Out of focus

ASML has agreed to supply an extreme ultraviolet (euv) preproduction tool to Belgian research centre IMEC in 2010. The device will be installed in IMEC’s 300mm facility, where it will support cmos process technology research. The news reinforces opinion that euv is unlikely to become a viable process until at least 2012, when it may enable 22nm cmos processes. The technology has been promoted as a suitable successor to current lithography techniques, which are rapidly ‘running out of steam’. Two potential lithography approaches have been competing. Alongside euv is immersion lithography, in which materials with high refractive indices are used to focus a 193nm light source in order to etch patterns on the silicon substrate. Although IMEC is pursuing both avenues, it foresees problems in moving immersion lithography beyond the 32nm node. Kurt Ronse (pictured), director of IMEC’s advanced lithography programme, said: “The 32nm half pitch node will need materials with a refractive index of 1.6 to 1.7. A major candidate is LuAG, but whilst this has a high refractive index, there are problems with absorption. However, we have yet to find fluids with a refractive index higher than 1.7.” In Ronse’s opinion, 32nm immersion technology will be ‘late and a single generation solution’.