An extreme-ultraviolet (EUV) radiation source near the 13-nm wavelength generated in a small (1.1 J) pinch plasma is presented. The ignition of the plasma occurs in a pseudosparklike electrode geometry, which allows for omitting a switch between the storage capacity and the electrode system and for low inductive coupling of the electrically stored energy to the plasma. Thus energies of only a few joules are sufficient to create current pulses in the range of several kiloamperes, which lead to a compression and a heating of the plasmas to electron densities of more than 10(17) cm(-3) and temperatures of several tens of electron volts, which is necessary for emission in the EUV range. As an example, the emission spectrum of an oxygen plasma in the 11-18-nm range is presented. Transitions of beryllium- and lithium-like oxygen ions can be identified. Current waveform and time-resolved measurements of the EUV emission are discussed. In initial experiments a repetitive operation at nearly 0.2 kHz could be demonstrated. Additionally, the broadband emission of a xenon plasma generated in a 2.2-J discharge is presented.

Future extreme ultraviolet (EUV) lithography will require high radiation intensities at a wavelength around 13.5 nm. The limits of emission in this spectral range from discharge based plasmas are discussed theoretically. The discussion is based on a simple MHD approach for a xenon plasma discharge and atomic data from the ADAS software package for radiative transitions, excitation and ionization of different ionization levels. Discharge parameters are chosen for the Philips' hollow cathode triggered pinch plasma. The calculations show that the 13.5 nm emission originates only from of Xe10+ ions and is optically thin. Ideally, the conversion efficiency is expected to scale linearly with the electron density in this case. The MHD calculations, however, show a lower increase with density. The loss channels leading to this behaviour, like leakage currents, will be discussed in detail. The identification of these losses allow, on the other hand, for a systematic improvement of the electrode system and the electrical circuit. In addition, theoretical emission spectra of xenon and tin as the most promising emitters around 13.5 nm will be compared with respect to the possible optimization potential of spectral emission characteristics.

Extended ultraviolet (EUV) emission characteristics of a laser-produced lithium plasma are determined with regard to the requirements of x-ray photoelectron spectroscopy. The main features of interest are spectral distribution, photon flux, bandwidth, source size, and emission duration. Laser-produced lithium plasmas are characterized as emitters of intense narrow-band EUV radiation. It can be estimated that the lithium Lyman-alpha line emission in combination with an ellipsoidal silicon/molybdenum multilayer mirror is a suitable EUV source for an x-ray photoelectron spectroscopy microscope with a 50-meV energy resolution and a 10-mum lateral resolution.

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