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Fundamentals of Droplet Break-up Dynamics in a Laser Produced Plasma Light Source with Shaped Pre-Pulse Energy Distribution

Applicant Abhari Reza
Number 164026
Funding scheme R'EQUIP
Research institution Institut für Energietechnik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Material Sciences
Start/End 01.09.2016 - 30.11.2017
Approved amount 234'300.00
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All Disciplines (2)

Material Sciences
Plasma Physics

Keywords (4)

Time Resolved Imaging; Picosecond Burst Laser; Droplet Break-Up; Laser Produced Plasma

Lay Summary (Italian)

The plasmas produced by laser ablation are used in many scientific and industrial applications such as materials science, nuclear fusion and the semiconductor industry. The plasma is generated by the interaction of a metal target with a high-energy laser. This plasma emits radiation from the X-ray to the visible spectrum and can be used for a wide range of applications.In the semiconductor industry, the plasma light in the extreme ultraviolet region is used for extreme ultraviolet photolithography and microscopy for metrology applications.A key technology utilizes plasmas produced by a laser with micro droplets of liquid tin, which have a high emissivity in the far ultraviolet. This plasma generation method has the advantage of providing a continuous light source, which limits the production of plasma debris consisting of high-energy ions, neutral particles and tin fuel fragments.
Lay summary

I plasmi da prodotti da ablazione laser sono utilizzati in molte applicazioni scientifiche e industriali come la scienza dei materiali, la fusione nucleare e l’industria dei semiconduttori. Il plasma è generato dall’interazione di un laser ad alta energia con un bersaglio di metallo che emette radiazione dalla regione dei raggi X a quella del visibile e che può essere utilizzata per una vasta gamma di applicazioni.

Nell’industria dei semiconduttori, la luce del plasma nella regione dell’estremo ultravioletto è utilizzata per la Fotolitografia all’estremo ultravioletto e per applicazioni di microscopia metrologia.

Una tecnologia chiave utilizza plasmi prodotti dall’interazione laser con micro gocce di stagno liquido ad alta emissività nell’estremo ultravioletto. Queste hanno il vantaggio di fornire una sorgente di luce continua limitando la produzione di detriti derivanti dall’interazione laser-goccia e consistenti di ioni ad alta energia, particelle neutre e frammenti di goccia.

Direct link to Lay Summary Last update: 28.07.2016

Responsible applicant and co-applicants

Associated projects

Number Title Start Funding scheme
175927 Generation of Repeatable Microdroplets via Rayleigh Instability of a Non-Ideal Jet 01.10.2017 Project funding
156754 Influence of laser pre-pulsing on droplet-based laser-produced plasmas 01.10.2014 Project funding


Laser Produced Plasmas (LPPs) are employed in several scientific and industrial fields, going from material science to nuclear physics, to a wide range of industrial applications. The interaction of a laser with irradiances of 1010-1012 W/cm2 with a metal target generates a plasma emitting radiation from the Soft-X ray to the visible range. This radiation can be used for a wide range of appli-cations, particularly in the semiconductor industry, for extreme ultraviolet lithography (EUVL) and for inspection and metrology applications. Micro-sized droplet targets are a key technology for the LPP source as they limit the amount of produced debris that is formed of high energy ions, low energy par-ticles and neutral droplet fragments. One way to further reduce the debris and to increase the emission properties of the source in a desired bandwidth is with the use of a pre-pulse laser. The pre-pulse “pre-shapes” the target in order to increase the coupling efficiency between the target and the main laser. This proposal focuses on new pre-pulse schemes in order study new droplet break-up regimes that will improve the coupling efficiency between the target and the main laser. The main research objectives are the followings:•Introduce a novel picosecond burst pre-pulse scheme and discover new mechanisms of the droplet-break up dynamics and target shaping •Understand the impact of the pre-pulse on both the droplet-break up dynamics and subsequent plasma formation•Determine the optimum conditions to improve the source conversion efficiency and source stability, while reducing the neutral cluster debris.In order to reach the proposed goals we request a picosecond laser, an ICCD camera with a nanosecond time gating, a X-ray CCD camera and a software to simulate the radiation emission properties of the plasma. The proposed exper-iments will have an enormous impact on the fundamental physics of the drop-let-laser interaction, which is still not fully understood. At the same time, the main challenges related to source optimization (conversion efficiency, stability and debris reduction) will be investigated bringing great innovation to the field.