Development of Laser-Produced Tin Plasma-Based EUV Light Source Technology for HVM EUV Lithography

Fujimoto, Junichi; Hori, Tsukasa; Yanagida, Takeshi; Mizoguchi, Hideaki

doi:10.1155/2012/249495

Cited by 16 publications

(5 citation statements)

References 14 publications

(18 reference statements)

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“…A not−so−rough estimate of the required laser power for a pulse of 10ns FWHM duration and a peak intensity of 1·10 11 Wcm -2 on a~200 μm diameter [34] of the EUV emitting plasma [31] is possible with a knowledge of em− pirical CE values reported so far. Assuming a top−hat beam profile, one gets 315 mJ of required laser pulse energy, which after accounting for an experimental CE of 2.5% [35] obtained with~20 ns pulses and~25% of total EUV collection and transmission efficiency up to the IF of the source, yields about 2 mJ of in−band EUV energy per pulse of 10ns duration. The CO 2 laser driver must therefore deliver at least 18.1 kW average power to satisfy the HVM power requirement, with pulse repetition frequency higher than 57.5 kHz.…”

Section: Pulse Format Requirements For 135 Nm Lpp Euv Sourcementioning

confidence: 99%

CO2 laser drives extreme ultraviolet nano-lithography — second life of mature laser technology

Nowak

Ohta

Suganuma

et al. 2013

Opto-Electronics Review

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It was shown both theoretically and experimentally that nanosecond order laser pulses at 10.6 micron wavelength were superior for driving the Sn plasma extreme ultraviolet (EUV) source for nano-lithography for the reasons of higher conversion efficiency, lower production of debris and higher average power levels obtainable in CO2 media without serious problems of beam distortions and nonlinear effects occurring in competing solid-state lasers at high intensities. The renewed interest in such pulse format, wavelength, repetition rates in excess of 50 kHz and average power levels in excess of 18 kiloWatt has sparked new opportunities for a matured multi-kiloWatt CO2 laser technology. The power demand of EUV source could be only satisfied by a Master-Oscillator-Power-Amplifier system configuration, leading to a development of a new type of hybrid pulsed CO2 laser employing a whole spectrum of CO2 technology, such as fast flow systems and diffusion-cooled planar waveguide lasers, and relatively recent quantum cascade lasers. In this paper we review briefly the history of relevant pulsed CO2 laser technology and the requirements for multi-kiloWatt CO2 laser, intended for the laser-produced plasma EUV source, and present our recent advances, such as novel solid-state seeded master oscillator and efficient multi-pass amplifiers built on planar waveguide CO2 lasers.

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Section: Pulse Format Requirements For 135 Nm Lpp Euv Sourcementioning

confidence: 99%

CO2 laser drives extreme ultraviolet nano-lithography — second life of mature laser technology

Nowak

Ohta

Suganuma

et al. 2013

Opto-Electronics Review

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“…Coherent light from pulsed lasers, focused onto gaseous, liquid, or solid targets, can induce plasmas that are capable of emitting radiation from the soft X-ray [3] to the mid-infrared region [4]. Very hot plasmas, emitting in the EUV, can be generated by employing high powered, high repetition rate (>MHz) pulsed lasers focused onto a high pressure, pulsed jet of xenon gas that is sometimes mixed with particulate matter (e.g., Sn) to promote laser absorbance [5,6]. Another promising candidate for the generation of EUV radiation is pulsed capillary discharge sources [7,8].…”

Section: Introductionmentioning

confidence: 99%

An Inexpensive, Pulsed, and Multiple Wavelength Bench-Top Light Source for Biological Spectroscopy

Holman

Skidmore

Yates

2018

Plasma

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Since signal/noise ratios are proportional to the square root of the intensity, high intensity light sources are advantageous for many forms of UV–Vis and IR spectroscopy particularly with very low or high absorbance samples. We report the construction of a low-cost (≈ £6500 GBP, ca. 2016) bench-top spectrometer suitable for biological spectroscopy, which utilizes a hot plasma, generated with a pulsed Nd:YAG laser (λ = 1064 nm). The properties (reliability, intensity, and spectral profiles) of light generated with the plasma in different gaseous media (helium, neon, argon, and krypton) were investigated. Argon provided high intensity broadband light and was the most cost effective. The instrument was compared for spectral accuracy to a commercially available spectrometer (Thermo Scientific, GENESYS 10S) by measurement of the absorbance spectrum of the UV–Vis calibration standard holmium (III) oxide (4%, w/v) in perchloric acid (10%, w/v) and accurately replicated the results of the commercial spectrometer. This economical instrument can record consecutive absorbance spectra (between λ = 380 and 720 nm) for each laser pulse (6 Hz; ~160 ms/pulse), evinced by investigations into lysozyme aggregation in the presence of heparin. This instrument is suitable for use with lasers of a higher pulse power and repetition rates that would induce higher temperature plasmas. Higher temperature plasma sources offer increased signal to noise ratios due to the higher intensity emission generated.

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“…The latter solution reduces the amount of backscattered light and by decoupling both laser systems it prevents instabilities and potential damage to the lasers, at the expense of added complexity in the EUV lithography machine. The interaction between a tin droplet and a nanosecond pre-pulse leads to the generation of a high-density disk target and results in a reported conversion efficiency of 4.7% [25]. Alternatively, a picosecond pre-pulse could be employed that expands the droplet to a low-density diffuse target resembling an acorn [26,27], which has a significantly higher surface to volume ratio compared to a disk target, ensuring improved light absorption and, consequently, higher CE with the maximum reported value of 6% [1].…”

mentioning

confidence: 99%

Controlling ion kinetic energy distributions in laser produced plasma sources by means of a picosecond pulse pair

Stodolna

Pinto

Ali

et al. 2018

Journal of Applied Physics

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The next generation of lithography machines uses extreme ultraviolet (EUV) light originating from laser-produced plasma (LPP) sources, where a small tin droplet is ionized by an intense laser pulse to emit the requested light at 13.5 nm. Numerous irradiation schemes have been explored to increase conversion efficiency (CE), out of which a double-pulse approach comprising a weak picosecond Nd:YAG pre-pulse followed by a powerful pulse is considered to be very promising [1]. Nevertheless, even for such CE-optimized schemes, ion debris ejected from the plasma with kinetic energies up to several keV remain a factor that hampers the maximum performance of LPP sources. In this letter we propose a novel pre-pulse scheme consisting of a picosecond pulse pair at 1064 nm, which decreases the amount of undesirable fast ions, avoids back-reflections to the lasers and enables one to tailor the target shape.In the past two decades a large number of theoretical and experimental studies have been conducted on possible light sources for EUV lithography, including synchrotron radiation [2, 3], free-electron lasers [4,5], plasma sources [6-10] and high-harmonic generation [11]. From the aforementioned solutions, a tin-based laser-produced plasma source received the most attention due to its high conversion efficiency, robustness and scalability [12,13], resulting in a first commercial machine launched in 2010. In such an LPP source, narrowband radiation around 13.5 nm comes from multiple ionic states, Sn 8+ to Sn 14+ [14,15], collisionally excited by plasma electrons heated through interaction with a powerful CO2 laser. An effective coupling between laser light and plasma occurs near the critical density, which for CO2-laser-driven plasma is around 10 19 cm -3 , meaning that a mass-limited tin target should be expanded to reduce its density. At the same time the size of the EUV source cannot be too large to match the requirements for the maximum etendue [16]. The precise control of the target shape is thus crucial for the production of EUV light in an industrial setting.

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Development of Laser-Produced Tin Plasma-Based EUV Light Source Technology for HVM EUV Lithography

Cited by 16 publications

References 14 publications

CO2 laser drives extreme ultraviolet nano-lithography — second life of mature laser technology

CO2 laser drives extreme ultraviolet nano-lithography — second life of mature laser technology

An Inexpensive, Pulsed, and Multiple Wavelength Bench-Top Light Source for Biological Spectroscopy

Controlling ion kinetic energy distributions in laser produced plasma sources by means of a picosecond pulse pair

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