The paper describes recent progress on the development of an EUV source based on a hollow cathode triggered gas discharge (HCT). The principle of operation has been described in previous publications. When operated with Xe, a repetition frequency up to 4 kHz, conversion efficiency of 0.55% inband radiation in 2 pi and a pinch size below 3 mm in length was demonstrated. Today's requirements on a commercial EUV source for volume production of wafers still exceed the current performance by large factors both in terms of output power and life time. This paper will discuss the roadmap to high power and will also show elements of the way to extended life time. Particular focus will be put onto the physical limits of Xe as radiator and the advantages of using Sn instead. It will be demonstrated that the spectral efficiency of Sn is a factor of 3 higher than Xe
The paper describes progress of the Philips' hollow cathode triggered (HCT) gas discharge EUV source. The program has been focussed on three major areas: (1) Studying the basic physics of ignition, pinch formation and EUV generation. The paper reports on progress in this area and particularly describes the underlying atomic physics both for Xe and Sn. (2) Discharge based on Sn. Results on overall efficiency more than 5 times the Xe efficiency are reported as well as high frequency operation up to 6.5 kHz. This system shows all the necessary ingredients for scaling to production power levels. (3) Integration of the Xe source in an alpha tool. Results on integration issues like electrode life time, collector life time and dose control will be presented
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