High-power laser plasma EUV light source for lithography

Endo, Akira

doi:10.1117/12.548011

Cited by 4 publications

(4 citation statements)

References 13 publications

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“…In addition, a wide variety of pulsed discharge sources using xenon or xenon/helium mixtures are being actively investigated. A CE of 0.8% into a 2π solid angle has recently been reported [12].…”

Section: Introductionmentioning

confidence: 93%

UTA versus line emission for EUVL: studies on xenon emission at the NIST EBIT

Fahy¹,

Dunne²,

McKinney³

et al. 2004

J. Phys. D: Appl. Phys.

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Abstract:Spectra from xenon ions have been recorded at the NIST EBIT and the emission into a 2% bandwidth at 13.5 nm arising from 4d_5p transitions compared with that from 4d_4f and 4p_4d transitions in Xe XI and also with that obtained from the unresolved transition array (UTA) observed to peak just below 11 nm. It was found that an improvement of a factor of five could be gained in photon yield using the UTA rather than the 4d_5p emission. The results are compared with atomic structure calculations and imply that a significant gain in efficiency should be obtained using tin, in which the emission at 13.5 nm comes from a similar UTA, rather than xenon as an EUVL source material. BACKGROUND:The search for the optimum radiation source at 13.5 nm is one of the main challenges in EUV physics today. Currently the quest is to find a source with a conversion efficiency (CE) of 3% into 2% bandwidth as defined by the needs of the microelectronic industry [1]. The earliest work was performed with laser produced plasmas generated on solid targets. Kauffman et al. [2] attained a CE close to 1% into 3% bandwidth using 7.5 ns, 300 mJ frequency doubled Nd:YAG pulses focussed to a power density of 2×10 . In their work they performed an extensive survey of the emission from a large range of elements and found that the emission at the required wavelength peaked near tin. At higher power densities they noted that the intensity decreased. Shevelko et al. [4] also undertook an extensive study of the spectra of a large number of elements from laser produced plasmas with a KrF excimer laser focussed to a power density of 10 12 Wcm -2 onto planar targets including tin and found that the maximum intensity was in fact obtained for Ge and Re under these conditions. So early work already pointed to the sensitivity of the emission of specific elements to laser power density.In order to avoid the debris problems associated with solid targets other target materials were sought with strong emission in the 13-14 nm region. Jin and Richardson [5] used mass limited water ice targets, where the emission is from the O VI lines near 2 13 nm, to limit the debris. However, all of their early work with mass-limited targets produced significant levels of debris both in the form of ions and particulates of various sizes. The need to reduce particulate emission led to the choice of xenon. There is a line group between 13-14 nm in the spectrum of Xe which has been shown by a number of researchers to arise from 4d 8 _ 4d 7 5p transitions in Xe XI [6]. These lines have recently been identified by Churilov et al. [7] by comparison of new very high resolution data with atomic structure calculations using the suite of codes developed by Cowan [8]. Considerable work has been expended on exploring the feasibility of using laser produced plasmas of xenon clusters produced by supersonic jets or gas puffs from nozzles or solid xenon targets [9]. The highest conversion efficiencies (1.2% into 2% bandwidth) have been achieved using solid xenon by Shields et al. [1...

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Section: Introductionmentioning

confidence: 93%

UTA versus line emission for EUVL: studies on xenon emission at the NIST EBIT

Fahy¹,

Dunne²,

McKinney³

et al. 2004

J. Phys. D: Appl. Phys.

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“…The model is based on the partial differential equations (PDE) for the stationary heat convection and conduction. To solve the PDE's for laser rods with specific boundary conditions, the software Femlab from Comsol (Femlab 3.1, Comsol, 1994-2004 was utilized. The used material parameters for the Nd:YAG rod and the thin film coefficient of the water cooling flow are listed in Table 4.…”

Section: Thermal Properties Of Core Doped Ceramic Rodsmentioning

confidence: 99%

“…Examples of these applications are the generation of X-ray radiation for lithography (Endo, 2004), diagnostics of plasma by means of Thompson scattering (Mao et al, 2001), and inertial confinement fusion (ICF) (Kong et al, 2005a(Kong et al, , 2007. The Nd:glass gain medium exhibits larger volumes and a smaller cross section for stimulated emission than crystalline materials make it well suited to the storage requirements of high energy per pulse operation (Yamanaka et al, 1981).…”

Section: Introductionmentioning

confidence: 98%

Trends in stimulated Brillouin scattering and optical phase conjugation

et al. 2008

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An overview on current trends in stimulated Brillouin scattering and optical phase conjugation is given. This report is based on the results of the "Second International Workshop on stimulated Brillouin scattering and phase conjugation" held in Potsdam/Germany in September 2007. The properties of stimulated Brillouin scattering are presented for the compensation of phase distortions in combination with novel laser technology like ceramics materials but also for e.g., phase stabilization, beam combination, and slow light. Photorefractive nonlinear mirrors and resonant refractive index gratings are addressed as phase conjugating mirrors in addition.

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“…High-peak-power high energy pulse lasers of hundreds picoseconds play an important role in the fields of inertial confinement fusion (ICF) (Kong et al, 2005(Kong et al, , 2007a, diagnostics of plasma by means of Thompson scattering (Mao et al, 2001) and produce of X-ray radiation for lithography (Endo, 2004). Especially in the field of ICF, shock ignition is a new concept for direct-drive laser ICF that was proposed by Betti et al (2007).…”

Section: Introductionmentioning

confidence: 99%

The Current Trends in SBS and phase conjugation

et al. 2012

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The current trends in stimulated Brillouin scattering and optical phase conjugation are overviewed. This report is formed by the selected papers presented in the “Fifth International Workshop on stimulated Brillouin scattering and phase conjugation 2010” in Japan. The nonlinear properties of phase conjugation based on stimulated Brillouin scattering and photo-refraction can compensate phase distortions in the high power laser systems, and they will also open up potentially novel laser technologies, e.g., phase stabilization, beam combination, pulse compression, ultrafast pulse shaping, and arbitrary waveform generation.

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High-power laser plasma EUV light source for lithography

Cited by 4 publications

References 13 publications

UTA versus line emission for EUVL: studies on xenon emission at the NIST EBIT

UTA versus line emission for EUVL: studies on xenon emission at the NIST EBIT

Trends in stimulated Brillouin scattering and optical phase conjugation

The Current Trends in SBS and phase conjugation

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