Extreme Ultraviolet Spectroscopy of a Laser Plasma Source for Lithography

Shevelko, A. P.; Shmaenok, L. A.; Churilov, S S; Bastiaensen, R. K. F. J.; Bijkerk, F.

doi:10.1088/0031-8949/57/2/023

Cited by 43 publications

(19 citation statements)

References 16 publications

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“…Assuming an isotropic plasma emission, a conversion efficiency of 0.5% of the laser energy (4π sr, bandwidth 4% FWHM @ 13nm) for the Xe target and 0.1% for O 2 (bandwidth 0.5%) is obtained. As compared to results of other groups [19][20][21], and considering the narrow bandwidth especially for O 2 these data represent rather high efficiencies. In order to increase the soft X-ray intensity, the relationship between the laser energy and the EUV yield was investigated for the Xe target (single solenoid valve).…”

Section: Intensity Measurementssupporting

confidence: 54%

Plasma characterization in the extreme ultraviolet spectral range

Kranzusch¹,

Mann²,

Peth³

2002

SPIE Proceedings

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At Laser-Laboratorium Göttingen different laser-plasma sources were tested, which are going to be used for characterization of optical components and sensoric devices in the wavelength region from 11 to 13nm. In all cases EUV radiation is generated by focussing a Q-switched Nd:YAG laser into a gas puff target. By the use of xenon or oxygen as target gas, broadband as well as narrowband EUV radiation is obtained, respectively. Different types of valves and nozzles were tested in order to optimize the emitted radiation with respect to maximum EUV intensities, small source diameters and pointing stability. The investigation of these crucial source parameters was performed with specially designed EUV pinhole cameras, utilizing evaluation algorithms developed for standardized laser beam characterization. In addition, a rotatable pinhole camera was developed which allows spatially and angular resolved monitoring of the soft X-ray emission characteristics. With the help of this camera a strong angular dependence of the EUV intensity was found. The results were compared with fluorescence measurements for visualization of the target gas jet. To explain these results a theoretical model was developed, including the absorptance of the EUV radiation in the surrounding target gas.

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Section: Intensity Measurementssupporting

confidence: 54%

Plasma characterization in the extreme ultraviolet spectral range

Kranzusch¹,

Mann²,

Peth³

2002

SPIE Proceedings

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“…This extrapolated value of the trapping efficiency corresponds to a residual deposition rate of 0.01 ng/sr shot, a total de-contamination effect of FRT and foil trap applied at an initial source debris production of about 1 gig/shot. This, relatively high, value results from the specific target irradiation conditions used in these experiments, notably the long (27 ns) laser pulse duration [5].…”

Section: Results On Trapping Efficiencymentioning

confidence: 99%

Demonstration of a foil trap technique to eliminate laser plasma atomic debris and small particulates

et al. 1998

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A novel method of filtering out atoms and small particulates, emitted from a laser plasma EUV radiation source, has been developed and experimentally characterized. The method consists of elimination of debris species by an optically transparent assembly of foils positioned in a buffer gas environment near the source. A high trapping efficiency is achieved due to retardation and scattering of particles in the gas and subsequent deposition on the foils. The method imposes no limitations of the radiation acceptance angle. The foil trap technique, a debris suppression method universally applicable for different EUVL radiation sources, has been investigated in combination with a fast rotating laser plasma target. A target unit with a disk edge velocity of up to 500 rn/s enabling nearly full elimination of large particulates, served as a source of different debris components for experiments on foil trapping atoms and sub-micron particulates. An integrated suppression coefficient of 500 has been measured for debris with sizes of up to a micrometer using a pilot trap cooled down to -90 °C. Extrapolation of this data to conditions when debris of sub-micron size only is produced, resulted in a suppression coefficient of 2000.

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“…Depending on the application and the required wavelength region, different target concepts come into consideration. Highest conversion efficiencies from laser energy into EUV radiation are obtained when using high-Z solid state targets [20][21][22]; however, an unsolved problem is the generation of debris particles, which can easily damage optics and other components close to the plasma.…”

Section: Introductionmentioning

confidence: 99%

Compact laser-induced EUV source for metrology

et al. 2004

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At Laser-Laboratorium Goettingen different types of laser-plasma EUV sources based on gas and cluster targets were tested to optimize the spatially resolved EUV radiation with respect to maximum EUV intensities, small source diameters, and pointing stability. The EUV radiation is generated by focusing a Q-switched Nd:YAG laser at 1064nm into a pulsed gas puff target. By the use of different target gases, broad-band as well as narrow-band EUV radiation is obtained, respectively. The influence of the laser and target gas parameters on the plasma shape and EUV intensity was investigated by the help of specially designed EUV pinhole cameras, utilizing evaluation algorithms developed for standardized laser beam characterization. The properties of the gas jet determine crucial parameters of the source. A directed gas jet in vacuum with a high number density is needed for an optimal performance of the source. Therefore, conical nozzles with different cone angles were drilled with an excimer laser to produce a supersonic gas jet. The influence of the nozzle geometry on the gas jet was analyzed with a Hartmann-Shack wavefront senor, the first time to our knowledge. The deformation of a planar wavefront after passing the gas jet was analyzed with this sensor, out of which the gas density distribution was reconstructed. Thus, the gas jet was optimized resulting in an increase of EUV emission by a factor of two and decreasing the plasma size at the same time.

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Extreme Ultraviolet Spectroscopy of a Laser Plasma Source for Lithography

Cited by 43 publications

References 16 publications

Plasma characterization in the extreme ultraviolet spectral range

Plasma characterization in the extreme ultraviolet spectral range

Demonstration of a foil trap technique to eliminate laser plasma atomic debris and small particulates

Compact laser-induced EUV source for metrology

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