Enabling Manufacturing Technologies - Implications of Emerging Micro-and Nanotechnologies - page 127

FIGURE 4-2 Lithography examples. SOURCE: Nagel, D.J. 2002. Technologies for mi-
crometer and nanometer pattern and material transfer. Direct-Write Technologies for Rap-
id Prototyping Applications, A. Pique and D.B. Chrisey, eds. New York, N.Y.: Academic
Press. © 2002, Elsevier Science (USA), reproduced with permission of the publisher.
Currently, most aligners use 248-nanometer radiation from KrF lasers to
expose photoresist. The switch to ArF lasers, which have a wavelength of 193
nanometers, has already begun for the production of chips with 100-nanometer
linewidths. In a few years, the ITRS indicates that it will be necessary either to
continue this migration to a 157-nanometer wavelength advanced optical lithog-
raphy tool or to switch to a next-generation lithography approach. Both alterna-
tives are being intensively investigated and are likely to coexist for some time.
The leading contender in the United States for the next lithography technol-
ogy is extreme ultraviolet (EUV) radiation with a wavelength of 13 nanometers. 2
EUV lithography requires the use of plasma sources produced by high-power
laser irradiation of atomic xenon, all reflective optics (including the mask), and—
as usual for a different wavelength—new photoresists. Numerous technical barri-
ers must be overcome for EUV lithography to be ready for the production of
commodity ICs.
In Japan, there is still strong interest in x-ray lithography using 1-nanometer
wavelength radiation. 3 In this case, the “light” source would be either plasmas or
high-energy electrons orbiting in an evacuated toroid, so-called synchrotron ra-