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Master position: Tailoring of laboratory-scale extreme ultraviolet radiation sources to couple discharge and laser produced plasmas using a hybrid approach

Advertising institute: PGI-9 - Semiconductor Nanoelectronics
Reference number: D080/2014, Physics, engineering or related sciences

We offer a master position in the field of plasma-based EUV light source development. The project goal is to investigate a possible improvement of the radiance (brightness) of the gas-discharge plasma source by focusing pulsed laser into the discharge zone. High brightness is required in applications such as magneto-optical element-selective microscopy, Coherent Diffractive Imaging (CDI), lithographic nano-scale defect inspection and interference lithography. Since these are the active research areas of the group, the subject of the proposed project is highly advantageous for the entire group.

Background:
The goal of the project is to explore the fundamentals that will enable a new generation of highly brilliant and compact extreme ultraviolet (EUV) sources. This will be achieved by a combination of discharge plasmas and laser heating. The strategy is to use a discharge for plasma generation of a desired ionization degree and then, during maximum of compression, additionally heat a limited volume with characteristic lengths of a few tens of micrometers by a focused laser beam. This allows to match the source etendue and radiance to values required by various applications and improve the efficiency of EUV utilization by several orders of magnitude.

Project description:
The physics of laser-plasma interaction is an exciting research frontier with varied applications both in basic and applied sciences. Inverse-bremsstrahlung absorption is among the physical processes that take place when a pulsed high-power (e.g. 1 J, 15ns, 1064nm) laser interacts with a plasma of a few 10’s eV and density of 1018-1019cm-3. For efficient absorption of the laser energy, one has to tune both the laser and the target, in this case the discharge produced plasma. Hence the task of the student involves optimizing the plasma conditions (density, temperature and charge state of the plasma species) and the laser parameters (wavelength & energy fluency) focused in to a localized volume in order to increase the plasma temperature and hence increase the EUV emission from smaller volume which will ultimately translate into high brightness.

The project can be divided in two major tasks. The first one is to characterize the EUV emission spectra, radiance and radiation energy of the existing gas based discharge plasma source. The EUV radiation will be monitored by a combination of spectroscopic and imaging diagnostics. In addition the laser will be commissioned and with an optical bench it will be aligned and characterized. In the second part, the laser will be combined with the gas discharge plasma. Parameters of the laser to be explored include the focusing conditions, the harmonic wavelength selection, and the energy density. On the discharge side the input electrical energy and the gas pressure will be tailored for different gases. Subsequently the EUV spectral and radiation energy output will be diagnosed with a time resolved EUV spectrometer and EUV photodiode respectively. Time integrated visible images could also be coupled to aid the diagnosis of local laser heating.

Your profile:

  • Bachelor in physics, engineering or related sciences
  • good knowledge in electrodynamics & laser-matter interaction
  • passion for experimental work

We offer:

  • topical research
  • professional support and supervision
  • pleasant working atmosphere

Contact:

Mrs. Prof. Dr. rer. nat. Larissa Juschkin
Tel.: +49 (0) 2 41 / 89 06-313
E-Mail: Larissa.Juschkin@rwth-aachen.de

Mr. MSc. Girum Beyene
Tel.: +49 (0) 2461 61-6623
E-Mail: g.beyene@fz-juelich.de


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