CN112382915A - Method for improving power of LPP-EUV light source by burst mode pulse - Google Patents

Method for improving power of LPP-EUV light source by burst mode pulse Download PDF

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Publication number
CN112382915A
CN112382915A CN202011317370.XA CN202011317370A CN112382915A CN 112382915 A CN112382915 A CN 112382915A CN 202011317370 A CN202011317370 A CN 202011317370A CN 112382915 A CN112382915 A CN 112382915A
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CN
China
Prior art keywords
pulse
lpp
power
laser
euv
Prior art date
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Withdrawn
Application number
CN202011317370.XA
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Chinese (zh)
Inventor
吕欣林
彭宇杰
李妍妍
王温予
冯壬誉
冷雨欣
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Shanghai Institute of Optics and Fine Mechanics of CAS
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Shanghai Institute of Optics and Fine Mechanics of CAS
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Priority to CN202011317370.XA priority Critical patent/CN112382915A/en
Publication of CN112382915A publication Critical patent/CN112382915A/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
    • G03F7/2004—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70008—Production of exposure light, i.e. light sources
    • G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
    • H01S3/0085—Modulating the output, i.e. the laser beam is modulated outside the laser cavity

Abstract

A method of burst-mode pulsing boosting power of an LPP-EUV light source, comprising the steps of: modulating or converting a main drive carbon dioxide laser of LPP-EUV into a burst mode; amplifying a macro-pulse envelope formed by the pulse strings in a burst mode, wherein the pulse energy of the macro-pulse comprising a plurality of sub-pulses which is amplified and output is larger than the energy of a single pulse which is not modulated; the output average power of the high-frequency high-power carbon dioxide laser driving the LPP-EUV is improved, and the power of the LPP-EUV light source is further improved. The invention effectively reduces the nonlinear effect and the gain saturation effect brought by the laser amplification process, improves the output average power of the high-frequency high-power CO2 laser driving LPP-EUV, and has simple operation mode, science and effectiveness.

Description

Method for improving power of LPP-EUV light source by burst mode pulse
Technical Field
The invention belongs to the field of extreme ultraviolet light sources, and particularly relates to a method for improving the power of a laser plasma type extreme ultraviolet (LPP-EUV) light source by burst mode pulses. According to the method, the operation mode of the main drive carbon dioxide laser of the LPP-EUV light source is modulated into a burst mode, the peak power and flux density of a single laser pulse are reduced, the nonlinear effect and the gain saturation effect in the amplification process are reduced, the gain and extraction efficiency of the laser are improved, the output average power of the drive laser is improved, and therefore the power of the LPP-EUV light source is further improved.
Background
The development of integrated circuits has promoted the progress of the information society, and integrated circuits have been fabricated by integrating and packaging elements on a silicon wafer using a semiconductor fabrication process to form a microstructure having a certain circuit function. The photoetching machine is the core equipment for manufacturing the integrated circuit, the technical level determines the integration level of the integrated circuit, the current highest photoetching machine adopts an extreme ultraviolet light source as an exposure light source, and one of the core components is the extreme ultraviolet light source. The currently mainly adopted technical means for generating EUV light is Laser-driven plasma luminescence (LPP-EUV), specifically, picosecond short pulse pre-pulse Laser and nanosecond long pulse Carbon dioxide (Carbon dioxide, CO)2) The laser is irradiated on a target material such as tin, and radiation with the wavelength of 13.5nm is excited to be used as a light source of a photoetching machine. The currently commercially available EUV lithography machine light source can generate 250W of 13.5nm EUV radiation, and in order to meet the requirement of large-scale production of semiconductor lithography with a node less than 5nm, the output power of the lithography machine light source needs to be further improved.
In the currently common commercial EUV lithography machines, the EUV-driven laser is mostly composed of a pre-pulse laser and a main pump laser. Wherein the pre-pulse laser has high repetition rate (50kHz), high power (>100W), short pulses (<10ps), high stability (5%) solid state laser (wavelength 1 μm); the main pump laser has high repetition frequency (50kHz), high power (10-20 kW), long pulse (15-30 ns) and high beam quality (M)2<2) Carbon dioxide laser (wavelength 10.6 μm). Due to gain saturation and equal nonlinear effects in the laser amplification process, the output power is difficult to further improve.
Disclosure of Invention
The invention provides a method for improving the power of an LPP-EUV light source by burst mode pulses. The method is realized by driving main drive CO of LPP-EUV2The laser is modulated into a burst mode, a single laser pulse is modulated into a pulse train form containing a plurality of sub pulses, and a macro pulse envelope with the same repetition frequency as the original laser pulse is formed. In the mode, the high-frequency pulse strings form macro-pulse envelopes to be amplified, the peak power and the flux density of laser pulses are reduced, the nonlinear effect and the gain saturation effect brought in the laser amplification process can be reduced, high-gain amplification is realized, the pulse energy of each macro-pulse envelope amplified and output is larger than the energy of a single pulse which is not modulated, the output average power of the carbon dioxide laser is improved, and the power of the LPP-EUV light source is further improved.
The principle of the invention is as follows: in the currently commercially available EUV lithography machines, LPP-EUV main drive CO2Laser using high repetition frequency CO2The seed laser outputs pulsed light with average power higher than 10kW and repetition frequency of 50kHz through the technical scheme of laser amplification, and the pulse width is 15-30 ns. Because the laser pulse peak power and the flux density are higher, stronger nonlinear effect, gain saturation effect and the like exist in the laser amplification process, and the further improvement of the output power of the driving laser is limited. The laser is modulated or converted into burst mode operation by using a radio frequency excitation seed source or an electro-optical switch menu or the like, namely laser pulses are modulated into a pulse train comprising a plurality of sub-pulses, the time interval of each adjacent sub-pulse in a macro-pulse envelope is the same, and the repetition frequency of each macro-pulse envelope is the same as the repetition frequency (50kHz) of the unmodulated laser pulses. In a burst mode, a plurality of sub-pulses can be amplified simultaneously in one amplification period of the laser, the amplification capacity of the laser pulse is improved due to the fact that peak light intensity and energy flux density are reduced, nonlinear effect and gain saturation effect are relatively reduced, and finally the energy of each macro-pulse envelope amplified and output is larger than the energy of an unmodulated single laser pulse. The average output power of the carbon dioxide laser is increased in the burst mode, so that the output power of LPP-EUV light is further increased.
The invention is realized by the following technical scheme:
a method for improving the power of an LPP-EUV light source by burst mode pulse comprises the following specific steps:
firstly, a LPP-EUV main drive carbon dioxide laser is modulated or converted into a burst mode by methods of a radio frequency excitation seed source or an electro-optical switch and the like, namely, a single laser pulse is modulated into a pulse train form containing a plurality of sub-pulses, the time intervals of adjacent sub-pulses in the pulse train are the same, a macro-pulse envelope with the same repetition frequency as the original laser pulse is formed, and the peak power and the flux density of the single sub-pulse are reduced.
Amplifying the macro-pulse envelope formed by the pulse strings in a burst mode, wherein the peak power and the flux of the macro-pulse envelope are low, the nonlinear effect and the gain saturation effect brought in the laser amplification process can be reduced, high-gain amplification is realized, and the pulse energy of the amplified and output macro-pulse comprising a plurality of sub-pulses is larger than the energy of a single pulse which is not modulated.
And thirdly, the output average power of the high-frequency high-power carbon dioxide laser driving the LPP-EUV is improved, and the power of the LPP-EUV light source can be further improved.
The burst mode modulation method in the step (i) is, but not limited to, a radio frequency excitation seed source and an electro-optical on-state modulation method.
The invention has the following advantages:
the method can effectively reduce the nonlinear effect, the gain saturation effect and the like brought by the laser amplification process.
The method can effectively improve the output average power of the high-frequency high-power CO2 laser driving the LPP-EUV.
The method is simple in operation mode, scientific and effective.
Drawings
FIG. 1 shows raw CO without conditioning2Laser pulse time domain signal.
FIG. 2 is CO in burst mode2Laser pulse time domain signal.
Detailed Description
The invention aims to improve the power of an LPP-EUV light source. The method is used in an EUV lithography system, and the average output power of the laser is improved by modulating a main driving carbon dioxide laser of an LPP-EUV light source into a burst mode, so that the power of the LPP-EUV light source is further improved. The technology is simple, feasible, scientific and effective.
The invention is described in further detail below with reference to the figures and examples, but the scope of the invention should not be limited thereby. FIG. 1 shows raw CO without conditioning2The laser pulse time domain signal, the abscissa is time, and the repetition frequency is 50 kHz. FIG. 2 CO in burst mode2The laser pulse time domain signal, the abscissa is time, and the repetition frequency is 50 kHz. The invention aims to modulate the main drive carbon dioxide laser of the LPP-EUV light source shown in figure 1 into a burst mode shown in figure 2, namely, a single laser pulse is modulated into a pulse train form containing a plurality of sub-pulses, the time intervals of the adjacent sub-pulses in the pulse train are the same, and a macro-pulse envelope with the same repetition frequency as the original laser pulse is formed, so that the output average power of the carbon dioxide laser is improved, and the purpose of improving the power of the LPP-EUV light source is achieved.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

Claims (2)

1. A method for boosting power of an LPP-EUV light source by burst-mode pulses, the method comprising the steps of:
firstly, an LPP-EUV main drive carbon dioxide laser is modulated or converted into a burst mode, namely a single laser pulse is modulated into a pulse train form containing a plurality of sub-pulses, the time intervals of adjacent sub-pulses in the pulse train are the same, and a macro-pulse envelope with the same repetition frequency as the original laser pulse is formed;
amplifying a macro-pulse envelope formed by the pulse strings in a burst mode, wherein the pulse energy of the amplified and output macro-pulse comprising a plurality of sub-pulses is larger than the energy of a single pulse which is not modulated;
and thirdly, the output average power of the LPP-EUV high-frequency high-power carbon dioxide laser is driven to be improved, and the power of the LPP-EUV light source is further improved.
2. The method for boosting the power of an LPP-EUV light source by using burst-mode pulses as claimed in claim 1, wherein the burst-mode modulation method in step (i) is a radio frequency excitation seed source or an electro-optical open-light modulation method.
CN202011317370.XA 2020-11-23 2020-11-23 Method for improving power of LPP-EUV light source by burst mode pulse Withdrawn CN112382915A (en)

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Application Number Priority Date Filing Date Title
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101687102A (en) * 2007-07-13 2010-03-31 西默股份有限公司 Laser produced plasma EUV light source
CN102169269A (en) * 2011-01-26 2011-08-31 阮双琛 Light pulse repetition rate expander and laser application system
US20120223256A1 (en) * 2011-03-02 2012-09-06 Cymer, Inc. Systems and methods for optics cleaning in an euv light source
CN110364921A (en) * 2019-07-09 2019-10-22 大族激光科技产业集团股份有限公司 Laser pulse control system and laser pulse control method
CN111786251A (en) * 2020-07-28 2020-10-16 广东瀚盈激光科技有限公司 Fiber laser pulse train generation and amplification module and fiber laser

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101687102A (en) * 2007-07-13 2010-03-31 西默股份有限公司 Laser produced plasma EUV light source
CN102169269A (en) * 2011-01-26 2011-08-31 阮双琛 Light pulse repetition rate expander and laser application system
US20120223256A1 (en) * 2011-03-02 2012-09-06 Cymer, Inc. Systems and methods for optics cleaning in an euv light source
CN110364921A (en) * 2019-07-09 2019-10-22 大族激光科技产业集团股份有限公司 Laser pulse control system and laser pulse control method
CN111786251A (en) * 2020-07-28 2020-10-16 广东瀚盈激光科技有限公司 Fiber laser pulse train generation and amplification module and fiber laser

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Application publication date: 20210219