Patent Application
20240184211
The present application claims the benefit of Japanese Patent Application No. 2022-195004, filed on Dec. 6, 2022, the entire contents of which are hereby incorporated by reference.
The present disclosure relates to an extreme ultraviolet light generation system and an electronic device manufacturing method.
Recently, miniaturization of a transfer pattern in optical lithography of a semiconductor process has been rapidly proceeding along with miniaturization of the semiconductor process. In the next generation, microfabrication at 10 nm or less will be required. Therefore, it is expected to develop a semiconductor exposure apparatus that combines an apparatus for generating extreme ultraviolet (EUV) light having a wavelength of about 13 nm with a reduced projection reflection optical system.
As the EUV light generation apparatus, a laser produced plasma (LPP) type apparatus using plasma generated by irradiating a target substance with laser light has been developed.
An extreme ultraviolet light generation system according to an aspect of the present disclosure includes a chamber including a first region; a target supply unit configured to supply a target to the first region; a laser device configured to output pulse laser light; an optical system including an optical element configured to guide the pulse laser light to the first region; an irradiation position adjustment mechanism configured to adjust a laser irradiation position with respect to the target in a plane being perpendicular to an optical path axis of the pulse laser light entering the first region and intersecting the first region by changing a position or posture of the optical element; an EUV light concentrating mirror configured to reflect EUV light radiated from the first region and concentrate the EUV light to a second region, and arranged such that the pulse laser light passes outside the EUV light concentrating mirror and is guided to the first region; a plurality of EUV sensors configured to measure radiation energies of the EUV light radiated from the first region in mutually different radiation directions; and a processor configured to control the irradiation position adjustment mechanism as setting a target irradiation position of the pulse laser light to a laser irradiation position away from a reference position, at which an average value of the radiation energies measured by the EUV sensors is maximized, in a direction toward the EUV light concentrating mirror.
An electronic device manufacturing method according to an aspect of the present disclosure includes generating EUV light using an extreme ultraviolet light generation system; and outputting the EUV light to an exposure apparatus and exposing a photosensitive substrate to the EUV light in the exposure apparatus to manufacture an electronic device. Here, the extreme ultraviolet light generation system includes a chamber including a first region; a target supply unit configured to supply a target to the first region; a laser device configured to output pulse laser light; an optical system including an optical element configured to guide the pulse laser light to the first region; an irradiation position adjustment mechanism configured to adjust a laser irradiation position with respect to the target in a plane being perpendicular to an optical path axis of the pulse laser light entering the first region and intersecting the first region by changing a position or posture of the optical element; an EUV light concentrating mirror configured to reflect the EUV light radiated from the first region and concentrate the EUV light to a second region, and arranged such that the pulse laser light passes outside the EUV light concentrating mirror and is guided to the first region; a plurality of EUV sensors configured to measure radiation energies of the EUV light radiated from the first region in mutually different radiation directions; and a processor configured to control the irradiation position adjustment mechanism as setting a target irradiation position of the pulse laser light to a laser irradiation position away from a reference position, at which an average value of the radiation energies measured by the EUV sensors is maximized, in a direction toward the EUV light concentrating mirror.
An electronic device manufacturing method according to an aspect of the present disclosure includes inspecting a defect of a mask by irradiating the mask with EUV light generated by an extreme ultraviolet light generation system; selecting a mask using a result of the inspection; and exposing and transferring a pattern formed on the selected mask onto a photosensitive substrate. Here, the extreme ultraviolet light generation system includes a chamber including a first region; a target supply unit configured to supply a target to the first region; a laser device configured to output pulse laser light; an optical system including an optical element configured to guide the pulse laser light to the first region; an irradiation position adjustment mechanism configured to adjust a laser irradiation position with respect to the target in a plane being perpendicular to an optical path axis of the pulse laser light entering the first region and intersecting the first region by changing a position or posture of the optical element; an EUV light concentrating mirror configured to reflect the EUV light radiated from the first region and concentrate the EUV light to a second region, and arranged such that the pulse laser light passes outside the EUV light concentrating mirror and is guided to the first region; a plurality of EUV sensors configured to measure radiation energies of the EUV light radiated from the first region in mutually different radiation directions; and a processor configured to control the irradiation position adjustment mechanism as setting a target irradiation position of the pulse laser light to a laser irradiation position away from a reference position, at which an average value of the radiation energies measured by the EUV sensors is maximized, in a direction toward the EUV light concentrating mirror.
Embodiments of the present disclosure will be described below merely as examples with reference to the accompanying drawings.
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 contents of the present disclosure. Also, all configurations and operation described in the embodiments are not necessarily essential as configurations and operation of the present disclosure. Here, the same components are denoted by the same reference numerals, and duplicate description thereof is omitted.
The laser system 3 includes a main pulse laser device MPL, high reflection mirrors 301, 302, 304, a beam splitter 303, and an energy sensor 305. The main pulse laser device MPL corresponds to the laser device in the present discloser, and outputs pulse laser light 31. The pulse energy of the pulse laser light 31 is controlled based on the measurement result of the pulse energy by the energy sensor 305.
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 27 containing 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 thereof.
A through hole is formed in a wall of the chamber 2. The through hole is blocked by a window 21 and pulse laser light 32 output from the laser system 3 passes through the window 21. An EUV light concentrating mirror 23 having a spheroidal reflection surface is arranged in the chamber 2. The EUV light concentrating mirror 23 has first and second focal points. A multilayer reflection film in which molybdenum and silicon are alternately stacked is formed on a surface of the EUV light concentrating mirror 23. The EUV light concentrating mirror 23 is arranged such that the first focal point is located in a plasma generation region 25 and the second focal point is located at an intermediate focal point 292. The plasma generation region 25 corresponds to the first region in the present disclosure, and the intermediate focal point 292 corresponds to the second region in the present disclosure. A through hole 24 is formed at the center of the EUV light concentrating mirror 23, and pulse laser light 33 passes through the through hole 24.
The direction directing from the first focal point to the second focal point is represented by the Z direction. The travel direction of the target 27 perpendicular to the Z direction is represented by the −Y direction, and the opposite direction is represented by the Y direction. The direction perpendicular to both the Y direction and the Z direction is represented by the X direction.
The EUV light generation apparatus 1 includes a processor 5, a target sensor 4, EUV sensors ES1 to ES3, and the like. The processor 5 is a processing device including a memory 501 in which a control program is stored, and a central processing unit (CPU) 502 for executing the control program. The processor 5 is specifically configured or programmed to perform various processes included in the present disclosure. The target sensor 4 detects at least one of the presence, trajectory, position, and velocity of the target 27. The target sensor 4 may have an imaging function. Each of the EUV sensors ES1 to ES3 is arranged as being oriented toward the plasma generation region 25, and measures the radiation energy of the EUV light radiated from the plasma generation region 25 in mutually different radiation directions. The EUV sensor ES1 corresponds to the first sensor in the present disclosure, and the EUV sensor ES2 corresponds to the second sensor in the present disclosure.
Further, the EUV light generation apparatus 1 includes a connection portion 29 providing communication between the internal space of the chamber 2 and the internal space of an EUV light utilization apparatus 6. The EUV light utilization apparatus 6 may be an exposure apparatus 6a shown in
Further, the EUV light generation apparatus 1 includes a laser light transmission device 34, a laser light concentrating mirror 22, a target collection unit 28 for collecting the target 27, and the like. The laser light transmission device 34 includes high reflection mirrors 341, 342, 343 and an actuator 344. The high reflection mirrors 341, 342, 343 define the transmission state of the laser light, and the actuator 344 adjusts the laser irradiation position by changing the position, posture, and the like of the high reflection mirror 341. The actuator 344 may be arranged at any one of the optical elements from the high reflection mirror 301 to the laser light concentrating mirror 22. The actuator 344 corresponds to the irradiation position adjustment mechanism in the present disclosure, and the optical elements from the high reflection mirror 301 to the laser light concentrating mirror 22 correspond to the optical system in the present disclosure.
Operation of the EUV light generation system 11 will be described with reference to
The target supply unit 26 outputs the target 27 toward the plasma generation region 25 in the chamber 2. The target 27 is irradiated with the pulse laser light 33. The target 27 irradiated with the pulse laser light 33 is turned into plasma, and radiation light 251 is radiated from the plasma. EUV light included in the radiation light 251 is reflected by the EUV light concentrating mirror 23 with higher reflectance than light in other wavelength ranges. Reflection light 252 including the EUV light reflected by the EUV light concentrating mirror 23 is concentrated at the intermediate focal point 292 and output to the EUV light utilization apparatus 6. Here, one target 27 may be irradiated with a plurality of pulses included in the pulse laser light 33.
The processor 5 controls the entire EUV light generation system 11. The processor 5 processes a 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, and the like. Further, the processor 5 controls oscillation timing of the laser system 3, a travel direction of the pulse laser light 32, the concentration position of the pulse laser light 33, and the like. The above-described various kinds of control are merely examples, and other control may be added as necessary.
In S11, the processor 5 reads a laser irradiation position map Sm (x, y) from a storage device such as a memory 501.
Referring to
In S14, the processor 5 causes the target 27 to be irradiated with the pulse laser light 33, and acquires the average value Eavg of the radiation energies E1 to E3 measured by the plurality of EUV sensors ES1 to ES3.
Assuming that the optical path axis of the pulse laser light 33 coincides with the center of the target 27, the distribution of the radiation energy E is axisymmetric with respect to the optical path axis of the pulse laser light 33. At this time, the average value Eavg calculated by the following equation is considered to be the maximum value.
Eavg=(E1+E2+E3)/3
On the other hand, when the optical path axis of the pulse laser light 33 is shifted from the center of the target 27, it is considered that the distribution of the radiation energy E becomes an asymmetric distribution with respect to the optical path axis of the pulse laser light 33, and the average value Eavg decreases.
Therefore, the optimum position of the laser irradiation can be calculated by calculating the average value Eavg at each of the laser irradiation positions included in the laser irradiation position map Sm (x, y).
Referring to
Referring to
Referring to
In S18, the processor 5 determines whether or not the adjustment amount in S17 is less than a threshold value. The adjustment amount is an adjustment amount from the center coordinate of the laser irradiation position map Sm (x, y). When the adjustment amount is less than the threshold value (S18: YES), the laser irradiation position adjustment is completed, and the processor 5 ends processing of the present flowchart. When the adjustment amount is equal to or more than the threshold value (S18: NO), the processor 5 advances processing to S19.
In S19, the processor 5 updates the center coordinate of the laser irradiation position map Sm (x, y) to the optimum position. After S19, the processor 5 returns processing to S11.
However, as described with reference to
Embodiments of the present disclosure described below relate to improving output energy of the EUV light by shifting the optical path axis of the pulse laser light 33 away from a reference position Pini in a direction toward the EUV light concentrating mirror 23a.
3. EUV Light Generation System 11a with Optical Path Axis of Pulse Laser Light 33 Shifted
In the first embodiment, a signal line connecting the EUV light utilization apparatus 6 and the processor 5 is added. The EUV light utilization apparatus 6 measures the output energy of the EUV light reaching the intermediate focal point 292 and transmits the measurement result to the processor 5 via the signal line. The processor 5 receives the output energy from the EUV light utilization apparatus 6. The EUV light utilization apparatus 6 may be the exposure apparatus 6a, the inspection apparatus 6b, or a measurement instrument for measuring the output energy of the EUV light reaching the intermediate focal point 292.
In S31, the processor 5 causes the target 27 to be irradiated with the pulse laser light 33, and sets the laser irradiation position at which the average value Eavg of the radiation energies E1 to E3 measured by the plurality of EUV sensors ES1 to ES3 is maximized as the reference position Pini. This processing is similar to that of the laser irradiation position adjustment described with reference to
In S32, the processor 5 causes the EUV light to be output toward the EUV light utilization apparatus 6, and receives the measurement result of the output energy of the EUV light reaching the intermediate focal point 292 for each laser irradiation position. The laser irradiation position at this time is set to gradually move from the reference position Pini in the direction toward the EUV light concentrating mirror 23a in the XY plane, for example. The processor 5 sets the laser irradiation position at which the output energy is higher than that when the reference position Pini is irradiated with the pulse laser light 33 as an improved irradiation position Pmax. The improved irradiation position Pmax is preferably the laser irradiation position at which the output energy is maximized.
Referring to
Referring to
After S34 or S35, in S36, the processor 5 calculates correction coefficients k1 to k3 of the plurality of EUV sensors ES1 to ES3. The correction coefficients k1 to k3 are used to calculate a correction average value Ewavg instead of the average value Eavg. In the comparative example, the optical path axis of the pulse laser light 33 is brought close to the center of the target 27 by controlling the laser irradiation position so that the average value Eavg increases, whereas in the first embodiment, the optical path axis is brought close to the target irradiation position Pop by controlling the laser irradiation position so that the correction average value Ewavg increases. Specifically, the laser irradiation position is controlled so that the correction average value Ewavg is maximized. Details of S36 will be described with reference to
In S361, the processor 5 calculates the correction coefficients k1 to k3 such that the correction average value Ewavg of the radiation energies E1 to E3 is larger when the target irradiation position Pop is irradiated with the pulse laser light 33 than when the reference position Pini is irradiated with the pulse laser light. Specifically, the correction coefficients k1 to k3 that maximize the correction average value Ewavg when the target irradiation position Pop is irradiated with the pulse laser light 33 is calculated.
Ewavg=(k1·E1+k2·E2+k3·E3)/3
For example, when the correction coefficients k2, k3 are set to values larger than the correction coefficient k1, the correction average value Ewavg becomes larger by increasing the radiation energies E2, E3 than by increasing the radiation energy E1. By maximizing the correction average value Ewavg thus set, the radiation energies E2, E3 are increased, and the peak of the radiation energy E of the EUV light is inclined in the X direction, that is, in the direction toward the EUV light concentrating mirror 23a, so that the energy of the EUV light being incident on the EUV light concentrating mirror 23a can be increased. Here, the present invention is not limited to the case in which the correction average value Ewavg of the radiation energies E1 to E3 is used, but also the sum value obtained by weighting the radiation energies E1 to E3 by the correction coefficients k1 to k3 may be used.
The correction coefficients k1 to k3 can be calculated as follows based on positional deviation dP (dx, dy) from the reference position Pini to the target irradiation position Pop.
R(θt,Φt)=α·dP(dx,dy)
When these position vectors P1 to P3 are weighted by the correction coefficients k1 to k3, the following correction position vectors Pw1 to Pw3 are given.
For example, increasing the correction coefficients k2, k3 corresponds to extending the sum of the correction position vectors Pw2, Pw3 in the X direction and the −Z direction.
The geometric centroid of the correction position vectors Pw1 to Pw3 is referred to as the correction geometric centroid vector C of the EUV sensors ES1 to ES3, and the correction geometric centroid vector C can be expressed as follows.
C=[rc(k1,k2,k3),θc(k1,k2,k3),Φc(k1,k2,k3)]
For example, increasing the correction coefficients k2, k3 larger than the correction coefficient k1 corresponds to inclining the correction geometric centroid vector C in the X direction. As described with reference to
From the above description, setting the correction coefficients k1 to k3 such that the correction geometric centroid vector C is inclined in the X direction corresponds to inclining the peak of the radiation energy E of the EUV light in the X direction. When the direction of the correction geometric centroid vector C becomes close to the EUV radiation direction R(θt, Φt), the correction average value Ewavg increases, and when the direction of the correction geometric centroid vector C coincides with the EUV radiation direction R(θt, Φt), the correction average value Ewavg is maximized. Therefore, the correction coefficients k1 to k3 can be calculated such that an objective function O given by the following equation is minimized.
O=(θt−θc(k1,k2,k3))2+(Φt−Φc(k1,k2,k3))2
Here, the correction coefficients k1 to k3 are all set to 1 or more, magnitude rc(k1, k2, k3) of the correction geometric centroid vector C is set to 0 or more, θc(k1, k2, k3) is set to −π or more and n or less, and Φc(k1, k2, k3) is set to −π/2 or more and π/2 or less.
Here, the case in which the correction coefficients k1 to k3 for calculating the correction average value Ewavg are calculated using the three EUV sensors ES1 to ES3 has been described, but the correction coefficients k1, k2, . . . , ki for calculating the correction average value Ewavg may be calculated using three or more EUV sensors ES1, ES2, . . . , ESi.
Referring to
In S362, the processor 5 causes the target 27 to be irradiated with the pulse laser light 33, and controls the laser irradiation position so that the correction average value Ewavg calculated using the correction coefficients k1 to k3 is maximized. The processor 5 sets that laser irradiation position as an adjusted irradiation position Padj.
In S363, the processor 5 determines whether or not the distance between the adjusted irradiation position Padj and the target irradiation position Pop is less than a threshold value. When the distance is less than the threshold value (S363: YES), the processor 5 ends processing of the present flowchart and returns to processing shown in
In S364, the processor 5 corrects the correction coefficients k1 to k3 so that the adjusted irradiation position Padj becomes close to the target irradiation position Pop. For example, when the adjusted irradiation position Padj is shifted in the −X direction with respect to the target irradiation position Pop, the correction coefficient k1 of the EUV sensor ES1 is decreased or the correction coefficients k2, k3 of the EUV sensors k2, k3 are increased in order to adjust the adjusted irradiation position Padj in the X direction.
After S364, the processor 5 returns processing to S362, and verifies again whether or not the corrected correction coefficients k1 to k3 are appropriate.
(1) According to the first embodiment, the EUV light generation system 11a includes the chamber 2, the target supply unit 26, the main pulse laser device MPL, the optical system including the high reflection mirror 341, the actuator 344, the EUV light concentrating mirror 23a, the plurality of EUV sensors ES1, ES2, and the processor 5. The chamber 2 includes the plasma generation region 25. The target supply unit 26 supplies the target 27 to the plasma generation region 25. The main pulse laser device MPL outputs the pulse laser light 33. The optical system including the high reflection mirror 341 guides the pulse laser light 33 to the plasma generation region 25. The actuator 344 adjusts the laser irradiation position on the target 27 in the XY plane perpendicular to the optical path axis of the pulse laser light 33 entering the plasma generation region 25 and intersecting the plasma generation region 25 by changing the position or posture of the high reflection mirror 341. The EUV light concentrating mirror 23a reflects the EUV light radiated from the plasma generation region 25 and concentrates the EUV light at the intermediate focal point 292, and is arranged such that the pulse laser light 33 passes outside the EUV light concentrating mirror 23a and is guided to the plasma generation region 25. The EUV sensors ES1, ES2 measure the radiation energy E of the EUV light radiated from the plasma generation region 25 in mutually different radiation directions. The processor 5 controls the actuator 344 as setting the target irradiation position Pop of the pulse laser light 33 to the laser irradiation position away from the reference position Pini, at which the average value Eavg of the radiation energies E1, E2 measured by the EUV sensors ES1, ES2 is maximized in the direction toward the EUV light concentrating mirror 23a.
According to this, the radiation energy distribution of the EUV light can be inclined such that the radiation energy E of the EUV light toward the EUV light concentrating mirror 23a is increased by irradiating the laser irradiation position away from the reference position Pini in the direction toward the EUV light concentrating mirror 23a with the pulse laser light 33. As a result, it is possible to increase the output energy of the EUV light reaching the intermediate focal point 292.
(2) According to the first embodiment, the processor 5 acquires, as the improved irradiation position Pmax, the laser irradiation position at which the output energy of the EUV light reaching the intermediate focal point 292 becomes larger than that when the reference position Pini is irradiated with the pulse laser light 33. The processor 5 sets the target irradiation position Pop based on the improved irradiation position Pmax.
According to this, the target irradiation position Pop can be set such that the output energy becomes larger than that when the reference position Pini is irradiated with the pulse laser light 33.
(3) According to the first embodiment, the processor 5 irradiates the target 27 with the pulse laser light 33 while changing the laser irradiation position, acquires the measurement result of the output energy at each laser irradiation position, and acquires the improved irradiation position Pmax based on the measurement result.
According to this, by acquiring the improved irradiation position Pmax based on the actual measurement result, it is possible to accurately obtain the improved irradiation position Pmax at which the output energy is increased.
(4) According to the first embodiment, the improved irradiation position Pmax is the laser irradiation position at which the output energy of the EUV light reaching the intermediate focal point 292 is maximized.
According to this, the output power of the EUV light can be increased.
(5) According to the first embodiment, the processor 5 sets the target irradiation position Pop to the laser irradiation position away from the reference position Pini in the direction toward the improved irradiation position Pmax.
According to this, it is possible to set the target irradiation position Pop so as to increase the output energy of the EUV light.
(6) According to the first embodiment, when the distance between the reference position Pini and the improved irradiation position Pmax is equal to or less than the allowable value dPfrg, the processor 5 sets the target irradiation position Pop to the improved irradiation position Pmax. When the distance between the reference position Pini and the improved irradiation position Pmax is larger than the allowable value dPfrg, the processor 5 sets the target irradiation position Pop to a position away from the reference position Pini in the direction toward the improved irradiation position Pmax by the allowable value dPfrg.
According to this, it is possible to suppress a problem caused by the laser irradiation position being shifted from the reference position Pini while increasing the output energy of the EUV light as much as possible.
(7) According to the first embodiment, the processor 5 sets the target irradiation position Pop such that the distance between the reference position Pini and the target irradiation position Pop is equal to or less than the allowable value dPfrg set to be less than the radius of the target 27.
According to this, it is possible to suppress a problem caused by the laser irradiation position being shifted from the reference position Pini.
(8) According to the first embodiment, the allowable value dPfrg is 3 μm or more and 8 μm or less.
According to this, it is possible to suppress the problem caused by the laser irradiation position being shifted from the reference position Pini while increasing the output energy of the EUV light.
(9) According to the first embodiment, the processor 5 sets the target irradiation position Pop such that the generation amount of debris derived from the target 27 is equal to or less than the allowable value.
According to this, it is possible to suppress generation of debris caused by deviation of the laser irradiation position from the reference position Pini.
(10) According to the first embodiment, the plurality of EUV sensors include the EUV sensor ES1 and the EUV sensor ES2 having a smaller deviation in the direction centered at the plasma generation region 25 with respect to the EUV light concentrating mirror 23a than the EUV sensor ES1. The processor 5 controls the actuator 344 so that the correction average value Ewavg obtained by correcting any of the radiation energies E1, E2 so as to emphasize the radiation energy E2 measured by the EUV sensor ES2 over the radiation energy E1 measured by the EUV sensor ES1 becomes larger when the laser irradiation position is irradiated with the pulse laser light 33 than when the reference position Pini is irradiated with the pulse laser light 33.
According to this, by emphasizing the radiation energy E2 measured by the EUV sensor ES2 whose direction from the plasma generation region 25 is close to the EUV light concentrating mirror 23a, irradiation of the pulse laser light 33 can be performed with the radiation distribution inclined toward the EUV light concentrating mirror 23a.
(11) According to the first embodiment, the processor 5 controls the actuator 344 so that the laser irradiation position at which the correction average value Ewavg is maximized is irradiated with the pulse laser light 33.
According to this, by maximizing the correction average value Ewavg, the optimum laser irradiation position can be irradiated with the pulse laser light 33.
(12) According to the first embodiment, the processor 5 corrects any of the radiation energies E1, E2 so that the correction average value Ewavg becomes larger when the target irradiation position Pop is irradiated with the pulse laser light 33 than when the reference position Pini is irradiated with the pulse laser light 33.
According to this, by performing correction so that the correction average value Ewavg when the target irradiation position Pop is irradiated with the pulse laser light 33 is increased, it is possible to irradiate the optimum laser irradiation position in the control based on the correction average value Ewavg.
(13) According to the first embodiment, the processor 5 calculates the correction coefficient k1 or k2 for correcting any of the radiation energies E1, E2 based on the positional deviation dP (dx, dy) between the reference position Pini and the target irradiation position Pop.
According to this, by calculating the correction coefficient k1 or k2 based on the positional deviation dP (dx, dy), it is possible to correct any of the radiation energies E1, E2 so that the target irradiation position Pop can be irradiated.
(14) According to the first embodiment, the processor 5 calculates, based on the positional deviation dP (dx, dy), the EUV radiation direction R(θt, Φt) in which the radiation energy E becomes larger than that in the −Z direction opposite to the incident direction of the pulse laser light 33 entering the plasma generation region 25. The processor 5 calculates the correction coefficient k1 or k2 such that the direction of the correction geometric centroid vector C obtained by weighting any of the first and second position vectors P1, P2 indicating the positions of the EUV sensors ES1, ES2 with the correction coefficient k1 or k2 is closer to the EUV radiation direction R (θt, Φt) than the −Z direction opposite to the incident direction.
According y calculating the correction coefficient k1 or k2 such that the direction of the correction geometric centroid vector C of the EUV sensors ES1, ES2 becomes close to the EUV radiation direction R(θt, Φt), the radiation energy E can be inclined in the EUV radiation direction R(θt, Φt) in the control of the laser irradiation position based on the correction average value Ewavg.
(15) According to the first embodiment, the processor 5 calculates, based on the positional deviation dP (dx, dy), the EUV radiation direction R(θt, Φt) in which the radiation energy E is maximized as a maximum radiation direction. The processor 5 calculates the correction coefficient k1 or k2 such that the direction of the correction geometric centroid vector C obtained by weighting any of the first and second position vectors P1, P2 indicating the positions of the EUV sensors ES1, ES2 with the correction coefficient k1 or k2 coincides with the maximum radiation direction.
According to this, by calculating the correction coefficient k1 or k2 such that the direction of the correction geometric centroid vector C of the EUV sensors ES1, ES2 coincides with the maximum radiation direction of the EUV light, the radiation energy E can be inclined in the maximum radiation direction in the control of the laser irradiation position based on the correction average value Ewavg.
(16) According to the first embodiment, the processor 5 calculates the correction coefficient k1 or k2 such that the direction component, perpendicular to the optical path axis of the pulse laser light 33, of the correction geometric centroid vector C obtained by weighting any of the first and second position vectors P1 and P2 indicating the positions of the EUV sensors ES1, ES2 with the correction coefficient k1 or k2 for obtaining the correction average value Ewavg is the direction toward the EUV light concentrating mirror 23a from the optical path axis.
According to this, by calculating the correction coefficient k1 or k2 such that the direction of the correction geometric centroid vector C of the EUV sensors ES1, ES2 becomes close to the EUV light concentrating mirror 23a, the radiation energy E can be inclined in the direction toward the EUV light concentrating mirror 23a in the control of the laser irradiation position based on the correction average value Ewavg.
(17) According to the first embodiment, the processor 5 corrects the correction coefficient k1 or k2 when the distance between the laser irradiation position at which the correction average value Ewavg is maximized and the target irradiation position Pop is equal to or more than the threshold value.
According to this, it is possible to determine whether or not the calculated correction coefficient k1 or k2 is appropriate and to correct the correction coefficient k1 or k2.
In other respects, the first embodiment is similar to the comparative example.
Before the pulse laser light 33 output from the main pulse laser device MPL is radiated to the target 27, the prepulse laser device PPL outputs prepulse laser light to be radiated to the target 27. The prepulse laser light diffuses the droplet-shaped target 27 to reduce the density of the target 27, so that the pulse laser light 33 output from the main pulse laser device MPL can efficiently excite the target 27 to turn the target 27 into plasma.
The beam combiner 304b reflects one of the pulse laser light 31 output from the main pulse laser device MPL and the prepulse laser light output from the prepulse laser device PPL and transmits the other thereof so that the optical paths of the both substantially coincide with each other. As a result, the prepulse laser light enters the plasma generation region 25 as passing through the optical path common with the pulse laser light 31, 32, 33 output from the main pulse laser device MPL.
The actuator 306b controls the position or posture of the high reflection mirror 302 on which the pulse laser light 31 output from the main pulse laser device MPL is incident before merging with the prepulse laser light. Accordingly, the optical path axis of the pulse laser light 31 can be adjusted separately from the prepulse laser light. The actuator 344 can adjust both the optical path axis of the pulse laser light 31 and the optical path axis of the prepulse laser light.
The laser irradiation position away from the reference position Pini in the direction toward the EUV light concentrating mirror 23a is irradiated with the pulse laser light 33 output from the main pulse laser device MPL, whereas a position closer to the reference position Pini than the laser irradiation position of the pulse laser light 33 is irradiated with the prepulse laser light. Preferably, the optical path axis of the prepulse laser light coincides with the center of the droplet-shaped target 27. Accordingly, the target 27 can be diffused substantially axisymmetrically with respect to the optical path axis of the prepulse laser light.
(18) According to the second embodiment, the EUV light generation system 11b includes the prepulse laser device PPL that outputs prepulse laser light that is radiated to the target 27 before the target 27 is irradiated with the pulse laser light 33. The position closer to the reference position Pini than the laser irradiation position of the pulse laser light 33 is irradiated with the prepulse laser light.
According to this, by irradiating the position close to the reference position Pini with the prepulse laser light, it is possible to improve the diffusion state of the target 27.
In other respects, the second embodiment is similar to the first embodiment.
In
In
Although
The description above is intended to be illustrative and the present disclosure is not limited thereto. Therefore, it would be obvious to those skilled in the art that various modifications to the embodiments of the present disclosure would be possible without departing from the spirit and the scope of the appended claims. Further, it would be also obvious to those skilled in the art that embodiments of the present disclosure would be appropriately combined.
The terms used throughout the present specification and the appended claims should be interpreted as non-limiting terms unless clearly described. For example, terms such as “comprise”, “include”, “have”, and “contain” should not be interpreted to be exclusive of other structural elements. Further, indefinite articles “a/an” described in the present specification and the appended claims should be interpreted to mean “at least one” or “one or more.” Further, “at least one of A, B, and C” should be interpreted to mean any of A, B, C, A+B, A+C, B+C, and A+B+C as well as to include combinations of the any thereof and any other than A, B, and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-195004 | Dec 2022 | JP | national |
