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If you can find the post on SVGI/SVGL claims, perhaps I could sort it out.
In the absence of the article here is my guess. The Micrascan optics are based more on mirrors ( like reflector telescope) than the more recent systems ( Nikon) which are based more on lenses (like refractor telescopes-spyglasses). The mirrors are more efficient at passing light from the source to the wafer, they are also more tolerant of slightly more colors/flavors of light (wider spectrum or broadband). The mercury arc lamp (just like those in the lights at the ballpark) emits light in many colors/flavors broad spectrum. However there are specific flavors-wavelengths that are brighter than others. If you plot intensity (brightness) vs wavelength (flavor) you will see certain peaks or lines in the spectrum. These peaks have names (like G, H, I line). The Hg lamp also emits some DUV. Perkin Ekmer took advantage of the efficiencies of their optics expertise with mirrors (those spy telescopes aforementioned) and this output to make DUV systems. The first of these were full field scanners, the step and scan came later (first installed in mid to late 80's). These scanners also required very sensitive (fast) photoresists to work, fortunately they had partner that could develop these photoresists which were proprietary.
So I guess that SVGL is being clever and claiming the lead in DUV because they claim these bulb based systems. As the refractive systems came along, they needed brighter and purer Flavor ( narrow spectrum/band) light to work. Cymer filled this need. Hence my paranoia, competitors (Nikon, Canon, ASML) do come along to fill need.
TI2
PS: Keep up the great work policing the rumor mongers, I don't mind reading the corrections at all. |
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