A
On the output end side from the optical fiber 131 of the laser excitation light
The fiber-type block along the direction of travel of the laser excitation light.
Ragg diffraction grating 133 _6A, Fiber Bragg grating
133_5A, ..., Fiber type Bragg diffraction grating 133_2Aof
They are arranged in order.

Further, the fiber type Bragg diffraction grating 133.
_{1B to} 133 _5B are fiber type Bragg diffraction gratings 133 _2A
And the WDM 172, the fiber Bragg diffraction grating 133 _1B , the fiber Bragg diffraction grating 133 _2B , ..., The fiber Bragg diffraction grating 133 _5B are arranged in this order along the traveling direction of the laser excitation light. further,
The fiber Bragg diffraction grating 133 _6B is arranged on the emission end side of the light of wavelength λ _S in the amplification optical fiber 171.

In this embodiment, the fiber type
Bragg diffraction grating 133_2A~ 133 _6AAnd fiber type
Ragg diffraction grating 133_1B~ 133_5BThe same light phi
It is formed in Ba.

As the excitation light source 132, a semiconductor laser light source is used in this embodiment. further,
As the amplification optical fiber 171, an optical fiber in which erbium (Er) is added to its core is adopted. Since the amplification optical fiber 171 amplifies the pulsed light whose peak power is significantly higher than that of the signal light in the optical fiber communication, the amplification optical fiber 171 has a shorter length than that of the amplification optical fiber in the optical fiber communication. A short amplification optical fiber is used.

The optical fiber amplifier 167 configured as described above operates as follows, amplifies the light of wavelength λ _S emitted from the optical branching device 166, and the wavelength conversion unit 163.
Shoot towards.

In this optical amplification, first, the optical fiber amplifier 167 is set in a state capable of amplifying the light of wavelength λ _S. Upon this setting, the excitation light source 132 emits laser excitation light. The laser excitation light emitted from the excitation light source 132 enters the optical fiber (laser medium) 131 after passing through the fiber grating 133 _1A and travels in the optical fiber 131. As a result, Yb extra-shell electrons added to the laser medium 131 are excited with respect to the supplied excitation light energy, and an inverted distribution in the energy level distribution of Yb extra-shell electrons is generated.

Spontaneous radiation is generated in the state of the population inversion, and light having a wavelength of 1117 nm is generated. The light having a wavelength of 1117 nm generated in this way has a wavelength 111 with the fiber grating 133 _1A and the fiber grating 133 _1B at both ends and the laser medium 131 as a part of the optical path.
It travels back and forth within the optical cavity for 7 nm light. In the propagation of the light having the wavelength of 1117 nm, stimulated emission is generated when passing through the laser medium 131, and the light having the wavelength of 1117 nm is amplified. As a result, the energy density of the 1117 nm wavelength light in the optical resonator for the 1117 nm wavelength light becomes very large.

When such light having a wavelength of 1117 nm having a very large energy density travels through the optical fiber, light having a wavelength of 1175 nm is efficiently generated by stimulated Raman scattering. Most of the light having the wavelength of 1175 nm thus generated reciprocates in the optical resonator for the light having the wavelength of 1175 nm having the fiber grating 133 _1A and the fiber grating 133 _1B at both ends. Since the energy density of light having a wavelength of 1175 nm in this optical resonator becomes very large, the stimulated Raman scattering in the optical resonator for the light having a wavelength of 1175 nm causes a wavelength of 1240 nm.
Light is emitted.

Thereafter, the wavelength of 1240 nm due to stimulated Raman scattering in the optical resonator for the light of wavelength 1175 nm.
1315nm, 139 by the same mechanism as the generation of light
Light of 5 nm and 1480 nm is generated stepwise. Then, a state in which light of these wavelengths has a very large energy density in the optical resonator corresponding to each wavelength is realized.

An amplification optical fiber 171 is arranged on the optical path of the light having a wavelength of 1480 nm having a very high energy density in the optical resonator 135 thus generated. As a result, in the amplification optical fiber 171, the energy density of the light having the wavelength of 1480 nm, which is the excitation light for the amplification optical fiber 171, becomes very high. That is,
A very strong pumping light is supplied to the amplification optical fiber 171. As a result, the amplification optical fiber 17
The extra-shell electrons of Er added to 1 are efficiently excited,
An population inversion occurs in the energy level distribution of the extra-shell electrons of Er, and an optical amplification enabled state having a large optical amplification capability is realized even with a shortened fiber.

When the light of wavelength λ _S emitted from the optical branching device 166 enters the amplification optical fiber 171 through the WDM 172 and travels through the amplification optical fiber 171, the amplification factor is high. Is amplified by.
Then, the amplified light of the wavelength λ _S is emitted from the amplification optical fiber 171.

The amplified light of wavelength λ _S emitted from the amplification optical fiber 171 passes through the fiber grating 133 _1B and is branched into two by the optical coupler 134, about 97% of which is in the next stage. Wavelength conversion unit 163
Head towards. On the other hand, the remaining about 3% is incident on the photoelectric conversion element 138. The light amount detection result of the photoelectric conversion element 138 is supplied to the light amount control device 16C. Then, in the light quantity control device 16C, each pumping light source 132 is feedback-controlled so that the optical output from each optical fiber amplifier 167 becomes constant (that is, balanced).

The wavelength conversion unit 163 has a plurality of nonlinear light beams.
Pulsed light from the optical amplifier 161 (wavelength 1
546.92 nm (= λ_S) Light) to its 8th harmonic
Wavelength converted and output wave almost the same as ArF excimer laser
Length (193.36 nm (= λ _S/ 8)) pulsed ultraviolet light
To occur.

FIG. 6 shows an example of the structure of the wavelength conversion section 163. Here, a specific example of the wavelength conversion unit 163 will be described based on this drawing. In FIG. 6, the light having the wavelength λ _S emitted from the optical amplification section 161 is used as a fundamental wave, and the wavelength is converted into an 8th harmonic (harmonic) by using a nonlinear optical crystal, which is almost the same as the ArF excimer laser. A configuration example for generating ultraviolet light having a wavelength λ _S , which is a wavelength, is shown.

In the wavelength converter 163 of FIG. 6, the fundamental wave (wavelength λ _S ) → doubled wave (wavelength (λ _S / 2)) → triple wave (wavelength (λ _S / 3)) → quadrupled wave ( Wavelength conversion is performed in the order of wavelength (λ _S / 4)) → 7th harmonic (wavelength (λ _S / 7)) → 8th harmonic (wavelength (λ _S / 8)).

More specifically, the light (fundamental wave) having a wavelength of 1546.92 nm (frequency ω) emitted from the optical amplification section 161 enters the first-stage nonlinear optical crystal 183. When the fundamental wave passes through this nonlinear optical crystal 183, 2
Double the frequency ω of the fundamental wave due to the generation of the second harmonic, that is, frequency 2ω (wavelength: 773.46 nm (= λ _S / 2))
Second harmonic wave is generated.

A LiB ₃ O ₅ (LBO) crystal is used as the first-stage nonlinear optical crystal 183, and the fundamental wave is 2
For the phase matching to convert the wavelength to a harmonic, a method by adjusting the temperature of the LBO crystal, NCPM (Non-Critical Phase Match)
ing) is used. Since NCPM does not cause an angle deviation (Walk-off) between the fundamental wave and the second harmonic wave in the nonlinear optical crystal, it enables highly efficient conversion into the second harmonic wave, and the generated second harmonic wave is the Walk. This is advantageous because the beam is not deformed by -off.

The fundamental wave transmitted without wavelength conversion by the nonlinear optical crystal 183 and the second harmonic wave generated by wavelength conversion are respectively delayed by a half wavelength and a wavelength by the wave plate 184 at the next stage. As a result, only the fundamental wave has its polarization direction rotated by 90 degrees. After this, the fundamental wave and the second harmonic wave are collected by the condenser lens 1.
The light enters the second-stage nonlinear optical crystal 186 via 85. An LBO crystal is used as the second-stage nonlinear optical crystal 186. This LBO crystal 186 is an NCPM whose temperature is different from that of the first stage nonlinear optical crystal (LBO crystal) 183.
Used in. In the non-linear optical crystal 186, the second harmonic generated in the first-stage non-linear optical crystal 183 and the fundamental wave that has passed through the non-linear optical crystal 183 without wavelength conversion generate a third harmonic (wavelength: 515). 0.62 nm (=
λ _S / 3)) is obtained.

Next, the 3 obtained by the nonlinear optical crystal 186 was used.
The dichroic mirror 187 separates the harmonic wave from the fundamental wave and the second harmonic wave that have passed through the nonlinear optical crystal 186 without wavelength conversion. The third harmonic wave reflected here is collected by the condenser lens 190 and the dichroic mirror 19.
The light passes through 3 and enters the fourth-stage nonlinear optical crystal 195.
On the other hand, the fundamental wave and the second harmonic wave transmitted through the dichroic mirror 187 pass through the condenser lens 188 and enter the third stage nonlinear optical crystal 189.

As the third-stage nonlinear optical crystal 189, L
The BO crystal is used, and the L
While passing through the BO crystal, the second harmonic wave is 2 in the LBO crystal.
4th harmonic (wavelength: 386.73nm)
(= Λ _S / 4)). Nonlinear optical crystal 189
The 4th harmonic and the fundamental wave transmitted therethrough are separated by the dichroic mirror 191, and the fundamental wave transmitted there passes through the condenser lens 194 and is reflected by the dichroic mirror 196 to form 5 stages. It is incident on the nonlinear optical crystal 198 of the eye. On the other hand, the fourth harmonic wave reflected by the dichroic mirror 191 reaches the dichroic mirror 193 through the condensing lens 192, where it is coaxially combined with the third harmonic wave reflected by the dichroic mirror 187 to form four stages. It is incident on the nonlinear optical crystal 195 of the eye.

As the fourth stage non-linear optical crystal 195,
β-BaB ₂ O ₄ (BBO) crystal is used,
7th harmonic (wavelength: 220.9
9 nm (= λ _S / 7)) is obtained. Nonlinear optical crystal 195
The 7th harmonic wave obtained in step 2 passes through the condenser lens 197,
The dichroic mirror 196 combines the fundamental wave that has passed through the dichroic mirror 191 coaxially with the fundamental wave and makes it enter the fifth-stage nonlinear optical crystal 198.

LB as the fifth stage non-linear optical crystal 198
An O crystal is used, and an 8th harmonic (wavelength: 193.36 nm (= λ _S / 8)) is generated by sum frequency generation from the fundamental wave and the 7th harmonic.
To get BBO crystal for 7th harmonic generation 1
Instead of the 95 and 8th harmonic LBO crystal 198,
CsLiB ₆ O ₁₀ (CLBO) crystal, Li ₂ B ₄ O ₇ (L
It is also possible to use B4) or CsB ₃ O ₅ (CBO) crystals.

Returning to FIG. 1, the illumination optical system 12 includes an optical integrator, a variable ND filter, a reticle blind and the like (all not shown). Here, as the optical integrator, a fly-eye lens, an internal reflection type integrator (rod integrator or the like), a diffractive optical element or the like is used. The configuration of such an illumination optical system is disclosed in, for example, Japanese Patent Laid-Open No.
It is disclosed in Japanese Patent Publication No. 0-112433. The exposure light IL emitted from the illumination optical system 12 has its optical path bent vertically downward by a mirror M, and then passes through a condenser lens 32 and a rectangular illumination region 42R on the reticle R held on the reticle stage RST. Illuminate with a uniform illuminance distribution.

The reticle R is placed on the reticle stage RST and is suction-held through a vacuum chuck or the like (not shown). The reticle stage RST is movable in a horizontal plane (XY plane) and is scanned by the reticle stage drive unit 49 in a predetermined stroke range in the scanning direction (here, the Y direction which is the left-right direction on the paper surface of FIG. 1). It has become. The position and rotation amount of the reticle stage RST during this scanning are determined by the reticle stage RS.
This laser interferometer 54R is measured by an external laser interferometer 54R via a movable mirror 52R fixed on T.
The measured value of is supplied to the main controller 50.

The projection optical system PL is, for example, a bilateral telecentric reduction system, and has a common optical axis AX in the Z-axis direction.
It is composed of a plurality of lens elements having. The projection optical system PL has a projection magnification β of, for example, ¼, ⅕, ⅙, or the like. Therefore, when the illumination area 42R on the reticle R is illuminated by the exposure light IL as described above, the illumination area 42R in the pattern formed on the reticle R is illuminated.
An image obtained by reducing a part of the image with a projection magnification β by the projection optical system PL is formed in a rectangular projection area 42W that is conjugate with the illumination area 42R in the field of view of the projection optical system PL, and the resist applied on the surface of the wafer W. The reduced image is transferred on top.

The XY stage 14 is two-dimensionally driven by the wafer stage drive unit 56 in the Y direction which is the scanning direction and the X direction which is orthogonal thereto (the direction orthogonal to the paper surface in FIG. 1). A wafer W is held on a Z tilt stage 58 mounted on the XY stage 14 by vacuum suction or the like via a wafer holder (not shown). The Z tilt stage 58 adjusts the position (focus position) in the Z direction of the wafer W by, for example, three actuators (piezo elements or voice coil motors), and at the same time, 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, XY
The position of the stage 14 is adjusted by the external laser interferometer 54W via the movable mirror 52W fixed on the Z tilt stage 58.
The measurement value of the laser interferometer 54W is supplied to the main controller 50.

Here, the movable mirror actually includes an X movable mirror having a reflection surface perpendicular to the X axis and a Y movable mirror having a reflection surface perpendicular to the Y axis. Interferometers for X-axis position measurement, Y-axis position measurement, and rotation (including yawing amount, pitching amount, rolling amount) measurement are also provided, but in FIG. 1, these are representative. , A moving mirror 52W and a laser interferometer 54W.

On the Z tilt stage 58, a fiducial mark plate FM used when performing reticle alignment or the like described later is provided. The surface of the fiducial 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.

Further, in the exposure apparatus 10 of the present embodiment, as shown in FIG. 1, under the control of the main controller, a large number of measurements are made on the image plane (XY plane) of the projection optical system PL. Irradiation optical system 60a for irradiating the image forming light beams for forming the images of the pinholes or slits toward the points from the oblique direction with respect to the optical axis AX, and the reflection of these image forming light beams on the surface of the wafer W. An oblique incident light type multipoint focus position detection system (focus sensor) including a light receiving optical system 60b that receives a light beam is provided. The detailed configuration of a multi-point focal position detection system (focus sensor) similar to that of this embodiment is as follows.
For example, it is disclosed in JP-A-6-283403.

At the time of scanning exposure or the like, main controller 50 determines the Z position and the Z position of the surface of a part of the shot area where the measurement point exists, based on the Z position detected for each measurement point from light receiving optical system 60b. While sequentially calculating the tilt amount, and controlling the Z position of the Z tilt stage 58 via a drive system (not shown) based on the calculation result, auto focus (automatic focusing) and auto leveling are executed.

The main control unit 50 includes a CPU (central processing unit), ROM (read only memory), RA
It is configured to include a so-called microcomputer (or workstation) including M (random access memory) and the like, and performs various controls described so far, and for example, a reticle R so that the exposure operation can be performed accurately. And synchronous scanning of the wafer W, stepping of the wafer W, exposure timing, etc. are controlled. Further, in the present embodiment, the main control device 50 controls the exposure amount at the time of scanning exposure as will be described later, and controls the entire device as a whole.

Specifically, main controller 50 causes reticle R to move in the + Y direction (or −Y direction) with respect to illumination region 42R at speed V _R = V during reticle stage RST during scanning exposure, for example. In synchronism with scanning, the wafer W is moved through the XY stage 14 in the −Y direction (or + Y direction) with respect to the projection area 42W at a velocity V _W = β · V (β is a projection from the reticle R onto the wafer W. So that scanning is performed at a magnification), the positions and speeds of the reticle stage RST and the XY stage 14 are respectively controlled via the reticle stage drive unit 49 and the wafer stage drive unit 56 based on the measurement values of the laser interferometers 54R and 54W. To do. Also,
At the time of stepping, main controller 50 uses wafer interferometer 54W to measure wafer stage drive unit 56 based on the measured value.
The position of the XY stage 14 is controlled via.

Next, regarding the exposure sequence in the case where the reticle pattern is exposed on a predetermined number (N) of wafers W in the exposure apparatus 10 of the present embodiment, the main controller 50
The control operation will be mainly described.

First, main controller 50 uses reticle loader (not shown) to load reticle R to be exposed onto reticle stage RST.

Next, reticle alignment is performed using a reticle alignment system (not shown), and baseline measurement of an off-axis type alignment system (not shown) is performed using the reference marks described above.

Next, main controller 50 instructs a wafer transfer system (not shown) to replace wafer W. As a result, the wafer transfer system and the wafer transfer mechanism (not shown) on the XY stage 14 perform wafer exchange (simple wafer loading when there is no wafer on the stage). Then, a series of alignment process steps such as fine alignment (EGA, etc.) are performed using the alignment system on which the baseline measurement is performed. Since these wafer exchanges and wafer alignments are performed in the same manner as in a known exposure apparatus, further detailed description will be omitted here.

Next, based on the above alignment result and shot map data, the operation of moving the wafer W to the scanning start position for the exposure of each shot area on the wafer W and the above-mentioned scanning exposure operation are repeated. Then, the reticle pattern is transferred to the plurality of shot areas on the wafer W by the step-and-scan method. During the scanning exposure, the main controller 50 gives a command to the light quantity controller 16C to control the exposure light quantity in order to give the target integrated exposure quantity determined according to the exposure condition and the resist sensitivity to the wafer W.

When the exposure of the first wafer W is completed, main controller 50 instructs a wafer transfer system (not shown) to replace the wafer W. As a result, the wafer transfer system and the wafer transfer mechanism (not shown) on the XY stage 14 perform wafer exchange, and thereafter, search alignment and fine alignment are performed on the exchanged wafer in the same manner as described above.

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

When the illuminance changes due to the change of the exposure condition and / or the reticle pattern, the light source device 1 is provided so that a proper exposure amount is given to the wafer (resist).
It is desirable to control at least one of the frequency and the peak power of the light emitted from No. 6. At this time, the scanning speed of the reticle and the wafer may be adjusted in addition to at least one of the frequency and the peak power.

As described above, the light source device 16 according to the present embodiment is provided with the laser oscillator 130 in which the intensity of the light having the wavelength of 1480 nm, which is the excitation light for the amplification optical fiber 171, becomes extremely high. Optical resonator 135
An amplification optical fiber 171 is arranged on the optical path of light having a wavelength of 1480 nm inside. As a result, very strong pumping light having a wavelength of 1480 nm is supplied to the amplification optical fiber 171. Therefore, with a simple configuration, it is possible to perform high-gain amplification of the light of wavelength λ _S , especially even during the high average output operation. Therefore, with a simple configuration, while maintaining the gain as the optical amplifier 167 constant, the wavelength λ _S
The output power of light can be dramatically increased.

Further, in the light source device 16 according to this embodiment, the laser medium in the laser oscillator 170 is a Yb-doped optical fiber type laser medium, and it relates to light of various wavelengths including an optical resonator for light of wavelength 1480 nm. The reflection element forming the optical resonator is a fiber grating 133 _{1A to} 13 which is a fiber Bragg diffraction grating.
3 _6A , 133 _{1B to} 133 _6B as the optical fiber amplifier 1
The optical component in 67 is an optical fiber type. As a result, the optical fiber amplifier 167 can be easily assembled by connecting the optical fiber type optical parts, and
It is possible to prevent the diffusion of light to the surroundings, and it is possible to efficiently amplify the amplified light (light of wavelength λ _S ).

Further, since the light of wavelength λ _S which has been efficiently amplified by the optical amplification section 161 is wavelength-converted by the wavelength conversion section 163, the wavelength-converted light can be obtained efficiently.

Further, the wavelength λ _{S of the} fundamental wave is a wavelength at which the wavelength of the eighth harmonic (λ _S / 8) used as the exposure light is different from the absorption peak wavelength of oxygen, and according to the International Telecommunication Union. 1 out of multiple standardized wavelengths
Since two wavelengths are selected, the DFB semiconductor laser 160A is a standard optical component mass-produced for generating ultraviolet light having the same wavelength as the ArF excimer laser that efficiently reaches the wafer W to be exposed. Can be used as

Further, according to the exposure apparatus of the present embodiment, the reticle R can be irradiated with the high-intensity illumination light IL in scanning exposure, so that the pattern formed on the reticle R is transferred onto the wafer W with high accuracy and efficiency. be able to.

In the above embodiment, an optical fiber having a core portion added with a rare earth element is used as the amplifying medium. For example, a rod-shaped glass body with a rare earth element added to the core portion is used. It is also possible to irradiate this with excitation light.

In the above embodiment, the optical resonator 13
The optical fiber 171 for amplifying Er added as the medium for amplifying light arranged in 5 is adopted, but for example, a rod-shaped glass body in which a rare earth element such as Er is added to the core portion can be adopted. Is. Furthermore, in the above embodiment, the Er-doped fiber is adopted as the amplification optical fiber, but other rare earth element-doped fibers can be adopted.

Further, in the above embodiment, the cascade Raman laser resonator is used as the laser resonator 130, but it is also possible to use another laser resonator.

In the above embodiment, the fiber gratings 133 _{1A to} 133 _6A and 133 are used as the reflecting elements.
Using _1B to 133 _6B, but if a reflective element having a same wavelength selectivity as the above embodiment, it is also possible to use a mirror of the multi-layer film structure.

In the above embodiment, the wavelength of 1480n
The amplification optical fiber 171 is arranged outside the optical resonator 135 having a wavelength of 1395 nm, which is the preceding stage of the wavelength of 1480 nm in the cascade Raman laser resonator, in the optical resonator 135 for the light of m. The amplification optical fiber 171 can be arranged at any position on the optical path of the light having the wavelength of 1480 nm.

Further, the configuration of the wavelength conversion unit in the above embodiment is an example, and it goes without saying that the configuration of the wavelength conversion unit of the present invention, the material of the nonlinear optical crystal, the output wavelength, etc. are not limited to this. For example, a fundamental wave having a wavelength of 1.57 μm emitted from the optical amplification unit 163 is subjected to harmonic generation of a 10th harmonic using a non-linear optical crystal, and ultraviolet light of 157 nm having the same wavelength as that of the F ₂ laser is generated. You can also It is also possible to use a CBO crystal when generating the 8th harmonic by the sum frequency generation.

In the above embodiment, the laser light source 1
Although the DFB semiconductor laser is used as 60A, other semiconductor lasers or fiber lasers may be used.

Further, the number of optical fiber amplifiers 167 arranged in parallel in the optical amplifying section 161 may be arbitrary, and the number may be decided according to the specifications required in the product to which the light source device according to the present invention is applied. Good. In particular, when a high output is not required for the light source device, the number of optical fiber amplifiers 167 can be reduced to simplify the configuration. If the optical fiber amplifier 167 is simplified to include only one, the branching device 166 is not necessary.

Further, in the above embodiment, the wavelength of the ultraviolet light emitted from the light source device is set to be substantially the same as that of the ArF excimer laser, but the setting wavelength may be arbitrary, and the wavelength should be set to this setting wavelength. According to the laser light source 160A
The oscillation wavelength, the configuration of the wavelength conversion unit 163, the harmonic magnification, and the like may be determined. Note that the set wavelength may be determined according to, for example, the design rule (line width, pitch, etc.) of the pattern to be transferred onto the wafer, and the exposure conditions and the type of reticle described above may be used for the determination. (Phase shift type or not) may be taken into consideration.

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. However, it is used in a device manufacturing process other than the exposure apparatus. The light source device according to the present invention can be applied to a device, for example, a laser repair device used to cut a part (a fuse or the like) of a circuit pattern formed on a wafer. Further, the present invention is not limited to a step-and-scan type scanning exposure apparatus, but a static exposure type, for example, a step-and-repeat type exposure apparatus (stepper or the like).
Can also be suitably applied to. Further, it can be applied to a step-and-stitch type exposure apparatus, a mirror projection aligner, and the like.

Further, in the above embodiment, an example in which the light source device according to the present invention is used as a light source device for generating the exposure illumination light has been described. However, light having substantially the same wavelength as the exposure illumination light is required. As a light source device for the reticle alignment described above, or as a light source device for an aerial image detection system that detects the projected image of a mark arranged on the object plane or image plane of the projection optical system to obtain the optical characteristics of the projection optical system. It is also possible to use.

The light source device of the present invention can be used in various devices other than the exposure device. For example, a light source used for a laser treatment device that irradiates a cornea with laser light to ablate the surface (or ablate the inside of the incised cornea) and correct the curvature or unevenness of the cornea to treat myopia, astigmatism, etc. It can be used as a device. The light source device of the present invention can also be used as a light source device in an optical inspection device or the like.

The light source device of the present invention can also be used for optical adjustment (optical axis alignment, etc.) or inspection of an optical system such as the projection optical system in the above embodiment. Further, in various devices having an excimer laser as a light source, the light source device of the present invention can be applied in place of the excimer laser.

Next, a device (semiconductor chip such as IC or LSI, which uses the exposure apparatus and method of the above embodiment,
Manufacturing of a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc. will be described.

First, in the design step, functional design of a device (for example, circuit design of a semiconductor device) is performed, and pattern design for realizing the function is performed. Subsequently, in a mask manufacturing step, a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in the wafer manufacturing step, a wafer is manufactured using a material such as silicon.

Next, in the wafer processing step, the mask and the wafer prepared in the above steps are used to form an actual circuit or the like on the wafer by a lithography technique, as will be described later.

This wafer processing step is, for example, in manufacturing a semiconductor device, an oxidation step for oxidizing the surface of the wafer, and a CV for forming an insulating film on the surface of the wafer.
It has a pretreatment process of each stage of the wafer process such as a D step, an electrode formation step of forming electrodes on the wafer by vapor deposition, an ion implantation step of implanting ions into the wafer, and a post-treatment process described later. The pretreatment process is selected and executed according to the required treatment at each stage of the wafer process.

At each stage of the wafer process, when the pretreatment process is completed, a photosensitive agent is applied to the wafer in the resist processing step, and subsequently, in the exposure step, the circuit pattern of the mask is printed on the wafer by the exposure apparatus 10 described above. Expose. Next, the exposed wafer is developed in the developing step, and subsequently, in the etching step, the exposed member other than the portion in which the resist remains is removed by etching. Then, in the resist removing step, the unnecessary resist after etching is removed.

As described above, by repeatedly performing the pretreatment process and the posttreatment process from the resist treatment step to the resist removal step, multiple circuit patterns are formed on the wafer.

When the wafer processing step is completed in this way, the wafer processed in the wafer processing step is diced into chips in the assembly step. This assembly includes steps such as an assembly step (dicing and bonding) and a packaging step (chip encapsulation).

Finally, in the inspection step, inspections such as an operation confirmation test and a durability test of the device manufactured in the assembly step are performed. After these steps, the device is completed and shipped.

As described above, a device in which a fine pattern is formed accurately can be manufactured with high mass productivity.

[0112]

As described in detail above, according to the light source device of the present invention, the pumping light wavelength provided in the laser oscillator in which the intensity of the light of the wavelength that is the pumping light for the amplifying medium becomes extremely high. The amplifying medium is arranged on the optical path of the light of the excitation light wavelength in the optical resonator. Therefore, it is possible to provide a light source device having a simple configuration and capable of dramatically increasing the (signal light) output power while keeping the gain as an optical amplifier constant.

Further, according to the light irradiation device of the present invention, the light emitted from the light source device of the present invention is applied to the object through the irradiation optical system, so that the light whose wavelength is efficiently converted is applied to the object. Can be irradiated.

[Brief description of drawings]

FIG. 1 is a diagram 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 for explaining the wavelength of light generated by the laser light source of FIG.

FIG. 4 is a block diagram showing a configuration of an optical amplification section in FIG.

5 is a diagram schematically showing a configuration of the optical fiber amplifier of FIG.

FIG. 6 is a diagram showing a configuration of a wavelength conversion unit in FIG.

[Explanation of symbols]

10 ... Exposure device (light irradiation device), 12 ... Illumination optical system (irradiation optical system), 16 ... Light source device, 130 ... Laser resonator,
131 ... Optical fiber (optical fiber type laser medium), 13
3 _6A , 133 _6B ... Fiber grating (fiber type Bragg diffraction grating), 135 ... Optical resonator, 160 ... Pulse light generating section (laser light generating section), 161 ... Optical amplifying section, 1
63 ... Wavelength conversion unit, 171 ... Optical fiber for amplification (optical amplification medium).

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01S 3/094 H01S 3/131 3/109 3/30 Z 3/131 3/094 S 3/30 H01L 21 / 30 515B 518 F term (reference) 2K002 AA04 AB12 AB30 BA01 CA02 CA15 DA10 EB15 HA20 HA24 5F046 BA05 CA03 DA01 5F072 AB07 AB09 AK06 HH02 HH04 HH06 JJ04 JJ05 KK07 MM07 PP07 QQ02 QQ07 YY09

Claims (8)

[Claims] 1. A light source device comprising: a laser light generator that generates light of a first wavelength; and an optical amplifier that amplifies the light generated by the laser light generator. A laser oscillator having an optical resonator for a second wavelength different from the first wavelength; arranged on the optical path of the light of the second wavelength in the optical resonator, and the light of the second wavelength is excitation light As the first incident
A light amplification medium for amplifying light of the wavelength. 2. The light source device according to claim 1, wherein the optical amplification medium is an amplification optical fiber in which an element excited by light to the second wavelength is added to a core portion. . 3. The light source device according to claim 2, wherein the first wavelength is a wavelength in the 1.55 μm band, and the element added to the amplification optical fiber is erbium. 4. A laser medium in the laser oscillator is an optical fiber type laser medium in which an element excited by light having a fourth wavelength is added to a core portion, and the laser medium has a wavelength of the second wavelength in the optical resonator. The light source device according to claim 1, wherein the light reflecting element is a fiber Bragg diffraction grating. 5. The light source device according to claim 5, wherein the laser oscillator is a Raman laser oscillator. 6. The wavelength conversion section for converting the light of the first wavelength amplified by the optical amplification section into the light of the third wavelength, further comprising a wavelength conversion section. The light source device according to claim 1. 7. The first wavelength is a wavelength that makes the light of the third wavelength different from the absorption peak wavelength of the medium component of the optical path of the third wavelength, and is standardized by the International Telecommunication Union. The light source device according to claim 6, wherein the light source device has one wavelength out of a plurality of wavelengths that are predetermined. 8. A light irradiation device for irradiating an object with light, comprising: the light source device according to claim 1; and directing light emitted from the light source device toward the object. And an irradiation optical system for emitting light.