In-situ measurements of VUV optical materials for F2 laser

Sumitani, Akira; Itakura, Yasuo; Yoshida, Fumika; Kawasa, Youichi; Zhang, Jing; Kanda, Noriyoshi; Itani, Toshiro

doi:10.1117/12.474557

Cited by 3 publications

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“…The development of high performance exposure components and tools requires therefore an evaluation system of 157nm optical materials and outgassed products. directly after laser irradiation 7 . We performed durability tests of un-coated and coated CaF 2 substrates with our 4kHz F 2 laser for more than 10 Bpls and pointed out that the elimination of contaminants from the laser, especially of silicon compounds, and the careful selection of coatings were indispensable for durable F 2 laser optical components.…”

Section: Introductionmentioning

confidence: 99%

Evaluation systems of F 2 laser lithography materials

et al. 2004

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In this paper, we present an evaluation system for F 2 laser lithography masks and resists and we report preliminary test results. The evaluation system has two subsystems that are based on very accurate measurement technology. One subsystem is used for mask evaluation, the other subsystem for resist evaluation. The mask subsystem consists of two units. One unit evaluates real size 6025 binary masks placed horizontally as inside steppers. This unit measures three parameters: 1) the real time in-situ transmittance at 157nm during F 2 laser irradiation, 2) the in-situ VUV transmittance using a VUV spectrophotometer and 3) the deformation of the pellicle. The precision of transmittance measurement at 157nm is +/-0.5%. The precision of the pellicle deformation measurement is +/-0.1μ m. The second unit of the mask subsystem collects samples of the mask outgassing and analyzes them in a gas chromatograph mass spectrometer. The resist evaluation subsystem consists of three units. 1) One unit determines negative effects of outgassing resist contaminants on the transmittance of optical materials under F 2 laser irradiation, 2) the second unit analyzes the outgassing from resists and 3) the third unit examines the effectiveness of exposure tool purge nozzles to reduce outgassing contamination.

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Section: Introductionmentioning

confidence: 99%

Evaluation systems of F 2 laser lithography materials

et al. 2004

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“…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 . The real-time transmittance measurement has a repeatability of +/-0.5%.…”

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

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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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Evaluation of outgassing from a fluorinated resist for 157nm lithography

Irie¹,

Hagiwara²,

Fujii³

et al. 2004

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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We have evaluated the outgassing products and the in situ transmittance of a contaminated CaF 2 substrate for monocyclic fluoropolymers with four protecting groups: methoxymethyl (MOM), tert-butoxycarbonyl (t-BOC), menthoxymethyl, and 2-cyclohexylcyclohexyloxymethyl. We found little correlation between the total amount of outgassing from the polymer and the decreasing rate of the CaF 2 substrate transmittance caused by outgassing adhesion. Although the MOM protecting group generated the largest amount of outgassing products, the most substantial decrease in the transmittance was observed for the t-BOC protecting group. Therefore, the absorption coefficient of the outgassing-contaminated CaF 2 substrate appears to be more sensitive to the type of protecting group, especially the t-BOC protecting group including a t-butyl unit. We conclude that in terms of material design of the fluoropolymer resist for 157 nm lithography, we need to pay attention to the protecting group of polymers, especially the protecting group including a t-butyl unit, which generates isobutene product during 157 nm irradiation.

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In-situ measurements of VUV optical materials for F2 laser

Cited by 3 publications

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Evaluation systems of F 2 laser lithography materials

Evaluation systems of F 2 laser lithography materials

Study of resist outgassing by F 2 laser irradiation

Evaluation of outgassing from a fluorinated resist for 157nm lithography

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