Historical research guide · 1086 · 2002

Optimization of a dense plasma focus device as a light source for EUV lithography

Igor V. Fomenkov · William N. Partlo · Richard M. Ness · Ian R. Oliver · Stephan T. Melnychuk · Oleh V. Khodykin · Norbert R. Boewering

In one minute

Cymer builds the light sources that print computer chips, and around the turn of the century the company put a dense plasma focus — the same coaxial capacitor-discharge pinch that fusion laboratories use — to work as a factory lamp. Squeeze xenon hard enough in that pinch and it radiates in the extreme ultraviolet, which is the band the next generation of chip printing needed. Igor Fomenkov and six colleagues report what it took to make that efficient. They mapped the parameter space: helium and xenon pressures and flow rates, electrode geometries, pre-ionisation, duty cycle. Where you inject the gas turned out to matter as much as how much. Their best arrangement feeds the helium buffer gas in symmetrically around the axis and the xenon straight through the central electrode, and it converts 0.42 percent of the 12.4 joules put in into extreme-ultraviolet light, shot to shot within ten percent. They also ran the machine continuously at 200 pulses a second on ordinary water cooling, and traced where the heat and the electrode debris actually go.

Connection

Chapter 9 is about pinched, self-organised plasma, and this is that physics running as production hardware rather than as an experiment — hundreds of pinches a second, continuously, with an engineering account of the heat load and the electrode erosion. A plasma focus that a semiconductor company can keep alive on a factory floor is a different kind of evidence from a plasma focus that fires once an afternoon.

From the source

A dense plasma focus can be run as an industrial extreme-ultraviolet light source. Cymer demonstrated EUV emission from its own dense plasma focus device with xenon as the source gas, and this paper reports the campaign that followed it: a systematic exploration of helium and xenon pressures and flow rates, electrode geometries, pre-ionisation characteristics and duty-factor performance.Abstract, sentences 1 and 2
Where the gas enters matters as much as how much of it there is. The location of the helium buffer-gas and xenon working-gas injection ports, along with the pressures and flow rates of the mixture, had a strong impact on the efficiency with which the pinch converts stored energy into extreme-ultraviolet light.Abstract, sentence 3
The gas recipe is constrained from two further directions at once: the gas itself absorbs the extreme-ultraviolet radiation the pinch produces, and the same gas has to be chosen for its debris-mitigation properties. The best results came from an axially symmetric buffer-gas injection scheme coupled with axial xenon injection through the central electrode.Abstract, sentences 4 and 5
The highest conversion efficiency obtained was 0.42 percent at 12.4 joules of input energy, and measurements of energy stability show a 10 percent standard deviation at near-optimum extreme-ultraviolet output.Abstract, sentence 6
How well the drive circuit is matched to the pinch can be read directly off the damping of the voltage-overshoot waveform, and that matching was found to depend strongly on the helium and xenon pressures — the electrical behaviour of the discharge and the gas recipe are one problem, not two. Energy-dispersive X-ray analysis of the emitted debris shows the central electrode and the insulator as its primary sources, with no evidence of cathode material.Abstract, sentences 7 and 8
What to watch: whether the thermal engineering scales. The first phase of that work produced continuous operation at 200 hertz with conventional direct water cooling, with higher repetition rates available at proportionally lower duty cycles, and a measured distribution of thermal power through the whole system — which is the data the authors say is needed to judge the high-volume manufacturing potential of the source.Abstract, final three sentences

The way in

https://doi.org/10.1117/12.472339

Historical source-access record. This guide links to the original; it does not reproduce the paper text.

SOURCE NOT REACHED IN FULL. SPIE holds this conference paper closed. Unpaywall and OpenAlex report no open version anywhere and Crossref registers no licence for the DOI; on 2026-09-08 the SPIE Digital Library answered a bot-challenge rather than the article. No text of the paper is reproduced here. WHAT THE CLAIMS REST ON. The authors’ own abstract as deposited with the paper, read on 2026-09-08 from the record held for this DOI, together with the Crossref bibliographic record, which fixes the venue exactly: Proceedings of SPIE volume 4688, Emerging Lithographic Technologies VI, edited by Roxann L. Engelstad, page 634, published 5 July 2002, from SPIE’s 27th Annual International Symposium on Microlithography in Santa Clara, California. Every locator below therefore points to a sentence of that abstract, or to the bibliographic record, rather than to a numbered section. The work is Cymer’s: the abstract names the device as Cymer’s Dense Plasma Focus device, and the author list is the company’s source-development group. THE WAVELENGTH. The abstract speaks of EUV radiation and does not print a wavelength, so none is asserted here. CHAPTERS. The skeleton carried none; this is a pinch discharge run as production hardware, so it is filed to chapter 9.

How to cite it

Igor V. Fomenkov, William N. Partlo, Richard M. Ness, Ian R. Oliver, Stephan T. Melnychuk, Oleh V. Khodykin, Norbert R. Boewering (2002) Optimization of a dense plasma focus device as a light source for EUV lithography doi:10.1117/12.472339

Where it sits in the curriculum

Plasmoids, charge clusters and the orbs