Monte Carlo modeling of the photo and Auger electron production in X-ray lithography with synchrotron radiation

Murata, Kenji; Kotera, Masatoshi; Nagami, Koichi; Namba, Susumu

doi:10.1109/t-ed.1985.22182

Cited by 29 publications

(19 citation statements)

References 15 publications

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“…This approximation was obtained by fitting numerical calculations of the CSDA range over the range of energies from 0.1 to 100 keV. The expression agrees with Murata's formulation [20,25] of the CSDA range to within 5% over these energies, based on a mean ionization energy of 70.9 eV and a zero lower bound on the electron energy.…”

Section: Mathematical Modelsupporting

confidence: 62%

“…However, there has been relatively little study of the effect of this distribution on the two-dimensional history of development and resulting developed feature geometry. A few previous papers have addressed this aspect of the problem [19,20,23], but these investigations were motivated by microelectronics manufacturing and addressed only soft x-rays and a resist thickness of 1 pm or less. Only two of these efforts [20,23] considered the multi-wavelength x-ray spectrum characteristic of synchrotron radiation.…”

Section: Introductionmentioning

confidence: 99%

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Fundamental limitations of LIGA x-ray lithography: sidewall offset, slope and minimum feature size

Griffiths¹

2004

J. Micromech. Microeng.

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and numerical methods are used to examine photoelectron d ,oses and th ieir effect on the dimensions of features produced by deep x-ray lithography. New analytical models describing electron doses are presented and used to compute dose distributions for several feature geometries. The history of development and final feature dimensions are also computed, taking into account the dose field, dissolution kinetics based on measured development rates, and the transport of PMMA fragments away from the dissolution front. We find that sidewall offsets, sidewall slope and producible feature sizes all exhibit at least practical minima and that these minima represent fundamental limitations of the LIGA process. The minimum values under optimum conditions are insensitive to the synchrotron spectrum, but depend strongly on resist thickness. This dependence on thickness is well approximated by simple analytical expressions describing the minimum offset, minimum sidewall slope, minimum producible size of positive and negative features, maximum aspect ratio and minimum radius of inside and outside corners.

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Section: Mathematical Modelsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Fundamental limitations of LIGA x-ray lithography: sidewall offset, slope and minimum feature size

Griffiths¹

2004

J. Micromech. Microeng.

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“…3 The photoionization cross section data and the fluorescence data were obtained from the physical reference data of the National Institute of Standards and Technology Physics Laboratory 11 and Ref. 12, respectively.…”

Section: Experimental and Simulation Methodsmentioning

confidence: 99%

“…Hence, the substrategenerated electrons easily overexpose the resist near the substrate. Since Maldonado et al first noted 1 this problem, numerous theoretical and experimental results [2][3][4][5][6][7][8][9] have been reported. Furthermore, some articles [5][6][7] introduced buffer layers to eliminate the substrate photoelectron effects.…”

Section: Introductionmentioning

confidence: 99%

Resist profile characteristics caused by photoelectron and Auger electron blur at the resist–tungsten substrate interface in 100 nm proximity x-ray lithography

Seo

Lee

Seo

et al. 2000

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

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The replicated resist pattern characteristics caused by photoelectrons and Auger electrons generated from the W substrate were investigated for 100 nm proximity x-ray lithography. In addition, simulations for a hard x-ray spectrum having 2.36 keV average energy were performed to investigate the substrate electron effects in hard x-ray lithography. In the experiments, it was found that the secondary electrons from the W substrate caused undercut and footing of resist profiles at the resist–substrate interface. Several buffer layers with varying thicknesses were tested to reduce the photoelectron effects from the W substrate. The best thickness of the buffer layers for a good resist pattern profile was discovered to be >30 nm. Furthermore, the experimental results were quantitatively compared to the results from computer simulations using the Monte Carlo method. For hard x rays, we predict that the exposure latitude is worse on both W and Si substrates.

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“…1͑c͒. 9 Finally, secondary electrons are absorbed in the resist. For lateral image formation, TOOLSET, an x-ray lithography simulator developed at the University of Wisconsin, is used.…”

Section: Introductionmentioning

confidence: 99%

Suppression of secondary electron blur by using Br-containing resists in x-ray lithography

Kise

Marumoto

Watanabe

et al. 2002

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

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Second generation proximity x-ray lithography (PXL-II), which uses shorter incident x-ray wavelengths and resist materials, is expected to be a candidate for next generation lithography. In the PXL-II technique, the x-ray wavelength absorbed in the resist becomes shorter, but degradation of the pattern quality due to secondary electron blur has not been sufficiently evaluated. In this article, we present our investigation of the secondary electron blur’s suppression in Br-containing resist using a lithographic simulator and a Monte Carlo simulator for electron scattering. By introducing the Br element into resist materials, the electron stopping power improves. In addition, secondary electron blur is suppressed in regions with wavelengths shorter than that of the Br absorption edge. In order to evaluate pattern resolution, the image contrast of the lateral absorbed image in the resist is defined. We found that image contrast is improved in Br-containing resist for the wavelength range down to about 4.5 Å, which is suitable for PXL-II. We also show that it should be possible to extend PXL-II for resolutions of less than 40 nm at a narrower gap.

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Monte Carlo modeling of the photo and Auger electron production in X-ray lithography with synchrotron radiation

Cited by 29 publications

References 15 publications

Fundamental limitations of LIGA x-ray lithography: sidewall offset, slope and minimum feature size

Fundamental limitations of LIGA x-ray lithography: sidewall offset, slope and minimum feature size

Resist profile characteristics caused by photoelectron and Auger electron blur at the resist–tungsten substrate interface in 100 nm proximity x-ray lithography

Suppression of secondary electron blur by using Br-containing resists in x-ray lithography

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