CN114624959A - A kind of high-efficiency extreme ultraviolet radiation generation method and system - Google Patents

Abstract

The invention discloses a high-efficiency extreme ultraviolet radiation generation method, which comprises the steps of generating extreme ultraviolet radiation by laser hitting a solid target, focusing laser, enabling the focused laser to act on the target, and enabling a laser source before focusing to be a femtosecond laser source; the invention also discloses a high-efficiency extreme ultraviolet radiation generating system, which comprises a laser source (1) and a target (2), wherein an off-axis parabolic mirror focusing device (4) is arranged between the laser source (1) and the target (2), and a plasma mirror device (5) is arranged between the laser source (1) and the off-axis parabolic mirror focusing device (4). The high-efficiency extreme ultraviolet radiation generation method and device have the advantages of high extreme ultraviolet radiation generation efficiency, adjustable spectrum bandwidth and spectrum and the like.

Description

A kind of high-efficiency extreme ultraviolet radiation generation method and system

technical field

The invention relates to a method and system for generating extreme ultraviolet radiation, in particular to a method and system for generating extreme ultraviolet radiation with high efficiency, and belongs to the technical field of extreme ultraviolet (EUV).

Background technique

The energy of EUV radiation is moderate, and the corresponding photon energy is about tens of eV, which just corresponds to the transition energy level of the outer or middle electrons of atoms. Therefore, the coupling effect of EUV radiation and outer or middle electrons can be used to detect electrons at the atomic level. Energy level structure and chemical bond composition, thus providing a brand-new research method of microscopic matter and helping to understand the physical reasons behind the properties of macroscopic matter. Due to the short wavelength of extreme ultraviolet radiation and the relatively small diffraction limit, if it is used for microscopic imaging, a resolution of tens of nanometers can be achieved, and the material structure can be better analyzed. For the same reason, EUV radiation is suitable for nanofabrication and high-precision lithography.

At present, there are electron synchrotron radiation sources (ECR), laser plasma sources (LPP) and discharge plasma sources (DPP) for generating EUV light sources. DPP earlier used high-temperature and high-density xenon (Xe) gas discharge. Method, later studies found that the EUV conversion efficiency of tin (Sn) is higher than that of Xe, but tin is solid at room temperature, so the surface of the solid Sn target is bombarded with a laser to generate Sn vapor and then discharged, that is, the laser-induced tin target discharge plasma ( LDP).

Electron synchrotron radiation sources (ECR) are bulky and expensive, making them difficult to apply in manufacturing.

Laser plasma technology (LPP) is to spray tin droplets through a nozzle, focus a high-energy laser on the tin droplets to vaporize and ionize them to generate plasma, and radiate 13.5nm extreme ultraviolet light. Because the tin droplets sprayed by the nozzle are unstable, There are disadvantages such as difficulty in positioning the tin droplet swinging in the air, difficulty in synchronizing the laser and the tin droplet, and inefficiency caused by the conversion of electrical energy into laser light first and then into extreme ultraviolet light.

Laser-induced discharge plasma technology (LDP) uses two discs partially immersed in liquid tin. When the disc rotates, surface tension and friction are used to adsorb a layer of tin film on its surface, and laser radiation generates pre-plasma on the tin film. There is a high voltage between the two discs, and the high voltage breaks down the pre-plasma to generate electricity. The main plasma generated by the power generation radiates 13.5nm extreme ultraviolet light. Although it can directly convert electrical energy into extreme ultraviolet light, the efficiency is higher, but When the disc is running at high speed, the tin droplets may separate from its surface and cause pollution, and there is also centrifugal force generated by high-speed rotation, which leads to uneven thickness of the tin film. To prevent the tin film from solidifying, the disc needs to be heated, and the laser acts on the disc to cause damage and changes. Its surface characteristics, complex mechanical structure and other disadvantages.

Therefore, it is necessary to study a new method and system for generating extreme ultraviolet radiation to solve the above problems.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned problems, the inventors of the present invention have carried out keen research, and on the one hand, provide a high-efficiency method for generating extreme ultraviolet radiation, which generates extreme ultraviolet radiation by hitting a solid target with a laser.

The extreme ultraviolet radiation is broad-spectrum extreme ultraviolet radiation, the wavelength range of which is 3-50 nm, and the spectral peak of the extreme ultraviolet radiation in the wavelength range is adjustable.

Specifically, the laser is focused, and the focused laser acts on the target. Preferably, the focused laser peak power is not lower than 10 ¹⁵ W/cm ² .

Further, the laser source before focusing is a femtosecond laser source, preferably a laser source with a single-shot laser energy of 0.001-100 joules and a pulse width of 1-100 femtoseconds;

The diameter of the laser focal spot after focusing is not more than 10 microns, and the energy concentration within 10 microns after focusing is not less than 50%.

According to the present invention, the target material of the target is a material that satisfies the characteristics of an average density between conventional solids and conventional gases, uniform distribution under micron size, and steep boundary. Preferably, the average density of the target material is 1-100 mg /cm ³ .

In a preferred embodiment, the target material of the target is a nanotube foam material, and the nanotube foam material refers to a material in which atoms are randomly arranged in space to form a nanoscale framework structure, which has a large number of nanometers. grade pore structure.

More preferably, the target material of the target is carbon nanotube foam material.

According to the present invention, metal atoms are loaded on the frame structure formed by the nanotubes.

In a preferred embodiment, before the laser is focused, the laser contrast is not less than 10 ¹⁰ before the main pulse 30 picoseconds.

On the other hand, the present invention also provides a high-efficiency extreme ultraviolet radiation generating system, comprising a laser source 1 and a solid target 2,

The laser source 1 is a femtosecond laser source;

The target material is a material whose average density is between solid and gas, uniform distribution in micron size, and steep boundary.

Further, an off-axis parabolic mirror focusing device 4 is also arranged between the laser source 1 and the solid target 2,

Preferably, a plasma mirror device 5 is provided between the laser source 1 and the off-axis parabolic mirror focusing device 4;

Preferably, the system further comprises a beam target coupling device 6 and an EUV radiation monitoring device 7 .

The beneficial effects of the present invention include:

(1) According to the high-efficiency extreme ultraviolet radiation generating method and device of the present invention, extreme ultraviolet radiation can be generated by means of laser targeting;

(2) According to the high-efficiency EUV radiation generating method and device according to the present invention, compared with the laser plasma light source (LPP) and the discharge plasma light source (DPP), the obtained EUV spectral band is wider;

(3) According to the high-efficiency EUV radiation generating method and device of the present invention, the obtained EUV radiation efficiency is higher;

(4) According to the high-efficiency extreme ultraviolet radiation generating method and device of the present invention, the spectrum of the generated extreme ultraviolet radiation can be adjusted.

Description of drawings

Fig. 1 shows the electron microscope photograph of the carbon nanotube foam target material according to a preferred embodiment of the present invention;

2 shows a schematic structural diagram of a high-efficiency EUV radiation generation system according to a preferred embodiment of the present invention;

3 shows a schematic structural diagram of a beam-target coupling device of a high-efficiency EUV radiation generation system according to a preferred embodiment of the present invention;

Fig. 4 shows the extreme ultraviolet radiation spectrum produced by different targets in Experimental Example 1;

Fig. 5 shows the extreme ultraviolet radiation spectrogram detected in Experimental Example 2;

FIG. 6 shows the energy angular distribution of EUV radiation generated by different targets in Experimental Example 3. FIG.

Description of reference numbers:

1- laser source;

2-target;

3-vacuum chamber;

31 - vacuum pump;

4- off-axis parabolic mirror focusing device;

5- plasma mirror device;

6-beam target coupling device;

61-long working distance microscope objective lens;

62-beam splitter;

63-imaging lens;

64-CCD;

65-LED light source;

7- Extreme ultraviolet radiation monitoring device.

Detailed ways

The present invention will be further described in detail below through the accompanying drawings and embodiments. The features and advantages of the present invention will become more apparent from these descriptions.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

On the one hand, the present invention provides a high-efficiency method for generating extreme ultraviolet radiation, which generates extreme ultraviolet radiation through a solid laser target. In the present invention, the laser targeting refers to bombarding the target with a laser, and generating extreme ultraviolet radiation Refers to the generation of radiation between soft X-rays and deep ultraviolet radiation, and the radiation wavelength range is 3-50nm.

Preferably, in the process of laser hitting a solid target, the laser is first focused, and the focused laser acts on the target.

More preferably, by moving the target or the laser so that the focal point of the laser acts on different positions of the target or different targets, continuous target shooting is achieved.

Further, since the air will affect the focusing and targeting effects of the laser, and extreme ultraviolet radiation (EUV) is easily absorbed in the air, the light source targeting is performed in a vacuum. In the present invention, the laser targeting is performed in a vacuum environment, preferably, the degree of vacuum is less than 10 ^-3 Pa.

The interaction between the femtosecond laser and the target has great advantages in the generation of extreme ultraviolet light. In this case, photoionization dominates, which can directly ionize atoms in the target, effectively increasing the power of EUV radiation.

In the present invention, the laser peak power after focusing is not lower than 10 ¹⁵ W/cm ² , more preferably, the laser peak power after focusing is not lower than 10 ¹⁸ W/cm ² , which satisfies the field of carbon in carbon nanotubes The ionization threshold can improve the conversion efficiency.

Preferably, the diameter of the focal spot after focusing is not greater than 10 microns, and the energy concentration within 10 microns after focusing is not less than 50%.

Preferably, the laser source before focusing is a femtosecond laser source, preferably a laser source with a single-shot laser energy of 0.001-100 joules and a pulse width of 1-100 femtoseconds is focused and then bombards the target.

The parameters of the laser source and the focal spot after focusing ensure that the light intensity after focusing is greater than 10 ¹⁸ W/cm ² , so that carbon atoms can be directly and rapidly ionized to pentavalent and hexavalent by the optical field, and the field ionization mechanism is dominant, which can quickly The target is ionized to produce EUV radiation with high intensity and short pulse width; if the parameters of the focal spot and light intensity are low, the collision ionization mechanism is dominant, and the resulting EUV radiation intensity will be weak.

Since the femtosecond laser has a pre-pulse, the pre-pulse will damage the target. In a preferred embodiment, before the laser is focused, the contrast of the laser is improved to protect the target.

The contrast refers to the ratio of the light intensity of the main laser pulse and the laser pre-pulse. Further, before the laser is focused, the laser contrast is not less than 10 ¹⁰ 30 picoseconds before the main pulse. In the present invention, the laser can be realized by a plasma mirror system. Contrast improvement.

The target material of the conventional target will mainly achieve particle acceleration and generate X-ray radiation under laser conditions, and what kind of target material can realize the excitation of extreme ultraviolet radiation is the key of the present invention.

According to the present invention, the solid target material is a material that satisfies the characteristics of low average density, uniform distribution in micron size, and steep boundary.

Further, the low average density means that the average density of the solid target material is between conventional solids and conventional gases, preferably 1-100 mg/cm ³ ;

The interaction of the femtosecond laser with this low-density target can obtain a critical density plasma, and the strong coupling of the laser to the plasma in the critical density plasma can significantly increase the laser absorption rate, thereby improving the generation efficiency of the final EUV radiation .

The high steepness of the boundary means that when the material forms a plasma state and interacts with the laser, the density gradient of the plasma is very large, and there is a sharp boundary, thereby inhibiting the propagation of the laser in the plasma whose density changes slowly. Instability such as filament formation.

In a preferred embodiment, the target material is a nanotube foam material, which is formed by the disordered arrangement of atoms in space to form a nanoscale frame structure, and has a large number of nanoscale pore structures, so it is called a foam material .

The foam-shaped material greatly improves the laser absorption efficiency of the target material, and its absorption efficiency to the laser light is much higher than that of the target material of ordinary structure.

More preferably, the target material is a carbon nanotube foam material. As shown in FIG. 1 , compared with other critical density targets, the carbon nanotube foam has a relatively steep boundary, and the diameter of the carbon nanotube filaments is in the tens of tens. Therefore, it is relatively uniform on the micrometer scale corresponding to the focal spot, and has many advantages such as easy formation of a tubular structure, low manufacturing difficulty, and low cost, and is especially suitable as a target for generating extreme ultraviolet radiation.

The carbon nanotube foam material can be single-walled or multi-walled carbon nanotubes, preferably a single-walled carbon nanotube material.

A typical example of a carbon nanotube foam target is a self-supporting carbon nanotube thin film target obtained through Chinese Patent Application No. 2020107630093.

In a preferred embodiment, the thickness of the target material is 5-200 microns, more preferably 10-100 microns. The inventor found that the target material with this thickness can support the mechanical strength of the millimeter-diameter hole. It is self-supporting, and after laser ionization, a plasma is formed, and the electron density is in the order of 10 ²¹ /cm ³ .

In a more preferred embodiment, the frame structure formed by the nanotubes can be loaded with different metal atoms, so that the extreme ultraviolet radiation formed after laser targeting has an adjustable spectral peak in the wavelength range. For example, when photolithography requires To generate extreme ultraviolet radiation with an energy peak of 13.5nm, metal tin can be used to modify carbon nanotubes to form tin-loaded carbon nanotube foam materials; for example, gold (Au) can be used to modify carbon nanotubes, and the obtained extreme ultraviolet radiation The peak is at 4-5 nm.

Preferably, the metal atoms are supported on the frame formed by carbon nanotubes by vapor deposition method, which can be realized by floating catalysis method or modification of carbon nanotubes, which will not be repeated in the present invention.

In a preferred embodiment, before the laser hits the target, the focus of the laser and the position of the target are monitored to ensure that the focus of the laser is on the target.

In a preferred embodiment, after laser targeting, the spectrum and energy of the generated EUV radiation are detected to monitor the laser targeting process.

On the other hand, the present invention also provides a high-efficiency extreme ultraviolet radiation generating system, comprising a laser source 1 and a solid target 2 .

The laser source 1 is a device capable of providing laser light, and the laser light generated by the laser source acts on the target, thereby generating extreme ultraviolet radiation.

Further, the laser source 1 is a femtosecond laser source, preferably, a device capable of providing a single-shot energy of 0.001-100 joules and a pulse width of 1-100 femtosecond laser beams.

The solid target 2 has a target material, and the target material of the solid target is a material that satisfies the average density between conventional solids and conventional gases, uniform distribution in micron size, and steep boundaries.

Preferably, the average density of the target material is 1-100 mg/cm ³ .

In a preferred embodiment, the target material is a nanotube foam material.

More preferably, the target material is a carbon nanotube foam material, and the carbon nanotube foam material can be a single-walled or multi-walled carbon nanotube, preferably a single-walled carbon nanotube material.

Due to the self-supporting characteristics of the carbon nanotube foam material, when it is used as a target material, there is no need to provide other support structures for the target material, which not only simplifies the structural complexity of the target 2, but also reduces the impact of the target material support structure on the target. Improved system stability.

In a preferred embodiment, the nanotube foam material is loaded with different metal atoms, so that the spectrum of the extreme ultraviolet radiation formed after laser targeting is adjustable.

Preferably, the target 2 further comprises a target body moving device, the target body moving device has a translation stage, the translation stage is connected with a motor, a plurality of target materials are installed on the translation stage, and the movement of the translation stage is driven by the motor to realize The movement of the target by the target moving device enables the laser to act on different targets, thereby continuously generating extreme ultraviolet radiation.

In a more preferred embodiment, the translation stage of the target moving device is a six-dimensional translation stage, which can be moved and rotated up and down, left and right, and front and rear respectively, so that the position of the target can be precisely adjusted, thereby realizing the different The position of the target material is precisely moved to the laser target position.

In the present invention, the specific structure of the translation stage is not particularly limited, as long as it can meet the above functions, such as the six-dimensional translation stage produced by Wuhan Hongxingyang Technology Co., Ltd., Beijing Zhuoli Hanguang Instrument Co., Ltd., etc.

According to the present invention, the target 2 is installed in the vacuum chamber 3 , and the vacuum chamber 3 is provided with a vacuum pump 31 .

In a preferred embodiment, an off-axis parabolic mirror focusing device 4 is further arranged between the laser source 1 and the target 2 to focus the laser beam provided by the laser source 1. Further, the off-axis parabolic mirror focusing device 4 is also provided in the vacuum chamber 3 .

Further, the diameter of the laser spot after being focused by the off-axis parabolic mirror focusing device 4 is not greater than 10 microns, and the energy concentration within 10 microns is not less than 50%.

Further, the laser peak power after focusing by the off-axis parabolic mirror focusing device 4 is not lower than 10 ¹⁵ W/cm ² , preferably, the laser peak power after focusing is not lower than 10 ¹⁸ W/cm ² , which satisfies The field ionization threshold of carbon in carbon nanotubes can improve the conversion efficiency.

In the present invention, the specific structure of the off-axis parabolic mirror focusing device 4 is not particularly limited, as long as the above requirements can be met, such as an off-axis parabolic mirror from Thorlabs in the United States.

In a preferred embodiment, a plasma mirror device 5 is further arranged between the laser source 1 and the off-axis parabolic mirror focusing device 4 to remove the pre-pulse in the femtosecond laser and improve the laser contrast. The plasma mirror device 5 is arranged in the vacuum chamber 3 .

In the present invention, the specific manufacturer and model of the plasma mirror device 5 are not particularly limited, as long as the laser source 1 can be processed to obtain a laser contrast of not less than 10 ¹⁰ before the main laser pulse of 30 ps.

In a preferred embodiment, the plasma mirror device includes a plasma mirror, and the plasma mirror (PM) is a transparent material coated with an antireflection coating. When the pre-pulse of the main laser reaches the surface of the plasma mirror, the high The transmittance film material will make only one thousandth of the pre-pulse reflected, and most of the pre-pulse will be transmitted; and when the main pulse is about to arrive, the laser intensity increases with time, and the pulse front will continuously generate plasma on the surface of the plasma mirror , when the density of these plasmas exceeds the critical density, the plasma mirror will no longer be transparent and the main laser light will be mostly reflected. The final result in the time domain is that the pre-pulse intensity of the laser decreases by three orders of magnitude, while the main pulse intensity does not change much, so the contrast of the laser is improved by more than two orders of magnitude.

The use of the plasma mirror system will lose part of the laser energy, and its reflectivity is related to the energy of the incident laser. The inventors found that the absorption of the s-polarized laser on the plasma surface is weak, and the reflectivity is generally higher.

In a more preferred embodiment, a half-wave plate is further arranged in front of the plasmonic mirror to change the polarization of the main laser to realize the s-polarized incidence of the plasmonic mirror.

In a preferred embodiment, the system further includes a beam-target coupling device 6, which is a microscopic imaging system that can be used to observe the laser and the target.

Further, the depth of field of the beam-target coupling device 6 is not greater than 10 microns, so that the laser and the target can be observed clearly.

In the present invention, any existing beam-target coupling device can be used, preferably, the beam-target coupling device includes a long working distance microscope objective lens 61, a beam splitter 62, an imaging lens 63, two CCDs 64 and The LED light source 65, as shown in FIG. 3, the LED light source 65 is arranged in front of the target 2, and the light emitted by the LED light source 65 provides the illumination of the target body transmission imaging, and the long working distance microscope objective lens 65 and the beam splitter 62 are sequentially arranged on After the target 2, two CCDs 64 are respectively arranged on the reflected light path and the transmitted light path of the beam splitter 62 to provide images of the target spots with different magnification speeds. The imaging lens 63 is arranged on the transmitted light path of the beam splitter 62, located in the between the film 62 and the CCD 64.

Through the above settings, the two CCDs can achieve 50x and 10x magnification imaging at the same time. Among them, the 50x magnification imaging is used for the precise positioning of the laser spot and the target, and the 10x magnification imaging is used for the adjustment and centering of the target angle. point OK.

Further, the long working distance microscope objective lens 61 , beam splitter 62 , imaging lens 63 and CCD 64 are installed on the three-dimensional motorized translation stage, through which the target 2 can be adjusted, and the repeated positioning accuracy of the target material of 0.5 μm can be achieved.

In a preferred embodiment, the system also has an EUV radiation monitoring device 7, which includes a flat-field grating spectrometer and an AXUV diode, the flat-field grating spectrometer is used to measure the EUV radiation spectrum, and the AXUV diode is matched with a specific polar The ultraviolet filter is used to measure the absolute energy of extreme ultraviolet radiation, and the feedback signal obtained by the measurement is transmitted to the target moving device to adjust the position of the target.

The flat-field grating may have multiple pieces to measure EUV radiation in different wavelength bands respectively, and preferably has two pieces, whose line pairs are 1200 and 300 respectively, and the corresponding measurement spectral ranges are 3.3-30nm and 20-80nm.

The AXUV diode is a photodiode developed by IRD for the extreme ultraviolet radiation band, and is also one of the standard measurement components recommended by NIST, and is widely used in laser plasma light sources and synchrotron radiation devices.

Example

Example 1

Experiments were conducted using a laser source to target the target to generate extreme ultraviolet radiation.

During the experiment, the position of the target is adjusted by the beam-target coupling device, so that the laser generated by the laser source passes through the plasma mirror and the off-axis parabolic mirror focusing device in turn and hits the target, and the extreme ultraviolet radiation monitoring device is used to monitor the generated extreme ultraviolet radiation. For detection, the plasma mirror, the off-axis parabolic mirror focusing device, the target and the beam-target coupling device are all set in a vacuum chamber, and the vacuum environment of the vacuum chamber is lower than 10 ^-3 Pa.

Among them, the laser source is a 200TW commercial laser produced by French company THALES, which can generate a 30 femtosecond pulse laser, and the output energy is 5 joules per shot. The energy concentration of /e ² is 60%, the estimated power density of the available laser is 6.6×10 ¹⁹ W/cm ² , and the corresponding normalized light intensity is a ₀ =5.5;

The target material is carbon nanotube foam, prepared by chemical vapor deposition (CVD) method, its thickness is 40 microns, and the density is 4 mg/cm ³ , and its electron microscope photo is shown in Figure 1;

The target moving device is a device with a six-dimensional translation stage, and its repeated positioning accuracy is not less than 10 microns, and the target moving platform is adjusted so that the angle of the laser incident on the target is within 1°;

The EUV radiation monitoring device includes two flat-field grating spectrometers and AXUV diodes. The line logarithms of the two flat-field grating spectrometers are 1200 and 300 respectively. The AXUV diode model is AXUV100AL.

Example 2

The same experiment as in Example 1 was carried out, except that the thickness of the target was 60 microns.

Example 3

The same experiment as in Example 1 was carried out, except that the thickness of the target was 80 microns.

Comparative Example 1

The same experiment as in Example 1 was carried out, except that the target material was a plastic target with a thickness of 120 microns.

Experimental example 1

Detecting the extreme ultraviolet radiation spectrum produced by Comparative Example 1 and Examples 1 and 2, as shown in Figure 4, it can be clearly seen that no extreme ultraviolet radiation is observed when the laser interacts with the plastic target, as shown in a) in the figure;

During the interaction between the laser and the carbon nanotube foam target, a broad spectrum of EUV radiation can be generated. The EUV radiation in b) and c) in the figure appears as many discrete line radiations and a quasi-continuous background radiation. It is worth noting However, due to the different diffraction efficiencies and spectral resolutions of the 1200-line and 300-line gratings, there will be a discontinuity at 25 nm of the stitched spectrum.

Experimental example 2

The spectrum is reversely solved from the data collected by the flat-field grating spectrometer in Example 2, and the result is shown in Figure 5, where the insert in the upper left corner is the radiation energy signal measured by the AXUV diode in the 15-degree direction in the experiment .

From the solved spectrum, it can be seen that in the radiation section with wavelength less than 10nm, the characteristics of line radiation are obvious, while in the radiation section with wavelength greater than 10nm, relatively flat quasi-continuous radiation is dominant.

Experimental example 3

Observe the energy angular distribution of the extreme ultraviolet radiation measured by the AXUV diode in Examples 1 to 3. The results are shown in Figure 6, where the point with * represents the actual measured value of the AXUV diode, and the radiation energy of other angles is obtained by linear interpolation and symmetry. The radial value represents the radiation yield in mJ/Sr.

It can be seen that the interaction of the lasers in Examples 1 to 3 with the carbon nanotube foam target can generate extreme ultraviolet radiation, and the generated extreme ultraviolet radiation has a certain forward direction. After considering the radiation distribution, the total solid angle of radiation is estimated to be 3π, the corresponding total EUV radiation yield is 240 mJ, and the corresponding conversion efficiency is 22%.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front", "rear", etc. is based on the working state of the present invention The orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention . Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection, Or an integral connection is common; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

The present invention has been described above with reference to the preferred embodiments, but these embodiments are merely exemplary and serve only for illustrative purposes. On this basis, various substitutions and improvements can be made to the present invention, which all fall within the protection scope of the present invention.

Claims (10)

1. A high-efficiency method for generating extreme ultraviolet radiation, wherein extreme ultraviolet radiation is generated by hitting a solid target with a laser. 2. high-efficiency extreme ultraviolet radiation generation method according to claim 1, is characterized in that, The EUV radiation is broad-spectrum EUV radiation with a wavelength range of 3-50 nm. 3. high-efficiency extreme ultraviolet radiation generation method according to claim 1, is characterized in that, The extreme ultraviolet radiation has tunable spectral peaks in the wavelength range. 4. high-efficiency extreme ultraviolet radiation generation method according to claim 1, is characterized in that, The target material of the solid target is a material that satisfies the characteristics of an average density between conventional solids and conventional gases, uniform distribution under the micron size, and steep boundaries. Preferably, the average density of the target material is 1-100 mg/cm ³ . 5. high-efficiency extreme ultraviolet radiation generation method according to claim 1, is characterized in that, The target material of the target is a nanotube foam material, and the nanotube foam material refers to a material in which atoms are randomly arranged in space to form a nanoscale frame structure, which has a large number of nanoscale pore structures; Preferably, the frame structure formed by the nanotubes is loaded with metal atoms. 6. The method for generating high-efficiency extreme ultraviolet radiation according to one of claims 1 to 5, characterized in that, Before laser focusing, the laser contrast is not less than 10 ¹⁰ 30 picoseconds before the main pulse. 7. The method for generating high-efficiency extreme ultraviolet radiation according to one of claims 1 to 5, characterized in that, The laser is focused, and the focused laser acts on the target. Preferably, the peak power of the focused laser is not lower than 10 ¹⁵ W/cm ² . 8. The method for generating high-efficiency extreme ultraviolet radiation according to claim 7, characterized in that, The laser source before focusing is a femtosecond laser source, preferably a laser source with a single-shot laser energy of 0.001-100 joules and a pulse width of 1-100 femtoseconds; The diameter of the laser focal spot after focusing is not more than 10 microns, and the energy concentration within 10 microns after focusing is not less than 50%. 9. A high-efficiency extreme ultraviolet radiation generating system, comprising a laser source (1) and a solid target (2), The laser source (1) is a femtosecond laser source; The target material of the solid target is a material with an average density between conventional solids and conventional gases, uniform distribution in micron size, and steep boundaries. 10. The high-efficiency EUV radiation generating system according to claim 1, wherein, An off-axis parabolic mirror focusing device (4) is also arranged between the laser source (1) and the target (2), Preferably, a plasma mirror device (5) is provided between the laser source (1) and the off-axis parabolic mirror focusing device (4); Preferably, the system further comprises beam target coupling means (6).

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