A laser plasma type extreme ultraviolet lithography light source system

Abstract

The present disclosure provides a laser plasma type extreme ultraviolet (LPP-EUV) lithography machine light source system, including: a main pump laser, which adopts a high repetition rate TEA CO2 laser system for generating a main pulse laser; a pre-pumped picosecond laser for generating a picosecond laser; a beam combining device for combining the main pulse laser and the picosecond laser to obtain a combined laser beam; a target material tin liquid particle generator for generating a tin liquid particle string, which forms a mist ball under the bombardment of the picosecond laser, and the mist ball forms a high-temperature plasma under the bombardment of the main pulse laser and then emits 13.5nm extreme ultraviolet light; an extreme ultraviolet light collecting mirror for collecting and converging extreme ultraviolet light. The present disclosure provides a laser plasma type extreme ultraviolet lithography machine light source system, which is relatively miniaturized, making the EUV lithography machine compact and small, suitable for mass production and supply to the market, and further using a gadolinium target material generator or other target materials can generate EUV light with a wavelength of 6.7nm or shorter.

Description

Technical Field

[0001] The present invention relates to the technical field of laser plasma extreme ultraviolet (LPP-EUV) lithography machine light source system, and in particular to an LPP-EUV lithography machine light source system using a high repetition rate TEA CO2 laser system as a main pump laser. Background Art

[0002] EUV (Extreme Ultraviolet) lithography machines are mainly composed of three parts: EUV light source system, EUV reflector optical system and precision machinery and control system (including workpiece stage, mask stage, silicon wafer transmission system, etc.), among which EUV light source system is the core part of the lithography machine. The wavelength of the light source of the lithography machine has developed from 436nm (Hg-g), 365nm (Hg-i) to 248nm (KrF), 193nm (ArF) and 157nm (F2), and is developing towards 13.5nm (EUV), 6.7nm (EUV) and even shorter wavelengths.

[0003] According to the generation method of EUV light source, its types mainly include: synchrotron radiation light source, laser produced plasma (LPP), discharge plasma (DPP), laser-assisted discharge plasma (LDP) and free electron laser. Due to their large size, complex equipment, high cost and poor flexibility, synchrotron radiation light source and free electron laser are limited in their application in commercial lithography production. Discharge plasma is difficult to be practical due to technical problems such as serious debris contamination and difficulty in handling. LPP-EUV light source generates EUV radiation by irradiating target materials (Sn or Gd, etc.) with high-power laser to form plasma. This type of light source has the characteristics of small light-emitting area, high EUV collection efficiency and light debris contamination, and has become the most potential EUV lithography light source.

[0004] The EUV light source currently used in mass production of high-end mobile phone chips is a LPP-EUV light source pumped by a continuous discharge CO2 laser MOPA (master oscillator and power amplifiers) structure with a wavelength of 13.5nm. The pump source used by ASML was developed by Cymer, an American company. The continuous discharge laser works under low gas pressure (about 0.1atm) and has a low working gas density. Therefore, the output pulse energy density and pulse power density are low. When used as an amplifier, the gain coefficient is small (about 0.004cm -1 ), it needs to go through multiple stages of amplification to achieve the required parameter indicators of the pump laser. Therefore, ASML's existing EUV lithography machine is an ultra-large device. Its application is also limited by its large size, complex device, high cost, poor flexibility and other factors. It has become a "bottleneck" problem in my country's high-end chip industry. In addition, it is difficult for ASML to further increase the laser pulse power and pulse energy, which makes it difficult to develop LPP-EUV for other more promising elements, such as gadolinium plasma at a radiation wavelength of 6.7nm. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present disclosure provides a laser plasma extreme ultraviolet (LPP-EUV) lithography machine light source system, which improves the performance of the light source system and the integration of the EUV lithography machine and makes it miniaturized. Further, by replacing the gadolinium target material or other target materials, EUV light with a wavelength of 6.7nm or shorter can be generated.

[0006] The present invention provides a laser plasma type extreme ultraviolet lithography light source system, comprising: a main pump laser, which adopts a high repetition frequency TEA CO2 laser system, and is used to generate a main pulse laser; a pre-pumped picosecond laser, which is used to generate a picosecond laser; a beam combining device, which is used to combine the main pulse laser and the picosecond laser to obtain a combined laser beam; a target material tin liquid particle generator, which is used to generate a tin liquid particle string, the tin liquid particle string forms a mist ball under the bombardment of the picosecond laser, and the mist ball forms a high-temperature plasma under the bombardment of the main pulse laser and then emits 13.5nm extreme ultraviolet light; an extreme ultraviolet light collecting mirror, which is used to collect and converge the extreme ultraviolet light; a debris magnetic deflector, which is arranged around the focus of the pump laser focusing mirror, and is used to clean up the ion fragments generated after the tin liquid particle string is bombarded debris; a vacuum chamber, used to provide a vacuum environment for a target tin liquid particle generator, an extreme ultraviolet light collecting mirror and a debris magnetic deflector; wherein a pump laser focusing mirror is arranged on the vacuum chamber, and the pump laser focusing mirror is used to focus the combined laser beam onto the liquid particles; an automatic synchronous control system, which is electrically connected to a main pump laser, a pre-pump picosecond laser, a target tin liquid particle generator and a debris magnetic deflector, and is used to electrically control the main pump laser, the pre-pump picosecond laser, the target tin liquid particle generator and the debris magnetic deflector; wherein the pulse repetition frequency of the pre-pump picosecond laser, the target tin liquid particle generator and the debris magnetic deflector is the same as that of the main pump laser.

[0007] Furthermore, the main pump laser adopts a MOPA laser structure or an ILS laser structure.

[0008] Furthermore, the MOPA laser structure includes: a CO2 laser master oscillator for generating pulsed laser; a modulator for modulating the pulsed laser to obtain a seed laser; and a TEA CO2 laser power amplifier for amplifying the power of the seed laser for output.

[0009] Furthermore, the TEA CO2 laser power amplifier adopts a folded optical path, including: a first folding mirror and a second folding mirror, wherein the first folding mirror and the second folding mirror are arranged opposite to each other and are used for reflecting the optical path for power amplification.

[0010] Further, the CO2 laser oscillator is a laser emitting from a single transition band or a multi-band laser.

[0011] Furthermore, the modulator is a gallium arsenide or cadmium telluride electro-optic modulator.

[0012] Furthermore, the modulator is a semiconductor light modulator, which includes: a semiconductor Brewster angle plate and a nanosecond pulse YAG laser.

[0013] Furthermore, the ILS laser structure includes: a CO2 laser master oscillator for generating pulsed laser; a modulator for modulating the pulsed laser to obtain a seed laser; a main pump laser for injecting the seed laser to obtain a main pulse laser; or, a nanosecond pulsed YAG laser for generating pulsed laser; a nonlinear converter for selectively outputting a seed laser from the pulsed laser; and a main pump laser for injecting the seed laser to obtain a main pulse laser.

[0014] Further, the CO2 laser master oscillator is a laser emitting from a single transition band or a multi-band laser.

[0015] Furthermore, the modulator is a gallium arsenide or cadmium telluride electro-optic modulator.

[0016] Furthermore, the modulator is a semiconductor light modulator, which includes: a semiconductor Brewster angle plate and a nanosecond pulse YAG laser.

[0017] Furthermore, the pulse repetition frequencies of the main pump laser, the pre-pump picosecond laser, the target tin liquid particle generator and the debris magnetic deflector are the same.

[0018] Furthermore, the pulse repetition frequency of the main pump laser ranges from 1 kHz to 10 kHz.

[0019] Furthermore, the pulse repetition frequencies of the main pump laser, the pre-pump picosecond laser, the target tin liquid particle generator and the debris magnetic deflector are the same.

[0020] Furthermore, the pulse power of the main pump laser is 20MW to 200MW.

[0021] Furthermore, the pulse length of the main pump laser is 10ns to 30ns.

[0022] Furthermore, a gadolinium target generator is used to replace the target tin liquid particle generator, which can generate 6.7nm EUV light.

[0023] The embodiments of the present disclosure propose a laser plasma extreme ultraviolet (LPP-EUV) lithography machine light source system. The light source system adopts a high-power, multi-kilohertz repetition rate, short-pulse TEA CO2 laser system as the main pump laser, so that the EUV lithography machine has the advantages of compact structure, flexibility, and is easy to build, transport, install and maintain. It is suitable for mass production to supply the market, and to solve the urgent needs of my country in the manufacturing of high-end chips, especially special high-end chips such as artificial intelligence chips, micro robots, and brain-like intelligent chips as soon as possible; and further replacement of gadolinium target generators or other target materials can generate EUV light with a wavelength of 6.7nm or shorter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0025] Figure 1A The structure configuration diagram of EUV light source system in the prior art is schematically shown;

[0026] Figure 1B The structure configuration diagram of the ASML high-power pulsed CO2 laser system in the prior art is schematically shown;

[0027] Figure 2 The structure diagram of the light source system of the laser plasma extreme ultraviolet lithography machine according to an embodiment of the present disclosure is schematically shown;

[0028] Figure 3 A schematic diagram of the MOPA structure according to an embodiment of the present disclosure is shown;

[0029] Figure 4 The schematic diagram shows a structure of a triple-folded optical path according to an embodiment of the present disclosure;

[0030] Figure 5 Schematically shows a structural schematic diagram of a triple-folded optical path according to another embodiment of the present disclosure;

[0031] Figure 6 A schematic diagram of the MOPA structure according to another embodiment of the present disclosure is shown;

[0032] Figure 7 Schematically shows a normalized CO2 laser gain spectrum in a low-pressure long-pulse CO2 laser oscillator 11 of a MOPA structure and an ILS laser structure according to an embodiment of the present disclosure;

[0033] Figure 8 The schematic diagram of the structure of the ILS laser structure according to an embodiment of the present disclosure is shown;

[0034] Fig. 9 The schematic diagram of the structure of the ILS laser structure according to another embodiment of the present disclosure is shown;

[0035] Fig.10 The schematic structural diagram of an ILS laser structure according to yet another embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0037] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0038] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0039] Figure 1A The structure configuration diagram of the EUV light source system in the prior art is schematically shown. Figure 1B The schematic diagram shows the structure configuration diagram of the ASML high-power pulsed CO2 laser system in the prior art.

[0040] like Figure 1A As shown in the figure, a high-power short-pulse CO2 laser is used as the main pump laser, the pre-pump laser is a pulse solid laser with a pulse width of 1ns or shorter, and the target material is a high-speed moving string of tin liquid particles with a diameter of about 20μm. Under the bombardment of the pre-pump laser, the tin liquid particles expand into a mist-like ball with a diameter of about 200μm, and then form a high-temperature plasma under the bombardment of the main pulse laser, emitting extreme ultraviolet light with a wavelength of 13.5nm. The extreme ultraviolet light is collected and focused at the IF point by the extreme ultraviolet optical focusing mirror. After the target material is bombarded, ion "debris" is generated, and the direction of movement is deflected and removed after passing through a strong magnetic field, thereby preventing the reflector from being contaminated.

[0041] Experiments have shown that Figure 1B As shown in the figure, the 0.1mJ energy "seed laser" is amplified by the second stage to the pre-power amplifier, and then amplified by the third stage power amplifier to achieve the required pulse energy of 250mJ and pulse power of 15MW. Isolators are also set between the amplifiers, and the total optical path is more than 100 meters. It is more difficult to further increase the power by increasing the amplification length of the amplifier.

[0042] Another reason why ASML lithography machines are such super-large devices is that the pump laser must operate at a high repetition frequency close to 100kHz. This is determined by the dynamic principle of CO2 lasers. Lower repetition frequencies do not significantly increase the pulse energy and pulse power of a single laser pulse, but only reduce the average output power and electro-optical conversion efficiency of the laser. Only under the condition of high repetition frequency operation close to 100kHz can the average output power, pulse output power and electro-optical conversion efficiency of the laser be taken into account at the same time to achieve the optimal value.

[0043] In summary, if Figure 1B The EUV light source system structure shown has at least the following defects:

[0044] 1) The EUV lithography machine in ASML's solution is a super-large device. The light source system is developed by the United States. Its main pump laser uses a continuous discharge CO2 laser amplifier MOPA structure to produce high-power, high-repetition-frequency lasers. Because it works under low pressure (about 0.1atm) and the working gas density is low, the energy density and power density of the output pulses are low, and the gain coefficient is small (about 0.004cm -1 ), it needs to go through multiple stages of amplification to achieve the required laser parameter indicators. On the other hand, since the laser pulse energy (250mJ) and pulse power (15MW) required for the plasma generated by the tin liquid particles to emit extreme ultraviolet light are both very high, in order to achieve the indicators required for plasma emission of extreme ultraviolet light, a long amplifier and isolator optical path is required. Therefore, the system is large in size (e.g., 11.3m×6.1m×2.3m), and the internal optical path is more than 100 meters long.

[0045] 2) The pulse repetition frequency of the above-mentioned CO2 laser must be around 50kHz to 100kHz, which is determined by the dynamic principle of the CO2 laser. A lower repetition frequency cannot significantly increase the pulse energy and pulse power of a single laser pulse, but will only reduce the average output power and electro-optical conversion efficiency of the laser. Only under the high repetition frequency operating conditions close to 50kHz to 100kHz can the average output power, pulse output power and electro-optical conversion efficiency of the laser be taken into account at the same time to achieve the optimal value. In this case, the average power output of the laser is as high as 27,000kW, which requires hundreds of thousands of watts of electricity.

[0046] 3) The high repetition frequency of 100kHz puts forward high requirements for the research and development of other units of the EUV light source system. For example, the tin liquid particle generator must send one million high-speed tin liquid particles per second; the laser beam must accurately aim at the high-speed moving target and automatically control the synchronization; the pulse magnetic field deflection system used to remove "debris" must also operate at a high repetition rate and accurately control the synchronization automatically. There are many technical difficulties in the research and development, manufacturing and assembly process of the tin liquid particle generator and the precision automatic synchronization control system. At the same time, the scale of the precision machinery and control system of the EUV lithography machine (including the workpiece stage, mask stage, silicon wafer transmission system, etc.) will also be very large. This feature, together with the first point mentioned above, determines that the ASML solution must be an ultra-large device. This leads to great difficulties in the imitation research and development, manufacturing, transportation, installation and maintenance of the ASML solution.

[0047] 4) ASML’s R&D and construction plan lacks flexibility. It cannot be developed and constructed step by step from small to large, from simple to complex. It is necessary to develop and build a super-large pump laser system in one step to achieve the laser parameter indicators.

[0048] 5) It is difficult for ASML to further improve the laser pulse power and pulse energy, which leads to technical difficulties in further studying the optimal pump parameters of 13.5nm EUV of tin plasma; the limitations of laser pulse power and pulse energy make it difficult for ASML to develop LPP-EUV of other more promising elements, such as gadolinium plasma at a radiation wavelength of 6.7nm.

[0049] In order to overcome the many defects of the existing light sources, the embodiments of the present disclosure propose a laser plasma extreme ultraviolet (LPP-EUV) lithography machine light source system, which is a small extreme ultraviolet lithography machine light source pumped by a multi-kilohertz repetition frequency TEA CO2 laser. By replacing the main pump laser structure, the light source system is miniaturized, and the EUV lithography machine has the advantages of compact structure, flexibility, convenience in construction, transportation, installation and maintenance, and is suitable for mass production to supply the market. Further, the use of a gadolinium target generator or other target materials can generate EUV light with a wavelength of 6.7nm or shorter. .

[0050] Figure 2 The schematic diagram shows the structure of a laser plasma extreme ultraviolet lithography light source system according to an embodiment of the present disclosure.

[0051] like Figure 2 As shown, the LPP-EUV lithography machine light source system includes: a main pump laser 1, a pre-pump picosecond laser 2, a beam combining device 3, a target tin liquid particle generator 4, an extreme ultraviolet light collecting mirror 5, a debris magnetic deflector 6, a vacuum chamber 7, a pump laser focusing mirror 8 and an automatic synchronization control system 9.

[0052] In the embodiment of the present disclosure, the main pump laser 1, which adopts a high repetition rate TEA CO2 laser system, is used to generate a main pulse laser, and its output end is connected to an input end of a beam combining device 3. The pre-pumped picosecond laser 2 is used to generate a picosecond laser, and its output end is connected to another input end of the beam combining device 3. The beam combining device 3 is used to combine the main pulse laser and the picosecond laser and then output to obtain a combined laser beam. The target tin liquid particle generator 4 is used to generate a plurality of tin liquid particle strings, which form a mist ball under the bombardment of the picosecond laser, and the mist ball forms a high-temperature plasma under the bombardment of the main pulse laser and then emits extreme ultraviolet light. The extreme ultraviolet light collecting mirror 5 is used to collect and converge extreme ultraviolet light at the IF point. The debris magnetic deflector 6 is arranged around the focus of the pump laser focusing mirror 8 (i.e., around the tin liquid particles), and is used to clean the ion debris generated after the tin liquid particle target is bombarded to avoid contaminating the extreme ultraviolet light collecting mirror 5. The target material tin liquid particle generator 4, the extreme ultraviolet light collecting mirror 5 and the debris magnetic deflector 6 are arranged in the EUV vacuum chamber 7, and the EUV vacuum chamber 7 is used to provide a vacuum environment for the target material tin liquid particle generator 4, the extreme ultraviolet light collecting mirror 5 and the debris magnetic deflector 6. Specifically, a pump laser focusing mirror 8 is arranged on the EUV vacuum chamber 7, and the pump laser focusing mirror 8 is arranged corresponding to the output end of the beam combining device 3, and is used to focus the combined laser beam onto the target material tin liquid particles.

[0053] Specifically, the main pump laser 1 can adopt a single high-power, multi-kilohertz repetition rate, short-pulse TEACO2 laser or MOPA laser structure or ILS laser structure, with a pulse repetition frequency between 1kHz and 10kHz, preferably, the pulse repetition frequency is 5kHz, the pulse width is 10 to 30ns, and the pulse power is about 20MW to 200MW (preferably 25MW to 50MW).

[0054] It should be noted that a high-power, multi-kHz repetition rate, short-pulse TEA CO2 laser is used as the main pump laser 1. The high-power, multi-kHz repetition rate, short-pulse TEA CO2 laser can be a single TEACO2 laser, which can be achieved by changing the technical parameters of the laser, such as: gas pressure, gas composition, fast discharge circuit structure, laser resonant cavity Q value, etc. The embodiments of the present disclosure are not limited to this.

[0055] In the embodiment of the present disclosure, a low-speed moving tin liquid particle string is sent through the target tin liquid particle generator 4, and the diameter of the tin liquid particle string can be, for example, about 20 μm. Under the bombardment of the pre-pump picosecond laser, the tin liquid particles expand into a mist ball with a diameter of about 200 μm, and then form a high-temperature plasma under the bombardment of the main pulse laser, emitting extreme ultraviolet light (EUV), whose wavelength is 13.5 nm. The emitted EUV is collected by the extreme ultraviolet light collecting mirror 5 and focused around the focus IF of the extreme ultraviolet light collecting mirror 5.

[0056] It should be noted that the target tin liquid particle generator 4 can also use a gadolinium target generator or other metal target generator to replace the EUV light with a wavelength of 6.7nm or shorter. The embodiments of the present disclosure do not limit the target generator that replaces the target tin liquid particle generator 4.

[0057] In the embodiments of the present disclosure, the pulse repetition frequency of the pre-pumped picosecond laser 2, the target tin liquid particle generator 4 and the debris magnetic deflector 6 is the same as that of the main pump laser 1, and they are all electrically connected to the automatic synchronization control system 9 to realize electrical control of the main pump laser 1, the pre-pumped picosecond laser 2, the target tin liquid particle generator 4 and the debris magnetic deflector 6 through the automatic synchronization control system 9.

[0058] It should be noted that the diameter of the tin liquid particle string, the diameter of the tin liquid particle string after expansion, and the wavelength of the extreme ultraviolet light in the above-mentioned embodiment are only exemplary descriptions, and do not constitute limitations of the embodiments of the present disclosure. They can be adjusted accordingly according to actual needs. For example, adjusting the pulse power output by the main pump laser 1 to above 100 megawatts can meet the emission of extreme ultraviolet light with a shorter wavelength.

[0059] According to the embodiments of the present disclosure, Figure 3 As shown, the main pump laser 1 can adopt a laser master oscillator plus laser power amplifier (MOPA) structure. Figure 2 The difference in the structure of the light source system shown is that the MOPA laser structure includes: a CO2 laser master oscillator 11, a modulator 12 and a TEA CO2 laser power amplifier 13. The CO2 laser master oscillator 11 is a low-pressure long-pulse CO2 laser master oscillator, which is used to generate a low-pressure long-pulse CO2 laser and output it to the modulator 12. The modulator 12 selects a short-pulse CO2 laser as a seed laser and inputs it to the TEA CO2 laser power amplifier 23 for power amplification and output.

[0060] Specifically, the modulator 12 may be a gallium arsenide or cadmium telluride electro-optic modulator 12 , and the pulse width of the short pulse CO 2 laser selected by the gallium arsenide or cadmium telluride electro-optic modulator 12 may be 8 to 20 ns.

[0061] According to an embodiment of the present disclosure, the TEA CO2 laser power amplifier 13 in the MOPA structure may adopt a folded optical path, which includes: a plurality of folding mirrors. Specifically, as Figure 4 and Figure 5 As shown, the TEA CO2 laser power amplifier 13 can adopt a three-fold optical path, specifically including: a first folding mirror 131 and a second folding mirror 132, wherein the first folding mirror 131 and the second folding mirror 132 are arranged opposite to each other for reflecting the optical path.

[0062] Specifically, the first folding mirror 131 and the second folding mirror 132 may be arranged in a manner that they are approximately parallel to each other and form a certain angle with the horizontal line, such as Figure 4 Or, the first folding mirror 131 and the second folding mirror 132 may be arranged in a non-parallel manner and at a certain angle to the horizontal line, such as Figure 5 As shown, it is used to realize the three-fold optical path. In the embodiment of the present disclosure, Figure 5 In the folded optical path shown, the folded beams can have more overlap in the gain region of the laser power amplifier, thereby improving efficiency.

[0063] In the embodiments of the present disclosure, the number of folding mirrors in the folded optical path is not limited to two, and the folded optical path is not limited to three. It can be set according to actual applications to meet the optical path folding requirements, and the embodiments of the present disclosure do not limit this. In addition, depending on the number of folding mirrors set, the optical path power after reflection is also different. It should be understood that the laser output power increases with the increase of the folded optical path.

[0064] According to the embodiments of the present disclosure, Figure 6 As shown, the modulator 12 in the MOPA structure can also be a semiconductor light modulator, which is composed of a semiconductor Brewster angle plate 14 and a nanosecond pulse YAG laser 15, wherein the semiconductor Brewster angle plate 14 is approximately perpendicular to the laser beam of the nanosecond pulse YAG laser 15. Specifically, the semiconductor plate material of the semiconductor light modulator can be silicon, germanium or gallium arsenide, etc., and the nanosecond laser pulse width is 8 to 20ns.

[0065] According to the embodiments of the present disclosure, the low-pressure long-pulse CO2 laser oscillator 11 in the MOPA structure can be a laser emitting from a single transition band or multiple laser lines emitted simultaneously from multiple transition bands. The latter is called a multi-band laser, and its operating principle is as follows: Figure 7 The normalized gain spectrum of CO2 laser is shown. The CO2 laser oscillator 11 has about 100 laser transition lines in the wavelength range of 9μm to 11μm, which belong to four transition bands: 10P, 10R, 9P, and 9R. 0 1-10 0 0 band and 000 1-02 0 0 band). The laser lines of the four transition bands all originate from the same upper energy level 00 0 1. The peak spectral lines of the gain distribution are 10P20, 10R18, 9P20 and 9R18 lines. In the freely oscillating CO2 laser oscillator 11 without any dispersive element in the resonant cavity, the laser output power is always concentrated on one or two spectral lines in a band with the highest gain as a result of gain competition. The gain of the 10P20 transition line is the highest. Therefore, the laser spectral line output by the freely oscillating CO2 laser oscillator 11 is usually 10P20 with a wavelength of 10.6μm. A multi-band laser can be successfully developed by adopting a special laser resonant cavity design. The low-pressure long-pulse CO2 laser oscillator 11 in the MOPA structure provided in the present disclosure can adopt a multi-band laser, which has the advantage of improving the pulse power and energy extraction efficiency of the TEA CO2 laser power amplifier 13 under the short pulse laser width requirements.

[0066] According to the embodiments of the present disclosure, Figure 7 to Figure 9 As shown, the main pump laser 1 can also be implemented by using an ILS laser structure (i.e., a seed laser injection locking system, Injection Locking System), that is, the seed laser injection locking system ILS structure is used to implement Figure 2 The main pump laser 1 is shown to achieve short pulse laser output.

[0067] In one embodiment, if Figure 8 As shown, this structure is similar to Figure 2 The structural difference of the main pump laser 1 shown is that the seed laser injection locking system ILS structure includes: a low-pressure long pulse CO2 laser oscillator 11, a gallium arsenide or cadmium telluride electro-optical modulator 12 and a main pump laser 1. Among them, the seed laser is composed of a low-pressure long pulse CO2 laser 11 and a gallium arsenide or cadmium telluride electro-optical modulator 12. The pulse width of the short pulse CO2 laser selected by the gallium arsenide or cadmium telluride electro-optical modulator 12 is 8 to 20ns. The low-pressure long pulse CO2 laser oscillator 11 is a laser emitting from a single transition band or a multi-band laser.

[0068] In one embodiment, if Fig. 9 As shown, this structure is similar to Figure 2The structural difference of the main pump laser 1 shown is that the seed laser injection locking system ILS structure includes: a low-pressure long-pulse CO2 laser oscillator 11, a semiconductor optical modulator and a main pump laser 1. In this structure, the seed laser is composed of a low-pressure long-pulse CO2 laser oscillator 11 and a semiconductor optical modulator. Among them, the semiconductor optical modulator includes: a semiconductor Brewster horn 14 and a nanosecond pulse YAG laser 15. The semiconductor material can be silicon, germanium or gallium arsenide. The pulse width of the nanosecond pulse YAG laser 15 is 8 to 20ns. The low-pressure long-pulse CO2 laser selects a short-pulse CO2 laser as a seed laser input to the main pump laser 1 through the semiconductor optical modulator. The low-pressure long-pulse CO2 laser oscillator 11 emits a laser or a multi-band laser from a single transition band.

[0069] In one embodiment, if Fig.10 As shown, this structure is similar to Figure 2 The main pump laser 1 shown in the figure has a structural difference in that the seed laser injection locking system ILS structure includes: a nanosecond pulse YAG laser 15, a nonlinear converter 16 and a main pump laser 1. The seed laser is a nanosecond pulse YAG laser 15 generated by a nonlinear converter 16, and its pulse width is 8 to 20 ns.

[0070] It should be noted that if Figures 3 to 6 The MOPA laser structure shown in Figures 8 to 10 The ILS laser structure shown is only an exemplary description and does not constitute a limitation of the embodiments of the present disclosure. Figure 2 The main pump laser 1 shown in the figure is used to achieve high power, multi-kHz repetition rate, short pulse laser output. The other components in the LPP-EUV lithography machine light source system composed of the MOPA laser structure and the ILS laser structure are similar to those in the example Figure 2 The structures shown are consistent, and the embodiments of the present disclosure will not describe these components one by one.

[0071] In the embodiments of the present disclosure, by adopting a high-power, multi-kilohertz repetition rate, short-pulse TEA CO2 laser 1, a MOPA laser structure (laser master oscillator plus laser power amplifier structure) or an ILS laser structure (seed laser injection locking system ILS) achieves high-power, multi-kilohertz repetition rate, short-pulse laser output, in which the high-power, multi-kilohertz repetition rate, short-pulse laser bombards the expanded tin liquid particles to form a high-temperature plasma and then emits extreme ultraviolet light. The wavelength of the extreme ultraviolet light that can be achieved is 13.5nm, thereby achieving a small extreme ultraviolet lithography machine light source pumped by a multi-kilohertz repetition rate, short-pulse TEA CO2 laser.

[0072] Compared with the prior art, the embodiments of the present disclosure have at least the following beneficial effects:

[0073] (1) The TEA CO2 laser used as the pump source in the embodiments of the present disclosure operates at atmospheric pressure or more than atmospheric pressure, with high pulse power, large pulse energy, and large gain coefficient (about 0.04 cm -1 ), which is most suitable as a pump laser for generating plasma extreme ultraviolet light (LPP-EUV). The pulse laser index achieved by the embodiment of the present disclosure is a pulse power of 25 to 50 MW, which is higher than the index achieved in the ASML solution. Higher pulse power is conducive to the generation of plasma extreme ultraviolet light. In addition, if the MOPA structure is adopted, only one laser power amplifier is needed instead of multiple amplifiers, so the total optical path of the system is shorter and the beam direction stability is good. However, the internal optical path of the ASML solution is long and the device volume is large.

[0074] (2) The pulse repetition frequency is set to 5kHz or lower, and the pump laser will be a relatively small device. This advantage, together with the first point mentioned above, determines the relatively small characteristics of the light source system, and makes the EUV lithography machine compact, flexible, and easy to build, transport, install, and maintain. It is suitable for mass production and supply to the market, and can quickly solve the urgent needs of my country in the manufacturing of high-end chips, especially in the manufacturing of special high-end chips such as artificial intelligence chips, micro-robots, and brain-like intelligent chips. Since the pulse repetition frequency is set to a lower value of 5kHz or lower, the target tin liquid particle generator and the corresponding precision automatic synchronous control system in the EUV light source are easier to implement. In the ASML solution, the target tin liquid particle generator sends 100,000 tin liquid particles per second, and the speed of the tin liquid particles is 100 meters per second. The generator and the precision automatic synchronous control system are both difficult to implement.

[0075] (3) The embodiments of the present disclosure can be implemented in stages according to the pulse repetition frequency, namely, the 1kHz stage, the 3kHz stage, and the 5kHz stage. The extreme ultraviolet lithography light sources that achieve output in these three different stages can all be used for chip production.

[0076] (4) The light source system provided by the embodiments of the present disclosure has a lot of room for research and development in further improving the pulse energy and pulse power of the TEA CO2 laser, which is conducive to further exploring the optimal pump parameters of the 13.5nm EUV of tin plasma. Years of theoretical and experimental research abroad have proved that the temperature of laser plasma is roughly proportional to the power of the pump laser multiplied by the square of the wavelength, and the conversion efficiency of LPP-EUV is closely related to the temperature of the laser plasma. The CO2 laser is near 10.6μm and is the highest-power laser with the longest wavelength. The use of TEA CO2 laser can develop EUV light sources with wavelengths shorter than the existing 13.5nm tin plasma, such as the wavelength of gadolinium plasma at 6.7nm. This will be a new milestone for the lithography machine to advance to 1nm. However, the ASML solution cannot further significantly increase the pulse power of the pump laser to more than 100 megawatts, and therefore cannot further develop the gadolinium plasma solution.

[0077] While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive.

[0078] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of scopes, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of scopes without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0079] Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, it should be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-mentioned embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A LPP-EUV lithography light source system, characterized in that: include: A main pump laser (1), which uses a high repetition rate TEA CO2 laser system to generate a main pulse laser; A pre-pumped picosecond laser (2) for generating picosecond laser light; A beam combining device (3), used for combining the main pulse laser and the picosecond laser to obtain a combined laser beam; A target material tin liquid particle generator (4) is used to generate a tin liquid particle string, wherein the tin liquid particle string forms a mist ball under the bombardment of the picosecond laser, and the mist ball forms a high-temperature plasma under the bombardment of the main pulse laser and then emits 13.5nm extreme ultraviolet light; An extreme ultraviolet light collecting mirror (5), used for collecting and converging the extreme ultraviolet light; A debris magnetic deflector (6), which is arranged around the focus of the pump laser focusing mirror (8) and is used to clean up ion debris generated after the tin liquid particle string is bombarded; A vacuum chamber (7) is used to provide a vacuum environment for the target tin liquid particle generator (4), the extreme ultraviolet light collecting mirror (5) and the debris magnetic deflector (6); wherein the pump laser focusing mirror (8) is arranged on the vacuum chamber (7), and the pump laser focusing mirror (8) is used to focus the combined laser beam onto the liquid particles; An automatic synchronous control system (9) electrically connected to the main pump laser (1), the pre-pump picosecond laser (2), the target tin liquid particle generator (4) and the debris magnetic deflector (6), and used for electrically controlling the main pump laser (1), the pre-pump picosecond laser (2), the target tin liquid particle generator (4) and the debris magnetic deflector (6); Wherein, the pulse repetition frequency of the pre-pump picosecond laser (2), the target tin liquid particle generator (4) and the debris magnetic deflector (6) is the same as that of the main pump laser (1); The main pump laser (1) adopts a MOPA laser structure, wherein the MOPA laser structure comprises: A CO2 laser master oscillator (11), used to generate pulsed laser light; A modulator (12) is used to modulate the pulsed laser to obtain a seed laser; A TEA CO2 laser power amplifier (13) is used to amplify the power of the seed laser and then output it, wherein the TEA CO2 laser power amplifier (13) adopts a folded optical path and comprises: a first folding mirror (131) and a second folding mirror (132), wherein the first folding mirror (131) and the second folding mirror (132) are arranged opposite to each other and are used to reflect the optical path for power amplification.

2. The LPP-EUV lithography light source system according to claim 1, characterized in that: The CO2 laser master oscillator (11) is a laser emitting from a single transition band or a multi-band laser.

3. The LPP-EUV lithography light source system according to claim 1, characterized in that: The modulator (12) is a gallium arsenide or cadmium telluride electro-optic modulator.

4. The LPP-EUV lithography light source system according to claim 1, characterized in that: The modulator (12) is a semiconductor light modulator, which comprises a semiconductor Brewster angle plate (14) and a nanosecond pulse YAG laser (15).

5. A LPP-EUV lithography light source system, characterized in that: include: A main pump laser (1), which uses a high repetition rate TEA CO2 laser system to generate a main pulse laser; A pre-pumped picosecond laser (2) for generating picosecond laser light; A beam combining device (3), used for combining the main pulse laser and the picosecond laser to obtain a combined laser beam; A target material tin liquid particle generator (4) is used to generate a tin liquid particle string, wherein the tin liquid particle string forms a mist ball under the bombardment of the picosecond laser, and the mist ball forms a high-temperature plasma under the bombardment of the main pulse laser and then emits 13.5nm extreme ultraviolet light; An extreme ultraviolet light collecting mirror (5), used for collecting and converging the extreme ultraviolet light; A debris magnetic deflector (6), which is arranged around the focus of the pump laser focusing mirror (8) and is used to clean up ion debris generated after the tin liquid particle string is bombarded; A vacuum chamber (7) is used to provide a vacuum environment for the target tin liquid particle generator (4), the extreme ultraviolet light collecting mirror (5) and the debris magnetic deflector (6); wherein the pump laser focusing mirror (8) is arranged on the vacuum chamber (7), and the pump laser focusing mirror (8) is used to focus the combined laser beam onto the liquid particles; An automatic synchronous control system (9) electrically connected to the main pump laser (1), the pre-pump picosecond laser (2), the target tin liquid particle generator (4) and the debris magnetic deflector (6), and used for electrically controlling the main pump laser (1), the pre-pump picosecond laser (2), the target tin liquid particle generator (4) and the debris magnetic deflector (6); Wherein, the pulse repetition frequency of the pre-pump picosecond laser (2), the target tin liquid particle generator (4) and the debris magnetic deflector (6) is the same as that of the main pump laser (1); The main pump laser (1) adopts an ILS laser structure, wherein the ILS laser structure comprises: A CO2 laser master oscillator (11) is used to generate pulsed laser light; a modulator (12) is used to modulate the pulsed laser light to obtain a seed laser light; a main pump laser (1) is used to perform an injection process on the seed laser light to obtain a main pulsed laser light; or, A nanosecond pulse YAG laser (15) is used to generate pulse laser; a nonlinear converter (16) is used to selectively output seed laser from the pulse laser; and a main pump laser (1) is used to inject the seed laser into the seed laser to obtain main pulse laser.

6. The LPP-EUV lithography light source system according to claim 5, characterized in that: The CO2 laser master oscillator (11) is a laser emitting from a single transition band or a multi-band laser.

7. The LPP-EUV lithography light source system according to claim 5, characterized in that: The modulator (12) is a gallium arsenide or cadmium telluride electro-optic modulator.

8. The LPP-EUV lithography light source system according to claim 5, characterized in that: The modulator (12) is a semiconductor light modulator, which comprises a semiconductor Brewster angle plate (14) and a nanosecond pulse YAG laser (15).

9. The LPP-EUV lithography light source system according to any one of claims 1 or 5, characterized in that: The pulse repetition frequency of the main pump laser (1) is 1kHz~10kHz.

10. The LPP-EUV lithography light source system according to any one of claims 1 or 5, characterized in that: The pulse power of the main pump laser (1) is 20MW~200MW.

11. The LPP-EUV lithography light source system according to any one of claims 1 or 5, characterized in that: The pulse length of the main pump laser is 10ns~30ns.

12. The LPP-EUV lithography light source system according to any one of claims 1 or 5, characterized in that: A gadolinium target material generator is used to replace the target material tin liquid particle generator (4), which can generate 6.7 nm EUV light.

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