Status of Philips' extreme UV source

Abstract

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

Calculation of tin atomic data and plasma properties.

“…Accordingly to the results calculated by the CRE model and reported in [14], the concentrations of xenon ions at were 20% Xe+9, 25% Xe+10, 20% Xe+11, and 13% Xe+12, as shown by gray shading in the second column of Table 1. As seen from the other data in the table, our calculations generally agree with these figures, except that we obtained a twice larger value at eV 31 = e T for the concentration of Xe+10 ions.…”

Development of the ASML EUV alpha demo tool

“…The triangle symbols in Figure 5b represent the progress that was made over the years for the resulting Xe collector lifetime. To our knowledge, the best Xe lifetime published so far is 5xl08 pulses without reflection degradation within the reported reflectivity measurement error of 2% [7]. This would translate to a collector lifetime of at least 5xl09 pulses or -140 h (again, using a repetition rate of 10 kHz).…”

“…We exposed a Rucoated Si sample to the equivalent of 30 and 100 cleaning cycles, without intermittent Sn deposition. The 100 successful cleaning cycles caused a transmission loss of 4±2% (for details, see [12]), which equates to a tool productivity loss of 2±1%. The extrapolated collector lifetime then would amount to -1500 h (or 5.5±2.5x10'° pulses, see Figure 5a).…”

“…The use of alternative source fuels has three potential benefits: i) a 4-6x higher conversion efficiency compared to Xe [4,8], ii) inherently smaller source size and thus more efficient coupling of collected power into the optical system [7, 1 1], and iii) possibility for higher heat loads and electrode lifetime through multiplexing [8]. Figure 4 shows the learning curve of the source power of several source suppliers and their prognoses for the future [7,9,10]. On the vertical axis the calculated collected in-band EUV power at intermediate focus is plotted, where for discharge source suppliers 1 and 2 the published data (emitted EUV power in the plasma in a solid angle of 2it) is converted to power at intermediate focus using a sourcecollector configuration that could be implemented in a production tool -using a so-called grazing-incidence it-collector, where 'it' refers to the solid angle of collection.…”

“…production tools. In the last year source suppliers and researchers have been focusing on alternative target materials, including Li and Sn [6][7][8][9][10]. In the following section we will present some of the recent development results.…”