Extreme ultraviolet light source device

Abstract

This invention relates to an extreme ultraviolet (EUV) light source device, comprising a seed laser generator, an electron source, an electron linear accelerator, a first modulation section, a first dispersion section, a second modulation section, a second dispersion section, and an amplifier. A first electron beam generated by the electron source is accelerated by the electron linear accelerator to form a second electron beam. The seed laser generator generates a seed laser, and both the seed laser and the second electron beam are injected into the first modulation section to induce a first energy modulation in the second electron beam, resulting in a third electron beam. The first dispersion section compresses the third electron beam to form a fourth electron beam. The second modulation section induces coherent radiation in the fourth electron beam, which is then subjected to a second energy modulation by the coherent radiation to form a fifth electron beam. The second dispersion section compresses the fifth electron beam to form a sixth electron beam. The amplifier causes the sixth electron beam to radiate and emit kilowatt-level EUV light. The EUV light source device of this invention can generate EUV light with an average power in the kilowatt range and has a compact structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanolithography, and more particularly to an extreme ultraviolet light source device suitable for nanolithography. BACKGROUND

[0002] With the further development of today's society, people's interest in fully coherent short wavelength light source is growing, especially in the extreme ultraviolet (EUV) band. In the field of frontier science, the EUV light source plays an important role in exploring the structure of matter and nonlinear optics with its ultrafast time scale, and a high average power EUV light source can greatly improve the efficiency of imaging and spectroscopy experiments. In the field of industrial manufacturing, EUV light source is particularly suitable for photolithography technology (EUV lithography technology for short) for manufacturing nanochip, and the power of EUV light source is the main technical limitation for the commercial operation of the scale of photolithography technology. Therefore, a compact EUV light source device that can be applied to both academic research and industrial manufacturing and can generate fully coherent, high average power, and ultrashort EUV pulses is of great importance.

[0003] There are various EUV light sources in the prior art, including high harmonic generation (HHG) EUV light source by impinging inert gas with intense laser pulses, laser-produced plasma (LPP) EUV light source, accelerator-driven EUV light source, free-electron laser (FEL) based EUV light source, and the like.

[0004] However, the average power of the existing EUV light sources is low and cannot reach the kilowatt level. SUMMARY

[0005] The present application relates to the field of nanolithography, and more particularly to an extreme ultraviolet light source device suitable for nanolithography.

[0006] In order to achieve the above object, the present application provides an extreme ultraviolet light source device, comprising an electron source, an electron linear accelerator, a first modulation section, a first dispersion section, a second modulation section, a second dispersion section and an amplifier arranged in sequence along the direction of electron beam propagation, and a seed laser generator arranged upstream of the first modulation section; the electron source is configured to generate a first electron beam, the first electron beam is accelerated by the electron linear accelerator to form a second electron beam; the seed laser generator is configured to generate a seed laser, the seed laser and the second electron beam are injected into the first modulation section, so that the second electron beam is modulated in energy for the first time under the action of the seed laser to obtain a third electron beam; the first dispersion section is configured to compress the third electron beam to form a fourth electron beam; the second modulation section is configured to generate coherent radiation from the fourth electron beam, the fourth electron beam is modulated in energy for the second time by the coherent radiation to form a fifth electron beam; the second dispersion section is configured to compress the fifth electron beam to form a sixth electron beam; and the amplifier is configured to generate radiation from the sixth electron beam and emit kilowatt-level extreme ultraviolet light.

[0007] Further, the first modulation section and the second modulation section are undulators, and the amplifier comprises a plurality of undulators arranged in sequence along the direction of electron beam propagation.

[0008] Further, the first energy modulation generated on the second electron beam is more than 1 times the initial energy spread of the second electron beam.

[0009] Further, the length of the second modulation section is at least twice the gain length of the fourth electron beam.

[0010] Further, the spacing of the plurality of undulators of the amplifier gradually increases along the direction of electron beam propagation.

[0011] Further, the second modulation section resonates on the fundamental wave of the seed laser or resonates on the harmonic wave of the seed laser.

[0012] Further, the first dispersion section comprises a first dipole magnet, a second dipole magnet, a third dipole magnet and a fourth dipole magnet arranged in sequence along the direction of electron beam propagation and having the same length, the first dipole magnet and the second dipole magnet are symmetrically distributed with the third dipole magnet and the fourth dipole magnet; and the second dispersion section comprises a fifth dipole magnet, a sixth dipole magnet, a seventh dipole magnet and an eighth dipole magnet arranged in sequence along the direction of electron beam propagation and having the same length, the fifth dipole magnet and the sixth dipole magnet are symmetrically distributed with the seventh dipole magnet and the eighth dipole magnet.

[0013] Further, the electron source is a photocathode electron gun.

[0014] Further, the electron linear accelerator comprises an injector and a main accelerator, the injector accelerates the first electron beam to a preset energy, and the main accelerator further accelerates the first electron beam of the preset energy to form a second electron beam.

[0015] Further, the seed laser generator is a ytterbium-doped fiber laser, and the seed laser has the same repetition frequency as the second electron beam.

[0016] The extreme ultraviolet light source device has the following beneficial effects:

[0017] 1) The electron linear accelerator and the seed free electron laser based on superconducting frequency technology generate kilowatt-level, fully coherent and stable EUV light, and the structure is compact.

[0018] 2) The average pulse energy of 100 EUV light pulses generated by the device is about several hundred microjoules, the full width at half maximum of the pulse length is about hundreds of femtoseconds, and the single pulse photon number is about 10 13 The average power can reach 1kW in the 3MHz operation mode of the electron beam repetition frequency, and the amplifier has the potential to further improve the average power of the EUV radiation to 10kW through the waveguide gradual change technology. The EUV light pulse generated by the present application is close to the Fourier transform limit, has good energy stability and good coherence, and has high single pulse flux, and is especially suitable for nanolithography technology and extreme ultraviolet optical experiments. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a structure schematic diagram of the extreme ultraviolet light source device according to the embodiment of the present application;

[0020] Figure 2A It is an energy-time distribution diagram of the second electron beam according to the embodiment of the present application;

[0021] Figure 2B It is an energy-time distribution diagram of the third electron beam according to the embodiment of the present application;

[0022] Figure 2C It is an energy-time distribution diagram of the fourth electron beam according to the embodiment of the present application;

[0023] Figure 2D It is an energy-time distribution diagram of the fifth electron beam according to the embodiment of the present application;

[0024] Figure 2E It is an energy-time distribution diagram of the sixth electron beam according to the embodiment of the present application;

[0025] Figure 3 It is a structure schematic diagram of the first dispersion section according to the embodiment of the present application;

[0026] Figure 4 This is a schematic diagram of the structure of the second dispersion segment according to an embodiment of the present invention. Detailed Implementation

[0027] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0028] like Figure 1 As shown, this embodiment of the invention provides an extreme ultraviolet (EUV) light source device, including an electron source 10, an electron linear accelerator 20, a first modulation section 40, a first dispersion section 50, a second modulation section 60, a second dispersion section 70, and an amplifier 80 arranged sequentially along the electron beam propagation direction. A seed laser generator 30 is also disposed upstream of the first modulation section 40. The electron source 10 is used to generate a first electron beam, which is accelerated by the electron linear accelerator 20 to obtain a second electron beam that meets preset requirements, such as... Figure 2A As shown; the seed laser generator 30 is used to generate a seed laser. Both the seed laser and the second electron beam are injected into the first modulation section 40, so that the second electron beam undergoes a first energy modulation under the action of the seed laser, resulting in a third electron beam, as shown. Figure 2B As shown, the third electron beam has a slight energy-time chirp; the first dispersion section 50 is used to compress the third electron beam and generate density modulation, forming and outputting a fourth electron beam with a certain micro-clustering, such as... Figure 2C As shown; the second modulation section 60 is used to generate coherent radiation in the fourth electron beam, and the fifth electron beam is formed by the second energy modulation of its own coherent radiation, as shown. Figure 2D As shown, the fifth electron beam exhibits a significant energy-time chirp; the second dispersion section 70 is used to compress the fifth electron beam and generate density modulation, forming and outputting as shown in the figure. Figure 2E The sixth electron beam shown has a certain micro-clustering; the amplifier 80 is used to make the sixth electron beam radiate and emit fully coherent EUV light 200 in the kilowatt range.

[0029] In some embodiments, the electron source 10 can be a photocathode electron gun for emitting a high-quality first electron beam. The charge of the first electron beam can be 600 pC (picocoulomb).

[0030] In some embodiments, the electron linear accelerator 20 can include an injector 21 and a main accelerator 22 arranged in sequence, the injector 21 being configured to further accelerate the first electron beam to a preset energy, for example, at the order of 100 MeV (mega-electron-volt). Since the first electron beam has a low energy, the space charge effect cannot be ignored, and thus the injector can employ a solenoid to focus the first electron beam, so that the energy flow intensity, beam length, and emittance of the first electron beam can meet the injection requirements of the main accelerator 22. The main accelerator 22 can employ a superconducting radio frequency technology, and in a continuous wave operation mode, a high gradient electric field further accelerates the first electron beam, and through magnetic compression, the lateral size, length, and flow intensity of the first electron beam are changed, and finally the second electron beam is obtained. The energy of the second electron beam can reach 1.4 GeV (giga-electron-volt), the root mean square (rms) energy spread is about 50 keV (kilo-electron-volt), the lateral emittance is less than 1 mm.mrad, the peak flow intensity is 700 A (ampere), the repetition frequency is 3 MHz (mega-hertz), and the average flow intensity is 1.8 mA (milli-ampere) at the repetition frequency, thereby meeting the requirements of high repetition frequency operation of the extreme ultraviolet light source device.

[0031] In some embodiments, the seed laser generator 30 can employ a Yb-doped (Yb) fiber laser based on an optical parametric chirped pulse amplification (OPCPA) technology to generate a high repetition frequency infrared light, and then generate an ultraviolet seed laser after frequency doubling, for example, Yb:YAG (Yb-doped yttrium aluminum garnet) crystal, Yb:KGW crystal (Yb-doped potassium gadolinium tungstate), Yb:CaF2 crystal (Yb-doped calcium fluoride), and Yb:KYW crystal (Yb-doped yttrium potassium tungstate) laser, etc. The Yb-doped fiber laser can generate a MHz order repetition frequency, a ps order or shorter ultraviolet light. Compared with the Nd:YAG crystal laser and the titanium-doped sapphire laser commonly used in low repetition frequency seed laser systems, a high concentration of doping can be achieved in the Yb-doped laser material, and thus the gain medium has a larger gain bandwidth, a higher emission cross section, a lower quantum defect rate, and a lower thermal load. Taking the Yb:YAG crystal laser as an example, the strongest line is usually at 1030 nm, and the 4th harmonic 257.5 nm is the working wavelength of the seed laser. The seed laser is used to generate energy modulation on the second electron beam in the first modulation section 40 and is extracted at the outlet of the first modulation section 40 and used only once. The repetition frequency of the seed laser is the same as the repetition frequency of the second electron beam, and the two are synchronized in the lateral and time directions when they interact in the first modulation section 40. In an exemplary embodiment, the parameters of the seed laser are: wavelength 266 nm, full width at half maximum pulse width 1 ps, Rayleigh length 5 m, peak power 400 kW, average power 1.2 W at a repetition frequency of 3 MHz.

[0032] In some embodiments, the first modulation segment 40 can be an undulator, which refers to a magnetic array that generates a periodic magnetic field. The electron beam satisfies the following resonance relationship in the first modulation segment 40:

[0033]

[0034] Where λr is the radiation wavelength (i.e., the undulator resonant wavelength, which is equal to the seed laser wavelength in the first modulation segment), λu is the undulator period, and K is the undulator magnet strength.

[0035] In the first modulation section 40, the second electron beam undergoes its first energy modulation under the influence of the seed laser, resonating on the fundamental frequency of the seed laser. After passing through the first modulation section 40, the second electron beam transforms into a third electron beam and exits from the first modulation section 40, entering the first dispersion section 50. The energy-time distribution of the third electron beam is sinusoidal. In some embodiments, the energy modulation amplitude introduced in the first modulation section 40 is more than one time the initial energy dispersion of the second electron beam, for example, 1.3 times the RMS energy dispersion.

[0036] The basic principle of the first dispersion section 50 is as follows: Since the third electron beam is modulated by the seed laser and has energy-time chirp, electrons with different energies follow different paths in the dispersion section. When the cluster is compressed, the tail electrons chase the head electrons, thereby achieving longitudinal / temporal compression of the cluster, ultimately producing micro-clusters at the target wavelength. After passing through the first dispersion section 50, the energy modulation of the third electron beam is converted into density modulation, forming a fourth electron beam with micro-clusters. The fourth electron beam then enters the second modulation section 60.

[0037] like Figure 3 As shown, in some embodiments, the first dispersion segment 50 may be a magnetic compressor (chicane), including a first diode 51, a second diode 52, a third diode 53 and a fourth diode 54 arranged in sequence. The first diode 51, the second diode 52 and the third diode 53 and the fourth diode 54 are symmetrically distributed and have the same length.

[0038] The dispersion intensity of the dispersion segment can be represented by the dispersion parameter, which is mainly determined by the arrangement and intensity of the diodes in the dispersion segment. In some embodiments, the dispersion parameter R of the first dispersion segment 50 is... 56

[0039]

[0040] Where L1 is the length of the first diode 51, L2 is the distance between the first diode 51 and the second diode 52 along the direction of electron beam propagation, L21 is the distance between the first diode 51 and the second diode 52 along the horizontal direction, and θ represents the deflection angle of the third electron beam as it passes through the first diode 51 (i.e., the angle of deviation from the horizontal direction). Its magnitude is related to the magnetic field strength of the first diode 51 and can be adjusted by adjusting the magnitude of its coil current. L21 = L2 / cosθ. When θ is very small, L21 and L2 are approximately equal.

[0041] In some embodiments, the lengths of the first diode 51, the second diode 52, the third diode 53, and the fourth diode 54 are all 0.3m, the horizontal distance L21 between the first diode 51 and the second diode 52 is 1m, θ is 0-3 degrees, R is 0-7mm, the horizontal distance between the second diode 52 and the third diode 53 is 1m, and the total length of the first dispersion segment 50 is 4.2m.

[0042] In some embodiments, the second modulation section 60 may be an undulator with a periodic magnet array, and its structure may be the same as that of the first modulation section 40. In other embodiments, the second modulation section 60 may also have a different structure from the first modulation section 40, and can be configured according to actual needs. The fourth electron beam resonates with the fundamental wave of the seed laser in the second modulation section 60. In the second modulation section 60, the fourth electron beam generates coherent radiation and is simultaneously modulated a second time by its own coherent radiation, thereby forming a fifth electron beam with a quasi-sinusoidal energy-time distribution. The fifth electron beam is output from the second modulation section 60 and enters the second dispersion section 70. Since no seed laser is introduced in the second modulation section 60, and the fourth electron beam is modulated by its own coherent radiation energy, the second modulation section 60 can also be called a self-modulation section.

[0043] like Figure 4 As shown, in some embodiments, the second dispersion section 70 may include a fifth diode 71, a sixth diode 72, a seventh diode 73, and an eighth diode 74 arranged sequentially along the electron beam propagation direction and of equal length. The arrangement of the diodes is the same as that of the first dispersion section 50, that is, the fifth diode 71, the sixth diode 72, the seventh diode 73, and the eighth diode 74 are symmetrically distributed. The difference between the second dispersion section 70 and the first dispersion section 50 lies in their dispersion intensity. After the fifth electron beam passes through the second dispersion section 70, it forms a micro-clustered sixth electron beam, which then enters the amplifier 80.

[0044] In some embodiments, the lengths of the fifth dipole 71, the sixth dipole 72, the seventh dipole 73 and the eighth dipole 74 are all 0.3 m (i.e., L1’ = 0.3 m), the horizontal distance between the fifth dipole 71 and the sixth dipole 72 is L21’ = 0.8 m, the horizontal distance between the sixth dipole 72 and the seventh dipole 73 is L3’ = 0.5 m, the electron beam deflection angle of the second dispersion section 70 is θ’ = 0-1.5 degrees, the distance between the fifth dipole 71 and the sixth dipole 72 along the electron beam propagation direction is L2’ = L21’ / cos θ’, the dispersion strength range of the second dispersion section 70 is 0-1.4 mm, and the total length of the second dispersion section 70 is 3.3 m.

[0045] In some embodiments, the second modulation section 60 can resonate on the seed laser fundamental wave, and the coherent energy modulation of the fourth electron beam is further amplified. At this time, the energy dispersion of the fifth electron beam is relatively large, but after passing through the second dispersion section 70, micro-clustering can be generated on the high harmonic wave. The 20th harmonic wave of the extreme ultraviolet band corresponds to the seed laser, which is about 13.3 nm, and therefore, in order to obtain the sixth electron beam of the extreme ultraviolet band, the dispersion strength of the second dispersion section 70 needs to be optimized so that the fifth electron beam generates micro-clustering on the 20th harmonic wave to obtain the sixth electron beam.

[0046] In some other embodiments, the second modulation section 60 can resonate on the harmonic wave of the seed laser, and the fourth electron beam amplifies the coherent energy modulation under the harmonic wave radiation, which is referred to as harmonic self-modulation. At this time, the energy dispersion of the electron beam is relatively small, and by optimizing the dispersion strength of the second dispersion section 70, micro-clustering can also be generated on the 20th harmonic wave of the seed laser.

[0047] In some embodiments, the amplifier 80 can include a plurality of wave oscillators arranged in sequence. In the amplifier 80, a high gain process of the free electron laser occurs, i.e., a positive feedback process of energy modulation-density modulation-optical field enhancement. The sixth electron beam with micro-clustering of the extreme ultraviolet band further radiates in the amplifier 80 to emit high repetition frequency full-coherent EUV light 200. In some embodiments, beam collimation and diagnosis devices and the like can also be placed between any two adjacent wave oscillators of the amplifier 80. In some embodiments, the amplifier 80 can adopt a wave oscillator gradual change technology, i.e., the spacing between the wave oscillators gradually increases along the electron beam propagation direction. In this way, as the electron beam continuously loses energy, the gradually increasing spacing of the wave oscillators correspondingly reduces the magnetic field strength of the wave oscillators, so as to maintain the resonance relationship of the wave oscillators and continuously amplify the radiation light, which has the potential to improve the average power of the EUV to the order of 10 kilowatts. By adopting the wave oscillator gradual change technology, the conversion efficiency of the free electron laser can be improved, and the pulse energy can be generally improved by 3 to 5 times.

[0048] In one exemplary embodiment, the amplifier 80 can include 4 undulators, the distance between any two adjacent undulators is 1 m, the period of each undulator is 5 cm, the length of each undulator is 3 m, and the total length of the amplifier is 15 m.

[0049] According to the seed-type free electron laser theory, the micro-bunching electron beam generates coherent harmonic radiation in the first three gain lengths, which is in the quadratic gain region and close to the exponential gain region. According to the one-dimensional free electron laser gain theory, the Pierce parameter used to estimate the FEL gain is:

[0050]

[0051] where [JJ]1is the Bessel function, I A is the Alfven current, I is the electron beam current, σ x is the electron beam rms transverse size. The corresponding gain length is: The gain length is mainly determined by the electron beam transverse size and the electron beam current. Further, in the quadratic gain process, the power of the coherent harmonic radiation in the self-modulation section can be estimated by:

[0052]

[0053] where Z0is the vacuum impedance, b n is the n-th harmonic bunching factor, and L is the length of the self-modulation section. It can be seen that the coherent radiation power can be improved by increasing the length of the self-modulation section, reducing the electron beam transverse size, increasing the electron beam current, and increasing the harmonic bunching factor, thereby further taking advantage of the self-modulation technology.

[0054] In some embodiments, the length of the second modulation section 60 is at least twice the gain length of the fourth electron beam to ensure the modulation efficiency. By adjusting the magnetic focusing structure before and after the second modulation section 60 to optimize the electron beam trajectory and the beam envelope size, the self-modulation process efficiency can be significantly improved, and the seed laser power requirement can be significantly reduced. The length of the first modulation section 40 can be the same as the length of the second modulation section 60, which is convenient for actual manufacturing.

[0055] In one exemplary embodiment, the Pierce parameter of the second modulation section 60 is 0.007, the corresponding gain length is 0.5m, the length of the second modulation section 60 is 1.6m, which is 3.2 times of the gain length, the energy modulation amplitude of the second modulation section 60 is 24.5 times of the rms energy spread; the energy modulation amplitude of the first modulation section 40 is 1.3 times of the rms energy spread; the seed laser of 266nm generates EUV light, the corresponding harmonic conversion number is 20, if sufficient 20th harmonic signal is generated, nearly 20 times of energy modulation is needed, and in the present embodiment, the electron beam only introduces 1.3 times of energy modulation to generate EUV radiation with sufficient intensity. Therefore, the second modulation section 60 greatly reduces the power requirement of the seed laser in the first modulation section 40 (which can be reduced by nearly two orders of magnitude), making it possible to generate high-repetition-frequency seed-type free electron laser.

[0056] The extreme ultraviolet light source device of the embodiment of the present application has the following beneficial effects:

[0057] 1) The electron linear accelerator and the seed-type free electron laser based on superconducting frequency technology generate EUV light with average power of kilowatt level, full coherence and stability, and the structure is compact.

[0058] 2) The average pulse energy of 100 EUV light pulses generated by the device of the present application is about several hundred microjoules, the full width at half maximum of the pulse length is about hundreds of femtoseconds, and the single pulse photon number is about 10 13 orders of magnitude. In the 3MHz operation mode of the electron beam repetition frequency, the average power can reach 1kW, and the amplifier has the potential to further improve the average power of the EUV radiation to 10kW through the waveguide gradual change technology. The EUV light pulses generated by the present application are close to the Fourier transform limit, have good energy stability and coherence, and have high single pulse flux, which are especially suitable for nanolithography technology and extreme ultraviolet optical experiments.

[0059] 3) The self-modulation technology is used for the first time to generate high-repetition-frequency and full-coherent EUV light, thereby greatly reducing the power of the seed laser.

[0060] The above is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application. The above embodiment of the present application can be variously changed. Any simple, equivalent changes and modifications made in accordance with the content of the claims and the specification of the present application fall within the scope of protection of the present application. The present application is not described in detail.

Claims

1. An extreme ultraviolet light source apparatus, characterized by comprising: The device comprises an electron source, an electron linear accelerator, a first modulation section, a first dispersion section, a second modulation section, a second dispersion section and an amplifier arranged in sequence along the direction of electron beam propagation, and a seed laser generator arranged upstream of the first modulation section; the electron source is configured to generate a first electron beam, the first electron beam is accelerated by the electron linear accelerator to form a second electron beam; the seed laser generator is configured to generate a seed laser, the seed laser and the second electron beam are injected into the first modulation section to cause the second electron beam to be modulated in energy for the first time under the action of the seed laser to obtain a third electron beam; the first dispersion section is configured to compress the third electron beam to form a fourth electron beam; the second modulation section is configured to cause the fourth electron beam to generate coherent radiation, the fourth electron beam is modulated in energy for the second time by the coherent radiation to form a fifth electron beam; the second dispersion section is configured to compress the fifth electron beam to form a sixth electron beam; and the amplifier causes the sixth electron beam to generate radiation and emit kilowatt-level extreme ultraviolet light.

2. The extreme ultraviolet light source apparatus according to claim 1, wherein The first modulation section and the second modulation section are undulators, and the amplifier comprises a plurality of undulators arranged in sequence along the direction of electron beam transmission.

3. The extreme ultraviolet light source apparatus according to claim 1, wherein The first energy modulation generated on the second electron beam is more than 1 times the initial energy spread of the second electron beam.

4. The extreme ultraviolet light source apparatus according to claim 3, wherein The length of the second modulation section is at least twice the gain length of the fourth electron beam.

5. The extreme ultraviolet light source apparatus of claim 2, wherein The spacing of the plurality of undulators of the amplifier gradually increases along the direction of electron beam propagation.

6. The extreme ultraviolet light source apparatus of claim 1, wherein The second modulation section resonates on the fundamental wave of the seed laser or resonates on the harmonic wave of the seed laser.

7. The extreme ultraviolet light source apparatus according to claim 1, wherein The first dispersion section comprises a first dipole magnet, a second dipole magnet, a third dipole magnet and a fourth dipole magnet arranged in sequence along the direction of electron beam transmission and having the same length, the first dipole magnet, the second dipole magnet and the third dipole magnet are symmetrically distributed with the fourth dipole magnet; the second dispersion section comprises a fifth dipole magnet, a sixth dipole magnet, a seventh dipole magnet and an eighth dipole magnet arranged in sequence along the direction of electron beam transmission and having the same length, the fifth dipole magnet, the sixth dipole magnet and the seventh dipole magnet are symmetrically distributed with the eighth dipole magnet.

8. The extreme ultraviolet light source apparatus of claim 1, wherein The electron source is a photocathode electron gun.

9. The extreme ultraviolet light source apparatus according to claim 1, wherein The electron linear accelerator comprises an injector and a main accelerator, the injector accelerates the first electron beam to a preset energy, and the main accelerator further accelerates the first electron beam at the preset energy to form a second electron beam.

10. The extreme ultraviolet light source apparatus of claim 1, wherein The seed laser generator is a ytterbium-doped fiber laser, and the seed laser has the same repetition frequency as the second electron beam.

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