Assumptions and trade-offs of extreme ultraviolet optics contamination modeling

Jindal, V. K.; Garg, Rashi; Denbeaux, Gregory; Wüest, Andrea

doi:10.1117/12.814188

Cited by 8 publications

(5 citation statements)

References 6 publications

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“…We found that the low-wavelength rate is approximately 4 times lower than the in-band rate over the pressure range (10 -8 to 10 -6 ) mbar. This trend of increasing contamination rate with wavelength is consistent with independent measurements 18 and calculations 19 . The wavelength dependence of other factors affecting the scaling behavior of contamination rates such as photon-stimulated desorption rates and intensity saturation are not known.…”

Section: Discussionsupporting

confidence: 90%

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Optics contamination studies in support of high-throughput EUV lithography tools

et al. 2011

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We report on optics contamination rates induced by exposure to broad-bandwidth, high-intensity EUV radiation peaked near 8 nm in a new beamline at the NIST synchrotron. The peak intensity of 50 mW/mm2 allows extension of previous investigations of contamination by in-band 13.5 nm radiation at intensities an order of magnitude lower. We report nonlinear pressure and intensity scaling of the contamination rates which is consistent with the earlier lower-intensity studies. The magnitude of the contamination rate per unit EUV dose, however, was found to be significantly lower for the lower wavelength exposures. We also report an apparent dose-dependent correlation between the thicknesses as measured by spectroscopic ellipsometry and XPS for the carbon deposits created using the higher doses available on the new beamline. It is proposed that this is due to different sensitivities of the metrologies to variations in the density of the deposited C induced by prolonged EUV irradiation

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Section: Discussionsupporting

confidence: 90%

“…The general trend of increasing contamination rate with wavelength in the rage (10 to 80) nm has been observed experimentally 18 and predicted by models 19 . A likely explanation of this behavior is that both the (gas phase) photoadsorption cross section and the secondary electron yield for C increase to a maximum around 70 nm.…”

Section: Wavelength Scalingmentioning

confidence: 82%

Optics contamination studies in support of high-throughput EUV lithography tools

et al. 2011

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“…Contamination of EUV optics by the interaction of radiation with residual hydrocarbons is still one of the major concerns with EUV exposure tools [1][2][3][4][5][6][7][8] . It is well known that the carbonaceous contamination on the surfaces of EUV mirrors is caused only in the region of the mirror exposed to radiation.…”

Section: Introductionmentioning

confidence: 99%

“…

Optics contamination remains one of the challenges in extreme ultraviolet (EUV) lithography [1][2][3][4][5][6][7][8] . Dependence of contamination rates on key EUV parameters was investigated.

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mentioning

confidence: 99%

Dependence of contamination rates on key parameters in EUV optics

et al. 2011

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Optics contamination remains one of the challenges in extreme ultraviolet (EUV) lithography [1][2][3][4][5][6][7][8] . Dependence of contamination rates on key EUV parameters was investigated. EUV tools have optics at different illumination angles. It was observed that at shallower angles, the carbon contamination rate and surface roughness was higher on the optics surface. This is a concern in EUV optics as higher roughness would increase the scattering of the EUV radiation. Secondary ion time of flight mass spectrometer (TOF-SIMS) data indicated that the carbon contamination film might be a polymer. Three chemical species were used to investigate the dependence of polymerization and reactivity on the contamination rate. Acrylic acid was found to have a measurable contamination rate above background compared to propionic acid and methyl methacrylate. Secondary electron dissociation is one of the mechanisms considered to be a cause for the growth of the carbon contamination film 1 . Multiple experiments with two substrates having different secondary electron yields were performed. The substrate with the higher secondary electron yield was found to give a higher contamination rate.

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“…Theoretical investigations were also carried out concerning the nonlinearity. 5,[10][11][12] We have studied contamination protection for surface oxidation 9,13) and carbon thin-film growth 14) using a highintensity undulator light source. We found that the nonlinear behavior of contamination growth is observed many times, such as the dependence of the decrease in reflectivity per unit dose of multilayer mirrors on EUV irradiance or the reflectivity distribution of doughnut shape, namely, high at the irradiation center, low in the surrounding area, and high in the non-irradiated area.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Behavior of Decrease in Reflectivity of Multilayer Mirrors for Extreme Ultraviolet Lithography Optics by High-Flux Extreme Ultraviolet Irradiation in Various Vacuum Environments

Niibe

Koida

Kakutani

et al. 2011

Jpn. J. Appl. Phys.

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The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl 4 following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photoninduced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states/doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl 4 lead to a remarkably enhanced production of anionic, Si − and Cl − , fragments and excited neutral atomic, Si * , fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl 4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.

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Assumptions and trade-offs of extreme ultraviolet optics contamination modeling

Cited by 8 publications

References 6 publications

Optics contamination studies in support of high-throughput EUV lithography tools

Optics contamination studies in support of high-throughput EUV lithography tools

Dependence of contamination rates on key parameters in EUV optics

Nonlinear Behavior of Decrease in Reflectivity of Multilayer Mirrors for Extreme Ultraviolet Lithography Optics by High-Flux Extreme Ultraviolet Irradiation in Various Vacuum Environments

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