WO2002095486A1 - Light source device and light irradiation device, and device manufacturing method - Google Patents

Abstract

A light source device comprises a phase modulator (132) which is disposed in an optical path from a light generation unit (160) to a wavelength conversion unit (163) and performs phase modulation for canceling at least a part of self phase modulation of the light propagated through the optical path. The phase modulator (132) performs the phase modulation according to the intensity of the light at each instant. As a result, the effect of the self phase modulation is suppressed, and an increase in the spectral width of the light incident on the wavelength conversion unit can be suppressed.

Description

 Specification

Light source device, light irradiation device, and device manufacturing method

 The present invention relates to a light source device, a light irradiation device, and a device manufacturing method. More specifically, the present invention relates to a light source device that converts light amplified by an optical amplifier to generate light of a desired wavelength, and a light source device. The present invention relates to a light irradiation device provided with the light irradiation device, and a device manufacturing method using the light irradiation device in a lithographic process. Background art

Conventionally, light irradiation devices have been used for inspection of the fine structure of an object, fine processing of an object, and treatment for vision correction. For example, in a lithographic process for manufacturing semiconductor characters, etc., a pattern formed on a mask or reticle (hereinafter, collectively referred to as an “r reticle”) is converted into a wafer or a resist coated via a projection optical system. In order to transfer onto a substrate such as a glass plate (hereinafter referred to as “substrate” or “wafer” as appropriate), an exposure apparatus, which is a type of light irradiation apparatus, is used. Such exposure apparatuses include a static exposure type projection exposure apparatus that employs a step-and-repeat method (so-called stepper) and a scanning exposure-type projection exposure apparatus that employs a step-and-scan method (so-called scanning). Are mainly used. In addition, a type of light irradiation device is used to correct myopia and astigmatism by performing ablation of the corneal surface (PRK: Photorefractive Keratectomy) or abrasion inside the cornea (LASIK: Laser Intrastromal Keratomileusis) to correct vision. Is used. For such light irradiation devices, many developments have been made on light sources that generate short-wavelength light. The direction of development of such short-wavelength light sources is roughly divided into the following two types. Is done. One is the development of excimer laser light sources where the laser oscillation wavelength itself is short, and the other is the development of short wavelength light sources that utilize the generation of harmonics from infrared or visible light lasers.

 Along the former direction, a light source device using a KrF excimer laser (wavelength: 248 nm) has been developed. At present, an ArF excimer laser (wavelength 1) is used as a shorter wavelength light source. The development of light source devices that use (93 nm) etc. is in progress. However, these excimer lasers have disadvantages as a light source device, such as being large in size, and using toxic fluorine gas, which makes the maintenance of the laser complicated and expensive.

 Therefore, using the nonlinear optical effect of a nonlinear optical crystal, which is a method of shortening the wavelength along the latter direction, converts long-wavelength light (infrared light and visible light) into shorter-wavelength ultraviolet light. The way to do is getting attention. As a light source device using such a method, there is, for example, a light source device disclosed in International Publication WO99 / 46853 (hereinafter simply referred to as “conventional example”).

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. It is difficult to say that the generation efficiency of the optical effect is high. Therefore, in order to obtain high-intensity ultraviolet light, it is necessary to make high-intensity infrared light or visible light incident on the nonlinear optical crystal. Therefore, in the above-described conventional example, the infrared light or the negligible light (hereinafter, also referred to as “basic light”) of substantially a single wavelength generated by a semiconductor laser or the like is converted into an optical fiber for amplification to which a rare earth element is added. The optical fiber amplifier has a configuration in which the light is amplified and incident on the nonlinear optical crystal. By the way, when the basic light is amplified by the optical amplification action of the amplification optical fiber of the optical fiber amplifier, high-intensity light travels in the amplification optical fiber (and the optical fiber at the subsequent stage). As a result, self-phase modulation (SP), a type of nonlinear optical phenomenon, occurs in the optical fiber. Then, as the light progresses, the spectrum width increases. Such an increase in the spectral width increases as the optical energy density in the optical fiber increases. On the other hand, a projection optical system in an exposure apparatus usually uses a lens which is a refractive optical element. For this reason, if the spectrum width of the exposure illumination light is increased, the color difference is increased, and the imaging characteristics of the projection optical system are degraded. As a result, the transfer accuracy of the pattern onto the substrate is degraded.

 That is, when the conventional light source device is used as the exposure light source of the exposure apparatus, if the luminance of the exposure illumination light is increased to improve the throughput, the chromatic aberration increases due to an increase in the spectrum width of the exposure illumination light, As a result, the transfer accuracy of the pattern to the substrate is deteriorated. In addition, if the spectral width of the exposure illumination light remains large, it becomes difficult to design and manufacture the projection optical system. For this reason, it has been desired to realize a light source device capable of emitting light with high luminance and small spectral width.

 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 emitting light of high luminance and small spectrum width with a simple configuration. It is in.

 Further, a second object of the present invention is to provide a light irradiation device capable of irradiating an object with light of high luminance and small spectrum width.

 Further, a third object of the present invention is to provide a device manufacturing method capable of improving device productivity. Disclosure of the invention

According to the findings obtained by the present inventors from the results of the research, self-phase modulation that occurs when light propagates in a medium is based on the fact that the propagating light itself undergoes phase modulation due to a change in the refractive index due to the propagation of the light. It is caused by being done. Here, assuming that the propagation direction of light in the light propagation medium is the Z direction, the time is t, and the light intensity of the propagation light in the light propagation medium is I (Z, t), each Z position of the light propagation medium and Refraction at each time The rate n (Z, t) is

n (Z, t) = n ₀ + n ₂ ■ I (Z, t)... (1) (1) In the equation, parameter no is the linear refractive index, parameter one data n ₂ is the nonlinear refractive index, both of which are shall Sadama the type of material of the light propagating medium.

Strictly speaking, the term “non-linear refractive index” includes higher-order components of light intensity I (Z, t), but such higher-order components are small enough to be ignored. Therefore, in this specification, the term “non-linear refractive index” is used to refer to an amount obtained by multiplying the parameter n ₂ in equation (1) by the light intensity I (Z, t). .

 Then, for example, the self-phase modulation amount 0NL after the light propagates through the light propagation medium is given by the length of the light propagation medium,

0NL = C ■ n ₂ ■ L ■ I o… (2)

It is expressed as Here, the parameter C is a constant determined by the beam shape or the like of the propagating light, and the parameter I. Is the peak light intensity at the time of incidence on the light propagation medium.

 Therefore, if the specification of the initial light and the specification of the light propagation system in the light source device are determined, the self-phase modulation amount 0NL (t) of the light passing through the light propagation system can be known. If the phase modulation having the opposite polarity is performed at an arbitrary position on the optical path, it is possible to suppress the expansion of the spectrum width due to the self-phase modulation in the light passing through the light propagation system.

 The present invention has been made based on such knowledge, and employs the following configuration.

According to a first aspect of the present invention, there is provided a light generating unit including a light generator for generating light of a predetermined wavelength; an optical amplifying unit for amplifying the light of the predetermined wavelength; A wavelength conversion unit that performs wavelength conversion; and is disposed in an optical path from the light generation unit to the wavelength conversion unit, and performs at least a part of self-phase modulation of light traveling along the optical path. And a phase modulator for performing phase modulation to kill.

 According to this, the light generated by the light generating unit is amplified by passing through the optical amplifying medium of the optical amplifying unit. (Nelgi density) propagates and undergoes self-phase modulation. However, since the phase modulator disposed in the optical path from the light generation unit to the wavelength conversion unit performs phase modulation to cancel at least a part of the self-phase modulation before or after the self-phase modulation, The amount of phase modulation is reduced. Therefore, it is possible to suppress an increase in the spectrum width of light incident on the wavelength conversion unit, and consequently, it is possible to suppress an increase in the spectrum width of light emitted from the wavelength conversion unit.

 In the first light source device of the present invention, the phase modulator is arranged on the optical path and performs phase modulation according to the amplitude of the supplied modulation electric signal; and the electro-optic modulation element. And a signal supply unit that supplies an electric signal having an amplitude corresponding to the intensity of light passing through the electro-optical modulation element as the modulation electric signal to the electro-optic modulation element.

 In this case, the phase modulator may be arranged in an optical path from the light generation unit to the light amplification unit.

 In the first light source device of the present invention, the phase modulator includes a nonlinear optical member made of a material having a polarity opposite to a polarity of a nonlinear refractive index of a light propagation medium in the light amplifying unit. It can be.

In this case, the nonlinear optical member, I m - may be to consist gamma P _Y mixed crystal - x G a _X A si.

 Further, in the first light source device of the present invention, the light generator generates continuous light, and is arranged at a stage immediately after the light generator, and extracts a pulse light from the continuous light. May be further provided.

In the first light source device of the present invention, the light generator generates a laser beam having a substantially single wavelength within a wavelength range from an infrared region to a visible region, and the wavelength converter emits ultraviolet light. You can do it.

 In the first light source device of the present invention, the optical amplification unit may include an amplification optical fiber.

 According to a second aspect of the present invention, there is provided a light generator that generates light of a predetermined wavelength; and a phase modulator that cancels at least a part of self-phase modulation in an optical path where light generated by the light generator enters. A second light source device, comprising: a driving signal supply unit that supplies a driving signal on which a phase modulation signal to be performed is superimposed to the light emitting unit; and an optical amplifying unit that amplifies the light having the predetermined wavelength.

 According to this, the phase modulation signal is superimposed on the drive signal supplied to generate light from the light generator, and the self-phase modulation in the optical path where the light generated by the light generator enters can be performed. Since at least a portion is canceled, the amount of self-phase modulation is reduced. Therefore, expansion of the spectrum width due to self-phase modulation can be suppressed.

 The second light source device of the present invention further includes a pulse modulator that is disposed in an optical path from the light generator to the light amplifying unit and that cuts out pulse light from light emitted from the light generator. It can be.

 Further, the second light source device of the present invention may further include a wavelength converter for converting the wavelength of the light amplified by the optical amplifier.

 In this case, the light generator may generate a single-wavelength laser light within a wavelength range from an infrared region to a visible region, and the wavelength conversion unit may emit ultraviolet light.

 In the second light source device of the present invention, the optical amplifier may include an amplification optical fiber.

According to a third aspect of the present invention, there is provided a light irradiation device for irradiating an object with light, comprising: a light source device of one of the first and second light source devices of the present invention; An irradiation optical system that emits the emitted light toward the object. An irradiation device.

 According to this, since the light emitted from the light source device is emitted toward the object via the irradiation optical system, the wavelength-converted high-brightness light having a narrow spectrum width is applied to the object. be able to.

 In this case, various objects are used as the object to be irradiated with the light depending on the purpose of use of the light irradiation device. For example, when the light irradiation device is used for forming a device pattern, a mask having a predetermined pattern formed as the object can be used. In this case, the light irradiation device is emitted from the mask. And a projection optical system for projecting the reflected light onto the photosensitive object. In such a case, light having high brightness and a narrow spectrum width is irradiated on the mask, and light passing through the mask is incident on the projection optical system. Therefore, when the projection optical system includes a refractive optical element, its chromatic aberration Can be suppressed.

 According to a fourth aspect of the present invention, there is provided an exposure apparatus for transferring a pattern of a mask onto a photosensitive object, comprising: a light source device of one of the first and second light source devices of the present invention; An illumination optical system for irradiating the mask with light emitted from the apparatus.

 According to this, since the light emitted from the light source device is radiated to the mask via the illumination optical system, it is possible to irradiate the mask with the wavelength-converted high-brightness light having a narrow spectrum width. The photosensitive object is exposed to light through the mask. Therefore, it is possible to transfer the pattern of the mask onto the photosensitive object with high accuracy. In this case, a control device for controlling the light source device in order to adjust the intensity of light or the integrated light amount applied to the photosensitive object via the mask may be further provided.

In the lithographic process, the photosensitive object is exposed through the mask (and the projection optical system) using any one of the light irradiation apparatus of the present invention using a mask as an object and the exposure apparatus of the present invention. The flutter of the mask on the photosensitive object This makes it possible to form micro-devices with high precision, and thereby to manufacture highly integrated microdevices with good productivity (including yield). Therefore, from another viewpoint, the present invention can be said to be a device manufacturing method using any of the light irradiation apparatus of the present invention using a mask as an object and the exposure apparatus of the present invention. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a view schematically showing a configuration of an exposure apparatus according to a first 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 control device.

 FIG. 3A is a diagram schematically showing the configuration of the pulse modulator of FIG. 2, and FIG. 3B is a timing chart for explaining the operation of the pulse modulator of FIG.

 FIG. 4A is a diagram schematically showing the configuration of the phase modulator of FIG. 2, and FIG. 4B is a timing chart for explaining the operation of the phase modulator of FIG.

 FIG. 5 is a diagram schematically showing an optical fiber amplifier constituting the optical amplifying unit of FIG. 2 and a peripheral portion thereof.

 6A and 6B are diagrams for explaining the effect of suppressing the expansion of the spectrum width by the phase modulation.

 FIG. 7 is a diagram illustrating a configuration of the wavelength conversion unit in FIG.

 FIG. 8 is a block diagram showing an internal configuration of the light source device according to the second embodiment together with a main control device.

 FIG. 9 is a diagram schematically showing an optical fiber amplifier constituting the optical amplifying unit in FIG. 8 and a peripheral portion thereof.

FIG. 1OA is a diagram schematically showing the configuration of the phase modulator of FIG. 9, and FIG. 1OB is a timing chart for explaining the operation of the phase modulator of FIG. FIG. 11 is a block diagram showing an internal configuration of a light source device according to the third embodiment together with a main control device.

 FIG. 12 is a timing diagram for explaining the phase modulation operation in the light source device of FIG.

 FIG. 13 is a flowchart for explaining the device manufacturing method of the present invention.

 FIG. 14 is a flowchart showing a specific example of step 204 of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

 << 1st Embodiment >>

 Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

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

 The exposure apparatus 10 is an illumination system including a light source device 16 and an illumination optical system 12 as an irradiation optical system, and illumination light for exposure (hereinafter, referred to as “exposure light”) IL from the illumination system. A reticle stage RST that holds a reticle R as a mask to be exposed, a projection optical system P that projects exposure light IL through the reticle R onto a wafer W as a photosensitive object, and a Z tilt stage that holds the wafer W 5 8 And an XY stage 14 on which is mounted, and a control system for these.

The light source device 1 6 is, for example, ultraviolet wavelength 1 9 3 nm (A r F excimer laser beam substantially the same wavelength) ultraviolet pulse light, or wavelength 1 5 7 nm (F ₂ laser beam with almost the same wavelength) of This is a harmonic generator that outputs pulsed 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 system including a main body column (not shown) on which these components are mounted. Temperature, pressure, humidity, etc. with high accuracy along with the main unit It is housed in a regulated environmental chamber (hereinafter referred to as “chamber”) 1 1.

 In the present embodiment, all the light source devices 16 are arranged in the chamber. However, only a part of the light source device 16, for example, only a wavelength conversion unit 163 described later, is disposed in the chamber, particularly, the illumination optical system 12. The wavelength converter 163 and the main body of the light source 16 may be connected by an optical fiber or the like.

 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 section 16A, a laser control device 16B, a modulation control device 16C, and the like.

 The light source section 16A includes a continuous light generating section 160, a current driver 136 as a drive signal supplier, an electro-optic modulator (hereinafter referred to as “EOM”) 131 as a pulse modulator, and a phase modulator. , A light amplification section 161, a wavelength conversion section 163, and a beam monitor mechanism 164.

 The continuous light generator 160 includes a laser light source 160 as a light generator, an optical cutoff BS, an optical isolator 16 OB, and the like.

 As the laser light source 16 OA, here, a single-wavelength oscillation laser, for example, an oscillation wavelength of 1.544 jtm, a continuous wave output (hereinafter referred to as “CW output”) 20 mW of InGaAsP, DFB semiconductor lasers are used. In the following, the laser light source 160 A is also referred to as “DFB semiconductor laser 16 OA” as appropriate. The DFB semiconductor laser 16 OA is driven by the current signal DV supplied from the current driver 136, and generates a laser beam having an amount of light corresponding to the magnitude of the current signal DV.

The DFB semiconductor laser is usually provided on a heat sink, and these are housed in a housing. In the present embodiment, a temperature regulator (for example, a Peltier element) is provided on a heat sink attached to the DFB semiconductor laser 16 OA. The laser controller 16B controls the temperature so that the oscillation wavelength can be controlled (adjusted).

 As the optical coupler BS, one having a transmittance of about 97% is used. Therefore, the laser light from the DFB semiconductor laser 16 OA is split into two by the optical coupler BS, and about 97% of the laser light travels toward the next-stage optical isolator 160B, and the remaining about 3% The beam enters the beam monitor mechanism 164.

 The beam monitor mechanism 164 includes an energy monitor (not shown) including a photoelectric conversion element such as a photodiode. The output of this energy monitor is supplied to the main controller 50 via the laser controller 16B. The main controller 50 detects the energy (power) of the laser beam based on the output of the energy monitor, and By controlling the current driver 136 via the controller 16B, the amount of laser light oscillated by the DFB semiconductor laser 16OA is controlled as necessary.

 The optical isolator 160B passes only the light in the direction from the optical coupler BS to the EOM 131, and blocks 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 131 converts the laser light (CW light (continuous light)) L1 that has passed through the optical isolator 160B into pulsed light. As shown in FIG. 3A, this EOM 131 responds to both the waveguide 310 and the two-branched waveguide that join again after the optical path where the incident light L 1 enters is branched into two. Electrodes 31 1, 312 provided in the same manner. Here, the waveguide 310 is made of a material whose refractive index of the voltage application section changes according to the voltage value when a voltage is applied. The electrode 311 is composed of _two electrode plates 311 1 and 3112 provided so as to sandwich the waveguide, and this electrode 311 (more precisely, one electrode 3 11 i) is supplied with one voltage signal MD 11 constituting the pulse modulation signal MD 1 from the modulation control device 16 C. Here, the other electrode 31 1 ₂ is at the ground level (hereinafter, referred to as “GND”). The electrode 31 2, waveguides is composed of two electrode plates 3 1 2 teeth 31 2 ₂ provided therebetween, this electrode 31 2 (more precisely, one of the electrodes 31 21) to Is supplied with one voltage signal MD12 constituting the pulse modulation signal MD1 from the modulation controller 16C. Here, the other electrode 3 1 2 ₂ is at the GND level.

 Here, in FIG. 3A, for ease of explanation, each of the above-mentioned electrode plates is shown apart from the waveguide 310, but these electrode plates are actually It is desirable to be in contact with 310. The same applies to the electrode plate in each embodiment described later.

 In the following description, the voltage signal MD 11 and the voltage signal MD 12 are collectively referred to as “pulse modulation signal MD 1”.

 Note that the two branch optical path lengths in the waveguide 310 are set such that the amount of the emitted light L2 becomes 0 when no voltage is applied to both of the electrodes 31 1 and 312. When different voltage signals are applied to the electrodes 311 and 312, light having an intensity corresponding to the difference between the applied voltages is emitted.

In this EOM 131, as shown in FIG. 3B, continuous light L1 having almost constant intensity is incident, but the voltage signal MD1 constituting the pulse modulated signal MD1 from the modulation controller 16C is inputted. When 1 and MD12 are OV, the light quantity of the emitted light L2 is almost zero. A pulse signal having a positive voltage peak is supplied as the voltage signal MD 11 from the modulation control device 16 C, and the voltage signal MD 12 has a negative voltage peak in synchronization with the voltage signal MD 11. When the pulse signal is supplied, light having an amount of light corresponding to the difference between the voltage level of the voltage signal MD11 and the voltage level of the voltage signal MD12 is emitted as emission light L2. Thus, the modulation controller 16 C Under this control, the pulse of the incident light L 1 is cut out, that is, pulse modulation is performed, and the optical pulse train is emitted from the EOM 131 as the emitted light 2.

 It is desirable that the output light be pulsed by using both the voltage applied to the EOM 131 and the control of the current supplied to the DFB semiconductor laser 16 OA. In such a case, the extinction ratio can be improved. This makes it possible to easily generate a pulse light with a narrow pulse width while improving the extinction ratio as compared with the case where only EOM131 is used, and to make it easier to generate the pulse light at intervals and start oscillation. And it becomes possible to control the stop and the like more easily.

 Also, an acousto-optic modulator (AOM) can be used in place of EOM131.

Returning to FIG. 2, the EOM 132 is for phase-modulating each pulse light of the light (optical pulse train) L2 emitted from the EOM 1331. This EOM1 32 includes, as shown in FIG. 4A, a waveguide 320 in which the incident light L2 enters, and an electrode 321. Here, when a voltage is applied, the waveguide 320 is made of a material whose refractive index of the voltage application unit changes according to the voltage value. The electrode 321 is composed of _two electrode plates 3211 and 3212 provided so as to sandwich the waveguide. The electrode 321 (more precisely, one electrode plate 321 ι) has a modulation control The phase modulated signal MD2 from the device 16C is supplied. Here, the other electrode plate 3212 is at the GND level.

In this EOM 132, as shown in FIG. 4B, the phase modulation signal MD 2 having a voltage level corresponding to the intensity of the light passing through the waveguide 320 is applied to the electrode 321 so that the incident light L 2 At each moment, the nonlinear refractive index of the voltage application portion of the waveguide 320 changes according to the intensity. As a result, phase modulation is performed in accordance with the above-mentioned equation (2). As shown in FIG. 4B, the phase modulation amount 0PM imparted to the emission light L3 by such phase modulation depends on the intensity of the emission light L3 at each instant. It should be noted that the phase modulation amount 0PM is determined by the fact that each light pulse of the emitted light L3 The amount is such that the amount of self-phase modulation received in the optical path up to the conversion section ₁₆₃ cancels out 0 _SPM . Adjustment of such phase modulation amount 0PM is Ru obtained from pre-measurement results of the design information of the configuration of the light source device 1 6 or self-phase modulation amount ø s _P M. Then, the waveform of the phase modulation signal MD2 is determined from the obtained self-phase modulation amount 0SPM, the electro-optical characteristics of the material of the waveguide 320, the size of the electrode 321, and the like.

 The optical amplifying unit 16 "Ui amplifies the pulse light L3 from the EOM 132. As shown in FIG. 5, the pulse light from the EOM 132 is periodically distributed in time sequence and branched ( For example, it is configured to include an optical splitter 166 that branches into 128 branches and a plurality of optical fiber amplifiers 167.

As shown in FIG. 5, the optical fiber amplifier 167 includes a first-stage optical amplifier 141 and a second-stage optical amplifier 142. Here, the pre-stage optical amplifier 141 combines the pumping semiconductor laser 178ι to generate the amplification optical fiber 175 pumping light (pumping light), and the output light of the EOM 132 and the pumping light, It has a wavelength division multiplexing device (Wavelength Division Multiplexers DM) 179i that supplies the combined light to one amplification optical fiber 5i. Moreover, subsequent optical amplifier 1 42 combines the amplification optical fiber 1 7 5 _2, the pumping semiconductor laser 1 7 8 ₂ for generating excitation light, and及beauty front optical amplifier 1 4 1 of the output light and the excitation light has the wavelength division multiplexer for supplying the combined light to the amplification optical full multiplexing 1 7 5 ₂ 1 7 9 _2. An optical filter 1 76 that selectively transmits light having substantially the same wavelength as the light generated by the DFB semiconductor laser 16 OA is provided between the first optical amplifier 14 1 and the second optical amplifier 142, and an optical isolator. 1 7 7 are arranged.

Said amplifying optical fiber 1 7 5 _1; 1 75 ₂ (hereinafter, when generically referred to as "amplification optical fiber 1 75 J) is a silica glass or phosphate glass as a main material, has a core and a cladding, the core An optical fiber doped with erbium (E r) or two ions of Er and ytterbium (Y b) at a high density Used.

In the optical fiber amplifier 1 67 configured as described above, the amplification optical Huai Ba 1 75Iota, 1 75 to _2, excitation light exciting semiconductor laser 1 78 1 78 ₂ has occurred WDM 1 79ι, 1 79 ₂ while being supplied via the pulse light through the WDM 1 79丄is you progress through the core of the amplifying optical fiber 1 75 1 75 ₂ incident stimulating radiation is generated, a pulse light is amplified You. In such an optical amplifier, since the amplification optical fiber 1 75 ^ 1 75 ₂ has a high gain, unity of wavelength is outputted a high high-intensity pulsed light. Therefore, light of a narrow band can be obtained efficiently.

The pumping semiconductor laser 1 78 1 78 _2, D FB semiconductor laser 1 6 wavelength shorter than the oscillation wavelength in OA (e.g., 980 nm) to emit light as an excitation light. The excitation light is WDM 1 79Iota, is supplied to the amplification optical fiber 1 75 through 1 79 _2, whereby Karagai electrons E r is excited, inversion of the so-called energy level occurs. Incidentally, the pumping semiconductor laser 1 78 1 78 ₂ are controlled by the modulation control device 1 6 C.

 Further, in the present embodiment, in order to suppress the difference in gain between the optical fiber amplifiers 167, a part of the output light is branched by the optical fiber amplifiers 167, and the branched light is divided by the respective branches. The photoelectric conversion elements 17 1 provided at the ends perform photoelectric conversion respectively. Output signals of these photoelectric conversion elements 17 1 are supplied to a modulation control device 16 C.

The modulation control device 1 6 C, (as i.e. balance) so that the light output becomes constant from the optical fiber amplifier 1 67, feedback control of the drive current of each pumping semiconductor laser 1 78 1 7 8 ₂ It has become.

That is, the modulation control device 16C controls the above-described pulse modulation and phase modulation, and controls each pumping so that the optical output from each optical fiber amplifier 167 becomes constant (that is, balanced). Semiconductor laser 1 78 1 78 ₂ The feed current is controlled by feedback.

 The light L4 obtained by amplifying the light L3 by the light amplifying unit 161 configured as described above is emitted from the light amplifying unit 161 to the wavelength conversion unit 163.

The light L4 is then up to the optical path of the medium (mainly, amplified optical fiber 1 75Iota in the optical amplification section 1 61, 1 75 ₂₎ in the kicking receive self-phase modulation by traveling through (self-phase modulation Occurs). However, as described above, the light 3 that has been phase-modulated by the EOM 132 is made to enter the optical amplifier 161 so as to cancel the amount of phase modulation due to the self-phase modulation (see FIG. 4B), the amount of phase modulation in the light L4 is reduced. Therefore, in the light L4, the expansion of the spectrum width due to the self-phase modulation is suppressed.

 FIGS. 6A and 6B show examples of suppressing the spread of the spectrum width in the light 4. Here, FIG. 6A shows the spectrum distribution (comparative example) of the light 4 when the phase modulation by the EOM 132 is not performed, and FIG. The spectrum distribution of the light L4 according to the present embodiment is shown. As can be confirmed by comparing FIG. 6A and FIG. 6B, in the present embodiment, the expansion of the spectrum width of the light L4 is suppressed.

 The wavelength converting section 163 includes a plurality of nonlinear optical crystals, and converts the pulse light (light having a wavelength of 1.544 jUm) L4 from the optical amplifying section 161 into its eighth harmonic wavelength, and It generates pulsed ultraviolet light with the same output wavelength (193 nm) as the F excimer laser.

FIG. 7 shows a configuration example of the wavelength conversion unit 163. Here, a specific example of the wavelength conversion unit 163 will be described with reference to FIG. Note that Fig. 7 shows that the light L4 with a wavelength of 1.544 jtm emitted from the optical amplification unit 16 "I is used as a fundamental wave and converted into an eighth harmonic (harmonic) using a nonlinear optical crystal. , a r F Ekishimare the substantially _c configuration example is shown for generating ultraviolet light for 1 93 nm is the same wavelength In the wavelength converter 163 in Fig. 7, the fundamental wave (wavelength 1.544 jtm) → the second harmonic (wavelength 772 nm) → the third harmonic (wavelength 515 nm) → the fourth harmonic (wavelength 386 nm) → Wavelength conversion is performed in the order of 1st harmonic (wavelength 221 nm) → 8th harmonic (wavelength 193 nm).

 More specifically, the light L4 (fundamental wave) having a wavelength of 1.544 m (frequency) 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, a second harmonic is generated, which is twice the frequency ω of the fundamental wave, that is, a second harmonic of the frequency 2 ω (wavelength is 2 of 772 nm). I do.

As the nonlinear optical crystal 1 83 of the first _{stage, L i B 3 0 5 (} L BO) Irare use crystals, according to the temperature regulatory the LBO crystal phase matching for wavelength conversion of the fundamental wave to the second harmonic wave Method, NCPM (Non-Critical Phase Matching) is used. The N CPM does not cause a walk-off between the fundamental wave and the second harmonic in the nonlinear optical crystal, so it is possible to convert it to a second harmonic wave with high efficiency. This is advantageous because the beam is not deformed by the walk-off.

 The fundamental wave transmitted through the non-linear optical crystal 183 without wavelength conversion and the second harmonic generated by the wavelength conversion are delayed by half and one wavelength, respectively, by the next wave plate 184. However, only the fundamental wave rotates its polarization direction by 90 degrees and enters the second-stage nonlinear optical crystal 186. An LBO crystal is used as the second-stage nonlinear optical crystal 186, and the NBO PM at a temperature different from that of the first-stage nonlinear optical crystal (LBO crystal) 183 is used in the LBO crystal. In the nonlinear optical crystal 186, the second harmonic generated in the first-stage nonlinear optical crystal 183 and the fundamental wave transmitted through the nonlinear optical crystal 183 without wavelength conversion are generated by sum frequency generation. Obtain a harmonic (wavelength 515 nm).

Next, the third harmonic obtained by the non-linear optical crystal 186 and the fundamental wave and the second harmonic transmitted through the non-linear optical crystal 186 without wavelength conversion are dichroic. The third harmonic wave separated by the mirror 187 and reflected here passes through the condenser lens 190 and the dichroic mirror 193 and enters the fourth-stage nonlinear optical crystal 195. On the other hand, the fundamental wave and the second harmonic 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, a Hoshi BO crystal is used, and the fundamental wave passes through the LBO crystal without wavelength conversion, and the second harmonic is quadrupled by the second harmonic generation in the LBO crystal. Converted to waves (wavelength 386 nm). The fourth harmonic obtained by the nonlinear optical crystal 1189 and the fundamental wave transmitted therethrough are separated by dichroic ■ Mira — 191. The fundamental wave transmitted here passes through the condenser lens 194. In both cases, the dichroic light is reflected by the mirror 196 and enters the fifth-stage nonlinear optical crystal 198. On the other hand, the fourth harmonic reflected by the dichroic ■ mirror 191 reaches the dichroic mirror 193 through the condenser lens 192, where the third harmonic reflected by the dichroic ■ mirror 187 And is incident on the fourth-stage nonlinear optical crystal 195.

The nonlinear optical crystal 1 95 of the fourth _{stage,) S- B a B 2 0} 4 (BBO) crystal is used, 7 harmonic (wavelength 221 nm by sum frequency generation and a triple wave and fourth harmonic) Get. The 7th harmonic obtained by the nonlinear optical crystal 195 passes through the condenser lens 197, and is coaxially synthesized with the fundamental wave transmitted through the dichroic ミ Mira 191 in the dichroic mirror 196 Then, the light enters the fifth-stage nonlinear optical crystal 198.

An LBO crystal is used as the fifth-stage nonlinear optical crystal 198, and an eighth harmonic (wavelength 193 nm) is obtained from the fundamental wave and the seventh harmonic by generating a sum frequency. The arrangement smell Te, instead of 8 harmonic generation LBO crystal 1 98, C s and _{i B 6 O 10 (C LBO} ) crystal, or _{L i 2 B 4 0 7 (} LB4) can also be used as the crystalline It is. In this embodiment, the seventh harmonic is generated from the third harmonic and the fourth harmonic. For example, when the seventh harmonic is generated from the fundamental wave and the sixth harmonic, the nonlinear optical crystal is generated. For example, a BBO crystal, a CLBO crystal, an LB4 crystal, or an LBO crystal can be used.

 Returning to FIG. 1, the illumination optical system 12 is configured to include an optical integrator, a variable ND filter, a reticle blind, and the like (all not shown). Here, a fly-eye lens, an internal reflection type integrator (such as a rod integrator), or a diffractive optical element is used as the optical integrator. The configuration of such an illumination optical system is disclosed in, for example, Japanese Patent Application Laid-Open No. H10-124433, Japanese Patent Application Laid-Open No. H6-349701, and corresponding US Pat. No. 5,534,970. . To the extent permitted by the national laws of the designated or elected nations designated in this international application, the disclosures in the above US patents will be incorporated by reference as if set forth in this specification.

 Exposure light IL emitted from the illumination optical system 12 passes through a condenser lens 32 after the optical path is bent vertically downward by a mirror M, and then passes through a condenser lens 32 to form a rectangular illumination on a reticle R held on a reticle stage RST. Illuminate area 42R with a uniform illumination distribution.

 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 movable in a horizontal plane (XY plane), and is moved by a reticle stage driving unit 49 in a predetermined direction in the scanning direction (here, the Y-axis direction, which is the horizontal direction in FIG. 1). It is designed to be scanned in a range. The position and the amount of rotation of the reticle stage RST during this scanning are measured by an external laser interferometer 54R via a movable mirror 52R fixed on the reticle stage RST, and the measurement of the laser interferometer 54R is performed. The value is supplied to the main controller 50.

The projection optical system PL is, for example, a double-sided telecentric reduction system, and includes a plurality of lens elements having a common optical axis AX in the Z-axis direction.c As the projection optical system PL, Magnification; 8 is for example 14, 15, 1 No. 6 and others are used. Therefore, as described above, when the illumination area 42 R on the reticle R is illuminated by the exposure light I, the projection optical system of the illumination area 42 R portion of the pattern formed on the reticle R A reduced image (partial isometric image) by the PL is projected onto a rectangular projection area 42 W conjugated to the illumination area 42 R within the field of view of the projection optical system PL, and is projected onto a resist applied on the surface of the wafer W. The reduced image is transferred.

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

 Here, the moving mirror actually has 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. X-axis position measurement, Y-axis position measurement, and rotation (including jogging, pitching, and rolling) measurements are provided, respectively. In Figure 1, these are typically used as moving mirrors. Shown as 52 W, laser interferometer 54 W.

On the Z tilt stage 58, a reference mark plate FM used for performing reticle alignment or the like described later is provided. This fiducial mark plate FM has its surface almost at the same height as the surface of the wafer W. This fiducial mark plate has a reticle alignment fiducial mark and a baseline measurement fiducial mark on the surface of FM. Reference marks such as marks are formed.

 Further, in the exposure apparatus 10 of the present embodiment, as shown in FIG. 1, under the control of the main controller 50, a large number of meters set on the imaging plane (XY plane) of the projection optical system PL are provided. An irradiation optical system 60a for irradiating an imaging light beam for forming an image of a pinhole or a slit toward the measurement point from an oblique direction with respect to the optical axis AX, and a wafer W of the imaging light beam. An oblique incidence type multi-point focal position detection system (focus sensor) comprising a light receiving optical system 60b for receiving a light beam reflected on the surface is provided. The detailed configuration of the multi-point focal position detection system (focus sensor) similar to that of the present embodiment is described in, for example, Japanese Patent Application Laid-Open No. Hei 6-284304 and US Pat. , 332, etc. To the extent permitted by the national laws of the designated country or selected elected countries specified in this international application, the disclosures in the above-mentioned publications and US patents are incorporated herein by reference.

 At the time of scanning exposure, etc., the main controller 50 determines a part of the surface of the shot area where the measurement point exists based on the Z position detected for each measurement point from the light receiving optical system 60b. By sequentially calculating the Z position and the tilt amount, and controlling the Z position and the tilt angle of the Z tilt stage 58 via a drive system (not shown) based on the calculation results, auto focus (automatic focusing) and Perform auto-leveling. The main controller 50 includes a so-called microcomputer (or workstation) including a CPU (central processing unit), a ROM (read only memory), a RAM (random access memory), and the like. In addition to the various controls described above, for example, synchronous scanning of the reticle R and the wafer W, stepping of the wafer W, exposure timing, and the like are controlled so that the exposure operation is performed appropriately. Further, in the present embodiment, the main controller 50 controls the exposure amount at the time of scanning exposure as will be described later, and also controls the entire apparatus.

More specifically, for example, at the time of scanning exposure, reticle R moves reticle R to illuminated area 42R in the + Y direction (or one Y direction) via reticle stage RST. In synchronization with the scanning at the speed VB = V, the wafer W is moved in one Y direction (or + Y direction) with respect to the projection area 42 W via the XY stage 14 in synchronization with the speed _VW. =) S ■ V () 8 is a reticle stage drive unit 49 based on the measured values of the laser interferometers 54 R and 54 W so that the scanning is performed with the reticle R from the reticle R to the wafer W). The position and speed of reticle stage RST and X stage 14 are controlled via wafer stage drive unit 56, respectively. In stepping, the main controller 50 controls the position of the stage 14 via the wafer stage driving unit 56 based on the measurement value of the laser interferometer 54W.

 Next, an exposure sequence when a reticle pattern is exposed on a predetermined number (Ν) of wafers W in the exposure apparatus 10 of the present embodiment will be described focusing on the control operation of the main controller 50.

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

 Next, a reticle alignment is performed using a reticle alignment system (not shown), and a base line measurement of an off-axis type alignment system (not shown) is performed using the aforementioned reference marks. Preparation work such as reticle alignment and baseline measurement is described in detail in, for example, Japanese Patent Application Laid-Open No. 7-176468 and US Patent Nos. 5,646,413 corresponding thereto. To the extent permitted by the national law of the designated State designated in this International Application or of the elected State to which it is disclosed, a portion of the description herein shall be incorporated by reference to its disclosure in the above-mentioned publications and corresponding U.S. patents. And

Next, main controller 50 instructs a wafer transfer system (not shown) to replace wafer W. As a result, the wafer exchange (if there is no wafer on the stage, a simple wafer load) is performed by the wafer transfer system and a wafer transfer mechanism (not shown) on the stage 14. Since the wafer exchange is performed in the same manner as in a known exposure apparatus, a detailed description is omitted. Then, a search alignment and a so-called fine alignment using the alignment system in which the above-described baseline measurement was performed, for example, Japanese Patent Application Laid-Open No. 61-44929 and corresponding US Pat. Performs a series of alignment processes including EGA wafer alignment, etc., disclosed in detail in 780, 617, etc. To the extent permitted by the national laws of the designated or designated elected States in this International Application, the disclosures in the above-mentioned publications and corresponding US patents are incorporated herein by reference.

 Next, based on the alignment result and the shot map data, an operation of moving the wafer W to a scanning start position (acceleration start position) for exposure of each shot area on the wafer W; By repeatedly performing the scanning exposure operation, the reticle pattern is transferred to a 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 modulation controller 16C in order to give the target integrated exposure amount determined according to the exposure condition and the resist sensitivity to the wafer W. Control.

 When the exposure for 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 a wafer transfer mechanism (not shown) on the XY stage 14. Thereafter, search alignment and fine alignment are performed on the replaced wafer in the same manner as described above. Do.

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

The illuminance is changed by at least one of the exposure condition (including the light amount distribution of the exposure light IL on the pupil plane of the illumination optical system, that is, the illumination condition of the reticle R, the numerical aperture of the projection optical system PL) and the reticle pattern. When it changes, it is desirable to control at least one of the frequency and the peak power of the light emitted from the light source device 16 so that an appropriate exposure amount is given to the wafer (the resist). This and In addition, 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, according to the light source device 16 according to the present embodiment, after the continuous light generated by the continuous light generation unit 160 is pulse-modulated, the pulse light is converted into a wavelength conversion unit for each pulse light. The EOM 132 performs the phase modulation of the phase modulation amount that cancels the phase modulation amount caused by the self-phase modulation received when passing through the medium on the optical path up to 163. Therefore, it is possible to suppress an increase in the spectrum width of the light incident on the wavelength conversion unit 163, and to supply light with good monochromaticity to the wavelength conversion unit 163. Therefore, the monochromaticity of the wavelength-converted light emitted from the wavelength converter 163 can be improved.

 In addition, by disposing an EOM 132 for performing phase modulation between the EOM 131 for performing pulse modulation and the optical amplifying unit 161, for example, when the EOM 32 is disposed after the optical amplifying unit 161. The peak intensity of the light passing through the EOM132 can be reduced as compared with the case of FIG. This extends the life of the EOM 132 components.

 Furthermore, when an optical pulse having a relatively narrow pulse width is used, the pulse light emitted from the EOM 13 1 1 is arranged by placing the EOM 13 2 between the EOM 13 1 and the optical amplification section 161. Since the beam is incident on the EOM 132 with no (or almost no) inclusions, the phase modulation signal MD2 is supplied to the EOM 132 with high precision timing for phase modulation of the pulsed light. can do. Therefore, a phase modulation amount corresponding to the light intensity at each instant can be accurately given to the pulse light, and the expansion of the spectrum width of the light incident on the wavelength conversion unit 163 can be effectively suppressed. Can be.

In addition, since the EOM132 using a medium having an electro-optic effect is used as the phase modulator, the phase modulation can be accurately performed by adjusting the waveform of the voltage signal that can control the level value accurately and easily. It can be performed. In addition, in the stage immediately after the continuous light generating unit 160, pulse cutout is performed by pulse modulation using the EOM131.Thus, by controlling the light pulse cutout interval and the optical amplification rate, the light source device 16 can be used as a light source device. The configuration can be easily controlled.

 Further, according to the exposure apparatus of the present embodiment, the reticle R can be irradiated with the illumination light IL having high monochromaticity at the time of exposure, so that the chromatic aberration of the projection optical system PL can be effectively suppressed. The formed pattern can be accurately transferred to wafer W.

 In the above embodiment, the EOM 132 for performing phase modulation is arranged between the EOM 13 31 for performing pulse modulation and the optical amplifier 161. And the wavelength conversion unit 163. The point is that the EOM 132 should be placed in the optical path up to the wavelength conversion section 163 where the pulse light propagates.

 Further, in the above embodiment, the EOM 1 31 for performing the pulse modulation and the EOM 1 32 for performing the phase modulation are separately provided, but the voltage signals MD 1 1, By supplying a modulation signal in which the phase modulation signal MD 2 is superimposed on each of the MDs 12, pulse modulation and phase modulation may be performed simultaneously by one electro-optic modulator.

 Further, in the above-described embodiment, the electrodes 13 1 and 1 32 are arranged as the EOM 131 that performs pulse modulation according to each of the two branched waveguides. However, the electrodes are arranged only on one of the two branched waveguides. It can also be configured.

 << 2nd Embodiment >>

 Next, a second embodiment of the present invention will be described. The exposure apparatus according to the second embodiment has the same configuration as the exposure apparatus 10 according to the above-described first embodiment except that the configuration of the light source apparatus is different from that of the above-described first embodiment. I have.

That is, as shown in FIG. 8, the light source device 16 according to the second embodiment The difference from the light source device of the first embodiment (see FIG. 2) is that there is no EOM132 and that the optical amplifier 161 'is used instead of the optical amplifier 161. I do. Hereinafter, the second embodiment will be described focusing on such differences. In the description of the second embodiment, the same or equivalent elements as those of the first embodiment will be denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 9, the optical amplifying unit 161 ′ of the second embodiment is different from the optical amplifying unit 161 of the first embodiment (see FIG. 5) in the optical fiber amplifier 167. The difference is that an optical fiber amplifier 1 67 'is used instead. The optical fiber amplifier device 1 67 'are disposed between the front-stage optical amplifier 1 41 and the rear-stage optical amplifier 1 42 in the optical fiber amplifier 1 67, more precisely, the phase between the optical isolator 1 77 and WDM 1 79 ₂ The only difference from the optical fiber amplifier 167 is that the modulator 138 is provided.

The phase modulator 1 38, as shown in FIG. 1 OA, the amplification optical fiber 1 75Kai, a non-linear optical element 330 having a non-linear refractive index with a polarity opposite to that of the 1 75 ₂ nonlinear refractive index, the A DC power source 332 for applying a voltage to the nonlinear optical member 330 via an electrode 331 including a pair of electrode plates 33 11 and 3312 is provided. In the second embodiment, as the material of the nonlinear optical element 330, a semiconductor optical amplifier I _ni is also used as an amplification medium _{- x G a x A S l} - Y P Y mixed crystal is used.

This Im-xGaxA si-γ Ργ mixed crystal is an amplification optical fiber that is a main nonlinear optical member other than the nonlinear optical member 330 in the optical path of the pulse light from the EOM 131 that performs pulse modulation to the wavelength conversion section 163. It has a nonlinear refractive index of the opposite polarity to the silica force glass constituting the 1 75 ^ 1 75 _2. That is, while the Shirikagara scan has a positive nonlinear refractive _{index, I nnG a x A Sl -} Y P Y mixed crystal is negative nonlinear refractive index (= -2 X 1 O i 5 m 2 / "W: Grant et al., 1991, Appl. Phys. Lett. 58 (11), plll9), whose absolute value is 5 times higher than that of silica glass. It is about an order of magnitude larger. When no voltage is applied, I rn.xG ax A si-γ Ργ mixed crystal has absorptivity for light in the 1.55 m band, so that the gain should be Γ 1 j. A voltage is applied from the DC power supply 332 to the nonlinear optical member 330 via the electrode 331.

In the phase modulator 138, as shown in FIG. 10B, the incident pulse light L 21 hardly deforms by passing through the nonlinear optical member 330 (the intensity (amplitude) does not change). 2) The pulse light L22 is emitted. On the other hand, when the pulsed light passes through the nonlinear optical member 330, according to the above (2), _c such phase phase-modulated according to the intensity and the optical path length definitive nonlinear optical element within 330 of each moment of the pulsed light is performed As shown in FIG. 10B, the phase modulation amount 0 _PM imparted to the emission light L22 by the modulation depends on the intensity of the emission light L22 at each instant. Although the phase modulation amount 0PM is proportional to the optical path length in the nonlinear optical member 330, the optical path length in the nonlinear optical member 330 is such that the phase modulation amount 0PM by the phase modulator 138 is It is set to an amount to become long to cancel the self-phase modulation amount 0 _{S PM} that Ru received in the optical path to the conversion unit 1 63.

When the pulse light L2 'is incident on the optical fiber amplifier 167' configured as described above, the pulse light L2 'is passed through the amplification optical fibers 1 75ι and 175 ₂ as in the case of the first embodiment. There while being amplified, mainly amplifying optical fiber 1 75Iota, 1 75 self-phase modulation of the pulsed light in the _two is offset by our Keru phase modulation to the phase modulator 1 38. As a result, the spread of the pulse width of the pulse light due to the self-phase modulation is suppressed, and the high-intensity pulse light L 3 ′ having a high unity of the wavelength is transmitted from the optical amplification unit 161 ′ to the wavelength conversion unit 163. It is injected toward.

That is, in the light source device 16 of the second embodiment, in the same manner as in the first embodiment, a pulse is cut out by the EOM 131 from the continuous light L 1 ′ generated by the continuous light generation unit 160. Is performed to generate an optical pulse train L 2 ′. Each pulse light of each pulse train L 2 ′ of the optical pulse train generated in this way is supplied to the optical amplifier 161 ′. At the same time, the expansion of the spectrum width due to self-phase modulation is suppressed. Then, the light L3 ′ emitted from the optical amplifier 161 ′ enters the wavelength converter 163, is wavelength-converted, and is emitted as light emitted from the light source device 16. The pattern formed on the reticle R is transferred onto the wafer W using the light emitted from the light source device 16 in the same manner as in the first embodiment.

As described above, according to the light source device 16 according to the second embodiment, the same effects as those of the above-described first embodiment can be obtained, and as a result, the wavelength conversion unit 163 can be obtained. in addition to _c which can enhance the monochromaticity of the wavelength converted light emitted from, also as a phase modulator, nonlinear refractive index, the amplification optical fiber 1 75Iota, the polarity of the 1 75 ₂ nonlinear refractive index Since the nonlinear optical member having the opposite polarity is used, the phase modulation can be accurately performed without performing dynamic control in the phase modulation.

 In addition, according to the exposure apparatus of the second embodiment, the reticle R can be irradiated with the illumination light IL having high monochromaticity at the time of exposure, so that the chromatic aberration of the projection optical system PL can be effectively suppressed. The pattern formed on R can be transferred onto wafer W with high accuracy.

 In the second embodiment, the phase modulator 138 for performing the phase modulation is disposed between the first-stage optical amplifier 141 and the second-stage optical amplifier 142, but the optical path length in the nonlinear optical member is adjusted. A phase modulator of the same type as the phase modulator 138 may be disposed between the EOM 13 1 and the upstream optical amplifier 141, or the downstream optical amplifier 142 and the wavelength converter It may be arranged between 1 and 63. That is, similarly to the EOM 132 in the first embodiment, the phase modulator 138 can be arranged in the optical path for transmitting the pulse light to the wavelength converter 163.

Further, in the second embodiment, I ni-xG as the material of the nonlinear optical element 330 of the phase modulator _{1 38 a x A S l -} Y Ρ Υ was used mixed crystal, the amplifying optical fiber 1 75Iota, A material with a non-linear refractive index different in polarity from the non-linear refractive index of the material of 1 75 ₂ Material, it can be adopted as the material of the nonlinear optical member 330. << Third embodiment >>

 Next, a third embodiment of the present invention will be described. The exposure apparatus of the third embodiment has the same configuration as that of the exposure apparatus 10 of the first embodiment except that the configuration of the light source apparatus is different from that of the above-described first embodiment. I have.

 That is, as shown in FIG. 11, the light source device 16 according to the third embodiment does not have the EOM 13 2 as compared with the light source device according to the first embodiment (see FIG. 2). The difference is that a current driver 136 'for supplying a signal on which a phase modulation signal described later is superimposed is used instead of the current driver 136 for supplying a DC current signal. Hereinafter, the third embodiment will be described focusing on such differences. In the description of the third embodiment, the same or similar elements as those of the first embodiment are denoted by the same reference numerals, and duplicate description will be omitted.

 Here, the principle of the phase modulation used in the third embodiment will be briefly described.

 In a semiconductor laser device, a current flows through the active layer to cause a population inversion between the conduction band and the valence band, and the spontaneous emission in the population inversion state is supplied from the resonator as a trigger. A laser beam is generated according to the amount of current. The carriers are concentrated on the light emitting portion by the current supply for light emission, and the refractive index changes due to the concentration of the carriers. The change in the refractive index changes according to the concentration of the carrier, but the concentration of the carrier changes according to the amount of supplied current. That is, the refractive index of the light emitting portion changes due to the change in the supplied current amount, and the laser light emitted is phase-modulated by the change in the refractive index (see the above-mentioned equation (2)). The amount of the phase modulation can be changed by changing the supply current.

In the third embodiment, the phase modulation is performed by utilizing the above principle and performing amplitude modulation of the drive signal DV ′ for the continuous generation unit 16 and the semiconductor laser 16 OA. The generated laser light is generated.

 That is, as shown in FIG. 12, a drive signal DV ′ in which an AC component for phase modulation is superimposed on a DC component is supplied from the current driver 136 to the DFB semiconductor laser 1.

6 Supplied to OA. Here, the period of the AC component in the drive signal DV ′ is substantially equal to the light / loss width that is cut out later by the EOM. As a result, light L 1 "having an intensity waveform corresponding to the waveform of the drive signal DV 'is emitted from the DFB semiconductor laser 16 OA. Thus, the light L 1" emitted from the DFB semiconductor laser 16 OA is As described above, the phase is modulated according to the intensity at each instant.

 The light L 1 "emitted from the DFB semiconductor laser 16 OA is pulse-modulated by the EOM 13 1. In this pulse modulation, the EOM 13 1 outputs the modulated signal MD 1 from the modulation controller 16 C. The pulse light L 2 ”emitted from the EOM1 31 in response to the pulse cutout instruction by the EOM1 31 has a time change of the phase modulation amount 0 PM that can cancel the self-phase modulation amount 0 SPM received on the optical path to the wavelength conversion unit 163 at 0 PM. Perform pulse cutting. In this way, each pulsed light is emitted from the optical pulse train L2 "force EOM131, which has been subjected to phase modulation to cancel the self-phase modulation received later.

When the optical pulse train L 2 ″ generated as described above is incident on the optical amplifying unit 161, as in the case of the first embodiment, the optical pulse train L 2 ″ passes through the amplifying optical fiber 175 175 ₂ , Each pulsed light is amplified, and mainly the amplification optical fiber 1

75ι, 1 75 ₂ self-phase modulation of the pulsed light in is canceled by the phase modulation which has already been made at the time of injection from D FB semiconductor laser 1 6 OA. As a result, the expansion of the pulse width of the pulse light due to the self-phase modulation is suppressed, and a high-intensity pulse light having a high wavelength uniformity is directed from the 3 "power amplifier 161 to the wavelength converter 163. Is injected.

That is, in the light source device 16 of the third embodiment, the light is emitted from the continuous light generation unit 160. From the generated phase-modulated light L 1 ", the EOM 1331 performs pulse extraction at a timing at which the amount of phase modulation that cancels out the subsequent self-phase modulation changes with time, and an optical pulse train L 2" is generated. Each pulse of light pulses L 2 "produced in this way, along with the amplified in the optical amplifier unit 1 6 1, economies of Bae spectrum width due to self-phase modulation in the amplification optical fiber 1 7 5 1 7 5 ₂ Then, the light L 3 ″ emitted from the optical amplification unit 16 1 enters the wavelength conversion unit 16 3, is wavelength-converted, and is emitted as emission light from the light source device 16. . The pattern formed on the reticle R is transferred onto the wafer W using the light emitted from the light source device 16 in the same manner as in the first embodiment.

 As described above, according to the light source device 16 according to the third embodiment, the continuous light generated by the continuous light generation unit 160 is pulse-modulated when the continuous light generation unit 160 generates laser light. Then, for each pulse light, a phase modulation amount that cancels out the phase modulation amount caused by self-phase modulation received when the respective pulse light passes through the medium on the optical path up to the wavelength conversion unit 163. Perform phase modulation. Therefore, it is possible to suppress an increase in the spectrum width of the light incident on the wavelength conversion unit 163, and to supply light with good monochromaticity to the wavelength conversion unit 163. Therefore, the monochromaticity of the wavelength-converted light emitted from the wavelength converter 163 can be improved. Further, according to the exposure apparatus of the third embodiment, the reticle R can be irradiated with the illumination light IL having high monochromaticity at the time of exposure, so that the chromatic aberration of the projection optical system is effectively suppressed, and the reticle R is formed on the reticle R. The transferred pattern can be accurately transferred to the wafer W.

In the third embodiment, the phase modulation signal to the drive signal DV ′ is a continuous AC current component. However, the intensity modulation signal is almost equivalent to the pulse width in response to the pulse extraction instruction. The phase modulation signal may be superimposed on the DC component, and the light generated by driving with the drive signal DV ′ during the period in which the phase modulation signal is superimposed may be pulse-cut out by the EOM 131. It is needless to say that the phase modulation methods described in the first to third embodiments can be applied in any combination.

 Further, in each of the above embodiments, the phase modulation amount 0PM intentionally applied does not necessarily have to coincide with the amount that cancels the self-phase modulation amount 0SPM. For example, the phase modulation amount 0PM is made different from the self-phase modulation amount 0SPM within a range in which the spectrum width required by the above-described exposure apparatus can be obtained. In other words, the phase modulation amount 0PM is equal to the self-phase modulation amount 0SPM. It may be an amount that partially cancels out. Also in such a case, the effect of controlling the expansion of the spectrum width is exerted.

Further, the configuration of the wavelength conversion unit in each of the above embodiments is merely an example, and it goes without saying that the configuration of the wavelength conversion unit, the material of the nonlinear optical crystal, the output wavelength, and the like are not limited thereto. For example, the fundamental wave of wavelength 1. 57 jt m emitted from the optical amplifying portion 1 63 performs harmonic generation 1 0 harmonic by using a nonlinear optical crystal, 1 57 nm is the same wavelength as the F ₂ laser UV light can be generated.

 In each of the above embodiments, a DFB semiconductor laser was used as the laser light source 16 OA. However, other semiconductor lasers or ytterbium (Yb) -doped fiber having an oscillation wavelength of around 990 nm, for example, were used. A fiber laser such as a laser can also be used.

 In each of the above embodiments, the Er-doped fiber is used as the amplification optical fiber. However, a Yb-doped fiber or another rare-earth element-doped fiber may be used.

 In each of the embodiments described above, the optical fiber in which the rare earth element is added to the core is used as the amplification medium. For example, a rod-shaped glass body to which the rare earth element is added is used, May be irradiated.

Further, the number of optical fiber amplifiers arranged in parallel in the optical amplification section 161 or 161 'may be arbitrary, and the number may be determined according to the specifications required for the product to which the light source device according to the present invention is applied. Should be determined. In particular, high output as a light source device When the requirement is not required, the number of optical fiber amplifiers can be reduced and the configuration can be simplified. When simplifying to include only one optical fiber amplifier, the splitter 166 is not required.

 In addition, by connecting optical fiber amplifiers in series, the optical gain of one path can be increased. In such a case, an appropriate light amount control device may be provided between the optical fiber amplifier, which may be destroyed due to the generation of a giant pulse, and the wavelength converter.

 In each of the above embodiments, a single laser light source 16 OA is used. However, a plurality of laser light sources 16 OA are used, and at least one of the light source units 16 A shown in FIG. The same number of optical elements as the laser light source (optical isolators 16B, EOM 131, 1332, optical amplifiers 161, etc.) except for the part 163 should be provided. A large number of output lights L4 generated by the light source unit and the wavelength division multiplexing device described above may be configured to be incident on the wavelength conversion unit 163.

In each of the above embodiments, 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. However, the set wavelength may be arbitrarily set. The oscillation wavelength of the laser light source 16 OA, the configuration of the wavelength converter 16 3, the magnification of the harmonics, and the like may be determined according to the conditions. The set wavelength may be determined, for example, in accordance with the design rules (line width, pitch, etc.) of the pattern to be transferred onto the wafer. (Phase shift type or not) may be considered. Further, in each of the above embodiments, 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, but the apparatus used in a device manufacturing process other than the exposure apparatus is used. For example, the light source device according to the present invention can be applied to a laser repair device used for cutting a part (such as a fuse) of a circuit pattern formed on a wafer. Also the book The present invention can be suitably applied not only to a step-and-scan type scanning exposure apparatus, but also to a static exposure type, for example, a step-and-repeat type exposure apparatus (such as a stepper). Furthermore, the present invention can be applied to a step-and-stick type exposure apparatus, a mirror projection aligner, and the like.

 Further, in each of the above embodiments, an example in which the light source device according to the present invention is used as a light source device for generating exposure illumination light has been described, but light having substantially the same wavelength as the exposure illumination light is required. A light source device for a reticle alignment described above, or a light source device for a spatial image detection system that detects a projection image of a mark arranged on an object plane or an image plane of the projection optical system and obtains optical characteristics of the projection optical system It is also possible to use as such. The light source device of the present invention can be used for various devices other than the exposure device. For example, it is used for laser treatment equipment that irradiates the cornea with laser light to ablate the surface (or ablation inside the incised cornea), corrects the curvature or ω convexity of the cornea, and treats myopia, astigmatism, etc. It can be used as a light source device. Further, the light source device of the present invention can be used as a light source device in an optical inspection device or the like.

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

 《Device manufacturing method》

 Next, the manufacture of devices (such as semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin-film magnetic heads, and micromachines) using the exposure apparatuses and methods of the above embodiments will be described.

FIG. 13 shows a flowchart of an example of manufacturing the device. As shown in FIG. 13, first, in step 201 (design step), a device function / performance design (for example, circuit design of a semiconductor device) is performed. A pattern is designed to realize the function. Subsequently, in step 202 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 203 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

 Next, in step 204 (wafer processing step), using the mask and the wafer prepared in steps 200 to 223, as described later, the actual Next, in step 205 (device assembly step), device assembly is performed using the wafer processed in step 204. In step 205, a dicing process and a bonding process are performed. Steps such as, and the packaging step (chip encapsulation) are included as necessary.

 Finally, in step 206 (inspection step), inspections such as an operation confirmation test and a durability test of the device created in step 205 are performed. After these steps, the device is completed and shipped.

 FIG. 14 shows a detailed flow example of the above step 204 in the semiconductor device. In FIG. 14, in step 2 11 (oxidation step), the surface of the wafer is oxidized. In step 2 12 (CVD step), an insulating film is formed on the wafer surface. In step 2 13 (electrode formation step), electrodes are formed on the wafer by vapor deposition. In step 2 14 (ion implantation step), ions are implanted into the wafer. Each of the above-mentioned steps 211 to 214 constitutes a pre-processing step of each stage of wafer processing, and is selected and executed according to necessary processing in each stage.

In each stage of the wafer process, when the above-described pre-processing step is completed, the post-processing step is executed as follows. In this post-processing step, first, in step 215 (resist forming step), a photosensitive agent is applied to the wafer. Subsequently, in step 2 16 (exposure step), the lithography described above was performed. The circuit pattern of the mask is transferred to the wafer by the stem (exposure apparatus) and the exposure method. Next, in Step 217 (development step), the exposed wafer is developed, and in Step 218 (etching step), the exposed members other than the portion where the resist remains are removed by etching. Then, in step 219 (resist removing step), the unnecessary resist after etching is removed.

 By repeating these pre-processing and post-processing steps, multiple circuit patterns are formed on the wafer.

 By using the device manufacturing method of the present embodiment described above, the exposure apparatus of each of the above-described embodiments is used in the exposure step (step 2 16), so that the reticle pattern can be accurately transferred onto the wafer. it can. As a result, highly integrated devices can be manufactured with good productivity (including yield). Industrial applicability

 As described in detail above, the light source device of the present invention is suitable for generating high-luminance light with improved wavelength unity. Further, the light irradiation device of the present invention is suitable for irradiating an object with high-intensity light having improved unity of wavelength, and particularly when the object is a mask, the light irradiation apparatus is formed on the mask. Suitable for transferring transferred patterns. Further, the device manufacturing method of the present invention is suitable for microdevice production.

Claims

The scope of the claims

1. a light generator including a light generator for generating light of a predetermined wavelength;

 An optical amplifier for amplifying the light of the predetermined wavelength;

 A wavelength converter for wavelength-converting the light amplified by the optical amplifier;

 And a phase modulator disposed in an optical path from the light generation unit to the wavelength conversion unit and performing a phase modulation for canceling at least a part of a self-phase modulation of light traveling in the optical path.

2. The light source device according to claim 1,

 The phase modulator,

 An electro-optic modulation element arranged on the optical path and performing phase modulation according to the amplitude of the supplied electric signal for modulation;

 A light source device for supplying an electric signal having an amplitude corresponding to the intensity of light passing through the electro-optic modulation element to the electro-optic modulation element as the modulation electric signal. .

3. The light source device according to claim 1,

 The light source device, wherein the phase modulator is arranged in an optical path from the light generation unit to the light amplification unit.

4. The light source device according to claim 1,

Wherein the phase modulator includes a nonlinear optical member made of a material having a polarity opposite to the polarity of the nonlinear refractive index of the light propagation medium in the optical amplification unit.

5. In the light source device according to claim 4,

 The light source device, wherein the nonlinear optical member is made of an Im-xGaxA si-γΡγ mixed crystal.

6. The light source device according to claim 1,

 The light generating unit generates continuous light,

 A light source device further comprising a pulse modulator arranged at a stage immediately after the light generation unit and for extracting pulse light from the continuous light.

7. The light source device according to claim 1,

 The light source device, wherein the light generator generates laser light of substantially a single wavelength within a wavelength range from an infrared region to a visible region, and the wavelength conversion unit emits ultraviolet light.

8. The light source device according to claim 1,

 The light source device, wherein the optical amplification unit includes an amplification optical fiber.

9. a light generator for generating light of a predetermined wavelength;

 A drive signal supply unit for supplying a drive signal on which a phase modulation signal for performing phase modulation for canceling at least a part of self-phase modulation in an optical path where light generated by the light generator is superimposed to the light generator to the light generator; When;

 A light amplification unit that amplifies the light of the predetermined wavelength.

10. The light source device according to claim 9,

A light source device further comprising a pulse modulator disposed on an optical path from the light generator to the light amplifying unit, and for extracting pulse light from light emitted from the light generator.

11. The light source device according to claim 9,

 The light source device further comprises a wavelength conversion unit that converts the wavelength of the light amplified by the optical amplification unit.

12. The light source device according to claim 11,

 The light source device, wherein the light generator generates laser light of substantially a single wavelength within a wavelength range from an infrared region to a visible region, and the wavelength conversion unit emits ultraviolet light.

13. The light source device according to claim 9,

 The light source device, wherein the optical amplification unit includes an amplification optical fiber.

1 4. A light irradiation device for irradiating an object with light,

 A light source device according to any one of claims 1 to 13;

 An irradiation optical system that emits light emitted from the light source device toward the object.

15. The light irradiation device according to claim 14, wherein

 The object is a mask on which a predetermined pattern is formed,

 A light irradiation device further comprising a projection optical system for projecting the light emitted from the mask onto a photosensitive object.

1 6. A device manufacturing method including a lithographic process,

16. A device manufacturing method comprising: exposing the photosensitive object through the mask and the projection optical system using the light irradiation device according to claim 15 in the lithographic process.

17. An exposure apparatus for transferring a pattern of a mask onto a photosensitive object, wherein the light source device according to any one of claims 1 to 13;

 An illumination optical system that irradiates the mask with light emitted from the light source device.

18. The exposure apparatus according to claim 17,

 An exposure apparatus, further comprising: a control device that controls the light source device to adjust the intensity of light or the integrated light amount applied to the photosensitive object via the mask.

1 9. A device manufacturing method including a lithographic process,

 18. A device manufacturing method, comprising: exposing the photosensitive object through the mask using the exposure apparatus according to claim 17 during the lithographic process.