Evaluation of characteristics of VUV optical materials irradiated by F 2 laser

Itakura, Yasuo; Yoshida, Fumika; Kawasa, Youichi; Sumitani, Akira; Wakabayashi, Osamu; Mizoguchi, Hideaki

doi:10.1117/12.435641

Cited by 2 publications

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“…laser power, laser repetition rate and laser temporal pulse shapes. Komatsu developed a VUV evaluation system, and presented cleaning effects by F 2 laser irradiation and 2 billion pulses (Bpls) durability test results of CaF 2 substrates and of F 2 laser coatings 5 . For high precision measurements of 157nm optical materials, Komatsu and Selete developed a system, which measures in-situ the real-time transmittance at 157nm during F 2 laser irradiation and the spectral transmittance in the VUV region directly after laser irradiation 6 .…”

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confidence: 99%

Study of resist outgassing by F 2 laser irradiation

Itakura

Kawasa

Sumitani

et al. 2003

Advances in Resist Technology and Processing XX

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F 2 laser lithography at 157nm is the most promising candidate of post-ArF excimer laser lithography. A major concern, however, is the deterioration of 157nm optics due to contamination under F 2 laser irradiation. An evaluation of outgassed products of 157nm resist and their effect on optical materials and is therefore indispensable for F 2 laser lithography. Semiconductor Leading Edge Technologies Inc. (Selete) and Komatsu Ltd. designed and constructed a resist outgassing evaluation system in order to develop exposure tools and resists for 157nm lithography. The system determines the negative effects of outgassing resist contaminants on the transmittance of optical materials under F 2 laser irradiation. The system has two units. One unit collects resist outgas and analyzes sampled gas in a gas chromatograph mass spectrometer (GC-MS). The other unit is a resist outgassing adhesion unit, which measures the transmittance change of optical materials due to contamination adhesion in real-time. Our analysis showed that most outgassed products were from the resist protecting groups and photo acid generators (PAG) including small hydrocarbons like isobutene, benzene derivatives and dimethoxymethane. After irradiating a 157nm lithography resist with a total dose of 30J/cm 2 the transmittance of a calcium fluoride (CaF 2 ) substrate decreased from initially 90% to 85%. This was due to adhesion contamination as x-ray photoelectron spectroscopy (XPS) analysis showed an organic contamination deposition of over 5nm thickness on the CaF 2 substrate.

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Section: Introductionmentioning

confidence: 99%

Study of resist outgassing by F 2 laser irradiation

Itakura

Kawasa

Sumitani

et al. 2003

Advances in Resist Technology and Processing XX

Self Cite

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“…5) CaF 2 is the primary material used in optics, including lenses in F 2 laser lithography, and the tolerance of vacuum-ultraviolet (VUV)grade CaF 2 single crystals against F 2 laser irradiation has been extensively investigated. [7][8][9] F-doped fused silica has also been developed with an improved transmittance at 157 nm, 10) and is expected as a material for photomasks, 6) not for lenses. Thus, there has been a strong request for the so-called ''second material'' to combine with CaF 2 for F 2 laser lithography.…”

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Effect of Annealing on the Tolerance of LiCaAlF₆ Single Crystals against F₂ Laser Irradiation

Kawaguchi¹,

Narazaki²,

Sato³

et al. 2004

Jpn. J. Appl. Phys.

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The optical tolerance of annealed LiCaAlF6 single crystals against F2 laser irradiation was investigated. Annealed LiCaAlF6 (t=1.45 mm) shows an improved transmittance at 157 nm, 94.4% after the compensation of the surface reflection loss. Furthermore, after the initial increase by F2 laser cleaning, transmittance at 157 nm remains almost unchanged even after irradiation with a F2 laser beam up to 105 pulses at a fluence of approximately 160 mJ cm-2 pulse-1.

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Evaluation of characteristics of VUV optical materials irradiated by F 2 laser

Cited by 2 publications

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Study of resist outgassing by F 2 laser irradiation

Study of resist outgassing by F 2 laser irradiation

Effect of Annealing on the Tolerance of LiCaAlF₆ Single Crystals against F₂ Laser Irradiation

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Evaluation of characteristics of VUV optical materials irradiated by F 2 laser

Cited by 2 publications

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Study of resist outgassing by F 2 laser irradiation

Study of resist outgassing by F 2 laser irradiation

Effect of Annealing on the Tolerance of LiCaAlF6 Single Crystals against F2 Laser Irradiation

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Effect of Annealing on the Tolerance of LiCaAlF₆ Single Crystals against F₂ Laser Irradiation