CN115842282A - Double-pulse driving light source of high-power EUV (extreme ultraviolet) photoetching light source - Google Patents

Abstract

The invention relates to the field of laser technology, and discloses a double-pulse driving light source of a high-power EUV lithography light source. A beam device, a pulse delay device, a pulse shaper and a laser pulse amplification system, wherein the pulse seed source includes a mode-locked oscillator and a nanosecond pulse seed source. The double pulse output by driving the light source can be generated by the same pulse seed source, and the double pulse output with adjustable time delay can be realized through the pulse beam splitting device and the pulse delay device. The laser pulse amplification system driving the light source includes at least one stage of pulse amplifier, and can The pulse width is adjusted by a pulse stretcher and a pulse compressor. The double pulses output by the driving source can also be generated by different pulse seed sources respectively. After the pulse sequence is reduced to a suitable repetition frequency by the pulse selector, the delayed output of the double pulse is realized by using the pulse delay device. The laser pulse amplification system includes at least one stage Pulse amplifier, and the pulse width can be adjusted by pulse stretcher and pulse compressor. The present invention replaces the current _CO2 laser used as a driving light source by utilizing the high average power, high wall insertion efficiency, and small device volume of a high-power 2μm-band all-solid-state laser to obtain a higher average power output and increase the power for exciting EUV radiation , to solve the problem of increasing the chip output of EUV lithography machines.

Description

A double-pulse driving light source for a high-power EUV lithography light source

technical field

The present invention relates to high-power all-solid-state lasers and laser plasma (LPP)-based driving laser light sources for extreme ultraviolet (EUV) lithography light sources. In particular, it relates to a double-pulse-driven laser light source system of an EUV lithography light source, which is used for irradiating targets such as tin droplets to generate EUV radiation for lithography.

Background technique

With the continuous development and mutual promotion of electronic information technology and integrated circuit manufacturing technology, the manufacturing technology of integrated circuits has been continuously improved, and the wavelength of the required lithography light source has reached the EUV band. Technologies for generating EUV radiation include Synchrotron radiation facility (SRF), Discharge-produced plasma (DPP), Free-electron laser (Free-electron laser, FEL) and laser-produced plasma (LPP). )wait. At present, the commercial EUV lithography light source adopts LPP technology, and the wavelength of EUV radiation obtained is 13.5nm, and the process of obtaining integrated circuits is less than 7nm, and mass production has been achieved. It uses a high-power _CO2 laser as the driving light source for EUV, and generates EUV radiation by bombarding a droplet tin target with double pulses. The droplet tin target is first bombarded by a pre-pulse, distributed into a specific geometric shape, and then bombarded by the main pulse, which can effectively improve the conversion efficiency of _CO2 laser to EUV radiation. The power of the high-power CO ₂ laser as the driving light source has reached more than 40kW, not only the power consumption and the overall volume are huge, but also it is very difficult to continue to increase the power with the existing technical route, which means that the available EUV radiation power is difficult Further improvement cannot meet the demand for mass production of EUV lithography in the future. Therefore, it is necessary to adopt a driving light source with higher average power to replace the currently used _CO2 laser.

Contents of the invention

The present invention provides a double-pulse driving light source of a high-power EUV lithography light source, aiming to use the wavelength of the Tm-doped all-solid-state laser to be equivalent to that of the CO ₂ laser in terms of EUV excitation efficiency, and the long life of the energy level on the Tm ion to realize The driving light source with high average power and high wall insertion efficiency can obtain a more economical and higher power solution than the current CO ₂ driving light source, obtain high-power EUV radiation output, and solve the problem of increasing the chip output of EUV lithography machines.

Technical solution of the present invention is as follows:

A double-pulse driving light source of a high-power EUV lithography light source, characterized in that the driving laser light source uses a Tm-doped material as a gain medium to obtain a double-pulse driving laser output with a wavelength range of 1800-2500 nm, and the time between pulses Delay is adjustable.

The Tm-doped materials include, but are not limited to, Tm-doped optical fibers or crystal materials such as Tm:YAG, Tm:YAP, Tm:YLF, Tm:LLF, and Tm:Lu ₂ O ₃ .

The double pulses for driving the light source include a first pulse and a second pulse. The pulse width of the first pulse ranges from 1 ps to 20 ns, and its energy can bombard the target droplet into a specific geometric distribution; the pulse width of the second pulse ranges from 1 ns to 20 ns, and its energy is sufficient to bombard the first The target after the pulse bombardment is converted into plasma emitting EUV light, and the time delay between the first pulse and the second pulse is adjustable.

The first pulse and the second pulse laser can be generated by the same pulse seed source through the same laser pulse amplification system or different laser pulse amplification systems, and can also be generated by different pulse seed sources through different laser pulse amplification systems, and the laser pulse The amplification system includes at least one stage of pulse amplifier, which is sufficient to amplify the input pulse to the required pulse energy.

Further, when the driving light source uses the same pulse seed source to generate double pulses, the driving laser light source system includes a mode-locked oscillator and a pulse selector. Pulse beam splitting device, pulse delay device and laser pulse amplification system.

Further, when the driving light source uses different pulse seed sources to generate double pulses respectively, the driving laser light source system includes a mode-locked oscillator, a nanosecond pulse seed source, and a pulse selector. Pulse delay device and laser pulse amplification system.

Further, the nanosecond pulse seed source includes a Q-switched oscillator, a cavity emptying oscillator, and a single-frequency oscillator modulated outside the cavity.

Furthermore, the laser pulse amplification system also includes a pulse stretcher and an optional pulse compressor to control the pulse width.

Further, the pulse picker includes an acousto-optic modulator and an electro-optic modulator.

Furthermore, the pulse amplifier in the laser pulse amplification system can be one or more of regenerative amplifiers, slab amplifiers, disc amplifiers and stacked chip amplifiers.

Optionally, the driving light source system includes a pulse shaper, which is used to change the pulse shape in time domain and space domain, so as to optimize the conversion efficiency of laser light to EUV light.

Compared with the prior art, the present invention has the following salient features:

High-power Tm-doped all-solid-state laser is used as the driving light source of _EUV lithography light source, which has higher average power, higher wall insertion efficiency, better pulse stability, better pulse shaping ability and More compact device volume, replacing _CO2 laser as the driving light source of EUV lithography light source.

Description of drawings

Fig. 1 is a schematic structural diagram of a double-pulse driving light source system of the EUV lithography light source in Example 1

Fig. 2 is a schematic structural diagram of the double pulse driving light source system of the EUV lithography light source in Embodiment 2

Fig. 3 is a schematic structural diagram of a double-pulse driving light source system of the EUV lithography light source in Embodiment 3

Fig. 4 is a schematic structural diagram of a double-pulse drive light source system of the EUV lithography light source in Example 4. Marks in the figure: 1. Mode-locked oscillator; 2. Pulse selector; 3. Pulse beam splitter; 4. Pulse delay device ;5, pulse shaper; 6, laser pulse amplification system; 7, nanosecond pulse seed source; 11, first pulse; 12, second pulse; 61, first laser pulse amplification system; 62, second laser pulse amplification System; 81. First laser pulse source; 82. Second laser pulse source; 601. Pulse stretcher; 602. Pulse amplifier; 603. Pulse compressor.

Detailed ways

In order to make the technical solutions in the embodiments of the present invention clear and complete, the present invention will be described in detail below in conjunction with the drawings in the embodiments of the present invention; obviously, the described embodiments are only part of the embodiments of the present invention, not all Example. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

The embodiment of the present invention provides a double-pulse driving light source for high-power EUV lithography light source, which aims to obtain a higher power than the current driving light source by utilizing the characteristics of Tm-doped all-solid-state lasers such as high average power, high wall insertion efficiency, and more compact volume. The higher average power of the CO ₂ laser solves the problem of increasing the chip yield of EUV lithography machines.

For a better understanding of the technical solution of the present invention, please refer to FIG. 1, which is a structural schematic diagram of a EUV lithography light source driving light source proposed by the present invention using the same pulse seed source and the same laser pulse amplification system 6 to generate driving pulse output . As shown in the figure, it includes a mode-locked seed source 1 , a pulse selector 2 , a pulse splitter 3 , a pulse delay device 4 , a pulse shaper 5 , and a laser pulse amplification system 6 . After the laser pulse generated by the mode-locked oscillator 1 is reduced to a suitable repetition frequency by the pulse selector 2, it is divided into the first pulse 11 and the second pulse 12 by the pulse splitter 3; the second pulse is made by the pulse delay device 4 12 Generate a time delay relative to the first pulse 11, and combine the first pulse 11 and the second pulse 12 into a pulse train with double pulses at the output of the device, and then pass through the The pulse shaper 5 performs shaping. After the laser pulse is stretched by the pulse stretcher 601, and then appropriately amplified by the pulse amplifier 602, the first pulse 11 is stripped and output from the pulse train by the pulse splitter 3, and then the pulse of the first pulse 11 can be compressed by the pulse compressor 603. The width is adjusted; the second pulse 12 is further amplified by the pulse amplifier 602 and then output directly. The number of pulse amplifiers 602 included in the laser pulse amplification system 6 in the embodiment is not fixed, and can be increased or decreased as required.

Please refer to FIG. 2 . FIG. 2 is a structural schematic diagram of another EUV lithography light source driving light source proposed by the present invention using the same pulse seed source and the same laser pulse amplification system 6 to generate driving pulse output. As shown in the figure, the driving light source of the EUV lithography light source of the present invention includes a mode-locked oscillator 1 , a pulse selector 2 , a pulse splitter 3 , a pulse delay device 4 , a pulse shaper 5 , and a laser pulse amplification system 6 . After the laser pulse generated by the mode-locked oscillator 1 is reduced to a suitable repetition frequency by the pulse selector 2, the pulse can be shaped by the pulse shaper 5 according to the shape of the pulse time domain and space domain. After the laser pulse is stretched by the pulse stretcher 601 and appropriately amplified by the pulse amplifier 602, a part of the output pulse is separated by the pulse splitter 3 as the first pulse 11, and the first pulse 11 can be output by the pulse compressor 603. The pulse width is adjusted; the remaining part of the output pulse is further amplified by the pulse amplifier 602 after passing through the pulse delay device 4, and finally output as the second pulse 12.

Please refer to FIG. 3 . FIG. 3 is a schematic structural diagram of an EUV lithography light source driving light source using the same pulse seed source and different laser pulse amplification systems to generate driving pulse output. As shown in the figure, the driving light source includes a mode-locked oscillator 1, a pulse selector 2, a pulse splitter 3, a pulse delay device 4, a pulse shaper 5, a first laser pulse amplification system 61, and a second pulse amplification system 62 . After the laser pulse generated by the mode-locked seed source 1 is reduced to a suitable repetition frequency by the pulse selector 2, it is divided into the first pulse 11 and the second pulse 12 by the pulse splitter 3. The shape of the space domain needs to be shaped by the pulse shaper 5, and then injected into the first laser pulse amplification system 61; the pulse is first stretched by the pulse stretcher 601, and then amplified by the pulse amplifier 602 to obtain the output of the first pulse 11 with sufficient energy, and finally it can be According to the needs of the pulse width, the pulse width of the first pulse 11 is adjusted by the pulse compressor 603; after the second pulse 12 passes through the pulse delay device 4, it can also be shaped by the pulse shaper 5 according to the needs of the pulse shape, After that, it is injected into the second laser pulse amplification system 62, the pulse is stretched by the pulse stretcher 601, and then amplified by the first-stage pulse amplifier 602 to obtain a second pulse 12 with sufficient energy for output.

Please refer to FIG. 4 . FIG. 4 is a schematic diagram of the structure of a driving light source for an EUV lithography light source using two different laser systems to generate dual driving pulse outputs. As shown in the figure, the driving light source includes a first laser pulse source 81 and a second pulse laser source 82 . After the first pulse 11 generated by the mode-locked oscillator 1 is reduced to a suitable repetition frequency by the pulse selector 2 , it can be shaped by the pulse shaper 5 according to the pulse shape, and then the laser is injected into the first laser pulse amplification system 61 . The first pulse 11 is first stretched by the pulse stretcher 601, and then amplified by the pulse amplifier 602 to finally obtain the output of the first pulse 11 with sufficient energy, and the pulse of the first pulse can be compressed by the pulse compressor 603 according to the needs of the pulse width. The width is adjusted; after the second pulse 12 output by the nanosecond pulse seed source 7 passes through the pulse delay device 4, it can also be shaped by the pulse shaper 5 according to the pulse shape, and then injected into the second laser pulse amplification system 62. After the pulse is amplified by the pulse amplifier 602, a second pulse 12 with sufficient energy is finally output.

Claims (6)

1. A double-pulse driving light source of a high-power EUV lithography light source is characterized in that a pulse seed source and a laser gain medium used by an amplifier in the driving light source are Tm-doped materials, and first pulses and second pulses with the laser wavelength range of 1800-2500 nm and the pulse width range of 1 ps-20 ns are output; the first pulse 11 is output before the second pulse 12, and the time delay between the first pulse 11 and the second pulse 12 is adjustable; the energy of the first pulse is sufficient to bombard the target droplets to a desired geometrical distribution and the energy of the second pulse 12 is sufficient to convert the target treated by the first pulse to a plasma emitting EUV light.

2. The double-pulse driving light source of the high-power EUV lithography light source as claimed in claim 1, wherein the Tm-doped material comprises Tm-doped fiber or Tm: YAG, tm: YAP, tm: YLF, tm: LLF and Tm: lu ₂ O ₃ A crystalline material.

3. A system for producing a double pulse driven light source for a high power EUV lithography light source as claimed in any one of claims 1 to 2, characterized by comprising a mode locked oscillator 1, a pulse selector 2, a pulse splitting device 3, a pulse delaying device 4 and a laser pulse amplification system 6;

the mode-locked oscillator 1 is used for generating ultrashort laser pulses with the wavelength ranging from 1800 nm to 2500 nm;

the pulse selector 2 is used for reducing the incident laser pulse sequence to a proper repetition frequency;

the pulse beam splitting device 3 is used for splitting an input laser pulse into a first pulse 11 and a second pulse 12;

the pulse delay device 4 is used for introducing an adjustable optical path difference between the first pulse and the second pulse 12 and combining the first pulse 11 and the second pulse 12 into a pulse train with double pulses when outputting;

the pulse shaper 4 is used for modulating the shapes of the time domain and the space domain of the first pulse 11 and the second pulse 12;

the laser pulse amplification system 6 comprises a pulse stretcher 601, at least one pulse amplifier 602, a pulse beam splitting device 3, and optionally a pulse compressor 603; the pulse stretcher 601 is used for stretching the pulse width of the incident pulse, the pulse amplifier 602 is used for amplifying the pulse energy of the incident pulse, and the pulse splitting device is used for separating a first pulse 11 and a second pulse 12 in the incident pulse train; when the pulse width of the first pulse 11 needs to be adjusted, the pulse width is adjusted by the pulse compressor 603.

4. A system for producing a double-pulse driven light source for a high-power EUV lithography light source as claimed in any of claims 1 to 2, comprising a mode-locked oscillator 1, a pulse selector 2 and a laser pulse amplification system 6, and further comprising a pulse shaper 5;

the mode-locked oscillator 1 is used for generating ultrashort laser pulses with the wavelength ranging from 1800 nm to 2500 nm;

the pulse selector 2 is used for reducing the pulse sequence to a proper repetition frequency;

the pulse shaper 5 is used for modulating the shapes of a time domain and a space domain of an input pulse;

the laser pulse amplification system 6 comprises a pulse stretcher 601, at least one pulse amplifier 602, a pulse beam splitting device 3, a pulse delay device 4, and optionally a pulse compressor 603; the pulse stretcher 601 is used for stretching the pulse width of the incident pulse, and the pulse amplifier 602 is used for amplifying the pulse energy of the incident pulse; the pulse beam splitting device 3 is used for splitting an input laser pulse into a first pulse 11 and a second pulse 12, wherein the pulse energy of the first pulse 11 is smaller than that of the second pulse 12; the pulse beam splitting device 4 is used for introducing an adjustable optical path difference between the first pulse and the second pulse 12; when the pulse width of the first pulse 11 needs to be adjusted, the pulse width is adjusted by the pulse compressor 603.

5. A system for producing a double pulse driven laser light source for a high power EUV lithography light source as claimed in any one of claims 1 to 2, comprising a mode locked oscillator 1, a pulse selector 2, a pulse beam splitting device 3, a pulse delay device 4, a first laser pulse amplification system 61 and a second laser pulse amplification system 62; also comprises a pulse shaper 5;

the mode-locked oscillator 1 is used for generating ultrashort laser pulses with the wavelength ranging from 1800 nm to 2500 nm;

the pulse selector 2 is used for reducing the incident pulse sequence to a proper repetition frequency;

the pulse beam splitting device 3 is used for splitting one laser pulse into two first pulses 11 and second pulses 12 with the same or different energies;

the pulse delay device 4 is used for introducing an adjustable optical path difference between the first pulse 11 and the second pulse 12;

the pulse shaper 5 is used for modulating the shapes of the time domain and the space domain of the incident first pulse 11 or second pulse 12;

the first laser pulse amplification system 61 comprises a pulse stretcher 601, at least one pulse amplifier 602 and optionally a pulse compressor 603; the pulse stretcher 601 is used for stretching the pulse width of the incident first pulse 11, and the pulse amplifier 602 is used for amplifying the pulse energy of the incident first pulse 11; when the pulse width of the first pulse 11 needs to be adjusted, the pulse width is adjusted by the pulse compressor 603.

The second laser pulse amplification system 62 is characterized by comprising a pulse stretcher 601 and at least one pulse amplifier 602, wherein the pulse stretcher 601 is used for stretching the pulse width of the incident second pulse 12, and the pulse amplifier 602 is used for amplifying the pulse energy of the incident second pulse 12;

6. a system for producing a double-pulse-driven laser light source for an EUV lithography light source according to any of claims 1 to 2, comprising a first laser pulse source 81 and a second laser pulse source 82;

the first laser pulse source 81 comprises a mode-locked oscillator 1, a pulse selector 2 and a first laser pulse amplification system 61; also comprises a pulse shaper 5;

the mode-locked oscillator 1 is used for generating ultrashort laser pulses with the wavelength range of 1800-2500 nm as first pulses 11; (ii) a

The pulse selector 2 is used for reducing the incident pulse sequence to a proper repetition frequency;

the pulse shaper 5 is used for modulating the shape of the time domain and the space domain of the first pulse 11;

the first laser pulse amplification system 61 comprises a pulse stretcher 601, at least one pulse amplifier 602 and optionally a pulse compressor 603; the pulse stretcher 601 is used for stretching the pulse width of the incident first pulse 11, and the pulse amplifier 602 is used for amplifying the pulse energy of the incident first pulse 11; when the pulse width of the first pulse 11 needs to be adjusted, the pulse width is adjusted by the pulse compressor 603.

The first laser pulse source 82 comprises a nanosecond pulse seed source 7, a pulse delay device 4 and a second laser pulse amplification system 62; optionally, the system further comprises a pulse shaper 5;

the nanosecond pulse seed source 7 is used for generating nanosecond laser pulses with the wavelength ranging from 1800 nm to 2500nm as second pulses 12;

the pulse delay device 4 is used for introducing an adjustable optical path difference between the first pulse 11 and the second pulse 12;

the pulse shaper 5 is used for modulating the shape of the time domain and the space domain of the second pulse 12;

the second laser pulse amplification system 62 comprises a pulse stretcher 601 and at least one pulse amplifier 602; the pulse stretcher 601 is used for stretching the pulse width of the incident first pulse 11, and the pulse amplifier 602 is used for amplifying the pulse energy of the incident first pulse 11.

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