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The ion emission of a Sn-based discharge produced extreme ultraviolet producing plasma is characterized with the combined use of different time-of-flight techniques. An electrostatic ion spectrometer is employed to measure the average charge distribution of the emitted Sn ions. A dedicated Faraday cup configuration is used to measure the total ion flux from the source for different discharge energies. High-energy Sn ions emitted by the plasma with energies up to 100 keV have been identified. The number of high-energy ions increases for higher electrical input energy into the plasma while the signal associated with the expanding plasma ions does not show such dependence. The ion energy distribution for a bulk of detected ions is calculated based on the Faraday cup measurements and compared with theoretical plasma expansion dynamics. [ABSTRACT FROM AUTHOR]

The origin and nature of the high-energy ions emitted by a discharge produced plasma source are studied using gated pinhole camera imaging. Time-of-flight analysis in combination with Faraday cup measurements enables characterization of the high-velocity component of the ionic debris. The use of an optional magnetic field allows mass-to-charge analysis of the first part of the Faraday cup signal. It is shown that this consists mainly of oxygen ions emitted from a region near the cathode. Time-resolved images of Sn ions with a kinetic energy of 45 keV visualize the regions in between the electrodes where the high-energy ion generation takes place. [ABSTRACT FROM AUTHOR]

This work reports on the measurements of ion flux composition and ion energy distribution functions (IEDFs) at surfaces in contact with hydrogen plasmas induced by extreme ultraviolet (EUV) radiation. This special type of plasma is gaining interest from industries because of its appearance in extreme ultraviolet lithography tools, where it affects exposed surfaces. The studied plasma is induced in 5 Pa hydrogen gas by irradiating the gas with short (30 ns) pulses of EUV radiation ( λ = 10–20 nm). Due to the low duty cycle (10–4), the plasma is highly transient. The composition and IEDF are measured using an energy resolved ion mass spectrometer. The total ion flux consists of H + , H 2 + , and H 3 + . H 3 + is the dominant ion as a result of the efficient conversion of H 2 + to H 3 + upon collision with background hydrogen molecules. The IEDFs of H 2 + and H 3 + appear similar, showing a broad distribution with a cut-off energy at approximately 8 eV. In contrast, the IEDF of H+ shows an energetic tail up to 18 eV. Most probably, the ions in this tail gain their energy during their creation process by photoionization and dissociative electron impact ionization. [ABSTRACT FROM AUTHOR]

Short-lived discharge plasmas are currently investigated as candidate sources of extreme ultraviolet (EUV) radiation for application in semiconductor lithography. They are operated in elements such as xenon and (more recently) tin, because of their favorable emission at 13.5 nm. A common property of these plasmas is the current-induced 'pinch' effect, that causes the plasma to collapse to an elongated, needle-like shape on the discharge axis. The typical plasma lifetime is in the tens to hundreds of ns. Various spectroscopic techniques can be applied for characterization of these plasmas. These include time-resolved EUV spectrometry and Stark broadening measurements at visible light wavelengths. Collective Thomson scattering of laser light can provide direct time and space resolved measurements of electron temperatures and densities. Specific experimental difficulties and the ranges of applicability of the different methods for measurements on pinch plasmas are discussed. Results of these measurements on a hollow cathode discharge in xenon and a vacuum-arc discharge in tin vapor are presented. [ABSTRACT FROM AUTHOR]