A reflectance measurement system for investigating radiation damage to EUVL mirrors in NewSUBARU

Kakutani, Yukinobu; Niibe, Masahito; Kakiuchi, Kazuya; Takase, Hiromitsu; Terashima, Shigeru; Kondo, Hiroyuki; Matsunari, Shuichi; Aoki, Takashi; Gomei, Yoshio; Fukuda, Yasunari

doi:10.1117/12.559395

Cited by 7 publications

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“…The atmosphere condition during the irradiation was selected at 1.3×10 2 Pa H 2 O to quickly observe the reflectance drop, because it occurred at higher water vapor pressure, as shown in Table 1. 3 The irradiation conditions are shown in Table 2 for the Si-capped MLMs and Table 3 for the Ru-capped MLMs. An individual sample was used for Table 1.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Reflectance drop rate as a function of the dose measured in the present and the previous report (?). 3 The power was varied because the SR was operated in the decay mode (not the top-up operation) when the previous work was performed. Reflectance drop rate was estimated by the line fitting using the least square method.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The specification of the system was described in the previous report. 3 Coarsely monochromized EUV by the MLM (not using for the sample) was irradiated onto the sample, which was mounted on x-z stages placed on the -2 stages, as shown in Fig. 1.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The result of the Si-capped sample irradiated at the base pressure was plotted in reference to the previous report. 3 The relative reflectances of the Si-capped samples were reduced by the increasing of the dose although those of the Ru-capped samples were kept at almost 1, as shown in Table 1. The Ru-capped sample was more resistant against water vapor than the Si-capped sample, as mentioned earlier.…”

Section: Difference Of the Capping Layermentioning

confidence: 97%

“…According to previous results, however, the reflectance of the Sicapped multilayer was quickly reduced by the EUV irradiation, and the Ru-capped one was slowly reduced in water vapor. 3 In this paper, EUV irradiations were performed for Si-and Ru-capped Mo/Si MLMs. Di erences in the irradiation power for Si-capped MLMs and in the top layer materials for capped MLMs are reported.…”

Section: Introductionmentioning

confidence: 99%

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Reflectance change of Si- and Ru-capped Mo/Si multilayer mirrors caused by intense EUV irradiation

Kakutani

Niibe

Takase³

et al. 2005

SPIE Proceedings

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An EUV irradiation and reflectance measurement system using intense EUV radiation emitted from a long undulator at the NewSUBARU synchrotron radiation (SR) facility was developed. The system can measure the real-time reflectance drop during intense EUV irradiation and reflectance mapping as well as the photoemission current after irradiation at a fixed energy for atom absorption. The irradiated EUV beam was very intense, and the power density was about 400 mW/mm 2 . The reflectances of Si-and Ru-capped Mo/Si multilayer mirrors (MLMs) were measured under several conditions of EUV power, i.e., 120, 15, and 5 mW/mm 2 for Si-capped MLMs, or of water vapor, i.e., 6.6×10 5 and 1.3×10 2 Pa for Ru-capped MLMs. Each reflectance was reduced as the dose was increased. The reflectance was significantly reduced at the higher partial pressure of water vapor. When the intensity of the beam flux was reduced using ND filters, the reflectance was significantly reduced under the same conditions of atmosphere and dose. Carbon cleaning and oxidation were progressed in the beam center although carbon deposition was much progressed in the beam fringe for Si-capped MLM. Ru-capped MLM was more resistant to radiation damage than Si-capped MLM at each partial pressure of water vapor. The results of X-ray photoelectron spectroscopy (XPS) for Ru-capped MLM showed that deposited and desorbed carbons were balanced at the beam center and carbon deposition occurred on the fringe of the beam.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Difference Of the Capping Layermentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Reflectance change of Si- and Ru-capped Mo/Si multilayer mirrors caused by intense EUV irradiation

Kakutani

Niibe

Takase³

et al. 2005

SPIE Proceedings

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Extreme ultraviolet lithography: A review

Wu¹,

Kumar²

2007

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

349

177

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Extreme ultraviolet lithography (EUVL) was thoroughly reviewed over a broad range of topics, including history, tools, source, metrology, condenser and projection optics, resists, and masks. Since 1988, many studies on EUVL have been conducted in North America, Europe, and Japan, through state sponsored programs and industrial consortiums. To date, no “show stopper” has been identified, but challenges are present in almost all aspects of EUVL technology. Commercial alpha lithography step-and-scan tools are installed with full-field capability; however, EUVL power at intermediate focus (IF) has not yet met volume manufacturing requirements. Compared with the target of 180W IF power, current tools can supply only approximately 55–62W. EUV IF power has been improved gradually from xenon- to tin-discharge-produced plasma or laser-produced plasma. EUVL resist has improved significantly in the last few years, with 25nm 1:1 line/space resolution being produced with approximately 2.7nm (3σ) line edge roughness. Actual adoption of EUVL will depend on the extension of current optical lithography, such as 193nm immersion lithography, combined with double patterning techniques. Mask fabrication and application technologies may be the most substantial challenges. Creating a defect-free EUVL mask is currently an obstacle to its application, although a combination of removable pellicle and thermophoretic protection may overcome nonpellicle challenge. Cost of ownership is a critical consideration for EUVL; nevertheless, it has been predicted that EUVL may be in pilot production at 32nm and in large-scale production at 22nm with the capability to extend to the next technology node.

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Effect of radiation on the defectivity and stability of Ru-capped MoSi multilayer blanks

Rastegar¹,

Durkaya²,

Cepler³

et al. 2012

SPIE Proceedings

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During their usage and fabrication, EUV masks are exposed to light radiation from λ=13.5 nm up to infrared wavelengths. During EUV exposure, masks are not only exposed to 13.5 nm radiation but also to out-of-band radiation which expands from λ=140 to 600 nm for a long period of time. The mask surface is also exposed to different chemicals during cleaning processes, depending on the usage of the mask. During its effective life, an EUV mask should undergo many cycles of cleaning and radiation. Consequently, the Ru surface is modified by photon energy (wavelength) as well as number of photons (intensity and energy). This modified Ru surface will react with chemicals in different ways. Exposure to 172 nm light followed by Ammonium Hydroxide/ Hydrogen peroxide/ water mixture (APM) will result in 0.5% loss of EUV light while 172nm light exposure followed by Sulfuric acid /Hydrogen peroxide mixture (SPM) will reduce EUV reflectivity by 3%. Higher radiation energy on the order of 200 Joules will damage the Ru surface and cause increased defectivity at the mask surface. In addition, higher radiation energies will result in thermal effects such as formation of Ru silicide and Mo silicide. Ru oxidation valence also depends on the radiation power and radiation wavelength. In the absence of radiation or low energy radiation, RuO 3 is preferred oxidation state but RuO is preferred in the higher radiation energies. Comparison between 532 nm and 1064 nm radiation showed that RuO 2 is the preferred oxidation state at a wavelength of 532 nm, despite much lower radiation power.

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A reflectance measurement system for investigating radiation damage to EUVL mirrors in NewSUBARU

Cited by 7 publications

References 0 publications

Reflectance change of Si- and Ru-capped Mo/Si multilayer mirrors caused by intense EUV irradiation

Reflectance change of Si- and Ru-capped Mo/Si multilayer mirrors caused by intense EUV irradiation

Extreme ultraviolet lithography: A review

Effect of radiation on the defectivity and stability of Ru-capped MoSi multilayer blanks

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