Extreme ultraviolet light generation system and method for manufacturing an electronic device

Abstract

To provide an exposure unit combining an extreme-ultraviolet light generator generating an extreme-ultraviolet light (EUV) and a reduced projection refractive optical system.SOLUTION: An extreme ultraviolet light generating system 11a comprises a laser unit 3 outputting a pulse laser light, an EUV condensing mirror 23 for condensing by reflecting an extreme ultraviolet light generated by irradiating a target with the pulse laser light, and a processor 5 that receives a first energy parameter of the extreme ultraviolet light to control an irradiation frequency of the laser light with which the target is irradiated so that a change of a second energy parameter relating to an energy per unit time of the extreme ultraviolet light reflected by the EUV condensing mirror 23 is suppressed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an extreme ultraviolet light generation system and a method for manufacturing an electronic device.

Background Art

[0002] In recent years, with the miniaturization of semiconductor processes, the miniaturization of transfer patterns in optical lithography of semiconductor processes has been rapidly progressing. In the next generation, microfabrication of 70 nm to 45 nm and further microfabrication of 32 nm or less will be required. For this reason, for example, in order to meet the requirements of microfabrication of 32 nm or less, the development of an exposure apparatus combining an extreme ultraviolet (EUV) light generation apparatus that generates EUV light having a wavelength of about 13 nm and a reduced projection reflection optics is expected.

[0003] As EUV light generation apparatuses, there are proposed three types of apparatuses: an LPP (Laser Produced Plasma) type apparatus that uses plasma generated by irradiating a target material with pulsed laser light, a DPP (Discharge Produced Plasma) type apparatus that uses plasma generated by discharge, and an SR (Synchrotron Radiation) type apparatus that uses synchrotron radiation light.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] An extreme ultraviolet light generation system according to one aspect of the present disclosure includes a laser device that outputs pulsed laser light, an EUV condenser mirror that condenses extreme ultraviolet light generated by irradiating a target with the pulsed laser light by reflecting the extreme ultraviolet light, and a processor that receives a first energy parameter of the extreme ultraviolet light and controls an irradiation frequency of the pulsed laser light irradiated to the target so as to suppress a change in a second energy parameter related to the energy per unit time of the extreme ultraviolet light reflected by the EUV condenser mirror.

[0006] A method for manufacturing an electronic device according to one aspect of the present disclosure includes generating extreme ultraviolet light in an extreme ultraviolet light generation system including a laser device that outputs pulsed laser light, an EUV condenser mirror that condenses extreme ultraviolet light generated by irradiating a target with the pulsed laser light by reflecting the extreme ultraviolet light, and a processor that receives a first energy parameter of the extreme ultraviolet light and controls an irradiation frequency of the pulsed laser light irradiated to the target so as to suppress a change in a second energy parameter related to the energy per unit time of the extreme ultraviolet light reflected by the EUV condenser mirror, outputting the extreme ultraviolet light to an exposure apparatus, and exposing the extreme ultraviolet light onto a photosensitive substrate in the exposure apparatus to manufacture the electronic device.

[0007] A method for manufacturing an electronic device according to one aspect of the present disclosure includes irradiating extreme ultraviolet light generated in an extreme ultraviolet light generation system including a laser device that outputs pulsed laser light, an EUV condenser mirror that condenses extreme ultraviolet light generated by irradiating a target with the pulsed laser light by reflecting the extreme ultraviolet light, and a processor that receives a first energy parameter of the extreme ultraviolet light and controls an irradiation frequency of the pulsed laser light irradiated to the target so as to suppress a change in a second energy parameter related to the energy per unit time of the extreme ultraviolet light reflected by the EUV condenser mirror onto a mask to inspect for defects in the mask, selecting the mask using the results of the inspection, and exposing and transferring a pattern formed on the selected mask onto a photosensitive substrate.

Brief Description of the Drawings

[0008] Some embodiments of the present disclosure will be described below by way of example only with reference to the accompanying drawings.

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[0009] <Content> 1. EUV Light Generation System 11 According to a Comparative Example 1.1 Configuration 1.2 Operation 1.3 Problems of the Comparative Example 2. EUV Light Generation System 11a That Controls the Irradiation Frequency F So That the Change in the Second Energy Parameter P2 Is Suppressed I 2.1 Configuration 2.2 Operation 2.2.1 First Operation Example for Increasing the Irradiation Frequency F I 2.2.2 Second Operation Example for Increasing the Irradiation Frequency F I 2.3 Function 3. EUV Light Generation System 11a That Gradually Increases the Irradiation Frequency F I 3.1 Configuration and Operation 3.2 Function 4. EUV Light Generation System 11a that Changes the Pulse Energy E of the Pulse Laser Light 33 4.1 Configuration and Operation 4.2 Function 5. Others

[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. Also, not all of the configurations and operations described in each embodiment are essential as the configurations and operations of the present disclosure. Note that the same reference numerals are assigned to the same components, and duplicate descriptions are omitted.

[0011] 1. EUV Light Generation System 11 According to the Comparative Example 1.1 Configuration FIG. 1 schematically shows the configuration of an LPP-type EUV light generation system 11 according to the comparative example. The EUV light generation apparatus 1 is used together with the laser apparatus 3. In the present disclosure, a system including the EUV light generation apparatus 1 and the laser apparatus 3 is referred to as an EUV light generation system 11. The EUV light generation apparatus 1 includes a chamber 2 and a target supply unit 26. The chamber 2 is a sealable container. The target supply unit 26 supplies a target substance into the chamber 2. The material of the target substance may include tin, terbium, gadolinium, lithium, xenon, or a combination of any two or more of them.

[0012] The wall of chamber 2 is provided with a through hole. The through hole is blocked by window 21, and pulsed laser light 32 output from laser device 3 passes through window 21. Inside chamber 2, an EUV condenser mirror 23 having a reflecting surface in the shape of a rotating ellipsoid is arranged. EUV condenser mirror 23 has first and second foci. On the surface of EUV condenser mirror 23, a multilayer reflective film in which molybdenum and silicon are alternately laminated is formed. EUV condenser mirror 23 is arranged such that its first focus is located in plasma generation region 25 and its second focus is located in intermediate focus point 292. A through hole 24 is provided in the central portion of EUV condenser mirror 23, and pulsed laser light 33 passes through through hole 24.

[0013] The EUV light generation device 1 includes a processor 5, a target sensor 4, etc. The processor 5 is a processing device including a memory 501 storing a control program and a CPU (central processing unit) 502 executing the control program. The processor 5 is specially configured or programmed to execute various processes included in the present disclosure. The target sensor 4 detects at least one of the presence, trajectory, position, and speed of the target 27. The target sensor 4 may have an imaging function.

[0014] In addition, the EUV light generation device 1 includes a connection portion 29 that communicates the inside of chamber 2 with the inside of the EUV light utilization device 6. An example of the EUV light utilization device 6 will be described later with reference to FIGS. 15 and 16. Inside the connection portion 29, a wall 291 having an aperture formed therein is provided. The wall 291 is arranged such that its aperture is located at the second focus of the EUV condenser mirror 23.

[0015] Furthermore, the EUV light generation device 1 includes a laser light transmission device 34, a laser light condenser mirror 22, a target recovery unit 28 for recovering the target 27, etc. The laser light transmission device 34 includes an optical element for defining the transmission state of the laser light and an actuator for adjusting the position, posture, etc. of this optical element.

[0016] 1.2 Operation Referring to FIG. 1, the operation of the EUV light generation system 11 will be described. The pulsed laser light 31 output from the laser device 3 passes through the laser light transmission device 34, passes through the window 21 as the pulsed laser light 32, and enters the chamber 2. The pulsed laser light 32 travels along the laser light path in the chamber 2, is reflected by the laser light condensing mirror 22, and is irradiated onto the target 27 as the pulsed laser light 33.

[0017] The target supply unit 26 supplies the target 27 containing the target material to the plasma generation region 25 inside the chamber 2. The target 27 is irradiated with the pulsed laser light 33. The target 27 irradiated with the pulsed laser light 33 is turned into plasma, and the emitted light 251 is emitted from the plasma. The EUV light contained in the emitted light 251 is reflected by the EUV condensing mirror 23 with a high reflectivity compared to the light in other wavelength ranges. The reflected light 252 containing the EUV light reflected by the EUV condensing mirror 23 is condensed at the intermediate condensing point 292 and output to the EUV light utilization device 6. When the target 27 includes a plurality of droplets, a single droplet may be irradiated with a plurality of pulses included in the pulsed laser light 33.

[0018] The processor 5 controls the entire EUV light generation system 11. The processor 5 processes the detection result of the target sensor 4. Based on the detection result of the target sensor 4, the processor 5 controls the timing at which the target 27 is output, the output direction of the target 27, etc. Further, the processor 5 controls the oscillation timing of the laser device 3, the traveling direction of the pulsed laser light 32, the condensing position of the pulsed laser light 33, etc. The above various controls are merely examples, and other controls may be added as necessary.

[0019] 1.3 Problems of the Comparative Example FIG. 2 is a graph showing the change in the EUV emission efficiency and the second energy parameter P2 in the comparative example. The horizontal axis in the graph of the present disclosure is the operating time, and the dashed-dotted line indicates that the events on each dashed-dotted line occur at the same timing.

[0020] The second energy parameter P2 is a parameter related to the energy per unit time of the EUV light reflected by the EUV condenser mirror 23, and includes one of EUV power, EUV power density, and EUV radiance. The EUV power is the energy per unit time at the focus point of the EUV light, and the unit is W (watt). The focus point refers to the intermediate focus point 292 or the focus point on the downstream side of the optical path of the EUV light with respect to the intermediate focus point 292. The EUV power density is a value obtained by dividing the EUV power by the cross-sectional area of the optical path at the focus point of the EUV light, and the unit is W / mm 2 . The EUV radiance is a value obtained by dividing the EUV power density by the solid angle before and after the focus point of the EUV light, and the unit is W / mm 2 sr. The first energy parameter P1 will be described later.

[0021] When the EUV light is generated by the EUV light generation system 11, the EUV emission efficiency may gradually decrease due to deterioration of the EUV condenser mirror 23 or the like. When the EUV emission efficiency decreases, even if various conditions such as the pulse energy E of the pulsed laser light 33 are the same, the second energy parameter P2 becomes low. EUV light with a low second energy parameter P2 may not be preferable for use in the EUV light utilization device 6.

[0022] As one solution, it is conceivable to design the EUV light generation system 11 to output, at the time of new product, EUV light having a second energy parameter P2 that is significantly higher than the lower limit of the second energy parameter P2 required by the EUV light utilization device 6. According to this, EUV light having a second energy parameter P2 higher than the lower limit can be obtained over a long period of time. However, the second energy parameter P2 may be too high at the time of new product.

[0023] In some examples of the present disclosure, the irradiation frequency F of the pulsed laser light 33 irradiated to the target 27 is controlled so that the change in the second energy parameter P2 is suppressed. The irradiation frequency F I is controlled. The irradiation frequency FI refers to the number of times the target 27 is irradiated with pulsed laser light 33 per second to be turned into plasma.

[0024] 2. The irradiation frequency F is controlled so that the change in the second energy parameter P2 is suppressed I EUV light generation system 11a 2.1 Configuration FIG. 3 schematically shows the configuration of the EUV light generation system 11a according to the first embodiment. The EUV light utilization device 6 that receives the EUV light generated in the EUV light generation system 11a includes a measurement device 61. The processor 5 included in the EUV light generation system 11a is connected to the measurement device 61 by a signal line via a processor (not shown) of the EUV light utilization device 6. The present disclosure is not limited to the case where the measurement device 61 is arranged in the EUV light utilization device 6. The measurement device 61 may be arranged in the chamber 2.

[0025] The measurement device 61 measures the first energy parameter P1 of the EUV light. The first energy parameter P1 includes one of EUV pulse energy, EUV power, EUV power density, and EUV emission luminance. The EUV pulse energy is the energy per pulse of the EUV light at the intermediate focus point 292, and the unit is J (joule).

[0026] The first energy parameter P1 may include a combination of one of the EUV pulse energy and the EUV power, and one of the EUV focusing size and the EUV emission size. The EUV focusing size is the spot diameter when the EUV light is focused at the focus point. The EUV emission size is the plasma diameter in the plasma generation region 25. The EUV focusing size can be calculated based on the EUV emission size. The focusing size at the intermediate focus point 292 can be calculated based on the EUV focusing size. The EUV power can be calculated based on the EUV pulse energy. The EUV power density and the EUV emission luminance can be calculated based on the combination of the EUV focusing size and the EUV power.

[0027] The processor 5 receives the first energy parameter P1 from the EUV light utilization device 6. The processor 5 calculates the second energy parameter P2 based on the first energy parameter P1.

[0028] As the first energy parameter P1, one of EUV power, EUV power density, and EUV emission luminance may be measured by the measuring device 61 and received by the processor 5. In this case, since the second energy parameter P2 is received as the first energy parameter P1, the processor 5 may not calculate the second energy parameter P2.

[0029] 2.2 Operation FIG. 4 is a graph showing the decrease in EUV emission efficiency in the first embodiment, the control of the irradiation frequency F I and the pulse energy E of the pulsed laser light 33, and the change in the second energy parameter P2.

[0030] In the comparative example, the second energy parameter P2 decreased as the EUV emission efficiency decreased, whereas in the first embodiment, the irradiation frequency F of the pulsed laser light 33 irradiated to the target 27 was adjusted so that the change in the second energy parameter P2 was suppressed. I That is, in the first embodiment, the irradiation frequency F I is controlled so as to increase as the EUV emission efficiency decreases. I The pulse energy E of the pulsed laser light 33 may not be changed. When the EUV emission efficiency decreases, the EUV pulse energy decreases, but by increasing the irradiation frequency F I instead, the change in the second energy parameter P2 can be suppressed.

[0031] 2.2.1 First operation example for increasing the irradiation frequency F I FIG. 5 shows the irradiation frequency F in the first embodiment. IIt is a flowchart showing a first operation example for increasing []. FIG. 6 shows the shape of the target 27 when the target supply unit 26 generates a jet-shaped target 27 and supplies it to the optical path of the pulsed laser light 33 in the first embodiment. The process shown in FIG. 5 is suitable when the target supply unit 26 generates a jet-shaped target 27.

[0032] In S10 of FIG. 5, the processor 5 receives the first energy parameter P1 measured by the measuring device 61 from the EUV light utilization device 6. In S11, the processor 5 calculates a second energy parameter P2 based on the first energy parameter P1. In S12, the processor 5 calculates the difference ΔP2 between the second energy parameter P2 and the target value.

[0033] In S13, the processor 5 determines the emission frequency F of the pulsed laser light 33 L For example, when the second energy parameter P2 is lower than the target value, the emission frequency F of the pulsed laser light 33 is increased according to the difference ΔP2 from the target value. L The control of the emission frequency F L may be performed by PID (proportional-integral-differential) control. The emission frequency F L refers to the number of pulses of the pulsed laser light 33 output by the laser device 3 per second. By increasing the emission frequency F of the pulsed laser light 33, L the irradiation frequency F of the pulsed laser light 33 irradiated on the target 27 increases. When all pulses of the pulsed laser light 33 are irradiated on the target 27 and a part of the target 27 is turned into plasma for each pulse, I the emission frequency F L and the irradiation frequency F I are the same.

[0034] In S14, the processor 5 changes the emission frequency F of the pulsed laser light 33 to the value determined in S13. L ​ After S14, the processor 5 ends the processing of this flowchart. The processing of this flowchart is repeated each time the operating time of the EUV light generation system 11a or the number of output pulses of EUV light reaches a predetermined value.

[0035] 2.2.2 Irradiation frequency F I Second operation example for increasing FIG. 7 is a flowchart showing a second operation example for increasing the irradiation frequency F in the first embodiment. FIG. 8 shows an arrangement of the droplets 27a when the target supply unit 26 sequentially generates a plurality of droplets 27a as the target 27 and supplies them to the optical path of the pulsed laser light 33 in the first embodiment. The processing shown in FIG. 7 is suitable when the target supply unit 26 sequentially generates the droplets 27a. I The processing from S10 to S12 in FIG. 7 is the same as that described with reference to FIG. 5.

[0036] The processing from S10 to S12 in FIG. 7 is the same as that described with reference to FIG. 5. After S12, in S13a, the processor 5 determines both the emission frequency F of the pulsed laser light 33 L and the generation frequency F of the droplets 27a D The generation frequency F D refers to the number of droplets 27a generated by the target supply unit 26 per second. When the second energy parameter P2 is lower than the target value, both the emission frequency F of the pulsed laser light 33 L and the generation frequency F of the droplets 27a D are increased. By increasing both the emission frequency F of the pulsed laser light 33 L and the generation frequency F of the droplets 27a D the irradiation frequency F of the pulsed laser light 33 irradiated on the target 27 I is increased.

[0037] In S14a, the processor 5 determines both the emission frequency F of the pulsed laser light 33 L and the generation frequency F of the droplets 27a DChange both to the values determined by S13a, respectively. After S14a, the processor 5 ends the processing of this flowchart. The processing of this flowchart is repeated every time the operating time of the EUV light generation system 11a or the number of output pulses of EUV light reaches a predetermined value.

[0038] 2.3 Operation (1) According to the first embodiment, the EUV light generation system 11a includes a laser device 3, an EUV condenser mirror 23, and a processor 5. The laser device 3 outputs pulsed laser light 33. The EUV condenser mirror 23 condenses by reflecting EUV light generated by irradiating the target 27 with the pulsed laser light 33. The processor 5 receives the first energy parameter P1 of the EUV light, and the irradiation frequency F of the pulsed laser light 33 irradiated to the target 27 is such that a change in the second energy parameter P2 related to the energy per unit time of the EUV light reflected by the EUV condenser mirror 23 is suppressed. I to control. According to this, by controlling the irradiation frequency F I it is possible to suppress the second energy parameter P2 from decreasing. Also, when the irradiation frequency F I is lowered, the number of plasma generations decreases, so the deterioration of the EUV condenser mirror 23 can be delayed and the life of the EUV condenser mirror 23 can be improved.

[0039] (2) According to the first embodiment, the first energy parameter P1 includes one of EUV pulse energy, EUV power, EUV power density, and EUV radiance, and the second energy parameter P2 includes one of EUV power, EUV power density, and EUV radiance. According to this, the EUV power can be calculated as the second energy parameter P2 based on the EUV pulse energy. Alternatively, one of the EUV power, the EUV power density, and the EUV radiance can be used as the second energy parameter P2. And by stabilizing the second energy parameter P2, the characteristics of the EUV light favorable for the EUV light utilization device 6 can be maintained.

[0040] (3) According to the first embodiment, the first energy parameter P1 includes a combination of one of the EUV pulse energy and the EUV power, and one of the EUV condensing size and the EUV emission size, and the second energy parameter P2 includes one of the EUV power, the EUV power density, and the EUV radiance. Based on these combinations, the EUV power density or the EUV radiance can be calculated as the second energy parameter P2. And by stabilizing the second energy parameter P2, the characteristics of the EUV light favorable for the EUV light utilization device 6 can be maintained.

[0041] (4) According to the first embodiment, the processor 5 is connected to the EUV light utilization device 6 that receives the EUV light generated in the EUV light generation system 11a, and receives the first energy parameter P1 from the EUV light utilization device 6. According to this, even if a measuring device for the first energy parameter P1 is not arranged in the EUV light generation system 11a, a change in the second energy parameter P2 can be suppressed.

[0042] (5) According to the first embodiment, the processor 5 calculates the second energy parameter P2 based on the first energy parameter P1. According to this, even if the second energy parameter P2 is not directly measured, the second energy parameter P2 can be calculated based on the first energy parameter P1 to suppress a change in the second energy parameter P2.

[0043] (6) According to the first embodiment, the processor 5 receives the second energy parameter P2 as the first energy parameter P1. According to this, even without calculating the second energy parameter P2, a change in the second energy parameter P2 can be suppressed.

[0044] (7) According to the first embodiment, the processor 5 increases the emission frequency F of the pulsed laser light 33 by the laser device 3 L to increase the irradiation frequency F. I According to this, even without changing the pulse energy E of the pulsed laser light 33, it is possible to suppress the second energy parameter P2 from decreasing.

[0045] (8) According to the first embodiment, the EUV light generation system 11a includes a target supply unit 26 that sequentially generates a plurality of droplets 27a as the target 27 and supplies them to the optical path of the pulsed laser light 33. The processor 5 increases both the generation frequency F of the plurality of droplets 27a by the target supply unit 26 and the emission frequency F of the pulsed laser light 33 by the laser device 3 D to increase the irradiation frequency F. L I According to this, even when the target 27 includes a plurality of droplets 27a, it is possible to suppress the second energy parameter P2 from decreasing. In other respects, the first embodiment is the same as the comparative example.

[0046] 3. Irradiation frequency F I The EUV light generation system 11a that increases step by step 3.1 Configuration and operation Figures 9 and 10 show the arrangement of droplets 27b and 27c when the target supply unit 26 sequentially generates a plurality of droplets 27b and 27c as the target 27 and supplies them to the optical path of the pulsed laser beam 33 in the second embodiment. The process in the second embodiment is suitable when the target supply unit 26 sequentially generates droplets 27b and 27c. The configuration of the EUV light generation system 11a in the second embodiment is the same as that described with reference to FIG. 3. The droplets 27b and 27c include a droplet 27c not irradiated with the pulsed laser beam 33 and a droplet 27b irradiated with the pulsed laser beam 33.

[0047] In FIGS. 9 and 10, one of the N continuously generated droplets 27b and 27c, i.e., a droplet 27b, is irradiated with the pulsed laser beam 33. The ratio of the number of droplets 27b irradiated with the pulsed laser beam 33 to the number of droplets 27b and 27c is 1 / N. N is an integer of 1 or more, preferably 5 or more and 20 or less. In FIG. 9, N is 10, and in FIG. 10, N is 9.

[0048] The generation frequency F of the droplets 27b and 27c D and the emission frequency F of the pulsed laser beam 33 by the laser device 3 L are related such that F L = F D / N. The generation frequency F D is, for example, 100 kHz or more and 200 kHz or less, and the emission frequency F L is, for example, 10 kHz or more and 20 kHz or less. By changing the value of N from a large value to a small value, the ratio 1 / N of the number of droplets 27b irradiated with the pulsed laser beam 33 to the number of droplets 27b and 27c can be increased.

[0049] When all the pulses of the pulsed laser beam 33 are irradiated onto separate droplets 27b, the emission frequency F L and the irradiation frequency F I are the same. The generation frequency FD Without changing it, by increasing the ratio 1 / N, the irradiation frequency F I can be increased. The irradiation frequency F I changes stepwise according to the value of N.

[0050] Figure 11 is a graph showing the decrease in EUV emission efficiency in the second embodiment, the control of the irradiation frequency F I corresponding thereto, and the change in the second energy parameter P2.

[0051] In the second embodiment, as the EUV emission efficiency decreases, the irradiation frequency F I is increased stepwise. That is, at a certain timing, the irradiation frequency F I is increased, and during the period other than that timing, the irradiation frequency F I is maintained without change. At the timing when the irradiation frequency F I is increased, the second energy parameter P2 also increases. During the period when the irradiation frequency F I is maintained without change, the second energy parameter P2 gradually decreases as the EUV emission efficiency decreases. Therefore, the second energy parameter P2 changes in a sawtooth shape.

[0052] Figure 12 is a flowchart showing an operation example for increasing the irradiation frequency F I stepwise in the second embodiment. The processes of S10 and S11 in Figure 12 are the same as those described with reference to Figure 5.

[0053] After S11, in S15, the processor 5 determines whether the second energy parameter P2 is equal to or greater than a threshold value P2th. The threshold value P2th is set to a value higher than the lower limit of the second energy parameter P2 required by the EUV light utilization device 6. When the second energy parameter P2 is equal to or greater than the threshold value P2th (S15: YES), the processor 5 ends the processing of this flowchart. When the second energy parameter P2 is less than the threshold value P2th (S15: NO), the processor 5 proceeds to S19.

[0054] In S19, the processor 5 updates the value of N by subtracting 1 from the current value of N. For example, when the current value of N is N1 and the new value of N is N2, the value of N is updated such that N2 = N1 - 1. However, the present disclosure is not limited to subtracting 1 from the current value of N each time. An integer of 2 or more may be subtracted.

[0055] In S20, the processor 5 L = F D increases the emission frequency F L of the pulsed laser light 33 according to the formula F I = F / N. Thereby, the irradiation frequency F

[0056] of the pulsed laser light 33 irradiated to the target 27 can be increased. After S20, the processor 5 ends the processing of this flowchart. The processing of this flowchart is repeated each time the operating time of the EUV light generation system 11a or the number of output pulses of the EUV light reaches a predetermined value.

[0057] In the second embodiment, the case where the irradiation frequency F I is increased when the second energy parameter P2 is lower than the threshold value P2th has been described, but the present disclosure is not limited thereto. The irradiation frequency F I may be increased when the operating time of the EUV light generation system 11a reaches a predetermined value. Alternatively, the irradiation frequency F IIt may be increased. These predetermined values are preset based on the prediction of EUV emission efficiency. In this case, the second energy parameter P2 may temporarily become lower than the second energy parameter P2 shown in FIG. 11, but at a timing based on the operating time of the EUV light generation system 11a or the number of output pulses of EUV light, the irradiation frequency F I can be recovered by increasing it. Also, when increasing the irradiation frequency F at a timing based on the operating time of the EUV light generation system 11a or the number of output pulses of EUV light, I the number to be subtracted from the current value of N may be determined based on the second energy parameter P2. For example, when the second energy parameter P2 becomes significantly lower than the threshold value P2th when the operating time of the EUV light generation system 11a reaches a predetermined value, by subtracting an integer of 2 or more from the current value of N, the irradiation frequency F I may be significantly increased.

[0058] 3.2 Function (9) According to the second embodiment, the target 27 includes a plurality of droplets 27b and 27c that are sequentially generated and supplied to the optical path of the pulsed laser light 33. The plurality of droplets 27b and 27c include a droplet 27c not irradiated with the pulsed laser light 33 and a droplet 27b irradiated with the pulsed laser light 33. The processor 5 increases the irradiation frequency F by increasing the ratio of the number of droplets 27b irradiated with the pulsed laser light 33 to the number of the plurality of droplets 27b and 27c. I to increase it. According to this, without changing the generation frequency F of the droplets 27b and 27c, D the irradiation frequency F I can be increased step by step.

[0059] (10) According to the second embodiment, the EUV light generation system 11a includes a target supply unit 26 that sequentially generates a plurality of droplets 27b and 27c as the target 27 and supplies them to the optical path of the pulsed laser light 33. The processor 5 controls the irradiation frequency F by setting the relationship between the generation frequency F of the plurality of droplets 27b and 27c by the target supply unit 26 and the emission frequency F of the pulsed laser light 33 by the laser device 3 as F = F / N1. Then, the irradiation frequency F is increased by setting F = F / N2. N1 is an integer of 2 or more, and N2 is an integer of 1 or more that is smaller than N1. D and the emission frequency F of the pulsed laser light 33 by the laser device 3, L such that the relationship between them is F L = F D / N1 to control the irradiation frequency F I . After that, the irradiation frequency F is increased by setting F L = F D / N2. I N1 is an integer of 2 or more, and N2 is an integer of 1 or more that is smaller than N1. According to this, an appropriate emission frequency F D can be calculated based on the generation frequency F of the droplets 27b and 27c. L

[0060] (11) According to the second embodiment, when the second energy parameter P2 is lower than the threshold value P2th, the processor 5 increases the irradiation frequency F. I According to this, it is possible to suppress the further decrease of the second energy parameter P2.

[0061] (12) According to the second embodiment, when the operation time of the EUV light generation system 11a reaches a predetermined value, the processor 5 increases the irradiation frequency F. I According to this, even if the second energy parameter P2 is not monitored, it is possible to determine the timing to increase the irradiation frequency F. I

[0062] (13) According to the second embodiment, when the number of output pulses of the EUV light reaches a predetermined value, the processor 5 increases the irradiation frequency F. I According to this, even if the second energy parameter P2 is not monitored, it is possible to determine the timing to increase the irradiation frequency F. IIt is possible to determine the timing to increase it. In other respects, the second embodiment is the same as the first embodiment.

[0063] 4. EUV light generation system 11a that changes the pulse energy E of the pulsed laser light 33 4.1 Configuration and operation FIG. 13 is a graph showing a decrease in EUV emission efficiency in the third embodiment, the control of the irradiation frequency F I and the pulse energy E of the pulsed laser light 33, and the change in the second energy parameter P2. The process in the third embodiment is suitable when the target supply unit 26 sequentially generates the droplets 27b and 27c (see FIGS. 9 and 10). The configuration of the EUV light generation system 11a in the third embodiment is the same as that described with reference to FIG. 3.

[0064] In the third embodiment, the pulse energy E of the pulsed laser light 33 is controlled so that the change in the second energy parameter P2 is suppressed. That is, as the EUV emission efficiency decreases, the pulse energy E of the pulsed laser light 33 is increased. It is desirable that the pulse energy E of the pulsed laser light 33 does not exceed the threshold value Eth. In the third embodiment, when the target pulse energy Et of the pulsed laser light 33 is higher than the threshold value Eth, instead of increasing the pulse energy E of the pulsed laser light 33, the irradiation frequency F I is increased. Irradiation frequency F I If the irradiation frequency F I is increased, the pulse energy E of the pulsed laser light 33 required to obtain the desired second energy parameter P2 becomes lower. Therefore, at the timing of increasing the irradiation frequency F

[0065] FIG. 14 is a flowchart showing an operation example for controlling the pulse energy E and the irradiation frequency F I of the pulsed laser light 33 in the third embodiment. The processing from S10 to S12 in FIG. 14 is the same as that described with reference to FIG. 5.

[0066] After S12, at S16, the processor 5 determines the target pulse energy Et of the pulsed laser light 33. For example, when the second energy parameter P2 is lower than the target value, the target pulse energy Et of the pulsed laser light 33 is increased according to the difference ΔP2 from the target value.

[0067] At S17, the processor 5 determines whether the target pulse energy Et of the pulsed laser light 33 determined at S16 is less than or equal to the threshold value Eth. When the target pulse energy Et of the pulsed laser light 33 is less than or equal to the threshold value Eth (S17: YES), the processor 5 proceeds to S18 for processing.

[0068] At S18, the processor 5 changes the pulse energy E of the pulsed laser light 33 so as to approach the target pulse energy Et determined at S16. The control of the pulse energy E may be performed by PID control. When the target pulse energy Et of the pulsed laser light 33 is increased at S16, when the processing of S18 is performed, the pulse energy E of the pulsed laser light 33 increases. By increasing the pulse energy E of the pulsed laser light 33, the ratio of the atoms excited by the pulsed laser light 33 among the atoms constituting the droplet 27b increases. Therefore, it is possible to suppress the decrease in the second energy parameter P2 as the EUV emission efficiency decreases. The processing of S16 to S18 corresponds to the first processing of the present disclosure. After S18, the processor 5 ends the processing of this flowchart.

[0069] When the target pulse energy Et of the pulsed laser light 33 is higher than the threshold value Eth (S17: NO), the processor 5 proceeds to S19 without changing the pulse energy E so as to approach the target pulse energy Et determined at S16. The processes of S19 and S20 are the same as those described with reference to FIG. 12.

[0070] After S20, in S21, the processor 5 lowers the pulse energy E of the pulsed laser light 33. Specifically, after lowering the target pulse energy Et of the pulsed laser light 33, the pulse energy E is controlled to approach this target pulse energy Et. The pulse energy E of the pulsed laser light 33 is such that the change in the second energy parameter P2 before and after increasing the emission frequency F of the pulsed laser light 33 in S20 L is suppressed. The processes of S19 to S21 correspond to the second process of the present disclosure. After S21, the processor 5 ends the processing of this flowchart.

[0071] The processing of this flowchart is repeated each time the operating time of the EUV light generation system 11a or the number of output pulses of the EUV light reaches a predetermined value.

[0072] In the third embodiment, the case where the irradiation frequency F is increased when the target pulse energy Et of the pulsed laser light 33 is higher than the threshold value Eth has been described, but the present disclosure is not limited thereto. I When the operating time of the EUV light generation system 11a reaches a predetermined value, the irradiation frequency F I may be increased. Alternatively, when the number of output pulses of the EUV light reaches a predetermined value, the irradiation frequency F I may be increased. These predetermined values are set in advance based on the prediction of the EUV emission efficiency. In this case, although the pulse energy E of the pulsed laser light 33 may temporarily become higher than the threshold value Eth, by increasing the irradiation frequency F I at a timing based on the operating time of the EUV light generation system 11a or the number of output pulses of the EUV light, an increase in the pulse energy E can be suppressed. Note that the threshold value Eth in this case is set to a value lower than the design upper limit of the pulse energy E of the pulsed laser light 33 in the EUV light generation system 11a.

[0073] 4.2 Function (14) According to the third embodiment, the processor 5 performs a first process (S16 to S18) of controlling the pulse energy E of the pulsed laser light 33 so that the change in the second energy parameter P2 is suppressed, and the irradiation frequency F I and a second process (S19 to S21) of increasing the irradiation frequency F and decreasing the pulse energy E of the pulsed laser light 33. According to this, even when the irradiation frequency F I is gradually increased, the variation in the second energy parameter P2 is suppressed by adjusting the pulse energy E of the pulsed laser light 33. The dynamic range of the pulse energy E of the pulsed laser light 33 may not be sufficient to compensate for the decrease in EUV emission efficiency, but by combining it with the stepwise adjustment of the irradiation frequency F I the decrease in EUV emission efficiency can be compensated.

[0074] (15) According to the third embodiment, in the first process (S16 to S18), the processor 5 increases the target pulse energy Et of the pulsed laser light 33 when the second energy parameter P2 is lower than the target value. Thereby, the variation in the second energy parameter P2 can be suppressed.

[0075] (16) According to the third embodiment, the processor 5 performs the second process (S19 to S21) when the target pulse energy Et of the pulsed laser light 33 is higher than the threshold value Eth. Thereby, an increase in the pulse energy E can be suppressed.

[0076] (17) According to the third embodiment, the target 27 includes a plurality of droplets 27b and 27c that are sequentially generated and supplied to the optical path of the pulsed laser light 33. The plurality of droplets 27b and 27c include a droplet 27c not irradiated with the pulsed laser light 33 and a droplet 27b irradiated with the pulsed laser light 33. In the second process (S19 to S21), the processor 5 increases the ratio of the number of droplets 27b irradiated with the pulsed laser light 33 to the number of the plurality of droplets 27b and 27c, thereby increasing the irradiation frequency F I to increase it. According to this, without changing the generation frequency F D of the droplets 27b and 27c, the irradiation frequency F I can be increased step by step.

[0077] (18) According to the third embodiment, the EUV light generation system 11a includes a target supply unit 26 that sequentially generates a plurality of droplets 27b and 27c as the target 27 and supplies them to the optical path of the pulsed laser light 33. The processor 5 controls the irradiation frequency F D by setting the relationship between the generation frequency F L of the plurality of droplets 27b and 27c by the target supply unit 26 and the emission frequency F L of the pulsed laser light 33 by the laser device 3 as F D = F I / N1. Then, in the second process (S19 to S21), the irradiation frequency F L is increased by setting F D = F I / N2. N1 is an integer of 2 or more, and N2 is an integer of 1 or more smaller than N1. According to this, an appropriate emission frequency F D can be calculated based on the generation frequency F L of the droplets 27b and 27c. In other respects, the third embodiment is the same as the second embodiment.

[0078] 5. Others FIG. 15 schematically shows the configuration of the exposure apparatus 6a connected to the EUV light generation system 11a. In FIG. 15, the exposure apparatus 6a as the EUV light utilization apparatus 6 (see FIG. 3) includes a mask irradiation unit 68 and a workpiece irradiation unit 69. The mask irradiation unit 68 illuminates the mask pattern on the mask table MT through a reflection optical system with the EUV light incident from the EUV light generation system 11a. The workpiece irradiation unit 69 forms an image of the EUV light reflected by the mask table MT on a workpiece (not shown) arranged on the workpiece table WT through a reflection optical system. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure apparatus 6a exposes the workpiece to the EUV light reflecting the mask pattern by synchronously translating the mask table MT and the workpiece table WT in parallel. By transferring the device pattern to the semiconductor wafer through the above exposure process, an electronic device can be manufactured.

[0079] FIG. 16 schematically shows the configuration of the inspection apparatus 6b connected to the EUV light generation system 11a. In FIG. 16, the inspection apparatus 6b as the EUV light utilization apparatus 6 (see FIG. 3) includes an illumination optical system 63 and a detection optical system 66. The illumination optical system 63 reflects the EUV light incident from the EUV light generation system 11a and irradiates the mask 65 arranged on the mask stage 64. The mask 65 here includes a mask blank before the pattern is formed. The detection optical system 66 reflects the EUV light from the illuminated mask 65 and forms an image on the light receiving surface of the detector 67. The detector 67 that receives the EUV light acquires an image of the mask 65. The detector 67 is, for example, a TDI (time delay integration) camera. Based on the image of the mask 65 obtained through the above process, the defects of the mask 65 are inspected, and using the inspection results, a mask suitable for the manufacture of electronic devices is selected. Then, an electronic device can be manufactured by exposing and transferring the pattern formed on the selected mask onto the photosensitive substrate using the exposure apparatus 6a.

[0080] The above description is intended to be illustrative only and not restrictive. Thus, it will be apparent to those skilled in the art that modifications may be made to the embodiments of the disclosure without departing from the scope of the claims. It will also be apparent to those skilled in the art that embodiments of the disclosure may be used in combination.

[0081] The terms used throughout this specification and the claims should be construed as "non-limiting" terms unless otherwise specified. For example, the terms "comprising" or "comprised of" should be construed as not being limited to the elements listed as such. The term "having" should be construed as not being limited to the elements listed as such. Also, the indefinite article "a" should be construed to mean "at least one" or "one or more". Also, the term "at least one of A, B, and C" should be construed as "A", "B", "C", "A + B", "A + C", "B + C", or "A + B + C". Furthermore, it should be construed to include combinations with things other than "A", "B", and "C".

Claims

1. A laser device that outputs pulsed laser light, an EUV condenser mirror that condenses extreme ultraviolet light generated by irradiating the pulsed laser light onto a target by reflecting the extreme ultraviolet light, a processor that receives a first energy parameter of the extreme ultraviolet light at a focal point of a reflecting surface of the EUV condenser mirror and at a condensing point of the extreme ultraviolet light reflected by the EUV condenser mirror, and controls an irradiation frequency of the pulsed laser light irradiated onto the target so that a change in a second energy parameter related to the energy per unit time of the extreme ultraviolet light reflected by the EUV condenser mirror is suppressed, a target supply unit that sequentially generates a plurality of droplets as the target and supplies the droplets to an optical path of the pulsed laser light, comprising: the processor controls the irradiation frequency by setting a relationship between a generation frequency FD of the plurality of droplets by the target supply unit and a light emission frequency FL of the pulsed laser light by the laser device as FL = FD / N1, where N1 is an integer of 3 or more, subsequently, sets the relationship as FL = FD / N2, where N2 is an integer of 2 or more and smaller than N1, subsequently, sets the relationship as FL = FD / N3, where N3 is an integer of 1 or more and smaller than N2 to gradually increase the irradiation frequency extreme ultraviolet light generation system.

2. The extreme ultraviolet light generation system according to claim 1, wherein the first energy parameter includes one of EUV pulse energy, EUV power, EUV power density, and EUV radiation luminance, and the second energy parameter includes one of EUV power, EUV power density, and EUV radiation luminance extreme ultraviolet light generation system.

3. The extreme ultraviolet light generation system according to claim 1, wherein the first energy parameter includes a combination of one of EUV pulse energy and EUV power and one of EUV condensing size and EUV light emission size, and the second energy parameter includes one of EUV power, EUV power density, and EUV radiation luminance extreme ultraviolet light generation system.

4. The extreme ultraviolet light generation system according to claim 1, ​ The processor calculates the second energy parameter based on the first energy parameter. Extreme ultraviolet light generation system.

5. The extreme ultraviolet light generation system according to claim 1, The processor receives the second energy parameter as the first energy parameter. Extreme ultraviolet light generation system.

6. The extreme ultraviolet light generation system according to claim 1, The processor increases the irradiation frequency when the second energy parameter is lower than a threshold value. Extreme ultraviolet light generation system.

7. The extreme ultraviolet light generation system according to claim 1, The processor increases the irradiation frequency when the operating time of the extreme ultraviolet light generation system reaches a predetermined value. Extreme ultraviolet light generation system.

8. The extreme ultraviolet light generation system according to claim 1, The processor increases the irradiation frequency when the number of output pulses of the extreme ultraviolet light reaches a predetermined value. Extreme ultraviolet light generation system.

9. The extreme ultraviolet light generation system according to claim 1, The processor, a first process of controlling the pulse energy of the pulsed laser light so that the change in the second energy parameter is suppressed, a second process of lowering the pulse energy of the pulsed laser light at the timing of increasing the irradiation frequency, An extreme ultraviolet light generation system that performs the above.

10. The extreme ultraviolet light generation system according to claim 9, In the first process, the processor increases the target pulse energy of the pulsed laser light when the second energy parameter is lower than a target value. Extreme ultraviolet light generation system.

11. The extreme ultraviolet light generation system according to claim 9, The processor performs the second process when the target pulse energy of the pulsed laser light is higher than a threshold value. Extreme ultraviolet light generation system.

12. A method for manufacturing an electronic device, a laser device that outputs pulsed laser light, an EUV condenser mirror that condenses by reflecting extreme ultraviolet light generated by irradiating the pulsed laser light onto a target Receiving a first energy parameter of the extreme ultraviolet light at the focal point of the reflecting surface of the EUV condenser mirror, which is the condensing point of the extreme ultraviolet light reflected by the EUV condenser mirror, and controlling the irradiation frequency of the pulsed laser light irradiated to the target so that a change in a second energy parameter related to the energy per unit time of the extreme ultraviolet light reflected by the EUV condenser mirror is suppressed, a processor; A target supply unit that sequentially generates a plurality of droplets as the target and supplies them to the optical path of the pulsed laser light; Comprising; The processor; Controlling the irradiation frequency by setting the relationship between the generation frequency FD of the plurality of droplets by the target supply unit and the emission frequency FL of the pulsed laser light by the laser device as FL = FD / N1, where N1 is an integer of 3 or more; Thereafter, setting the relationship as FL = FD / N2, where N2 is an integer of 2 or more that is smaller than N1; Thereafter, setting the relationship as FL = FD / N3, where N3 is an integer of 1 or more that is smaller than N2 Thereby, generating the extreme ultraviolet light in an extreme ultraviolet light generation system that gradually increases the irradiation frequency, Outputting the extreme ultraviolet light to an exposure apparatus; Exposing the extreme ultraviolet light on a photosensitive substrate in the exposure apparatus in order to manufacture an electronic device A method for manufacturing an electronic device, including this.

13. A method for manufacturing an electronic device, comprising: A laser device that outputs pulsed laser light; An EUV condenser mirror that condenses by reflecting the extreme ultraviolet light generated by irradiating the pulsed laser light onto a target; Receiving a first energy parameter of the extreme ultraviolet light at the focal point of the reflecting surface of the EUV condenser mirror, which is the condensing point of the extreme ultraviolet light reflected by the EUV condenser mirror, and controlling the irradiation frequency of the pulsed laser light irradiated to the target so that a change in a second energy parameter related to the energy per unit time of the extreme ultraviolet light reflected by the EUV condenser mirror is suppressed, a processor; A target supply unit that sequentially generates a plurality of droplets as the target and supplies them to the optical path of the pulsed laser light; Comprising; The processor; The irradiation frequency is controlled by setting the relationship between the generation frequency \(F_D\) of the plurality of droplets by the target supply unit and the emission frequency \(F_L\) of the pulsed laser light by the laser device as \(F_L = F_D / N_1\), where \(N_1\) is an integer of 3 or more. Thereafter, the relationship is set as \(F_L = F_D / N_2\), where \(N_2\) is an integer of 2 or more that is smaller than \(N_1\). Thereafter, the relationship is set as \(F_L = F_D / N_3\), where \(N_3\) is an integer of 1 or more that is smaller than \(N_2\). By doing so, the extreme ultraviolet light generated in the extreme ultraviolet light generation system that gradually increases the irradiation frequency is irradiated onto a mask to inspect for defects in the mask. A mask is selected using the results of the inspection. The pattern formed on the selected mask is exposed and transferred onto a photosensitive substrate. A method for manufacturing an electronic device, including this.

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