EUV light generation apparatus and method for manufacturing electronic devices

Abstract

When a pulsed laser is irradiated onto a target, the target turns into mist, and debris contained in the mist accumulates inside the chamber, requiring more frequent maintenance. [Solution] An EUV light generation apparatus according to one aspect of the present disclosure includes a chamber, a target supply device that supplies a target into the chamber, a first pulse laser device that irradiates the target in a plasma generation region in the chamber with a first pulse laser beam, an EUV focusing mirror that is disposed in the chamber and reflects the EUV light emitted from the plasma generation region toward an external device, and a second pulse laser device that irradiates a diffused object that is diffused by irradiation with the first pulse laser beam with a second pulse laser beam having an irradiation spot diameter larger than that of the first pulse laser beam, wherein the intensity of the EUV light generated by irradiation with the second pulse laser beam is smaller than the intensity of the EUV light generated by irradiation with the first pulse laser beam.

Description

[Technical Field]

[0001] The present disclosure relates to an EUV light generation apparatus and a method for manufacturing an electronic device. [Background technology]

[0002] In recent years, with the miniaturization of semiconductor processes, the miniaturization of transfer patterns in optical lithography for semiconductor processes has progressed rapidly. In the next generation, fine processing of 10 nm or less will be required. For this reason, there is a demand for the development of semiconductor exposure equipment that combines a device for generating extreme ultraviolet (EUV) light with a wavelength of approximately 13 nm and a reduced projection reflective optical system.

[0003] As an EUV light generation device, development is progressing on a Laser Produced Plasma (LPP) type device that uses plasma generated by irradiating a target with laser light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-186995 [Patent Document 2] Patent No. 6799645 Publication Overview

[0005] An EUV light generation apparatus according to one aspect of the present disclosure includes a chamber, a target supply device that supplies a target into the chamber, a first pulse laser device that irradiates the target in a plasma generation region in the chamber with a first pulse laser beam, an EUV collector mirror that is disposed in the chamber and reflects the EUV light emitted from the plasma generation region toward an external device, and a second pulse laser device that irradiates a diffused object that is diffused by the irradiation of the first pulse laser beam with a second pulse laser beam having an irradiation spot diameter larger than that of the first pulse laser beam, wherein the intensity of the EUV light generated by the irradiation of the second pulse laser beam is smaller than the intensity of the EUV light generated by the irradiation of the first pulse laser beam.

[0006] a first pulse laser device configured to irradiate a target in a plasma generation region within the chamber with a first pulse laser beam; an EUV collector mirror disposed within the chamber and configured to reflect EUV light emitted from the plasma generation region toward an external device; and a second pulse laser device configured to irradiate a diffused object diffused by the irradiation of the first pulse laser beam with a second pulse laser beam having an irradiation spot diameter larger than that of the first pulse laser beam, wherein the intensity of the EUV light generated by the irradiation of the second pulse laser beam is smaller than the intensity of the EUV light generated by the irradiation of the first pulse laser beam, the method including: outputting the EUV light generated by the EUV light generation device to an exposure device; and exposing a photosensitive substrate in the exposure device to the EUV light to manufacture an electronic device.

[0007] a first pulse laser device that irradiates a target in a plasma generation region within the chamber with a first pulse laser beam; an EUV collector mirror disposed within the chamber that reflects EUV light emitted from the plasma generation region toward an external device; and a second pulse laser device that irradiates a diffused object diffused by the irradiation of the first pulse laser beam with a second pulse laser beam having an irradiation spot diameter larger than that of the first pulse laser beam, wherein the intensity of the EUV light generated by the irradiation of the second pulse laser beam is smaller than the intensity of the EUV light generated by the irradiation of the first pulse laser beam, the method comprising: irradiating a mask with EUV light generated by the EUV light generation device, inspecting the mask for defects; selecting a mask using the inspection results; and exposing and transferring a pattern formed on the selected mask onto a photosensitive substrate. [Brief explanation of the drawings]

[0008] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of an EUV light generation system according to a comparative example, viewed from the horizontal direction. [Figure 2] FIG. 2 is a schematic diagram of an EUV light generation system according to a comparative example, viewed from the vertical direction. [Figure 3] FIG. 3 is a schematic diagram showing a state after the EUV light generation system according to the comparative example has been operated for a certain period of time. [Figure 4] FIG. 4 is an enlarged view showing the vicinity of the plasma generation region in FIG. [Figure 5] FIG. 5 is a schematic view of the EUV light generation system according to the embodiment, viewed from the vertical direction. [Figure 6] FIG. 6 is a diagram schematically illustrating PPL light, MPL light, and CUL light irradiated onto one target. [Figure 7] FIG. 7 is a diagram showing the relationship between the pulse width of the MPL light and the pulse width of the CUL light. [Figure 8] FIG. 8 is a diagram showing a modified example of the laser device. [Figure 9] FIG. 9 is a diagram showing another modified example of the laser device. [Figure 10] FIG. 10 is a diagram showing a schematic configuration of an exposure apparatus. [Figure 11] FIG. 11 is a diagram schematically showing the configuration of the inspection device. Embodiment

[0009] <Contents> 1. Comparative Example 1.1 Configuration 1.2 Operation 1.3 Challenges 2. Embodiment 2.1 Configuration 2.2 Operation 2.3 CUL light irradiation conditions 2.3.1 Irradiation spot diameter 2.3.2 Irradiation timing 2.3.3 Irradiation Intensity 2.3.4 Pulse Width 2.4 Effects 3. Variations 4. Manufacturing method of electronic devices

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Furthermore, not all of the configurations and operations described in the embodiments are necessarily essential as the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and redundant explanations will be omitted.

[0011] 1. Comparative Example 1.1 Configuration 1 and 2 show a schematic configuration of an EUV light generation system 2 according to a comparative example. Fig. 1 is a schematic view of the EUV light generation system 2 seen from a horizontal direction. Fig. 2 is a schematic view of the EUV light generation system 2 seen from a vertical direction.

[0012] The EUV light generation system 2 includes a chamber 3, a target supply device 4, and a laser device 5. The chamber 3 is a sealable container. The target supply device 4 supplies droplet-like targets TG into the chamber 3. The targets TG are liquid tin. The target supply device 4 ejects the targets TG from the nozzle 4a at regular intervals toward a plasma generation region AR located vertically below the nozzle 4a. The diameter of the targets TG is 10 μm to 30 μm.

[0013] The chamber 3 is formed with a window 31 for allowing a pulsed laser beam output from a laser device 5 arranged outside the chamber 3 to enter the chamber 3. The pulsed laser beam transmitted through the window 31 is irradiated onto the target TG in the plasma generation region AR.

[0014] Furthermore, a connection pipe 32 is connected to the chamber 3, which connects the inside of the chamber 3 with the inside of an external device 100. The external device 100 is an exposure device 100a or an inspection device 100b.

[0015] A first gas supply port 8a is formed in the connecting pipe 32. A first gas supply device 81 is connected to the first gas supply port 8a. The first gas supply device 81 includes a gas tank and supplies gas into the chamber 3 via the connecting pipe 32. A second gas supply port 8b is formed in the chamber 3. A second gas supply device 82 is connected to the second gas supply port 8b. The second gas supply device 82 includes a gas tank and supplies gas into the chamber 3. The first gas supply device 81 may be directly connected to the chamber 3.

[0016] The gas supplied by the first gas supply device 81 and the second gas supply device 82 includes, for example, hydrogen gas. This gas may be hydrogen gas with a hydrogen concentration of 100%. Alternatively, this gas may be a balance gas with a hydrogen gas concentration of about 3%. In this case, the balance gas includes, for example, nitrogen (N2) gas or argon (Ar) gas. Furthermore, the first gas supply device 81 and the second gas supply device 82 may each be provided with a flow rate adjustment valve that enables adjustment of the flow rate of the gas.

[0017] The chamber 3 is also fitted with a sensor 6 that measures the intensity of the EUV light 20 generated in the plasma generation region AR.

[0018] A target recovery device 41 is provided at a position facing the target supply device 4 in the chamber 3. The target recovery device 41 is a drain tank that recovers unnecessary targets TG that have not contributed to the generation of EUV light 20 in the plasma generation region AR.

[0019] The chamber 3 is also provided with a cylindrical partition wall 33 extending from the internal space of the chamber 3 to the external space. The partition wall 33 surrounds the plasma generation region AR. The partition wall 33 is made of stainless steel, metal molybdenum, or the like. Of the two opposing ends of the partition wall 33, a gas inlet 33a is formed at the end located in the internal space, and a gas outlet 33b is formed at the end located in the external space. The gas outlet 33b is connected to an exhaust device 7 including an exhaust pump via a pipe 7a. The exhaust device 7 exhausts gases supplied into the chamber 3 from a first gas supply device 81 and a second gas supply device 82.

[0020] A target inlet 33c and a target outlet 33d are formed in the partition wall 33. The target inlet 33c and the target outlet 33d are arranged to face each other on the trajectory of the target TG.

[0021] Furthermore, a laser entrance port 33e and a laser exit port 33f are formed in the partition wall 33. The laser entrance port 33e and the laser exit port 33f are arranged to face each other on the optical path of the pulsed laser light that passes through the window 31 and enters the chamber 3.

[0022] Furthermore, a monitoring opening 33g is formed in the partition wall 33. The monitoring opening 33g is disposed between the plasma generation region AR and the sensor 6. Observation light generated in or near the plasma generation region AR passes through the monitoring opening 33g and enters the sensor 6.

[0023] A partition wall 34 is provided in the chamber 3 to divide the external space of the partition wall 33 into two spaces. The partition wall 34 is connected between the inner wall of the chamber 3 and the partition wall 33. The partition wall 34 is made of stainless steel, metallic molybdenum, or the like.

[0024] Hereinafter, the internal space of the partition wall 33 will be referred to as the first space S1. Of the two spaces outside the partition wall 33 separated by the partition wall 34, the space that communicates with the connecting pipe 32 will be referred to as the second space S2, and the space that does not communicate with the connecting pipe 32 will be referred to as the third space S3. The plasma generation region AR is located in the first space S1. The gas inlet 33a is formed between the first space S1 and the second space S2. The target inlet 33c, the target outlet 33d, the laser inlet 33e, and the laser outlet 33f are formed between the first space S1 and the third space S3.

[0025] An EUV collector mirror 10 having a reflective surface 10a that is a part of an ellipsoid of revolution is disposed in the second space S2. A multilayer reflective film in which molybdenum and silicon are alternately stacked is formed on the reflective surface 10a. The EUV collector mirror 10 is disposed so that one focus of the ellipsoid of revolution is located in the plasma generation region AR.

[0026] The EUV light 20 emitted from the plasma in the plasma generation region AR enters the EUV collector mirror 10 arranged in the second space S2 from the first space S1 through the gas inlet 33a. The EUV collector mirror 10 reflects the EUV light 20 toward an external device 100 located in a direction different from the incident direction.

[0027] The second gas supply port 8b is formed at a position communicating with the third space S3. The sensor 6 is disposed in the third space S3. Also disposed in the third space S3 is a damper 9 for absorbing the pulsed laser light that passes from the plasma generation region AR through the laser emission port 33f and enters the third space S3.

[0028] The laser device 5 is disposed so that the output pulsed laser light enters the third space S3 in the chamber 3 through the window 31 and enters the plasma generation region AR through the laser entrance port 33e.

[0029] The laser device 5 outputs pre-pulse laser (PPL) light 51a and main pulse laser (MPL) light 52a as pulsed laser beams. Specifically, the laser device 5 includes a PPL device 51 that outputs PPL light 51a and an MPL device 52 that outputs MPL light 52a. For example, the PPL device 51 is an Nd:YAG laser device, and the MPL device 52 is an Nd:YAG laser device or a CO2 laser device. For example, the wavelength λ1 of the PPL light 51a and the wavelength λ2 of the MPL light 52a are equal, each being 1.06 μm. Furthermore, the PPL light 51a and the MPL light 52a are each linearly polarized light.

[0030] A beam combiner 55 is provided to combine the optical paths of PPL light 51a and MPL light 52a and allow them to enter chamber 3 through window 31. Beam combiner 55 is, for example, a polarizing beam splitter that reflects s-polarized light and transmits p-polarized light. Beam combiner 55 is positioned so that PPL light 51a output from PPL device 51 enters one surface as s-polarized light, and MPL light 52a output from MPL device 52 and reflected by reflecting mirror 56 enters the other surface as p-polarized light. PPL light 51a is reflected by beam combiner 55, and MPL light 52a passes through beam combiner 55, thereby combining the optical paths of PPL light 51a and MPL light 52a.

[0031] Note that reflecting mirror 56 is not necessarily required, and a configuration may be adopted in which MPL light 52a output from MPL device 52 is directly incident on beam combiner 55. Furthermore, when the wavelength λ1 of PPL light 51a and the wavelength λ2 of MPL light 52a are different, beam combiner 55 can be a dichroic mirror.

[0032] The pulse energy of the PPL light 51a is smaller than the pulse energy of the MPL light 52a. The laser device 5 outputs the PPL light 51a and the MPL light 52a in this order.

[0033] 1 and 2, the X direction is the direction from the plasma generation region AR toward the exhaust device 7, the Y direction is the vertical direction, and the Z direction is the direction along the optical path of the pulsed laser beam. In this comparative example, the X direction, Y direction, and Z direction are perpendicular to one another, but they do not necessarily have to be perpendicular to one another.

[0034] 1.2 Operation The operation of the EUV light generation apparatus 2 according to the comparative example will be described. First, the internal pressure of the chamber 3 is set to a predetermined pressure or lower. Then, the first gas supply device 81 and the second gas supply device 82 start supplying gas into the chamber 3. The gas supplied from the first gas supply device 81 flows from the second space S2 into the first space S1 via the gas inlet 33a. The gas supplied from the second gas supply device 82 flows from the third space S3 into the first space S1 via the target inlet 33c, the target outlet 33d, the laser inlet 33e, the laser outlet 33f, and the monitoring opening 33g. The gas that has flowed into the first space S1 flows out from the gas outlet 33b and is exhausted to the outside of the chamber 3 by the exhaust device 7.

[0035] Next, the target supply device 4 discharges the target TG from the nozzle 4a at regular intervals. The discharged target TG passes through the target inlet 33c and heads toward the plasma generation region AR. The laser device 5 irradiates the target TG, which is supplied to the plasma generation region AR at regular intervals, with PPL light 51a and MPL light 52a at regular intervals, thereby generating EUV light 20. The timing at which the laser device 5 outputs the PPL light 51a and MPL light 52a is determined based on a target TG passage timing signal from a timing sensor (not shown).

[0036] The EUV light 20 generated in the plasma generation region AR passes through the gas inlet 33a, is reflected by the EUV collector mirror 10, and enters the external device 100 via the connecting pipe 32. In the external device 100, a predetermined process is performed using the EUV light 20. In addition, the intensity of the EUV light 20 generated in the plasma generation region AR is measured by the sensor 6.

[0037] More specifically, droplet-like targets TG supplied to the plasma generation region AR are irradiated with PPL light 51a to become mist-like targets TGm. The mist-like targets TGm are irradiated with MPL light 52a to become plasma and generate EUV light 20. At this time, a portion of the mist-like targets TGm is not converted into plasma and diffuses as residual mist. This residual mist contains debris called fragments, such as minute particles of liquid tin having a certain size.

[0038] Although light including EUV light is generated by irradiating the target TG with the PPL light 51a, the intensity of the EUV light generated by irradiation with the PPL light 51a is lower than the intensity of the EUV light 20 generated by irradiating with the MPL light 52a. The targets TG and TGm are examples of "targets" according to the technology of the present disclosure. The residual mist is an example of "diffused matter" according to the technology of the present disclosure.

[0039] The above-mentioned flow of gas from the second space S2 to the first space S1 prevents the residual mist generated in the first space S1 from flowing into the second space S2 where the EUV collector mirror 10 is arranged.

[0040] 1.3 Challenges Fig. 3 shows a state after the EUV light generation system 2 according to the comparative example has been operated for a certain period of time. Fig. 4 is an enlarged view showing the vicinity of the plasma generation region AR in Fig. 3.

[0041] As described above, some of the debris contained in the residual mist scattered when the mist-like target TGm is irradiated with the MPL light 52a adheres to and accumulates on the inner surface of the partition wall 33 without being expelled by the gas. It has been found that most of the debris accumulation occurs within an angle range of 45 degrees from the plasma generation region AR to the irradiation axis A of the MPL light 52a.

[0042] 3 and 4 indicate debris deposits. When deposits F1 and F2 occur on the inner surface of the partition wall 33 as shown in FIG. 4, the deposits F1 and F2 narrow the first space S1, thereby reducing the gas exhaust efficiency. This increases the gas pressure in the first space S1, which may change the operating conditions of the EUV light generation system 2. The symbol R in FIG. 4 schematically indicates the region where the gas pressure increases.

[0043] 4, deposits F3 may form near the monitoring opening 33g on the inner surface of the partition wall 33. In this case, the gas exhaust efficiency similarly decreases, and the deposits F3 may interfere with the optical path through which the sensor 6 monitors the plasma generation region AR, blocking the observation light and possibly causing an abnormality in the operation of the sensor 6.

[0044] 3, deposits F4 may form on the optical elements of the sensor 6. In this case, the deposits F4 may interfere with the optical path through which the sensor 6 monitors the plasma generation region AR, blocking the observation light and possibly causing malfunctions in the operation of the sensor 6.

[0045] Furthermore, deposits (not shown) generated near the target inlet 33c may interfere with the trajectory of the target TG, which may cause abnormalities in the generation of the EUV light 20.

[0046] In the above comparative example, partitions 33 and 34 are provided inside the chamber 3, but even if partitions 33 and 34 are not provided, similar abnormalities can occur due to deposits forming on the inner surface of the chamber 3 or on the optical elements of the sensor 6.

[0047] Accumulation of debris generated in the chamber 3 in this way can cause abnormalities, so the EUV light generation system 2 needs to be periodically maintained. If abnormalities caused by debris accumulation occur frequently, the maintenance intervals need to be shortened, which shortens the operating time of the EUV light generation system 2.

[0048] The present disclosure aims to suppress the accumulation of debris in the chamber 3 and reduce the occurrence of abnormalities.

[0049] 2. Embodiment 2.1 Configuration An EUV light generation system 2a according to an embodiment of the present disclosure has the same configuration as the EUV light generation system 2 according to the comparative example, except that the laser device 5 has a different configuration.

[0050] FIG. 5 schematically illustrates the configuration of an EUV light generation system 2a according to an embodiment. FIG. 5 is a schematic diagram of the EUV light generation system 2a viewed from the vertical direction. In this embodiment, the laser device 5 includes a PPL device 51, an MPL device 52, and a CUL device 53 that outputs clean-up laser (CUL) light 53a. For example, the CUL device 53 is an Yb:YAG laser device. The CUL device 53 may also be an Nd:YAG laser device, an Nd:YLF laser device, a YVO4 laser device, or the like. The CUL light 53a is a pulsed laser light for decomposing residual mist.

[0051] In this embodiment, the wavelength λ3 of the CUL light 53a is different from the wavelength λ2 of the MPL light 52a. Also, in this embodiment, the wavelength λ2 of the MPL light 52a is equal to the wavelength λ1 of the PPL light 51a. In this embodiment, the PPL light 51a, the MPL light 52a, and the CUL light 53a are each linearly polarized light.

[0052] In this embodiment, a first beam combiner 55a and a second beam combiner 55b are provided to combine the optical paths of PPL light 51a, MPL light 52a, and CUL light 53a and allow them to enter chamber 3 through window 31. The first beam combiner 55a is a dichroic mirror that transmits light of wavelength λ3 and reflects light of wavelength λ2. The first beam combiner 55a is positioned so that MPL light 52a output from the MPL device 52 is incident on one surface, and CUL light 53a output from the CUL device 53 and reflected by a reflecting mirror 56 is incident on the other surface. The MPL light 52a is reflected by the first beam combiner 55a, and the CUL light 53a passes through the first beam combiner 55a, thereby combining the optical paths of MPL light 52a and CUL light 53a.

[0053] The second beam combiner 55b is a polarizing beam splitter that reflects s-polarized light and transmits p-polarized light. The second beam combiner 55b is positioned so that PPL light 51a output from the PPL device 51 enters one surface as s-polarized light, and MPL light 52a reflected by the first beam combiner 55a and CUL light 53a transmitted through the first beam combiner 55a enter the other surface as p-polarized light. The PPL light 51a is reflected by the second beam combiner 55b, and the MPL light 52a and CUL light 53a transmit through the second beam combiner 55b, thereby combining the optical paths of the PPL light 51a, MPL light 52a, and CUL light 53a.

[0054] The reflecting mirror 56 is not necessarily required, and the CUL light 53a output from the CUL device 53 may be configured to directly enter the beam combiner 55a.

[0055] The pulse energy of the PPL light 51a is smaller than the pulse energy of the MPL light 52a. The laser device 5 outputs the PPL light 51a, MPL light 52a, and CUL light 53a in this order. The output timing of the PPL light 51a, MPL light 52a, and CUL light 53a is controlled by a processor (not shown).

[0056] The MPL device 52 is an example of a "first pulse laser device" according to the technology of the present disclosure. The CUL device 53 is an example of a "second pulse laser device" according to the technology of the present disclosure. The PPL device 51 is an example of a "third pulse laser device" according to the technology of the present disclosure. The MPL light 52a is an example of a "first pulse laser light" according to the technology of the present disclosure. The CUL light 53a is an example of a "second pulse laser light" according to the technology of the present disclosure. The PPL light 51a is an example of a "third pulse laser light" according to the technology of the present disclosure.

[0057] 2.2 Operation The operation of the EUV light generation system 2a according to this embodiment is the same as that of the comparative example, except that the operation of the laser device 5 is different.

[0058] In this embodiment, the laser device 5 irradiates the CUL light 53a every time it irradiates the PPL light 51a and the MPL light 52a. Specifically, the laser device 5 irradiates the target TG, which is supplied to the plasma generation region AR at regular intervals, with the PPL light 51a and the MPL light 52a at regular intervals to generate the EUV light 20, and also irradiates the CUL light 53a onto the residual mist generated by the irradiation of the MPL light 52a.

[0059] FIG. 6 schematically shows PPL light 51a, MPL light 52a, and CUL light 53a irradiated onto one target TG. Irradiation of the target TG with PPL light 51a turns the target TG into mist. Irradiation of the mist-like target TGm with MPL light 52a converts the target TGm into plasma, generating EUV light 20, and some of the plasma becomes residual mist. Irradiation of the residual mist with CUL light 53a decomposes the residual mist into atoms, which are then exhausted together with gas to the outside of the chamber 3 by the exhaust device 7. Irradiation of the residual mist with CUL light 53a also generates light containing EUV light, but the intensity of this EUV light is lower than the intensity of EUV light 20 generated by irradiating the mist-like target TGm with MPL light 52a.

[0060] Because the irradiation time intervals between the PPL light 51a, MPL light 52a, and CUL light 53a are short, the center of gravity of the mist-like target TGm and the center of gravity of the residual mist hardly move in the vertical Y direction. However, the center of gravity of the mist-like target TGm moves along the irradiation axis A due to the irradiation of the target TG with the PPL light 51a. The center of gravity of the residual mist moves along the irradiation axis A due to the irradiation of the mist-like target TGm with the MPL light 52a. For this reason, as described above, the irradiation accuracy is improved by integrating the optical paths of the PPL light 51a, MPL light 52a, and CUL light 53a and irradiating them along the irradiation axis A.

[0061] 2.3 CUL light irradiation conditions Next, various irradiation conditions of the CUL light 53a for efficiently decomposing the residual mist will be described.

[0062] 2.3.1 Irradiation spot diameter Because the residual mist becomes larger in diameter D than the mist-like target TGm due to diffusion, the irradiation spot diameter φ2 of the CUL light 53a in the plasma generation region AR must be larger than the irradiation spot diameter φ1 of the PPL light 51a. For example, the irradiation spot diameter φ2 is preferably within a range of 1.5 to 5 times the irradiation spot diameter φ1, and more preferably within a range of 2 to 3 times. Note that the irradiation spot diameter is, for example, 1 / e of the maximum intensity in a Gaussian beam whose intensity distribution is symmetrical around the center. 2 It is defined as the diameter at which the diameter is doubled.

[0063] 2.3.2 Irradiation timing The CUL light 53a is preferably irradiated onto the residual mist after the intensity of the EUV light 20 generated by irradiating the mist-like target TGm with the MPL light 52a has decreased. This is because if the CUL light 53a is irradiated during the emission of the EUV light 20, the mist contained in the mist-like target TGm will diffuse and the intensity of the EUV light 20 will decrease.

[0064] Specifically, after irradiation with MPL light 52a, it is preferable to irradiate CUL light 53a before the residual mist diffuses and becomes larger than the irradiation spot diameter φ2 of CUL light 53a. In other words, it is preferable that the irradiation spot diameter φ2 of CUL light 53a is larger than the diameter D of the residual mist at the time of irradiation with CUL light 53a.

[0065] More specifically, as shown in FIG. 7, when the pulse width of the MPL light 52a is Tm, the pulse width of the CUL light 53a is Tc, and the delay time of the CUL light 53a relative to the MPL light 52a is Dt, it is preferable to satisfy the following formula (1): (Tm+Tc) / 2≦Dt≦100ns (1)

[0066] For example, the pulse widths Tm and Tc are each defined as a full width at half maximum, and the delay time Dt is defined as the difference between the time when the intensity of the MPL light 52a is at its maximum and the time when the intensity of the CUL light 53a is at its maximum.

[0067] 2.3.3 Irradiation Intensity In order to decompose the residual mist into atoms, the intensity of the CUL light 53a must be higher than the ablation threshold of tin, which is, for example, 2.5×10 when the pulse energy is 0.16 mJ, the spot diameter is 100 μm, and the pulse width is 80 ns. 7 W / cm 2 From this, it is known from experiments that the lower limit of the intensity of the CUL light 53a is 2.5 × 10 7 W / cm 2 It is preferable to set the following.

[0068] From the viewpoint of decomposing the residual mist to its atomic state, there is no upper limit to the intensity of the CUL light 53a. However, because the residual mist is liquid tin, irradiating it with high-intensity laser light generates high-energy ions, which may collide with and damage optical elements such as the EUV collector mirror 10 in the chamber 3. To protect the optical elements from such high-energy ions, a gas is supplied into the chamber 3. However, the characteristics of this gas are set based on the energy of the ions generated during irradiation with the MPL light 52a. Therefore, if increasing the intensity of the CUL light 53a generates ions with higher energy than those generated during irradiation with the MPL light 52a, the gas cannot protect the optical elements and may damage them. Because the energy of the generated ions is roughly proportional to the intensity, for example, if the upper limit of the intensity of the CUL light 53a is set to 1 / 10 of the intensity of the MPL light 52a, damage to the optical elements is negligible. From the above, for example, the upper limit of the intensity of the CUL light 53a is set to 5×10 9 W / cm 2 It is preferable to set the following.

[0069] 2.3.4 Pulse Width The pulse width of the CUL light 53a may be within a range that allows ablation of liquid tin, and experiments have shown that a lower limit of 20 ns is sufficient. Furthermore, a longer pulse width of the CUL light 53a is preferable because it increases the reaction time with tin. Experiments have shown that a preferred upper limit for the pulse width of the CUL light 53a is 200 ns. In other words, the pulse width of the CUL light 53a is preferably within a range of 20 ns to 200 ns. For example, it is preferable to set the pulse width of the CUL light 53a to about 100 ns.

[0070] 2.4 Effects In this embodiment, the residual mist generated by irradiation with the MPL light 52a is decomposed into atoms and discharged together with the gas to the outside of the chamber 3 by irradiating the CUL light 53a, thereby suppressing the accumulation of debris on the inner surface of the partition wall 33, etc. This reduces the occurrence of abnormalities in the EUV light generation system 2. Specifically, this reduces the reduction in gas exhaust efficiency, abnormal operation of the sensor 6, abnormal generation of the EUV light 20, etc., and extends the maintenance interval. This improves the operating time of the EUV light generation system 2.

[0071] 3. Variations Various modifications of the above embodiment will be described below.

[0072] In the above embodiment, the wavelength λ1 of the PPL light 51a and the wavelength λ2 of the MPL light 52a are the same, but they may be different wavelengths. That is, the wavelengths λ1, λ2, and λ3 may be different wavelengths. In this case, both the first beam combiner 55a and the second beam combiner 55b may be dichroic mirrors. For example, as in the above embodiment, the first beam combiner 55a may be a dichroic mirror that transmits light of wavelength λ3 and reflects light of wavelength λ2. Furthermore, the second beam combiner 55b may be a dichroic mirror that transmits light of wavelength λ3 and light of wavelength λ2 and reflects light of wavelength λ1.

[0073] Furthermore, in the above embodiment, the PPL device 51, the MPL device 52, and the CUL device 53 are arranged in this order from the downstream side of the optical path, but as shown in Fig. 8, they may also be arranged in the following order from the downstream side: CUL device 53, PPL device 51, and MPL device 52. In this case, the first beam combiner 55a is a polarizing beam splitter that reflects s-polarized light and transmits p-polarized light. The first beam combiner 55a is arranged so that PPL light 51a output from the PPL device 51 is incident on one surface as s-polarized light, and MPL light 52a output from the MPL device 52 and reflected by the reflecting mirror 56 is incident on the other surface as p-polarized light.

[0074] In this case, second beam combiner 55b is a dichroic mirror that transmits light of wavelength λ1 and light of wavelength λ2 and reflects light of wavelength λ3. Second beam combiner 55b is positioned so that CUL light 53a output from CUL device 53 is incident on one surface, and MPL light 52a transmitted through first beam combiner 55a and PPL light 51a reflected by first beam combiner 55a are incident on the other surface. CUL light 53a is reflected by second beam combiner 55b, and PPL light 51a and MPL light 52a transmit through second beam combiner 55b, thereby combining the optical paths of PPL light 51a, MPL light 52a, and CUL light 53a.

[0075] 8, reflecting mirror 56 is not necessarily required, and MPL light 52a output from MPL device 52 may be configured to directly enter first beam combiner 55a. Also, in the example shown in Fig. 8, if wavelengths λ1, λ2, and λ3 are different from one another, first beam combiner 55a and second beam combiner 55b can both be dichroic mirrors.

[0076] It is also possible to set the wavelengths λ1, λ2, and λ3 to the same wavelength. In this case, for example, as shown in Figure 9, an electro-optic modulator 57 that can change the polarization direction of light over time is placed on the optical path between the first beam combiner 55a and the second beam combiner 55b. The electro-optic modulator 57 is controlled by a processor (not shown).

[0077] 9, first beam combiner 55a and second beam combiner 55b are both polarizing beam splitters that reflect s-polarized light and transmit p-polarized light. First beam combiner 55a is positioned so that MPL light 52a output from MPL device 52 enters one surface as s-polarized light, and CUL light 53a output from CUL device 53 and reflected by reflecting mirror 56 enters the other surface as p-polarized light.

[0078] The MPL light 52a reflected by the first beam combiner 55a and the CUL light 53a transmitted through the first beam combiner 55a are incident on the electro-optic modulator 57. The electro-optic modulator 57 outputs the CUL light 53a without changing the polarization direction, and outputs the MPL light 52a after changing the polarization direction by 90 degrees.

[0079] The second beam combiner 55b is disposed so that the PPL light 51a output from the PPL device 51 is incident on one surface as s-polarized light, and the MPL light 52a and CUL light 53a output from the electro-optic modulator 57 are incident on the other surface as p-polarized light. The PPL light 51a is reflected by the second beam combiner 55b, and the MPL light 52a and CUL light 53a pass through the second beam combiner 55b, thereby combining the optical paths of the PPL light 51a, MPL light 52a, and CUL light 53a.

[0080] In addition to the above-described modifications, various modifications are possible for the configuration for integrating the optical paths of PPL light 51a, MPL light 52a, and CUL light 53a. It is sufficient that the optical paths of PPL light 51a and MPL light 52a at least partially overlap. It is also sufficient that the optical paths of MPL light 52a and CUL light 53a at least partially overlap.

[0081] Furthermore, the two beams of light incident on the polarizing beam splitter described in the above embodiments and modifications may have opposite polarization directions. Specifically, the polarizing beam splitter may be arranged so that the above-mentioned s-polarized light becomes p-polarized light, and the above-mentioned p-polarized light becomes s-polarized light. Furthermore, the polarization directions of the light reflected and transmitted by the polarizing beam splitter may be opposite. Specifically, the polarizing beam splitter may reflect p-polarized light and s-polarized light.

[0082] Furthermore, in the above embodiment and each of the above modifications, the laser device 5 is provided with the PPL device 51, but the laser device 5 does not necessarily have to be provided with the PPL device 51. That is, the droplet-shaped target TG may be irradiated with the MPL light 52a.

[0083] Although the PPL device 51 is not essential, by using the PPL device 51 to turn the droplet-like target TG into a mist-like target TGm, the generation efficiency of the EUV light 20 is improved, and the efficiency of decomposing the residual mist by the CUL light 53a is also improved. This is because by generating the mist-like target TGm, the fragments contained in the residual mist generated by irradiation with the MPL light 52a are decomposed into smaller fragments.

[0084] In addition, in the above embodiment, the partition walls 33 and 34 are provided in the chamber 3, but the partition walls 33 and 34 do not have to be provided in the chamber 3. Furthermore, of the partition walls 33 and 34, only the partition wall 33 may be provided in the chamber 3.

[0085] 4. Manufacturing method of electronic devices FIG. 10 shows a schematic configuration of an exposure apparatus 100a connected to an EUV light generation system 2a. In FIG. 10, the exposure apparatus 100a, which serves as an external apparatus 100, includes a mask irradiation unit 102 and a workpiece irradiation unit 104. The mask irradiation unit 102 illuminates a mask pattern on a mask table MT via a reflection optical system using EUV light 20 incident from the EUV light generation system 2a. The workpiece irradiation unit 104 focuses the EUV light 20 reflected by the mask table MT onto a workpiece (not shown) placed on a workpiece table WT via a reflection optical system. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure apparatus 100a exposes the workpiece to EUV light 20 reflecting the mask pattern by synchronously translating the mask table MT and the workpiece table WT. Electronic devices can be manufactured by transferring a device pattern onto a semiconductor wafer using the exposure process described above.

[0086] FIG. 11 shows a schematic configuration of an inspection system 100b connected to an EUV light generation system 2a. In FIG. 11, the inspection system 100b, which serves as an external device 100, includes an illumination optical system 110 and a detection optical system 112. The EUV light generation system 2a outputs EUV light 20 to the inspection system 100b as an inspection light source. The illumination optical system 110 reflects the EUV light 20 incident from the EUV light generation system 2a and irradiates a mask 116 placed on a mask stage 114. The mask 116 here includes a mask blank before a pattern is formed. The detection optical system 112 reflects the EUV light 20 from the illuminated mask 116 and forms an image on the light-receiving surface of a detector 118. The detector 118 receives the EUV light 20 and acquires an image of the mask 116. The detector 118 is, for example, a time delay integration (TDI) camera. The image of the mask 116 obtained by the above process is used to inspect the mask 116 for defects, and the inspection results are used to select a mask suitable for manufacturing an electronic device. Then, the pattern formed on the selected mask is exposed and transferred onto a photosensitive substrate using the exposure apparatus 100a, thereby manufacturing the electronic device.

[0087] The above description is intended to be illustrative, not limiting. Accordingly, it will be apparent to one skilled in the art that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. Terms used throughout this specification and claims should be construed as "open ended" unless expressly stated. For example, terms such as "comprise," "have," "comprise," and "equip" should be interpreted as meaning "without excluding the presence of elements other than those listed." The modifier "a" should be interpreted as "at least one" or "one or more." The term "at least one of A, B, and C" should be interpreted as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C," and should also be interpreted as including combinations other than "A," "B," and "C."

Claims

1. a chamber; a target supply device for supplying a target into the chamber; a first pulse laser device that irradiates the target with a first pulse laser beam in a plasma generation region within the chamber; an EUV collector mirror disposed in the chamber and configured to reflect the EUV light emitted from the plasma generation region toward an external device; a second pulse laser device that irradiates a diffused object that is diffused by irradiation with the first pulse laser beam with a second pulse laser beam having an irradiation spot diameter larger than that of the first pulse laser beam; Equipped with the intensity of the EUV light generated by irradiation with the second pulsed laser beam is lower than the intensity of the EUV light generated by irradiation with the first pulsed laser beam. EUV light generation device.

2. 2. The EUV light generation system according to claim 1, The irradiation spot diameter of the second pulsed laser beam is larger than the diameter of the diffused object.

3. 2. The EUV light generation system according to claim 1, The irradiation spot diameter of the second pulse laser beam is in the range of 1.5 to 5 times the irradiation spot diameter of the first pulse laser beam.

4. 2. The EUV light generation system according to claim 1, The irradiation spot diameter of the second pulse laser beam is in the range of two to three times the irradiation spot diameter of the first pulse laser beam.

5. 2. The EUV light generation system according to claim 1, The second pulse laser device irradiates the diffused object with the second pulse laser beam after the intensity of the EUV light generated by irradiation with the first pulse laser beam has decreased.

6. 6. The EUV light generation system according to claim 5, When the pulse width of the first pulse laser beam is Tm, the pulse width of the second pulse laser beam is Tc, and the delay time of the second pulse laser beam relative to the first pulse laser beam is Dt, the relationship (Tm+Tc) / 2≦Dt≦100 ns is satisfied.

7. 2. The EUV light generation system according to claim 1, The intensity of the second pulse laser beam is lower than the intensity of the first pulse laser beam.

8. The EUV light generation system according to claim 7 , The intensity of the second pulse laser beam is 1 / 10 or less of the intensity of the first pulse laser beam.

9. 2. The EUV light generation system according to claim 1, The pulse width of the second pulsed laser beam is within a range of 20 ns to 200 ns.

10. 2. The EUV light generation system according to claim 1, The second pulse laser device irradiates the diffused object with the second pulse laser beam every time the target is irradiated with the first pulse laser beam.

11. 2. The EUV light generation system according to claim 1, The optical path of the second pulsed laser beam at least partially overlaps with the optical path of the first pulsed laser beam.

12. 2. The EUV light generation system according to claim 1, The laser irradiation device includes a third pulse laser device that irradiates the target with a third pulse laser beam before irradiating the target with the first pulse laser beam.

13. The EUV light generation system according to claim 12, The intensity of the EUV light generated by irradiation with the third pulsed laser beam is lower than the intensity of the EUV light generated by irradiation with the first pulsed laser beam.

14. The EUV light generation system according to claim 12, The optical path of the second pulse laser beam at least partially overlaps with the optical path of the first pulse laser beam and the optical path of the third pulse laser beam.

15. The EUV light generation system according to claim 14, The laser beam splitter includes a first beam combiner and a second beam combiner that combine the optical path of the first pulsed laser beam, the optical path of the second pulsed laser beam, and the optical path of the third pulsed laser beam.

16. 2. The EUV light generation system according to claim 1, The apparatus includes a gas supply device that supplies gas into the chamber, and an exhaust device that exhausts the gas from the chamber.

17. The EUV light generation system according to claim 16, A partition wall is provided to surround the plasma generation region and is connected to the exhaust device.

18. The EUV light generation system according to claim 17, A sensor is provided that measures the intensity of the EUV light generated in the plasma generation region through a monitoring opening formed in the partition wall.

19. A method for manufacturing an electronic device, comprising: a chamber; a target supply device for supplying a target into the chamber; a first pulse laser device that irradiates the target with a first pulse laser beam in a plasma generation region within the chamber; an EUV collector mirror disposed in the chamber and configured to reflect the EUV light emitted from the plasma generation region toward an external device; a second pulse laser device that irradiates a diffused object that is diffused by irradiation with the first pulse laser beam with a second pulse laser beam having an irradiation spot diameter larger than that of the first pulse laser beam; Equipped with the intensity of the EUV light generated by irradiation with the second pulsed laser beam is lower than the intensity of the EUV light generated by irradiation with the first pulsed laser beam. outputting the EUV light generated by the EUV light generation system to an exposure system; exposing a photosensitive substrate to the EUV light in the exposure apparatus to manufacture an electronic device; A method for manufacturing an electronic device, comprising:

20. A method for manufacturing an electronic device, comprising: a chamber; a target supply device for supplying a target into the chamber; a first pulse laser device that irradiates the target with a first pulse laser beam in a plasma generation region within the chamber; an EUV collector mirror disposed in the chamber and configured to reflect the EUV light emitted from the plasma generation region toward an external device; a second pulse laser device that irradiates a diffused object that is diffused by irradiation with the first pulse laser beam with a second pulse laser beam having an irradiation spot diameter larger than that of the first pulse laser beam; Equipped with the intensity of the EUV light generated by irradiation with the second pulsed laser beam is lower than the intensity of the EUV light generated by irradiation with the first pulsed laser beam. irradiating a mask with the EUV light generated by an EUV light generation system and inspecting the mask for defects; selecting a mask using the results of said testing; transferring the pattern formed on the selected mask onto a photosensitive substrate by exposure; A method for manufacturing an electronic device, comprising:

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