CN118368794A - Extreme ultraviolet light source device - Google Patents
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- CN118368794A CN118368794A CN202410402622.0A CN202410402622A CN118368794A CN 118368794 A CN118368794 A CN 118368794A CN 202410402622 A CN202410402622 A CN 202410402622A CN 118368794 A CN118368794 A CN 118368794A
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Abstract
The invention relates to an extreme ultraviolet light source device, which comprises an accelerator, a first modulation section, a first dispersion section, a second modulation section, a second dispersion section and a radiation section which are sequentially arranged along the transmission direction of an electron beam, wherein a seed laser is arranged at the upstream of the first modulation section and is used for generating a first electron beam, the seed laser is used for generating a first seed laser and a second seed laser, and the first seed laser is used for enabling the first electron beam to generate first energy modulation to obtain a second electron beam; the first dispersion section compresses the second electron beam to obtain a third electron beam; the second seed laser enables the third electron beam to generate second energy modulation to obtain a fourth electron beam; compressing the fourth electron beam by the second dispersion section to obtain a fifth electron beam; the radiation section is used for enabling the fifth electron beam to generate harmonic radiation so as to emit full-coherence extreme ultraviolet light with the kilowatt magnitude. The extreme ultraviolet light source device can generate full-coherent extreme ultraviolet light reaching kilowatt level based on low-energy electron beams, and has low cost and compact structure.
Description
Technical Field
The invention relates to nano lithography, in particular to an extreme ultraviolet light source device.
Background
With the needs of industrial upgrading and technological development, an Extreme Ultraviolet (EUV) light source can be simultaneously applied to the nano lithography field of industrial manufacturing and the leading-edge scientific field of exploring a material structure by virtue of the special band advantages. EUV light sources can be used in EUV lithography to fabricate nano-chips, while the average power of EUV light sources is a major technical limitation for further performance enhancement by lithography. In addition, the EUV light source with space-time full coherence and ultra-short time scale has wide application prospect in the aspect of exploring the material structure, and the EUV light source with high average power can remarkably improve experimental efficiency.
There are various EUV light sources in the prior art, such as high-order harmonic generation (High Harmonic Generation, HHG) EUV light sources of intense Laser pulse bombardment inert gas, laser-driven plasma (Laser-Produced Plasma, LPP) EUV light sources, electron storage ring based synchrotron radiation (Synchrotron Radiation, SR) EUV light sources and Steady State Micro-Bunching (SSMB) EUV light sources, and Free Electron Laser (FEL) EUV light sources based on Electron linear accelerators. HHG-EUV light sources have been widely used in the scientific field, but have low energy conversion efficiency, low average power of EUV light, and are difficult to be applied industrially on a large scale. LPP-EUV light sources have been successfully applied in the nanolithography field, and the average power of LPP-EUV light sources can reach 500W at maximum by continuously optimizing the transmission efficiency of driving laser and EUV light paths, etc., and kW magnitude is still a technical bottleneck.
EUV light sources based on advanced accelerator driving are expected to produce EUV light on the order of kW of average power, unlike conventional EUV light source principles. The SR-EUV light source can generate EUV light with higher average power by virtue of the high repetition frequency of the electron storage ring, but has no temporal coherence and pulse width of the order of picoseconds, and also far from the lithography requirements. SSMB-EUV light sources, also based on electronic storage rings, have the potential to produce kW-magnitude full-coherence EUV light, but stable operation in multiple turns remains to be further verified.
FEL-EUV light sources based on electron linac drive have been widely used in various front-end science fields by virtue of their high intensity, short pulse, high coherence, short wavelength, etc. The basic principle is that a relativistic electron beam generated by an accelerator is used to interact with an undulator with a periodic magnetic field to generate high-power light pulses with wavelengths meeting resonance relation. For example, self-amplifying spontaneous emission type (SASE) starting from electron beam noise, the output pulses have only spatial coherence and no temporal coherence. In addition, the seed type free electron laser, such as high-gain higher harmonic generation (HGHG), echo enhancement type harmonic amplification (EEHG), phase convergence enhancement type harmonic amplification (PEHG) and the like inherit the characteristics of full coherence and the like of seed laser, can output full coherence EUV light, and even expands to shorter wave bands Beyond Extreme Ultraviolet (BEUV), soft X rays and the like. The FEL-EUV light source of high average power is still limited by the electron beam repetition frequency and quality produced by the accelerator.
From the electron beam, the electron storage ring and the FEL are combined to make up for the defect of the repetition frequency of the electron beam, but the electron beam intensity of the storage ring is low, the energy dissipation is large, the FEL extraction efficiency is low, and the EUV average power is limited. An electron linac based on superconducting radio frequency technology and an energy recovery electron linac (Energy Recovery Linac, ERL) can provide high average current Jiang Shu flow on the order of 10 mA. ERL in combination with SASE type FEL can produce EUV light of high average power, but in order to meet FEL gain requirements, such devices require high energy and high fluence high quality electron beams with poor output pulse coherence. For example, japanese research institute KEK is based on the SASE type FEL-EUV device of ERL design, the required electron beam energy reaches 800MeV, the linear accelerator and radiating section length reaches approximately 200m, and the cost is not very high and the size is huge.
Disclosure of Invention
The invention aims to provide an extreme ultraviolet light source device which combines an accelerator capable of generating high average current strong electron beams with a seed type free electron laser, operates in a harmonic mode, has a compact structure and low requirements on the electron beams, and can generate full-coherence extreme ultraviolet light with average power kilowatt magnitude.
Based on the above object, the present invention provides an euv light source device, which comprises an accelerator, a first modulation section, a first dispersion section, a second modulation section, a second dispersion section and a radiation section sequentially arranged along a transmission direction of an electron beam, wherein seed lasers are arranged at upstream of the first modulation section and the second modulation section, the accelerator is used for generating a first electron beam meeting preset requirements, the seed lasers are used for generating a first seed laser and a second seed laser which are longitudinally synchronized, and the first electron beam and the first seed laser are co-injected into the first modulation section so that the first electron beam generates first energy modulation under the action of the first seed laser to obtain a second electron beam; the first dispersion section is used for compressing the second electron beam to form a third electron beam; the third electron beam and the second seed laser are both injected into the second modulation section, so that the third electron beam generates second energy modulation under the action of the second seed laser and forms a fourth electron beam; the second dispersion section is used for compressing the fourth electron beam to form a fifth electron beam; the radiation section is used for enabling the fifth electron beam to generate harmonic radiation so as to emit full-coherence extreme ultraviolet light with the kilowatt magnitude.
Further, the first modulation section and the second modulation section are both resonant at the fundamental wave, and the radiation section outputs third harmonic radiation light as extreme ultraviolet light.
Further, the accelerator comprises an electron source for generating an initial electron beam and an injector for accelerating the initial electron beam to a preset energy to obtain a first electron beam, wherein the preset energy is 280MeV.
Further, the repetition frequencies of the first seed laser, the second seed laser, and the first electron beam are the same.
Further, the first modulation section and the second modulation section are undulators composed of periodically arranged magnetic arrays.
Further, the first dispersion section comprises a first diode iron, a second diode iron, a third diode iron and a fourth diode iron which are sequentially arranged along the transmission direction of the electron beam, the lengths of the first diode iron, the second diode iron, the third diode iron and the fourth diode iron are the same, and the first diode iron, the second diode iron, the third diode iron and the fourth diode iron are symmetrically distributed; the second dispersion section comprises a fifth diode iron, a sixth diode iron, a seventh diode iron and an eighth diode iron which are sequentially distributed along the transmission direction of the electron beam, the lengths of the fifth diode iron, the sixth diode iron, the seventh diode iron and the eighth diode iron are the same, and the fifth diode iron, the sixth diode iron, the seventh diode iron and the eighth diode iron are symmetrically distributed.
Further, the radiation section comprises a plurality of sections of undulators which are sequentially arranged along the transmission direction of the electron beam, a phase shifter is arranged between any two sections of undulators, the undulators are used for enabling the fifth electron beam to generate radiation, the phase shifter is used for adjusting phases of the fifth electron beam and radiation light, fundamental wave radiation light of the undulators is enabled to be remarkably cancelled, and therefore the radiation section outputs third harmonic radiation light of the undulators as extreme ultraviolet light.
Further, the magnetic field intensity of the multi-stage undulator becomes smaller in steps in order along the electron beam transmission direction.
Further, the phase shifter includes four magnets having different poles to generate a periodic magnetic field.
Further, the radiation section comprises 13 sections of undulators and 12 phase shifters, the period of each section of undulator is 12mm, the length is 0.24m, and the interval between any two sections of undulators is 0.12m; each phase shifter had a period of 20mm and a length of 80mm.
The extreme ultraviolet light source device has the following beneficial effects:
1) The low-energy electron beam and the seed type free electron laser based on high average power generate full-coherence EUV light with average power of kW magnitude, and have low cost and compact structure.
2) Only an electron beam on the order of 280MeV is required, which can significantly reduce the construction cost and size of the accelerator 10 compared to the same type of device; the length of the radiating section 70 can be shortened using a short cycle oscillator; the overall device length may be within 35 m.
3) The peak power of the generated extreme ultraviolet light reaches 90MW, the single pulse energy reaches 7.3 mu J, the full width at half maximum of the pulse length is of the order of hundred femtoseconds, and the spectral bandwidth is 0.04%. When the average electron beam current intensity reaches 10mA, the average power of EUV radiation can reach 1kW through an undulator gradual change technology.
Drawings
Fig. 1 is a schematic structural view of an euv light source device according to an embodiment of the present invention;
FIG. 2A is an energy-time profile of a first electron beam according to an embodiment of the present invention;
FIG. 2B is an energy-time profile of a second electron beam according to an embodiment of the present invention;
FIG. 2C is an energy-time profile of a third electron beam according to an embodiment of the present invention;
FIG. 2D is an energy-time distribution diagram of a fourth electron beam according to an embodiment of the present invention;
FIG. 2E is an energy-time distribution diagram of a fifth electron beam according to an embodiment of the present invention;
FIG. 3 is a schematic view of an accelerator according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a first dispersion section according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a second dispersion section according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a radiation segment according to an embodiment of the present invention;
FIG. 7A is a time domain distribution of extreme ultraviolet pulses generated by an extreme ultraviolet light source device according to an embodiment of the present invention;
FIG. 7B is a frequency domain distribution of extreme ultraviolet pulses generated by an extreme ultraviolet light source device according to an embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As shown in fig. 1, an embodiment of the present invention provides an euv light source device, which includes an accelerator 10, a first modulation section 30, a first dispersion section 40, a second modulation section 50, a second dispersion section 60, and a radiation section 70 sequentially disposed along a propagation direction of an electron beam, wherein a sub-laser 20 is disposed upstream of the first modulation section 30 and the second modulation section 50, and the accelerator 10 is configured to generate a first electron beam satisfying a preset requirement, as shown in fig. 2A; the seed laser 20 is configured to generate a seed laser and split the seed laser into a first seed laser and a second seed laser that are longitudinally synchronized (i.e. the time axis is kept synchronized), where the first electron beam and the first seed laser are co-injected into the first modulation segment 30, so that the first electron beam generates a first energy modulation under the action of the first seed laser, and a second electron beam is obtained, as shown in fig. 2B; the first dispersion section 40 is used for compressing the second electron beam to form a third electron beam, as shown in fig. 2C; the third electron beam and the second seed laser are both injected into the second modulation segment 50, so that the third electron beam generates a second energy modulation under the action of the second seed laser and forms a fourth electron beam, as shown in fig. 2D; the second dispersion section 60 is used to compress the fourth electron beam to form a fifth electron beam, as shown in fig. 2E; the radiation section 70 is used to generate high power undulator harmonic radiation for the fifth electron beam to emit full coherence euv light 200 in the kilowatt order.
In some embodiments, the repetition frequency of the first seed laser, the second seed laser, and each electron beam is the same.
In some embodiments, the accelerator 10 may sample any accelerator that may produce a high average stream intensity electron beam, such as a linear accelerator, a circular accelerator, or the like. For the linear accelerator, the first electron beam meeting the preset requirement means that the energy of the first electron beam needs to reach 280MeV, the relative energy dispersion is less than 0.01%, the peak current intensity reaches 420A, and the average current intensity reaches 10mA.
In an exemplary embodiment, the accelerator 10 is an electron linear accelerator, as shown in fig. 3, which includes an electron source 11 and an injector 12, the electron source 11 being configured to generate an initial electron beam, and the injector 12 being configured to accelerate the initial electron beam to a predetermined energy (e.g., 280 MeV) as a first electron beam.
In some embodiments, the electron source 11 may employ a photocathode electron gun, and the electron source 11 may generate a strong electron beam, i.e., an initial electron beam, with an amount of charge of 70pC by high-flux driving laser.
In some embodiments, injector 12 may operate in a continuous wave mode using superconducting radio frequency technology. The injector 12 may also employ a magnetic compression mechanism to compress the electron beam lift stream while the electron beam may be focused using a spiral line. In addition, the injector 12 may also employ a velocity compression mechanism to compress the beam lift stream due to the low first beam energy required. Finally, the energy of the first electron beam meeting the luminous requirement can reach 280MeV, the rms slice energy can be dispersed by about 20keV, the transverse emittance is less than 0.6mm & mrad, the peak current intensity is 420A, the repetition frequency is 143MHz, and the average current intensity is 10mA.
In some embodiments, the total length of the electron linear accelerator may be 22m, where the beam measuring device space 3m is reserved, the length of the electron source 11 is 1m, and the injector 12 may accelerate the electron beam to 280MeV at a high gradient electric field of 16MV/m, corresponding to a length of 18m.
In some embodiments, seed laser 20 may be configured to generate a full-coherence ultraviolet seed laser having an average power in the order of watts, a repetition frequency in the order of MHz, a tunable wavelength, a pulse length in the order of ps or fs based on near-infrared Optical Parametric Chirped Pulse Amplification (OPCPA) technology, starting with near-infrared light in the order of ps, which is generated by an ytterbium (Yb) doped fiber laser. The strongest line of ps-magnitude near infrared light output by the Yb-doped fiber laser is usually 1030nm, seed laser with 257.5nm wavelength can be generated through 4-frequency-doubling harmonic conversion process, and the output wavelength is fixed. However, the near infrared light output of the Yb-doped fiber laser can be mixed with the OPCPA output through a complex multistage nonlinear process, and the tunable range of the output ultraviolet seed laser wavelength is widened. The seed laser 20 may split the first seed laser and the second seed laser with the same parameters by a beam splitting system, which are used to ensure synchronization with the electron beam in the lateral direction and time and the same repetition frequency as the electron beam when the first modulation segment 30 and the second modulation segment 50 interact with the electron beam, respectively. The parameter requirements of the seed laser are: wavelength 243nm, full width at half maximum 200fs of pulse width, rayleigh length 0.5m, peak power 115kW, single pulse energy 23nJ, repetition frequency 143MHz, average power 3.3W.
In some embodiments, the first modulation section 30 and the second modulation section 50 are short wave oscillators composed of periodically arranged magnetic arrays, for example, permanent magnetic or electromagnetic wave oscillators may be used. The size of the magnetic field of the permanent magnetic undulator can be adjusted by adjusting the width of a gap between the two magnetic arrays, and the electromagnetic undulator is adjusted by the coil flow intensity.
The electron beam satisfies the following resonance relationship in the undulator:
where λs is the radiation wavelength (i.e., the resonant wavelength of the undulator), λu is the undulator period, K is the undulator parameter, n is the harmonic order, and γ is the Lorentz factor representing the electron beam energy.
According to the theory of linear harmonic generation in high-gain free electron lasers, if fundamental wave radiation is well suppressed, the undulator harmonic radiation can generate high-intensity, more stable and narrower-bandwidth FEL pulses to expand the wavelength coverage of the FEL device. During the generation of higher harmonics, the coupling factor is related to the undulator parameter K. When the K value is larger, the coupling factor is larger, and the duty ratio of the higher harmonic is higher. The saturated power estimation formula of the linear harmonic is:
Where ρ n is the FEL parameter of the n-th harmonic, ρ 1 is the FEL parameter of the fundamental wave, and P s1 is the saturated power of the fundamental wave.
According to equation (1), the ever decreasing undulator period, while satisfying the same coupling factor and K value required for harmonic generation, may result in a shorter wavelength λs of the undulator output radiation and correspondingly less electron beam energy required. To further reduce the required electron beam energy, embodiments of the present invention employ 3 rd harmonic radiation of the undulator to generate high average power EUV light while suppressing the fundamental radiation of the undulator.
In one exemplary embodiment, according to equation (1), when the K value is 1.43, the undulator period is selected to be 12mm, the electron beam energy corresponding to the output radiation wavelength of 13.5nm is 485MeV, and the saturated output peak power is 317MW when the resonance is at the fundamental wave; in contrast, when the radiation segment 70 selects the 3 rd harmonic radiation output (n=3), the undulator resonates at 40.5nm (13.5 nm×3) at the fundamental wave, the electron beam energy correspondingly drops to 280MeV, the fundamental wave output power can reach 264mw, the 3 rd harmonic FEL parameter is 0.0006, and the fundamental FEL parameter is 0.0023. According to the formula (2), the saturated output power of the linear 3 rd harmonic is about 22.8MW, the saturated output power is improved by 3 to 5 times through an undulator gradual change technology, the saturated output power is close to 100MW, and finally EUV light pulses with the magnitude of kW of average power can be generated. Therefore, when the fundamental wave is suppressed, the undulator 3 rd harmonic radiation output high average power EUV light is equally viable, and the electron beam energy requirement is reduced by a factor of approximately 1.7.
In some embodiments, the magnitude of the higher harmonic signal can be controlled by optimizing the operating points such as the energy modulation and density modulation intensity required by the seed free electron laser, and the radiation segment 70 generates radiation of a specific wavelength. As previously described, the undulator resonance corresponds to the 6 th harmonic of the seed laser at 40.5nm of the fundamental wave and the 13.5nm radiation of the 3 rd harmonic of the undulator corresponds to the 18 th harmonic of the seed laser. By optimizing the operating point so that the 6 th harmonic signal approaches the noise level, and the 18 th harmonic corresponding to the target 13.5nm has a larger harmonic component, the increase of fundamental wave radiation can be further suppressed while the harmonic is rapidly increased, and the power of the output EUV light 200 can be improved.
In some embodiments, the first energy modulation amplitude of the second electron beam formed through the first modulation segment 30 is 1 times the initial energy dispersion of the first electron beam; the second energy modulation amplitude of the fourth electron beam formed after passing through the second modulation section 50 is 1 time of the initial energy dispersion of the first electron beam. The undulator parameters of the first modulation segment 30 and the second modulation segment 50 are identical, each resonating at 40.5nm of the fundamental wave of the seed laser, having a wavelength of 243nm, a K value of 3.04, a period length of 26mm, a period number of 10, and a length of 0.26m.
As shown in fig. 4, in some embodiments, the first dispersion section 40 is a magnetic compressor (chicane), which may include a first diode 41, a second diode 42, a third diode 43, and a fourth diode 44 sequentially arranged along the electron beam transmission direction, where the first diode 41, the second diode 42, the third diode 43, and the fourth diode 44 have the same length, and the first diode 41, the second diode 42, and the third diode 43, and the fourth diode 54 are symmetrically distributed (symmetrical with respect to the dashed line).
The dispersion intensity of the dispersion section can be described by a dispersion parameter R 56, which is mainly perceived by the layout and intensity of the diode in the dispersion section. In some embodiments, the R 56 expression for the first dispersion section 40 is:
Wherein L1 is the length of the first diode iron 41, L21 is the distance between the first diode iron 41 and the second diode iron 42, θ represents the deflection angle of the electron beam passing through the diode iron, the magnitude of which is related to the intensity of the diode ferromagnetic field, and the deflection angle of the electron beam can be adjusted by adjusting the magnitude of the diode iron coil current. When θ is small, the L21 and L2 pitches are approximately equal.
In some embodiments, the lengths of the first, second, third and fourth diode irons 41, 42, 43 and 44 are all 0.15m, the distance L21 of the first and second diode irons 41 and 42 in the horizontal direction is 0.4m, and the distance L3 of the second and third diode irons in the horizontal direction is 0.1m. According to formula (3), when θ is 0 to 7.2 degrees, the corresponding R 56 ranges from 0 to 15.8mm, and the total length of the first dispersion section 40 is 1.5m.
As shown in fig. 5, in some embodiments, the second dispersion section 60 may have the same structure as the first dispersion section 40, and is also a magnetic compressor, and includes a fifth diode iron 61, a sixth diode iron 62, a seventh diode iron 63, and an eighth diode iron 64 that are sequentially arranged along the electron beam transmission direction and have the same length, where the fifth diode iron 61, the sixth diode iron 62, and the seventh diode iron 63, and the eighth diode iron 64 are symmetrically distributed (symmetrical with respect to the dotted line).
In some embodiments, the lengths of the fifth, sixth, seventh and eighth dipoles 61, 62, 63 and 64 are all 0.15m, the distances L21 'of the fifth and sixth dipoles 61 and 62 in the horizontal direction are 0.2m, and the distances L3' of the sixth and seventh dipoles in the horizontal direction are 0.1m. According to formula (3), when θ is 0 to 3.2 degrees, the corresponding R 56 ranges from 0 to 1.9mm, and the total length of the second dispersion section 60 is 1.1m.
In some embodiments, the first dispersion section 40 converts the first energy modulation amplitude of 1 times the second electron beam to a first intensity modulation, forming a third electron beam as shown in fig. 2C; the first dispersion section 40 has a larger dispersion intensity than the second dispersion section 60, and can erase the harmonic group signal of the electron beam, for example, the dispersion intensity R 56 of the first dispersion section 40 is 10.9mm.
In some embodiments, when the radiation segment 70 employs the undulator 3 rd harmonic radiation light as the euv light source output, the fine structure of the fifth electron beam at the entrance of the radiation segment 70 needs to be precisely optimized. As shown in fig. 2E, the second dispersion section 60 converts the second energy modulation of 1 times that of the fourth electron beam into the second density modulation, forms a fifth electron beam having a fine structure, and generates micro-clusters on 18 th harmonic of the seed laser; meanwhile, the dispersion intensity of the second dispersion section 60 is optimized to ensure that the harmonic signal corresponding to the fundamental wave of the undulator (i.e. the 6 th harmonic of the seed laser) approaches the noise level, for example, the dispersion intensity R 56 of the second dispersion section 60 is 0.63mm.
As shown in fig. 6, in some embodiments, the radiation section 70 may include a plurality of undulators 71 sequentially arranged along the transmission direction of the electron beam, where a phase shifter 72 is disposed between any two undulators 71, and the undulators 71 are used to radiate the fifth electron beam, and the phase shifter 72 is used to adjust the phases of the fifth electron beam and the radiation light field, so that the fundamental radiation light field of the undulators 71 is significantly cancelled, and the 3 rd harmonic light field is not affected, so as to generate the high average power euv light.
In some embodiments, undulator 71 is a short cycle undulator, which may be a high temperature superconducting undulator, and of conventional high temperature superconductors, bi2212 wire and Bi2223 tape are commonly referred to as first generation high temperature superconductors, and REBCO coated conductor tape/block is referred to as second generation high temperature superconductors. Compared with a low-temperature superconductor, REBCO has higher critical characteristic, so that the high-temperature superconductor undulator has higher magnetic field intensity, the period of the undulator can be shortened, and the radiation wavelength range of the undulator can be widened. The high temperature superconductive undulator can adjust the magnetic field intensity by the current of the power supply.
In some embodiments, the phase shifter 72 may include four magnets of different poles that can produce a magnetic field of one cycle, and thus may be considered an ultra-short undulator. The basic principle of the phase shifter 72 is to delay the electron beam by adjusting the current intensity, and to adjust the phases of the electron beam and the radiation light, thereby realizing precise phase control within 0-2 pi. For example, the phase shifter 72 provides a 2 pi/3 phase shift that causes significant destructive interference of the fundamental field, while the 3 rd harmonic field is unaffected. The phase shifter 72 can therefore be used to further suppress the fundamental radiation of the undulator 71 so that the harmonic radiation grows rapidly.
In the radiation section 70, a high gain process of free electron laser occurs, generation of fundamental radiation is suppressed by the phase shifter 72, and a fifth electron beam having micro-bunching of extreme ultraviolet band outputs 3 rd harmonic radiation of the undulator 71 in the radiation section 70.
In some embodiments, the radiation segment 70 may employ a stepped undulator gradient technique, i.e. the magnetic field intensity of each segment undulator 71 may be sequentially reduced in steps along the beam transmission direction, and the output radiation power may be increased by a factor of 3 to 5.
In some embodiments, the radiating section 70 may be composed of 13-section undulators 71 and 12 phase shifters 72, each section undulator 71 having a period of 12mm, a length of 0.24m, and a spacing between any two sections of 0.12m; each phase shifter 72 has a period of 20mm and a length of 80mm; the total length of the radiating section 70 is 4.7m.
In one exemplary embodiment, the radiation segment 70 produces an extreme ultraviolet peak power of 90MW, a single pulse energy of 7.3 μJ, a full width at half maximum of 77fs, a spectral bandwidth of 0.04%, and a time-bandwidth product of 0.68, approaching the Fourier transform limit. When the average current intensity of the electron beam reaches 10mA, the average power of EUV light can reach 1kW by combining with an undulator gradual change technology. The temporal and frequency domain distributions of EUV light pulses are shown in fig. 7A and 7B, respectively.
In some embodiments, the first electron beam may also be injected directly into the radiant section 70, with the radiant section structure unchanged, operating in SASE-type FEL mode; the fundamental radiation is suppressed by the phase shifter 72 and the undulator harmonic radiation is output. The average power of EUV light can also be up to 1kW, without temporal coherence, in combination with the undulator gradient technique.
In some embodiments, the euv light source device may output full coherent light pulses of high average power beyond the euv, soft X-ray, etc. bands in addition to the euv band.
In the embodiment of the present invention, the first modulating section 30, the first dispersing section 40, the second modulating section 50, the second dispersing section 60 and the radiating section 70 are formed as EEHG type free electron lasers, so as to output light pulses in bands such as extreme ultraviolet, beyond extreme ultraviolet, soft X-rays and the like; it will be appreciated that other types of free electron lasers, such as HGHG type and PEHG type, may be used in addition to EEHG type.
The extreme ultraviolet light source device provided by the embodiment of the invention has the following beneficial effects:
1) The low-energy electron beam and the seed type free electron laser based on high average power generate full-coherence EUV light with average power of kW magnitude, and have low cost and compact structure.
2) Only an electron beam on the order of 280MeV is required, which can significantly reduce the construction cost and size of the accelerator 10 compared to the same type of device; the length of the radiating section 70 can be shortened using a short cycle oscillator; the overall device length may be within 35 m.
3) The peak power of the generated extreme ultraviolet light reaches 90MW, the single pulse energy reaches 7.3 mu J, the full width at half maximum of the pulse length is of the order of hundred femtoseconds, and the spectral bandwidth is 0.04%. When the average electron beam current intensity reaches 10mA, the average power of EUV radiation can reach 1kW through an undulator gradual change technology.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and various modifications can be made to the above-described embodiment of the present invention. All simple, equivalent changes and modifications made in accordance with the claims and the specification of this application fall within the scope of the patent claims. The present invention is not described in detail in the conventional art.
Claims (10)
1. The extreme ultraviolet light source device is characterized by comprising an accelerator, a first modulation section, a first dispersion section, a second modulation section, a second dispersion section and a radiation section which are sequentially arranged along the transmission direction of an electron beam, wherein seed lasers are arranged at the upstream of the first modulation section and the upstream of the second modulation section, the accelerator is used for generating a first electron beam meeting preset requirements, the seed lasers are used for generating a first seed laser and a second seed laser which are longitudinally synchronous, and the first electron beam and the first seed laser are injected into the first modulation section together so that the first electron beam generates first energy modulation under the action of the first seed laser to obtain a second electron beam; the first dispersion section is used for compressing the second electron beam to form a third electron beam; the third electron beam and the second seed laser are both injected into the second modulation section, so that the third electron beam generates second energy modulation under the action of the second seed laser and forms a fourth electron beam; the second dispersion section is used for compressing the fourth electron beam to form a fifth electron beam; the radiation section is used for enabling the fifth electron beam to generate harmonic radiation so as to emit full-coherence extreme ultraviolet light with the kilowatt magnitude.
2. The euv light source device according to claim 1, wherein said first modulation section and said second modulation section are both resonating at a fundamental wave, and said radiation section outputs third harmonic radiation light as an euv light.
3. The euv light source device of claim 1, wherein the accelerator comprises an electron source for generating an initial electron beam and an injector for accelerating the initial electron beam to a preset energy to obtain a first electron beam, the preset energy being 280MeV.
4. The euv light source device of claim 1, wherein the repetition frequencies of said first seed laser, said second seed laser and said first electron beam are the same.
5. The euv light source device of claim 1, wherein said first modulation segment and said second modulation segment are undulators comprised of periodically arranged magnetic arrays.
6. The euv light source device according to claim 1, wherein the first dispersion section comprises a first diode iron, a second diode iron, a third diode iron and a fourth diode iron which are sequentially arranged along the electron beam transmission direction, wherein the lengths of the first diode iron, the second diode iron, the third diode iron and the fourth diode iron are the same, and the first diode iron, the second diode iron, the third diode iron and the fourth diode iron are symmetrically distributed; the second dispersion section comprises a fifth diode iron, a sixth diode iron, a seventh diode iron and an eighth diode iron which are sequentially distributed along the transmission direction of the electron beam, the lengths of the fifth diode iron, the sixth diode iron, the seventh diode iron and the eighth diode iron are the same, and the fifth diode iron, the sixth diode iron, the seventh diode iron and the eighth diode iron are symmetrically distributed.
7. The euv light source device according to claim 1, wherein the radiation section comprises a plurality of undulators arranged in order along a transmission direction of the electron beam, a phase shifter being provided between any two of the undulators, the undulators being configured to cause the fifth electron beam to generate radiation, and the phase shifter being configured to adjust phases of the fifth electron beam and the radiation light such that fundamental radiation light of the undulators is substantially canceled, so that the radiation section outputs third harmonic radiation light of the undulators as the euv light.
8. The euv light source device of claim 7, wherein the magnetic field strength of the multistage undulator decreases in a stepwise sequence along the electron beam transport direction.
9. The euv light source device of claim 7, wherein said phase shifter comprises four magnets of different poles to generate a periodic magnetic field.
10. The euv light source device of claim 7, wherein said radiation segment comprises 13 segment undulators and 12 phase shifters, each segment undulator having a period of 12mm, a length of 0.24m, and a spacing between any two segments undulators of 0.12m; each phase shifter had a period of 20mm and a length of 80mm.
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