JP2013007931A - Laser device, exposure device and inspecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser device able to stably control the power of output light.SOLUTION: The laser device comprises: a UV light output part I configured to output a UV laser beam whose wavelength is in an ultraviolet region; VIR light output parts II and III configured to output a VIR laser beam whose wavelength is in a visible to infrared regions; a DUV light conversion part IV configured to generate and output a DUV laser beam by wavelength-converting a UV laser beam output from a UV light output part I and a VIR laser beam output from the VIR light output part, the DUV laser beam having a wavelength shorter than a UV laser beam; and a control part 8 configured to control the operations of the UV light output part and VIR light output part. The control part 8 is configured such that when the power of DUV laser beam is changed, the power of UV laser beam is made substantially constant, and the power of VIR laser beam is changed.

Description

  The present invention includes a UV light output unit that outputs UV laser light in the ultraviolet region, a VIR light output unit that outputs VIR laser light in the visible to infrared region, and a UV laser by wavelength conversion from the UV laser light and the VIR laser light. The present invention relates to a laser apparatus configured to include a DUV light conversion unit that generates DUV laser light having a wavelength shorter than that of light, and a control unit that controls operations of the UV light output unit and the VIR light output unit.

  The laser device as described above is known as a light source suitable for a microscope, a shape measuring device, various inspection devices, an exposure device, and the like (see Patent Literature 1 and Patent Literature 2). A schematic configuration of the laser device LS9 described in Patent Document 1 is shown in FIG.

  The laser device LS9 includes a UV light output unit I that outputs UV laser light in the ultraviolet region, a VIR light output unit that outputs VIR laser light in the visible to infrared region, and wavelength conversion from UV laser light and VIR laser light. A DUV light conversion unit IV that generates DUV laser light and a control unit 908 that controls the operation of each unit including the UV light output unit and the VIR light output unit are configured. The VIR light output unit includes a first VIR light output unit II that outputs a first VIR laser beam in the visible to infrared region and a second VIR light output unit III that outputs a second VIR laser beam in the visible to infrared region. The

  In this configuration example, the UV light output unit I, the first VIR light output unit II, and the second VIR light output unit III are supplied with seed light from a common light source. That is, the seed light emitted from the seed light generation unit 910 is divided into three parts and is incident on the UV light output unit I, the first VIR light output unit II, and the second VIR light output unit III, respectively. The seed light emitted from the seed light generator 910 is laser light having a predetermined wavelength in the visible to infrared region, for example, infrared laser light having a wavelength of 1544 nm. The seed light is laser light having a fundamental wave.

  The UV light output unit I includes a fiber optical amplifier 921 that amplifies seed light, wavelength conversion optical elements 931, 932, 933, and the like. In addition, what is shown by an ellipse on each optical path in FIG. 7 is a lens for condensing and inputting laser light to each wavelength conversion optical element. The seed light emitted from the seed light generator 910 is amplified by the fiber optical amplifier 921, and the amplified seed light, that is, the fundamental laser light is condensed and incident on the wavelength conversion optical element 931.

  The wavelength conversion optical element 931 performs second harmonic generation (SHG) of the fundamental wave. That is, a second harmonic having a wavelength half that of the fundamental wave and twice the frequency is generated. The second harmonic generated by the wavelength conversion optical element 931 and the fundamental wave transmitted through the wavelength conversion optical element 931 are condensed and incident on the wavelength conversion optical element 932. In the wavelength conversion optical element 932, the sum frequency generation (SFG) of the fundamental wave and the second harmonic is performed. That is, a third harmonic having a wavelength of 1/3 of the fundamental wave and a frequency three times as large as that of the fundamental wave is generated.

  The third harmonic generated by the wavelength conversion optical element 932 and the second harmonic transmitted through the wavelength conversion optical element 932 are condensed and incident on the wavelength conversion optical element 933. The wavelength conversion optical element 933 generates the sum frequency of the second harmonic and the third harmonic. That is, a fifth harmonic having a wavelength 1/5 of the fundamental wave and a frequency five times is generated. The fifth harmonic generated in the wavelength conversion optical element 933 is UV laser light having a wavelength of 309 nm and in the ultraviolet region. The UV laser light that is the fifth harmonic generated by the wavelength conversion optical element 933 is emitted from the UV light output unit I and enters the dichroic mirror 941.

  The first VIR light output unit II includes a fiber optical amplifier 922 that amplifies seed light and a wavelength conversion optical element 934. The seed light emitted from the seed light generator 910 is amplified by the fiber optical amplifier 922. The amplified seed light, that is, the fundamental laser beam is condensed and incident on the wavelength conversion optical element 934. In the wavelength conversion optical element 934, second harmonic generation is performed, and a second harmonic having a wavelength ½ and a frequency twice that of the fundamental wave is generated. The second harmonic generated by the wavelength conversion optical element 934 is a first VIR laser beam having a wavelength of 772 nm and in the visible region. The first VIR laser light, which is the second harmonic generated by the wavelength conversion optical element 934, is emitted from the first VIR light output unit II and enters the dichroic mirror 942.

  The second VIR light output unit III includes a fiber optical amplifier 923 that amplifies seed light. The second VIR light output unit III is not provided with a wavelength conversion optical element. The seed light emitted from the seed light generator 910 is amplified by the fiber optical amplifier 923. The amplified seed light, that is, the fundamental laser light is emitted from the second VIR light output unit III as the second VIR laser light. The wavelength of the second VIR laser light is 1544 nm, which is laser light in the infrared region. The second VIR laser light emitted from the second VIR light output unit III is incident on the dichroic mirror 942.

  The dichroic mirror 942 is configured to transmit light in the fundamental wavelength band and reflect light in the second harmonic wavelength band. The dichroic mirror 941 is configured to transmit light in the fundamental and second harmonic wavelength bands and reflect light in the fifth harmonic wavelength band. Therefore, the first VIR laser light that is the second harmonic emitted from the first VIR light output unit II and the second VIR laser light that is the fundamental wave emitted from the second VIR light output unit III are coaxially connected by the dichroic mirror 942. In addition, the UV laser light, which is the fifth harmonic emitted from the UV light output unit I, is superimposed on the same axis by the dichroic mirror 941, and these three different wavelength laser beams are transmitted to the DUV light conversion unit IV. Incident.

  The DUV light conversion unit IV is provided with wavelength conversion optical elements 935 and 936. In the wavelength conversion optical element 935, the sum of the UV laser light that is the fifth harmonic emitted from the UV light output unit I and the first VIR laser light that is the second harmonic emitted from the first VIR light output unit II. Frequency generation is performed. That is, a first DUV laser beam having a wavelength that is 1/7 of the fundamental wave and a seventh harmonic whose frequency is seven times is generated. The second VIR laser light, which is a fundamental wave emitted from the second VIR light output unit III, passes through the wavelength conversion optical element 935 and enters the wavelength conversion optical element 936 together with the first DUV laser light generated by the wavelength conversion optical element 935. The wavelength conversion optical element 936 generates the sum frequency of the second VIR laser light that is the fundamental wave and the first DUV laser light that is the seventh harmonic wave. That is, the second DUV laser light having a wavelength of 1/8 of the fundamental wave and an eighth harmonic of 8 times the frequency is generated.

  The first DUV laser light generated by the wavelength conversion optical element 935 and the second DUV laser light generated by the wavelength conversion optical element 936 have wavelengths of 221 nm and 193 nm, respectively, and both are UV laser light emitted from the UV light output unit I It is a laser beam in the ultraviolet region having a shorter wavelength. The second DUV laser light generated by the wavelength conversion optical element 936 is output from the laser device LS9.

  In such a laser device, when the power of the second DUV laser light output from the laser device LS9 is changed, conventionally, the UV laser light emitted from the UV light output unit I according to the target power. The control unit 908 performs control to change the power of the first VIR laser light emitted from the first VIR light output unit II and the power of the second VIR laser light emitted from the second VIR light output unit III. Was configured.

  For example, the respective powers of the UV laser light, the first VIR laser light, and the second VIR laser light required in each case where the target power of the second DUV laser light is high and low are measured in advance. In accordance with the target power of the second DUV laser light, the control unit 908 outputs the UV light output unit I, the first VIR laser light, and the second VIR laser light so that each of the UV laser light, the first VIR laser light, and the second VIR laser light is emitted with appropriate power. The operation of the 1VIR light output unit II and the second VIR light output unit III is controlled. Specifically, the control unit 908 controls the excitation light intensity of the fiber optical amplifier 921 provided in the UV light output unit I, the excitation light intensity of the fiber optical amplifier 922 provided in the first VIR light output unit II, and the second VIR. Each of the pumping light intensities of the fiber optical amplifier 923 provided in the light output unit III is controlled to have a pumping light intensity corresponding to the target power of the second DUV laser light.

JP 2010-3771 A JP 2004-86193 A

  However, when changing the intensity of each pumping light for pumping the fiber optical amplifiers of the fiber optical amplifiers 921, 922, and 923 according to the target power of the second DUV laser light, the configuration of the control unit becomes complicated. . On the other hand, when the power of the second DUV laser light, which is the output light of the laser device LS9, is changed, the amount of change in the excitation light intensity of the fiber optical amplifier 921 for realizing the change in power, the excitation light of the fiber optical amplifier 922 There are a plurality of combinations of the change amount of the intensity and the change amount of the excitation light intensity of the fiber optical amplifier 923.

  For example, in order to change the power of the second DUV laser light from 200 mW to 400 mW, the rate of change of the excitation light intensity of the fiber optical amplifiers 922 and 923 is + 100%, respectively, whereas the excitation light of the fiber optical amplifier 921 The rate of change in intensity is + 40%. That is, in order to change the power of the second DUV laser light that is output light, it is most efficient to change the excitation light intensity of the fiber optical amplifier 921. Therefore, when the power of the second DUV laser light is to be changed in the range of 100 to 400 mW, the excitation light intensity of the fiber optical amplifiers 922 and 923 is the same value as that when the power of the second DUV laser light is 400 mW. If only the pumping light intensity of the fiber optical amplifier 921 is changed, the power of the second DUV laser light can be controlled efficiently.

  Based on the above viewpoint, the inventors have a UV light output unit I that outputs UV laser light in the ultraviolet region, a first VIR light output unit II that outputs VIR laser light in the visible to infrared region, and a second VIR light output. Controls the operation of the part III, the DUV light conversion part for generating a DUV laser light having a wavelength shorter than the UV laser light by wavelength conversion from the UV laser light and the VIR laser light, and the UV light output part and the VIR light output part A control unit, and when the control unit changes the power of the DUV laser light output from the DUV light conversion unit, the power of the VIR laser light output from the VIR light output unit is substantially constant, and the UV light output unit A laser apparatus has been devised that performs control to change the power of the output UV laser light.

  However, it has been found that it is difficult to keep the stability of the DUV laser light high in the conventional laser device described above and the laser device devised by the inventors. The UV laser light emitted from the UV light output unit is light in the ultraviolet region. An optical element that propagates ultraviolet light is likely to cause problems due to heat generation due to absorption of ultraviolet light. For example, in the laser device described above, the UV laser light, which is the fifth harmonic emitted from the wavelength conversion optical element 933 of the UV light output unit, has a wavelength of 309 nm and is close to the deep ultraviolet region. The problem of heat generation due to absorption is likely to occur. When heat is generated inside the crystal of the wavelength conversion optical element 933, phase mismatch occurs, and the wavelength conversion efficiency decreases and the beam pointing changes.

  When the beam pointing of the UV laser light emitted from the wavelength conversion optical element 933 fluctuates, the wavelength conversion optical element 935 superimposes the UV laser light that is the fifth harmonic and the first VIR laser light that is the second harmonic. As a result, the wavelength conversion efficiency and stability to the first DUV laser light are reduced. As a result, the wavelength conversion efficiency and power stability of the second DUV laser light, which is the output light of the laser device, are reduced. The same problem occurs with lenses, mirrors, and the like that guide the fifth harmonic emitted from the wavelength conversion optical element 933 to the wavelength conversion optical element 935.

  Therefore, in the method of changing the power of the UV laser light when changing the power of the second DUV laser light, which is the output light of the laser device, a change in heat generation due to absorption in each part due to the power change of the UV laser light, and accompanying this The problem that it was difficult to control the power of the second DUV laser light as the output light stably due to the decrease in the wavelength conversion efficiency and the fluctuation of the beam pointing occurred.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a laser apparatus capable of stably performing power control of DUV laser light that is output light of the laser apparatus. In addition, an object of the present invention is to provide an exposure apparatus and an inspection apparatus that have improved stability through stable power control.

  A first aspect illustrating the present invention is a laser device. The laser apparatus includes a UV light output unit that outputs UV laser light having a wavelength in the ultraviolet region, a VIR light output unit that outputs VIR laser light having a wavelength in the visible to infrared region, and UV output from the UV light output unit. A DUV light conversion unit that generates and outputs DUV laser light having a wavelength shorter than that of the UV laser light by wavelength conversion from the laser light and the VIR laser light output from the VIR light output unit, the UV light output unit, and the VIR light A control unit that controls the operation of the output unit. The control unit of the laser apparatus sets the power of the UV laser light output from the UV light output unit to be substantially constant when the power of the DUV laser light output from the DUV light conversion unit is changed. Control is performed to change the power of the VIR laser light to be output.

  The VIR light output unit includes a first VIR light output unit that outputs a first VIR laser beam having a wavelength in the visible to infrared region, and a second VIR light output that outputs a second VIR laser beam having a wavelength in the visible to infrared region. The DUV light conversion unit generates the first DUV laser light by generating the sum frequency of the UV laser light output from the UV light output unit and the first VIR laser light output from the first VIR light output unit. The first wavelength conversion optical element (for example, the wavelength conversion optical element 35 in the first configuration form, the wavelength conversion optical element 135 in the second configuration form), the first DUV laser light output from the first wavelength conversion optical element, and the first A second wavelength conversion optical element that generates a second DUV laser light by generating a sum frequency with the second VIR laser light output from the 2VIR light output unit (for example, the wavelength change in the first configuration form). The optical element 36 and the wavelength conversion optical element 136 in the second configuration form, and the control unit outputs from the UV light output unit when changing the power of the second DUV laser light output from the DUV light conversion unit. The power of the UV laser light is substantially constant, and control is performed to change the power of at least one of the first VIR laser light output from the first VIR light output unit and the second VIR laser light output from the second VIR light output unit. can do.

  Each of the UV light output unit and the VIR light output unit includes a fiber optical amplifier that amplifies laser light in the visible to infrared region, and the UV light output unit receives laser light in the visible to infrared region in the ultraviolet region. A wavelength conversion optical element that converts the laser light into a UV laser beam, and the control unit controls the operation of the fiber optical amplifier provided in the UV light output unit and the fiber optical amplifier provided in the VIR light output unit. Accordingly, the power of the UV laser light can be made substantially constant and the power of the VIR laser light can be changed.

  In this case, the fiber optical amplifier provided in the UV light output unit and the fiber optical amplifier provided in the VIR light output unit are both amplifiers that amplify a laser beam having a fundamental wave having a predetermined wavelength. The unit is configured to generate and output a UV laser beam that is the fifth harmonic from the fundamental wave amplified by the fiber optical amplifier of the UV light output unit, and the VIR light output unit includes the VIR light unit The fundamental wave amplified by the fiber optical amplifier of the light output unit is configured to generate and output a VIR laser beam that is the second harmonic, and the DUV light conversion unit outputs from the UV light output unit. The seventh harmonic of the fundamental wave can be generated from the generated UV laser light and the VIR laser light output from the VIR light output unit by sum frequency generation.

  In addition, the fiber optical amplifier provided in the UV light output unit, the fiber optical amplifier provided in the first VIR light output unit, and the fiber optical amplifier provided in the second VIR light output unit all have a basic wavelength. The UV light output unit generates and outputs the UV laser light that is the fifth harmonic of the fundamental wave amplified by the fiber optical amplifier of the UV light output unit. The first VIR light output unit is configured to generate and output a first VIR laser beam that is the second harmonic of the fundamental wave amplified by the fiber optical amplifier of the first VIR light output unit. The second VIR light output unit is configured to generate and output the second VIR laser light that is the fundamental wave amplified by the fiber optical amplifier of the second VIR light output unit. The first wavelength conversion optical element generates a first DUV laser light that is a seventh harmonic of the fundamental wave by generating a sum frequency of the UV laser light and the first VIR laser light, and the second wavelength conversion optical element The second DUV laser light, which is the eighth harmonic of the fundamental wave, is generated by sum frequency generation of the first DUV laser light output from the first wavelength conversion optical element and the second VIR laser light output from the second VIR light output unit. It can also be configured to occur.

  A second aspect illustrating the present invention is an exposure apparatus. This exposure apparatus is output from the laser apparatus according to the first aspect, a mask support part that holds a photomask on which a predetermined exposure pattern is formed, an exposure object support part that holds an exposure object, and the laser apparatus. An illumination optical system that irradiates the photomask held by the mask support with the laser beam and a projection optical system that projects the light transmitted through the photomask onto the exposure target held by the exposure target support. Composed.

  A third aspect illustrating the present invention is an inspection apparatus. This inspection apparatus irradiates the test object held by the test object support part with the laser apparatus of the first aspect, the test object support part that holds the test object, and the laser beam output from the laser apparatus. And an illumination optical system that detects the light from the test object (for example, the TDI sensor 615 in the embodiment).

  In the laser device of the first aspect, when the control unit of the laser device changes the power of the DUV laser light (output light) output from the DUV light conversion unit, the UV laser light output from the UV light output unit is changed. The power is set to be substantially constant, and control is performed to change the power of the VIR laser light output from the VIR light output unit. That is, in the laser device of the first aspect, when the power of the output light is changed, the power of the UV laser light in the ultraviolet region output from the UV light output unit is held substantially constant, and output from the VIR light output unit. It is controlled so as to change the power of the VIR laser light in the visible to infrared region.

  For this reason, even if the power control for changing the DUV laser light as the output light is performed, the change in the amount of heat generated by the absorption by the wavelength conversion element is small compared to the power control for changing the power of the UV laser light. There is little decrease in wavelength conversion efficiency and variation in beam pointing. Therefore, it is possible to provide a laser apparatus that can stably control the power of output light.

  The exposure apparatus according to the second aspect includes the laser apparatus according to the first aspect. Therefore, it is possible to provide an exposure apparatus with improved stability by stable power control.

  The inspection apparatus according to the third aspect includes the laser apparatus according to the first aspect. Therefore, it is possible to provide an inspection apparatus with improved stability by stable power control.

It is a schematic block diagram of the laser apparatus of the 1st form shown as an example of application of this invention. 2 is a block diagram of a control system mainly using power control in the laser apparatus. FIG. It is the schematic of the fiber optical amplifier in the said laser apparatus. It is a schematic block diagram of the laser apparatus of the 2nd form shown as an example of application of this invention. It is a schematic block diagram of the exposure apparatus provided with the laser apparatus of this invention. It is a schematic block diagram of the inspection apparatus provided with the laser apparatus of this invention. It is a schematic block diagram for demonstrating the conventional laser apparatus.

(First configuration form)
Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. As an example of the laser apparatus LS to which the present invention is applied, a schematic configuration of the laser apparatus LS1 of the first configuration form is shown in FIG. FIG. 2 shows a block diagram of a control system mainly using power control in the laser device LS1. The laser device LS1 is the same as the laser device LS9 described above except for the difference in the control form by the control unit. Hereinafter, the configuration of each unit will be described in detail. In addition, in each of the following drawings, what is indicated by an ellipse on each optical path is a lens for condensing and inputting laser light to each wavelength conversion optical element, and detailed description thereof is omitted.

  The laser device LS1 includes a UV light output unit I that outputs UV laser light in the ultraviolet region, a VIR light output unit that outputs VIR laser light in the visible to infrared region, and wavelength conversion from UV laser light and VIR laser light. A DUV light conversion unit IV that generates DUV laser light having a shorter wavelength than the UV laser light and a control unit 8 that controls the operation of each unit including the UV light output unit and the VIR light output unit are configured. The VIR light output unit includes a first VIR light output unit II that outputs a first VIR laser beam in the visible region and a second VIR light output unit III that outputs a second VIR laser beam in the infrared region.

  In the laser device LS1, seed light is supplied from a seed light generation unit 10 that generates seed light having a fundamental wavelength to the UV light output unit I, the first VIR light output unit II, and the second VIR light output unit III. The In other words, the seed light emitted from the seed light generation unit 10 is divided into three and is incident on the UV light output unit I, the first VIR light output unit II, and the second VIR light output unit III, respectively. Although not shown in detail, the seed light generator 10 has a laser light source that emits laser light having a predetermined wavelength in the visible to infrared region, and a part of the laser light emitted from the laser light source to cut out a predetermined waveform. And an electro-optic modulator (EOM) that outputs pulsed seed light.

  In the laser device LS1, a laser beam having a wavelength of 1547 nm is generated using a DFB semiconductor laser as a laser light source, a part thereof is cut out by an electro-optic modulator, and a pulsed seed having a repetition frequency of 1 MHz and an on-time of 1 to several nsec. Output light. The seed light emitted from the seed light generation unit 10 is divided into three by a splitter (coupler) (not shown) and is incident on the UV light output unit I, the first VIR light output unit II, and the second VIR light output unit III, respectively.

  The UV light output unit I is mainly composed of a fiber optical amplifier 21 that amplifies seed light, wavelength conversion optical elements 31, 32, and 33 that sequentially convert the wavelength of the amplified fundamental laser light.

  As shown schematically in FIG. 3, the fiber optical amplifier 21 emits an amplifying fiber 21a whose core is doped with a laser medium and excitation light for exciting the laser medium doped in the amplifying fiber 21a. An excitation light source 21b, a light guide fiber 21c for guiding the excitation light emitted from the excitation light source 21b to the amplification fiber 21a, a combiner 21d, and the like are included. The fiber optical amplifier 21 is an optical amplifier that amplifies light in the wavelength band of the seed light in the visible to infrared region. For example, an erbium-doped fiber optical amplifier in which the core of the amplification fiber 21a is doped with erbium (Er) ( EDFA) is preferably used. The fiber optical amplifiers 22 and 23 are similarly configured.

The operation of the fiber optical amplifier 21 is controlled by the control unit 8. That is, the control unit 8 controls the intensity of pumping light for pumping the laser medium doped in the core of the fiber optical amplifier 21 by controlling the power supplied to the pumping light source 21b. The seed light, that is, the fundamental laser beam La ₁ amplified by the fiber optical amplifier 21, is emitted from the fiber optical amplifier 21 and focused on the wavelength conversion optical element 31.

  In the wavelength conversion optical element 31, the second harmonic generation of the fundamental wave incident on this element is generated, and the second harmonic wave having a frequency twice that of the fundamental wave and a wavelength of 1/2 (774 nm) is generated. The second harmonic generated by the wavelength conversion optical element 31 and the fundamental wave transmitted through the wavelength conversion optical element 31 are condensed and incident on the wavelength conversion optical element 32. The wavelength converting optical element 32 generates a sum frequency of the fundamental wave and the second harmonic, and generates a third harmonic having a frequency three times that of the fundamental wave and a wavelength of 1/3 (516 nm).

As the wavelength converting optical element 31 for generating the second harmonic, a PPLN (Periodically Poled LiNbO ₃ ) crystal is preferably used. Further, as the wavelength converting optical element 32 for generating the third harmonic, an LBO (LiB ₃ O ₅ ) crystal is preferably used. The wavelength conversion optical element 31 may be a quasi phase matching crystal (QPM) such as a PPLT (Periodically Poled LiTaO ₃ ) crystal or a PPKTP (Periodically Poled LiTaO ₃ ) crystal, or an LBO crystal.

The third harmonic generated by the wavelength conversion optical element 32 and the second harmonic transmitted through the wavelength conversion optical element 32 are condensed and incident on the wavelength conversion optical element 33. In the wavelength conversion optical element 33, the sum frequency generation of the second harmonic and the third harmonic is performed, and a fifth harmonic having a frequency five times that of the fundamental wave and a wavelength of 1/5 (309 nm) is generated. As the wavelength converting optical element 33 for generating the fifth harmonic, a BBO (β-BaB ₂ O ₄ ) crystal is preferably used. An LBO crystal or a CLBO (CsLiB ₆ O ₁₀ ) crystal can also be used.

  The fifth harmonic generated by the wavelength conversion optical element 33 is emitted from the UV light output unit I, reflected by the dichroic mirror 41, and condensed and incident on the wavelength conversion optical element 35 of the DUV light conversion unit IV. The fifth harmonic emitted from the UV light output unit I has a wavelength of 309 nm and is laser light in the ultraviolet region. In the present specification, laser light having a wavelength in the ultraviolet region emitted from the UV light output unit I is referred to as “UV laser light”.

The first VIR light output unit II includes a fiber optical amplifier 22 that amplifies seed light, a wavelength conversion optical element 34 that converts the wavelength of the amplified fundamental laser light, and a timing adjuster 45 described later. The seed light emitted from the seed light generation unit 10 is amplified by the fiber optical amplifier 22, and the amplified fundamental wave laser light La ₂ is condensed and incident on the wavelength conversion optical element 34. The configuration and operation of the fiber optical amplifier 22 are the same as those of the fiber optical amplifier 21 described above, and the excitation light intensity of the fiber optical amplifier 22 is controlled by the control unit 8.

  In the wavelength conversion optical element 34, the second harmonic of the fundamental wave is generated, and a second harmonic having a frequency twice that of the fundamental wave and a wavelength of 1/2 (774 nm) is generated. As the wavelength conversion optical element 34 for generating the second harmonic, a PPLN crystal, a QPM crystal, or the like can be used. The second harmonic generated by the wavelength conversion optical element 34 is emitted from the first VIR light output unit II, and is condensed and incident on the wavelength conversion optical element 35 of the DUV light conversion unit IV via the dichroic mirrors 42 and 41. The second harmonic emitted from the first VIR light output unit II has a wavelength of 774 nm and is a laser beam in the visible region. In the present specification, laser light having a wavelength emitted from the first VIR light output unit II in the visible to infrared region is referred to as “first VIR laser light”.

The second VIR light output unit III includes a fiber optical amplifier 23 that amplifies seed light, that is, basic laser light, and a timing adjuster 46 described later. The seed light emitted from the seed light generation unit 10 is amplified by the fiber optical amplifier 23, and the amplified seed light, that is, the fundamental laser beam La ₃ is emitted from the second VIR light output unit III. The configuration and operation of the fiber optical amplifier 23 are the same as those of the fiber optical amplifiers 21 and 22 described above, and the excitation light intensity of the fiber optical amplifier 23 is controlled by the control unit 8.

  The fundamental laser beam emitted from the second VIR light output unit III passes through the dichroic mirrors 42 and 41 and the wavelength conversion optical element 35 and is condensed and incident on the wavelength conversion optical element 36. The fundamental laser beam emitted from the second VIR light output unit III has a wavelength of 1547 nm and is a laser beam in the infrared region. In the present specification, laser light having a wavelength of visible to infrared light emitted from the second VIR light output unit III is referred to as “second VIR laser light”.

  The dichroic mirror 42 is configured to transmit light in the fundamental wavelength band and reflect light in the second harmonic wavelength band. Further, the dichroic mirror 41 is configured to transmit light in the fundamental and second harmonic wavelength bands and reflect light in the fifth harmonic wavelength band. Therefore, the first VIR laser light that is the second harmonic emitted from the first VIR light output unit II and the second VIR laser light that is the fundamental wave emitted from the second VIR light output unit III are coaxially connected by the dichroic mirror 42. Are further superimposed on the same axis by the dichroic mirror 41, and the laser beams of these three different wavelengths are transmitted to the DUV light conversion unit IV. Incident.

  The DUV light conversion unit IV is provided with wavelength conversion optical elements 35 and 36. In the wavelength conversion optical element 35, the sum of the UV laser light that is the fifth harmonic emitted from the UV light output unit I and the first VIR laser light that is the second harmonic emitted from the first VIR light output unit II. Frequency generation is performed. That is, the first DUV laser light having the seventh harmonic with a frequency seven times that of the fundamental wave and a wavelength of 1/7 (221 nm) is generated. As the wavelength converting optical element 35 for generating the seventh harmonic, a CLBO crystal is preferably used. The fundamental wave emitted from the second VIR light output unit III passes through the wavelength conversion optical element 35 and enters the wavelength conversion optical element 36 together with the first DUV laser light that is the seventh harmonic generated by the wavelength conversion optical element 35.

  The wavelength conversion optical element 36 generates the sum frequency of the second VIR laser light that is the fundamental wave and the first DUV laser light that is the seventh harmonic, and the frequency is 8 times the fundamental wave and the wavelength is 1/8 (193 nm). The eighth harmonic is generated. A CLBO crystal is preferably used as the wavelength conversion optical element 36 for generating the eighth harmonic. The DUV laser light, which is the eighth harmonic generated by the wavelength conversion optical element 36, is emitted from the DUV light conversion unit IV and output from the laser device LS1.

  The seventh harmonic and the eighth harmonic generated in the DUV light conversion unit IV have wavelengths of 221 nm and 193 nm, respectively, both of which are in the ultraviolet region where the wavelength is shorter than the UV laser light emitted from the UV light output unit I. Laser light. In the present specification, laser light in the ultraviolet region having a shorter wavelength than the UV laser light generated in the DUV light conversion unit IV is referred to as DUV laser light. In addition, when there are a plurality of DUV laser beams generated in the DUV light conversion unit IV as in this configuration example, when identifying these, the first generated DUV laser beam (seventh harmonic) is The 1 DUV laser light and the next generated DUV laser light (eighth harmonic) are referred to as second DUV laser light.

  The timing adjuster 45 provided in the first VIR light output unit II and the timing adjuster 46 provided in the second VIR light output unit III are both devices for adjusting the timing of the seed light incident on the fiber optical amplifiers 22 and 23. is there. By adjusting the timing by the timing adjuster 45, the temporal superposition of the UV laser light that is the fifth harmonic and the first VIR laser light that is the second harmonic in the wavelength conversion optical element 35 is adjusted. Further, by adjusting the timing by the timing adjuster 46, the temporal superposition of the first DUV laser light that is the seventh harmonic and the second VIR laser light that is the fundamental wave in the wavelength conversion optical element 36 is adjusted.

  A little explanation will be given on this point. A substantial optical path length from when the seed light generated by the seed light generation unit 10 is emitted from the UV light output unit I as the fifth harmonic UV laser light and reaches the wavelength conversion optical element 35; In general, the substantial optical path length from the first VIR light output unit II, which is the second harmonic wave as the first VIR laser light, to the wavelength conversion optical element 35 is not the same. Therefore, the timings of the UV laser light and the first VIR laser light do not match. Therefore, when the seed light is pulse light with a short on-time, the timing adjustment described above is required to generate the DUV laser light with high efficiency in the wavelength conversion optical element 35 and the wavelength conversion optical element 36.

  The timing adjuster 45 gives a delay to the incident seed light. That is, the timing at which the first VIR laser light as the second harmonic enters the wavelength conversion optical element 35 is delayed so that the UV laser light as the fifth harmonic coincides with the timing at which the UV laser light enters the wavelength conversion optical element 35. Thus, temporal superposition of the UV laser light and the first VIR laser light in the wavelength conversion optical element 35 is performed. The same applies to the timing adjuster 46, and the timing at which the second VIR laser light, which is the fundamental wave, enters the wavelength conversion optical element 36 is delayed so as to coincide with the timing at which the first DUV laser light enters the wavelength conversion optical element 36. Thus, temporal superposition of the first DUV laser light and the second VIR laser light in the wavelength conversion optical element 36 is performed.

  By the timing adjusters 45 and 46, the wavelength conversion optical element 35 temporally superimposes the fifth harmonic and the second harmonic, and the wavelength conversion optical element 36 temporally superimposes the seventh harmonic and the fundamental wave. By overlapping, DUV laser light having a wavelength of 193 nm can be generated and emitted with high efficiency. Further, the fifth harmonic wave and the second harmonic wave in the wavelength conversion optical element 35 and the seventh harmonic wave and the fundamental wave in the wavelength conversion optical element 36 are shifted so that they do not overlap in time, thereby generating the eighth harmonic wave. The emission of DUV laser light from the laser device can be suppressed and turned off.

  The timing adjusters 45 and 46 can be configured by a plurality of delay fibers having different optical path lengths and an EOM that switches between delay fibers through which seed light propagates. The operation of the timing adjusters 45 and 46 is controlled by the control unit 8. Thereby, the DUV laser beam output from the laser device LS1 can be turned on / off at high speed.

  In the laser device LS1 configured in this way, the UV laser light (fifth harmonic) output from the UV light output unit I is used to change the power of the second DUV laser light (eighth harmonic) output from the laser device LS1. Wave) power is substantially constant, and at least one of the first VIR laser light (second harmonic) output from the first VIR light output unit II and the second VIR laser light (fundamental wave) output from the second VIR light output unit III Control to change the power. Below, the structural example which changes the power of both a 2nd harmonic and a fundamental wave is demonstrated.

  The control unit 8 is provided with a power controller 80 that performs power control of the laser device LS1. The power controller 80 includes a memory 82 storing a control program and various parameters, a processing circuit 83 that executes arithmetic processing based on the control program, and an optical amplifier driving circuit that drives the fiber optical amplifier based on a command from the processing circuit 83 85 (85a, 85b, 85c).

  The memory 82 stores, as a parameter (excitation light intensity parameter), the excitation light intensity of the fiber optical amplifiers 21, 22, and 23 necessary for the power of the second DUV laser light having a wavelength of 193 nm to be output from the laser device LS 1. The excitation light intensity parameter is composed of a No. 1 parameter value for the fiber optical amplifier 21, a No. 2 parameter value for the fiber optical amplifier 22, and a No. 3 parameter value for the fiber optical amplifier 23. Each parameter value is the second DUV laser beam. It is set in a map corresponding to the power of.

  The processing circuit 83 includes excitation light intensity parameters (No. 1 to No. 3 parameters) according to the power setting of the laser device LS1 input from the operation panel 81 of the laser device LS1 via an I / O board (not shown). A set of values) is read from the memory 82, and a drive command signal corresponding to each parameter value is output to the optical amplifier drive circuits 85a, 85b, 85c.

  Optical amplifier drive circuits 85a, 85b, and 85c are excitation light source drive circuits provided corresponding to the fiber optical amplifiers 21, 22, and 23, respectively, and No. 1 to No. 3 parameters output from the processing circuit 83. The pumping power corresponding to the value is supplied to the pumping light sources of the fiber optical amplifiers 21, 22 and 23 to drive them.

  The excitation light intensity parameter stored in the memory 82 is set as follows. It is assumed that the power range of the second DUV laser light to be output from the laser device LS1 is controlled to a range of 100 to 400 mW. In this case, the No. 1 parameter value that defines the excitation light intensity of the fiber optical amplifier 21 is set to a constant value regardless of the power of the second DUV laser light to be output from the laser device LS1.

  On the other hand, the No. 2 parameter value that defines the excitation light intensity of the fiber optical amplifier 22 and the No. 3 parameter value that defines the excitation light intensity of the fiber optical amplifier 23 change according to the power of the second DUV laser light. Set to For example, when the power setting of the laser device LS1 is 200 mW, the first VIR laser light (second harmonic) having the power necessary for outputting the second DUV laser light of 200 mW is output from the first VIR light output unit II. No.2 parameter value is set in. Further, the No. 3 parameter value is set so that the second VIR laser light (fundamental wave) having a power necessary for outputting the second DUV laser light of 200 mW is output from the second VIR light output unit III.

  Therefore, in the laser device LS1, when the second DUV laser light output from the laser device LS1 is on, the UV light output unit I always emits UV laser light (fifth harmonic) with constant power. On the other hand, the power of the first VIR laser light (second harmonic) emitted from the first VIR light output unit II and the power of the second VIR laser light (fundamental wave) emitted from the second VIR light output unit III are necessary. It is changed in accordance with the power of the second DUV laser light.

  The UV laser light emitted from the UV light output unit I has a wavelength of 309 nm and a wavelength region close to the deep ultraviolet region, and therefore, the absorption of the UV laser light by the wavelength conversion element or the like is relatively large. Therefore, in a laser apparatus having a conventional configuration in which the power of the UV laser light is varied, there is a great influence due to variation in heat generation in the wavelength conversion element or the like. In this regard, in the laser device LS1 of this configuration, even when the output of the second DUV laser light is changed, the power of the UV laser light in the UV light output unit I is always constant, so the wavelength of the UV light output unit I The conversion optical element 33, the lens that guides the UV laser light, the dichroic mirror 41, and the like are kept thermally constant. As a result, these optical elements do not change the amount of heat generation due to absorption of the UV laser light, and the resulting wavelength conversion efficiency is not lowered and beam pointing fluctuations do not occur, so that the power control of the second DUV laser light is stably performed. be able to.

  In the above, in controlling the power of the second DUV laser light, the first VIR laser light (second harmonic) output from the first VIR light output unit II and the second VIR laser light (fundamental wave) output from the second VIR light output unit III. Although the configuration in which both of the powers are changed is exemplified, it is also possible to change either one of the first VIR laser light and the second VIR laser light during power control.

  In this case, in the configuration for controlling the power of the second DUV laser light, which is the eighth harmonic, by changing only the power of the second VIR laser light, which is the fundamental wave output from the second VIR light output unit III, the wavelength conversion is performed. The power of the first DUV laser light (seventh harmonic) generated at the optical element 35 and having a wavelength of 221 nm can be kept substantially constant. According to such a configuration, in addition to the wavelength conversion optical element 33, the lens, the dichroic mirror 41, and the like, the wavelength conversion optical element 35 can be kept thermally constant, and the second DUV emitted from the laser device LS1. Laser light power control can be performed more stably.

(Second configuration form)
Next, the laser device LS2 of the second configuration form will be described with reference to FIG.

  The laser device LS2 includes a UV light output unit XI that outputs UV laser light in the ultraviolet region, a VIR light output unit that outputs VIR laser light in the infrared region, and a UV laser by wavelength conversion from the UV laser light and the VIR laser light. A DUV light conversion unit XIV that generates DUV laser light having a wavelength shorter than that of light and a control unit 108 that controls the operation of each unit including the UV light output unit and the VIR light output unit are configured. The VIR light output unit includes a first VIR light output unit XII that outputs the first VIR laser light in the infrared region and a second VIR light output unit XIII that outputs the second VIR laser light in the infrared region.

In the laser device LS2, the UV light output unit XI includes a seed light generation unit 111 that generates the first fundamental wave seed light, a fiber optical amplifier 121 that amplifies the generated first fundamental wave seed light, and the amplified first light. It is mainly composed of wavelength conversion optical elements 131 and 132 for converting the wavelength of the fundamental laser beam La ₁₁ .

  Although not shown in detail, the seed light generation unit 111 generates a pulsed seed light having a predetermined waveform by cutting out a laser light source that generates laser light having a wavelength of 1063 nm and a part of the laser light emitted from the laser light source. And an electro-optic modulator (EOM) for output. As the laser light source, a DFB semiconductor laser including the above wavelength in the oscillation band is used.

  The fiber optical amplifier 121 is the same as the fiber optical amplifier 21 described in the basic configuration. That is, an amplification fiber having a core doped with a laser medium, an excitation light source that emits excitation light for exciting the laser medium, a light guide fiber that guides the excitation light emitted from the excitation light source to the amplification fiber, and Composed of a combiner. This basic configuration is the same for the fiber optical amplifiers 122 and 123.

  The fiber optical amplifier 121 is an optical amplifier that amplifies the seed light of the first fundamental wave having a wavelength of 1063 nm. As the fiber optical amplifier 121, an ytterbium-doped fiber optical amplifier (YDFA) having a high gain in this wavelength band is preferably used. Note that the first fundamental wave laser beam output unit including the seed beam generator 111 and the fiber optical amplifier 121 may be configured by a Yb fiber laser using FBG or the like.

The intensity of the pumping light of the fiber optical amplifier 121 (power supplied to the pumping light source) is controlled by the control unit 108. The seed light amplified by the fiber optical amplifier 121, that is, the first fundamental laser beam La ₁₁ having a wavelength of 1063 nm, is emitted from the fiber optical amplifier 121 and focused on the wavelength conversion optical element 131.

  In the wavelength conversion optical element 131, the second harmonic generation of the first fundamental wave incident on this element is performed, the frequency is twice that of the first fundamental wave, and the wavelength is ½ (532 nm) of the first fundamental wave. A second harmonic is generated. The second harmonic generated by the wavelength conversion optical element 131 is condensed and incident on the wavelength conversion optical element 132. In the wavelength conversion optical element 132, second harmonic generation of the second harmonic generated in the wavelength conversion optical element 131 is performed, the frequency is four times the first fundamental wave, and the wavelength is 1/4 ( 266 nm) is generated. An LBO crystal is suitably used as the second harmonic generation wavelength conversion optical element 131, and a CLBO crystal is preferably used as the fourth harmonic generation wavelength conversion optical element 132.

  The fourth harmonic of the first fundamental wave generated by the wavelength conversion optical element 132 is emitted from the UV light output unit XI, and is condensed and incident on the wavelength conversion optical element 135 of the DUV light conversion unit XIV via the dichroic mirror 141. The fourth harmonic of the first fundamental wave emitted from the UV light output unit XI is UV laser light having a wavelength of 266 nm and in the ultraviolet region (deep ultraviolet region).

  The first VIR light output unit XII is mainly configured by a seed light generation unit 112 that generates seed light of the second fundamental wave, and a fiber optical amplifier 122 that amplifies the generated seed light of the second fundamental wave.

  The seed light generator 112 is a laser light source that generates a laser light having a wavelength of 2000 nm, and an electro-optic modulator that outputs a pulsed seed light having a predetermined waveform by cutting out a part of the laser light emitted from the laser light source ( EOM). As the laser light source, a DFB semiconductor laser including the above wavelength in the oscillation band is used.

  The fiber optical amplifier 122 is an optical amplifier that amplifies the seed light of the second fundamental wave having a wavelength of 2000 nm emitted from the seed light generation unit 112. As the fiber optical amplifier 122, a thulium-doped fiber optical amplifier (TDFA) having a high gain in this wavelength band is preferably used. Note that the second fundamental wave laser beam output unit including the seed beam generator 112 and the fiber optical amplifier 122 may be configured using a Tm fiber laser using FBG.

The excitation light intensity of the fiber optical amplifier 122 is controlled by the control unit 108. The seed light amplified by the fiber optical amplifier 122, that is, the second fundamental laser beam La ₁₂ having a wavelength of 2000 nm, is emitted from the first VIR light output unit XII, and passes through the mirror 143 and the dichroic mirrors 142 and 141 and is DUV light. The light is focused and incident on the wavelength conversion optical element 135 of the conversion unit XIV. The second fundamental wave emitted from the first VIR light output unit XII is a first VIR laser beam having a wavelength of 2000 nm and an infrared region.

  The second VIR light output unit XIII is mainly composed of a seed light generation unit 113 that generates seed light of the third fundamental wave and a fiber optical amplifier 123 that amplifies the generated seed light.

  The seed light generator 113 is a laser light source that generates laser light having a wavelength of 1102 nm, and an electro-optic modulator that outputs pulsed seed light having a predetermined waveform by cutting out part of the laser light emitted from the laser light source ( EOM). As the laser light source, a DFB semiconductor laser including the above wavelength in the oscillation band is used.

  The fiber optical amplifier 123 is an optical amplifier that amplifies the third fundamental wave seed light having a wavelength of 1102 nm emitted from the seed light generation unit 113. As the fiber optical amplifier 123, an ytterbium-doped fiber optical amplifier (YDFA) having a high gain in this wavelength band is preferably used. The third fundamental laser beam output unit including the seed beam generator 113 and the fiber optical amplifier 123 may be configured by a Yb fiber laser using FBG or the like.

The excitation light intensity of the fiber optical amplifier 123 is also controlled by the control unit 108 as in the case of the fiber optical amplifiers 121 and 122. Laser light La ₁₃ of the third fundamental wave seed light amplified by the fiber optical amplifier 123, that is, the wavelength of 1102nm is first 2VIR emitted from the light output section XIII, DUV light conversion section XIV through the dichroic mirror 142 and 141 The light is incident on the wavelength converting optical element 136. The third fundamental wave emitted from the second VIR light output unit XIII is a second VIR laser beam having a wavelength of 1102 nm and an infrared region.

  The dichroic mirror 142 is configured to transmit light in the wavelength band of the second fundamental wave having a wavelength of 2000 nm and reflect light in the wavelength band of the third fundamental wave having a wavelength of 1102 nm. The dichroic mirror 141 is configured to transmit light in the wavelength bands of the second fundamental wave and the third fundamental wave and reflect light in the wavelength band of the fourth harmonic of the first fundamental wave having a wavelength of 266 nm. . Therefore, the first VIR laser light (second fundamental wave) emitted from the first VIR light output unit XII and the second VIR laser light (third fundamental wave) emitted from the second VIR light output unit XIII are dichroic mirror 142. In addition, the UV laser light (fourth harmonic of the first fundamental wave) emitted from the UV light output unit XI is superimposed on the same axis by the dichroic mirror 141, and light of these three wavelengths is The light enters the DUV light conversion unit XIV.

  The DUV light conversion unit XIV is provided with wavelength conversion optical elements 135 and 136. In the wavelength conversion optical element 135, the UV laser light emitted from the UV light output unit XI (the fourth harmonic of the first fundamental wave having a wavelength of 266 nm) and the first VIR laser light emitted from the first VIR light output unit XII ( Sum frequency generation with a second fundamental wave having a wavelength of 2000 nm is performed, and a first DUV laser beam having a wavelength of 235 nm is generated. As the wavelength conversion optical element 135, an LBO crystal is preferably used. The second VIR laser light (third fundamental wave) emitted from the second VIR light output unit XIII passes through the wavelength conversion optical element 135 and enters the wavelength conversion optical element 136 together with the first DUV laser light generated by the wavelength conversion optical element 135. To do.

  The wavelength conversion optical element 136 generates a sum frequency of the first DUV laser light having a wavelength of 235 nm generated by the wavelength conversion optical element 135 and the third fundamental wave having a wavelength of 1102 nm emitted from the second VIR light output unit XIII. The second DUV laser light having a wavelength of 193 nm is generated. As the wavelength conversion optical element 136, a CLBO crystal is preferably used. The second DUV laser light having a wavelength of 193 nm generated by the wavelength conversion optical element 136 is emitted from the DUV light conversion unit XIV and output from the laser device LS2.

  In the laser device LS2, seed light generators 111, 112, and 113 are provided in the UV light output unit XI, the first VIR light output unit XII, and the second VIR light output unit XIII, respectively. For this reason, the control unit 108 controls the generation timing of the first, second, and third seed lights generated in the seed light generation units 111, 112, and 113, so that the UV laser light in the wavelength conversion optical element 135 and the first generation light are generated. The overlay with the 1 VIR laser beam can be adjusted appropriately. For the same reason, the superposition of the first DUV laser beam and the second VIR laser beam in the wavelength conversion optical element 136 can be appropriately adjusted.

  In the laser device LS2 configured in this manner, when the power of the second DUV laser light output from the laser device LS2 is changed, the UV laser light output from the UV light output unit XI (fourth harmonic of the first fundamental wave) And at least one of the first VIR laser beam (second fundamental wave) output from the first VIR light output unit XII and the second VIR laser beam (third fundamental wave) output from the second VIR light output unit XIII. Control to change the power. At this time, the configuration and operation of the control unit 108 are basically the same as those of the control unit 8 of the laser apparatus LS1 described above. Therefore, in the following, an outline of a configuration example in which the power of the third fundamental wave among the second fundamental wave and the third fundamental wave is changed will be described.

  The control unit 108 is provided with the same power controller 80 as in the first configuration form. The power controller 80 includes a memory 82, a processing circuit 83, an optical amplifier drive circuit 85 (85a, 85b, 85c), and the like similar to those in the first configuration (see FIG. 2).

  In the memory 82, the pumping light intensity of the fiber optical amplifiers 121, 122, and 123 necessary for the power of the second DUV laser light having a wavelength of 193 nm to be output from the laser device LS2 is stored as a pumping light intensity parameter. The excitation light intensity parameter is composed of a No. 1 parameter value for the fiber optical amplifier 121, a No. 2 parameter value for the fiber optical amplifier 122, and a No. 3 parameter value for the fiber optical amplifier 123. Each parameter value is the second DUV laser beam. It is set in a map corresponding to the power of.

  The processing circuit 83 reads a set of No. 1 to No. 3 parameter values stored in accordance with the power setting of the laser device LS2 input from the operation panel 81 of the laser device LS2 from the memory 82, and sets each parameter value. Are output to the optical amplifier drive circuits 85a, 85b, 85c. The optical amplifier drive circuits 85a, 85b, and 85c supply pumping powers corresponding to the No. 1 to No. 3 parameter values output from the processing circuit 83 to the pump light sources of the fiber optical amplifiers 121, 122, and 123, respectively. Drive.

  Among the pumping light intensity parameters, the No. 1 parameter value that defines the pumping light intensity of the fiber optical amplifier 121 and the No. 2 parameter value that defines the pumping light intensity of the fiber optical amplifier 122 should be output from the laser device LS2. The constant value is set regardless of the power of the second DUV laser beam.

  On the other hand, the No. 3 parameter value that defines the excitation light intensity of the fiber optical amplifier 123 is set so as to change according to the power of the second DUV laser light to be output from the laser device LS2. For example, when the power setting of the laser device LS2 is 300 mW, the second VIR laser beam (third fundamental wave) having a power necessary for outputting the second DUV laser beam of 300 mW is output from the second VIR light output unit XIII. No.3 parameter value is set in. That is, as the No. 3 parameter value, a value increased or decreased according to the required power of the second DUV laser light is set.

  Therefore, in the laser device LS2, when the second DUV laser light output from the laser device LS2 is on, the UV light output unit XI always emits UV laser light (fourth harmonic of the first fundamental wave) having a constant power. Then, the first VIR laser beam (second fundamental wave) having a constant power is always emitted from the first VIR light output unit XII. On the other hand, the power of the second VIR laser light (third fundamental wave) emitted from the second VIR light output unit XIII is changed according to the required second DUV laser light power.

  The UV laser light emitted from the UV light output unit XI has a wavelength of 266 nm, and the first DUV laser light generated by the wavelength conversion optical element 135 has a wavelength of 235 nm. Both of these laser lights are in the deep ultraviolet region. Therefore, the absorption of the UV laser light by the wavelength conversion element or the like is relatively large. Therefore, in a laser apparatus having a conventional configuration in which the power of the UV laser light is varied, there is a great influence due to variation in heat generation in the wavelength conversion element or the like. In this regard, in the laser device LS2 of this configuration, even when the output of the second DUV laser light is changed, the power of the UV laser light in the UV light output unit XI is always constant, and therefore the laser device LS2 outputs the laser light. Even if control is performed to change the power of the second DUV laser light, the wavelength conversion optical element 132 of the UV light output unit XI, the lens or dichroic mirror 141 that guides the UV laser light, and the wavelength conversion optical element 135 are thermally Kept constant. As a result, these optical elements do not change the amount of heat generation due to absorption of the UV laser light, and the resulting wavelength conversion efficiency is not lowered and beam pointing fluctuations do not occur, so that the power control of the second DUV laser light is stably performed. be able to.

  The laser apparatus LS (LS1, LS2) as described above is small and light and easy to handle, and is an optical processing apparatus such as an exposure apparatus or an optical modeling apparatus, an inspection apparatus such as a photomask or a wafer, a microscope or a telescope. The present invention can be suitably applied to systems such as observation devices such as measuring devices such as length measuring devices and shape measuring devices, and phototherapy devices.

  As a first application example of a system including a laser device LS, an exposure apparatus used in a photolithography process for manufacturing a semiconductor or a liquid crystal panel will be described with reference to FIG. The exposure apparatus 500 is in principle the same as photolithography, and a device pattern precisely drawn on a quartz glass photomask 513 is applied to an exposure object 515 such as a semiconductor wafer or glass substrate coated with a photoresist. Optically project and transfer.

  The exposure apparatus 500 includes the laser apparatus LS (LS1 or LS2) described above, the illumination optical system 502, the mask support 503 that holds the photomask 513, the projection optical system 504, and the exposure target that holds the exposure object 515. An object support table 505 and a drive mechanism 506 that moves the exposure object support table 505 in a horizontal plane are configured. The illumination optical system 502 includes a plurality of lens groups, and irradiates the photomask 513 held on the mask support 503 with the laser light output from the laser device LS. The projection optical system 504 is also composed of a plurality of lens groups, and projects the light transmitted through the photomask 513 onto the exposure object 515 on the exposure object support table.

  In the exposure apparatus 500 having such a configuration, the laser light output from the laser apparatus LS is input to the illumination optical system 502, and the laser light adjusted to a predetermined light flux is applied to the photomask 513 held on the mask support 503. Irradiated. The light that has passed through the photomask 513 has an image of a device pattern drawn on the photomask 513, and this light of the exposure object 515 held on the exposure object support table 505 via the projection optical system 504. A predetermined position is irradiated. Thereby, the image of the device pattern of the photomask 513 is image-exposed at a predetermined magnification on the exposure object 515 such as a semiconductor wafer or a liquid crystal panel.

  According to such an exposure apparatus 500, even if power control for changing the output of the DUV laser light output from the laser apparatus is performed, there is no change in absorption or heat generation by the optical element of the UV light output unit, and the DUV laser light. Can be stably controlled. Therefore, it is possible to provide an exposure apparatus with improved stability by stable power control.

  Next, as a second application example of the system including the laser device LS, FIG. 6 showing a schematic configuration of an inspection device used in an inspection process of a photomask, a liquid crystal panel, a wafer, or the like (test object). The description will be given with reference. An inspection apparatus 600 illustrated in FIG. 6 is suitably used for inspecting a fine device pattern drawn on a test object 613 having a light transmission property such as a photomask.

  The inspection device 600 includes the laser device LS (LS1 or LS2), the illumination optical system 602, the test object support 603 that holds the test object 613, the projection optical system 604, and the test object 613. A TDI (Time Delay Integration) sensor 615 that detects light and a drive mechanism 606 that moves the object support base 603 within a horizontal plane are configured. The illumination optical system 602 includes a plurality of lens groups, and adjusts the laser light output from the laser device LS to a predetermined light flux and irradiates the test object 613 held on the test object support base 603. The projection optical system 604 is also composed of a plurality of lens groups, and projects the light transmitted through the test object 613 onto the TDI sensor 615.

  In the inspection apparatus 600 having such a configuration, the laser beam output from the laser apparatus LS is input to the illumination optical system 602, and the laser beam adjusted to a predetermined luminous flux is held on the test object support base 603. The object 613 is irradiated. The light from the object 613 (transmitted light in this configuration example) has an image of a device pattern drawn on the object 613, and this light is transmitted to the TDI sensor 615 via the projection optical system 604. Projected and imaged. At this time, the horizontal movement speed of the test object support base 603 by the drive mechanism 606 and the transfer clock of the TDI sensor 615 are controlled in synchronization.

  Therefore, an image of the device pattern of the test object 613 is detected by the TDI sensor 615, and by comparing the detection image of the test object 613 detected in this way with a predetermined reference image set in advance, The defect of the fine pattern drawn on the test object is extracted. If the test object 613 does not have optical transparency like a wafer or the like, the reflected light from the test object is incident on the projection optical system 604 and guided to the TDI sensor 615 in the same manner. can do.

  According to such an inspection apparatus 600, even if power control for changing the output of the DUV laser light output from the laser apparatus is performed, there is no change in absorption or heat generation by the optical element of the UV light output unit, and the DUV laser light is not changed. Can be stably controlled. Therefore, it is possible to provide an inspection apparatus with improved stability by stable power control.

LS (LS1, LS2) Laser device LS1 Laser device I in the first configuration form UV light output unit
II First VIR light output unit (VIR light output unit)
III Second VIR light output section (VIR light output section)
IV DUV light conversion unit 8 control unit 10 seed light generation unit 21, 22, 23 fiber optical amplifier 31-36 wavelength conversion optical element (35 first wavelength conversion optical element, 36 second wavelength conversion optical element)
80 Power controller LS2 Laser apparatus of 2nd structure form
XI UV light output unit
XII First VIR light output unit (VIR light output unit)
XIII Second VIR light output section (VIR light output section)
XIV DUV light conversion unit 108 control unit 110 (111, 112, 113) seed light generation unit 121, 122, 123 fiber optical amplifier 131, 132, 135, 136 wavelength conversion optical element (135 first wavelength conversion optical element, 136 first (2 wavelength conversion optical element)
DESCRIPTION OF SYMBOLS 500 Exposure apparatus 502 Illumination optical system 503 Mask support stand 504 Projection optical system 505 Exposure target support table 513 Photomask 515 Exposure target 600 Inspection apparatus 602 Illumination optical system 603 Test target support 604 Projection optical system 613 Test target 615 TDI sensor (detector)
LS9 Conventional laser device 910 Seed light generation unit 921-923 Fiber optical amplifier 931-936 Wavelength conversion optical element

Claims (7)

A UV light output unit that outputs UV laser light having a wavelength in the ultraviolet region;
A VIR light output unit that outputs VIR laser light having a wavelength in the visible to infrared region;
DUV that generates and outputs DUV laser light having a wavelength shorter than that of the UV laser light by wavelength conversion from the UV laser light output from the UV light output unit and the VIR laser light output from the VIR light output unit A light conversion unit;
A control unit for controlling the operation of the UV light output unit and the VIR light output unit,
The control unit, when changing the power of the DUV laser light output from the DUV light conversion unit, makes the power of the UV laser light output from the UV light output unit substantially constant, and from the VIR light output unit A laser apparatus configured to perform control to change the power of the VIR laser light to be output. The VIR light output unit includes a first VIR light output unit that outputs a first VIR laser beam having a wavelength of visible to infrared region, and a second VIR light output unit that outputs a second VIR laser beam having a wavelength of visible to infrared region. Have
The DUV light converting unit generates a first DUV laser light by generating a sum frequency of the UV laser light output from the UV light output unit and the first VIR laser light output from the first VIR light output unit. A second DUV laser beam is generated by generating a sum frequency of the conversion optical element, the first DUV laser beam output from the first wavelength conversion optical element, and the second VIR laser beam output from the second VIR light output unit. A second wavelength conversion optical element,
The control unit makes the power of the UV laser light output from the UV light output unit substantially constant when changing the power of the second DUV laser light output from the DUV light conversion unit, and outputs the first VIR light output. 2. The apparatus according to claim 1, wherein control is performed to change a power of at least one of the first VIR laser light output from the unit and the second VIR laser light output from the second VIR light output unit. Laser equipment. The UV light output unit and the VIR light output unit each have a fiber optical amplifier that amplifies laser light in the visible to infrared region,
The UV light output unit has a wavelength conversion optical element that converts laser light in the visible to infrared region into the UV laser light in the ultraviolet region,
The control unit controls the operation of the fiber optical amplifier provided in the UV light output unit and the fiber optical amplifier provided in the VIR light output unit, thereby making the power of the UV laser light substantially constant, The laser apparatus according to claim 1, wherein the laser apparatus is configured to change the power of the VIR laser light. The fiber optical amplifier provided in the UV light output unit and the fiber optical amplifier provided in the VIR light output unit are both amplifiers that amplify a fundamental laser beam having a predetermined wavelength,
The UV light output unit is configured to generate and output the UV laser light that is the fifth harmonic from the fundamental wave amplified by the fiber optical amplifier of the UV light output unit,
The VIR light output unit is configured to generate and output the VIR laser light that is the second harmonic from the fundamental wave amplified by the fiber optical amplifier of the VIR light output unit,
The DUV light conversion unit generates the seventh harmonic of the fundamental wave by sum frequency generation from the UV laser light output from the UV light output unit and the VIR laser light output from the VIR light output unit. The laser device according to claim 3, wherein the laser device is configured as described above. The fiber optical amplifier provided in the UV light output unit, the fiber optical amplifier provided in the first VIR light output unit, and the fiber optical amplifier provided in the second VIR light output unit all have a fundamental wave of a predetermined wavelength. An amplifier that amplifies laser light;
The UV light output unit is configured to generate and output the UV laser light that is the fifth harmonic of the fundamental wave amplified by the fiber optical amplifier of the UV light output unit,
The first VIR light output unit is configured to generate and output the first VIR laser light that is the second harmonic of the fundamental wave amplified by the fiber optical amplifier of the first VIR light output unit,
The second VIR light output unit is configured to generate and output the second VIR laser light that is the fundamental wave amplified by the fiber optical amplifier of the second VIR light output unit,
The first wavelength conversion optical element generates the first DUV laser light that is the seventh harmonic of the fundamental wave by generating a sum frequency of the UV laser light and the first VIR laser light, and the second wavelength conversion optics. The element generates an eighth harmonic of the fundamental wave by generating a sum frequency of the first DUV laser light output from the first wavelength conversion optical element and the second VIR laser light output from the second VIR light output unit. The laser apparatus according to claim 3, wherein the laser apparatus is configured to generate a second DUV laser beam. A laser device according to any one of claims 1 to 5;
A mask support for holding a photomask on which a predetermined exposure pattern is formed;
An exposure object support for holding the exposure object;
An illumination optical system for irradiating the photomask held by the mask support with the laser beam output from the laser device;
An exposure apparatus comprising: a projection optical system that projects light transmitted through the photomask onto an exposure target held by an exposure target support. A laser device according to any one of claims 1 to 5;
An object support for holding the object;
An illumination optical system for irradiating a test object held by the test object support unit with laser light output from the laser device;
An inspection apparatus comprising: a detector that detects light from the test object.

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