11 February 2004--A gathering of semiconductor industry leaders meant to determine, among other things, which technology will be used to produce future generations of semiconductors through 2009 produced a clear winner. Industry leaders at International Sematech�s Lithography Forum, held 28 and 29 January in Los Angeles, agreed that when integrated circuit structures shrink to less than 60 nanometers they will use a variant of the 193-nm lithography tools just now moving into production in today�s most advanced ICs.
Such lithography tools project and focus laser light with a wavelength of 193 nm onto a silicon wafer through a mask that contains the circuit pattern. The new variant, called 193 immersion, adds a thin layer of water between the focusing lens and the wafer--which improves the ability of the tool to print the sub-60-nm structures that will populate future ICs. The choice of 193 immersion is considered conservative, because it requires much smaller changes to the manufacturing process than do other technologies that were considered, even though those other technologies may be extendible far beyond 2009. When lithography-tool manufacturers began developing 193 back in the 1990s, industry experts expected that it would be replaced with another technology by 2006.
The seven major contenders under consideration included electron projection, backed by Nikon Corp. [see "A Promising Lithography Gets Stuck," January 2004]. Another was photolithography using a 157-nm light source, which had been scheduled to go into production in 2007 but will likely be pushed farther out on the technology road map if it is used at all. A variant of 157, 157-nm immersion lithography, might be used beyond 2010 to build IC structures smaller than 40 nm.
Lithography using extreme ultraviolet radiation was also a contender. EUV, as it is called, is the subject of a major industry research effort backed by such heavyweights as IBM, Infineon, Intel and Motorola. It is scheduled to be ready by 2009, but if 193-nm immersion is adopted, EUV may not appear until 2012. Various technologies that require no photomask to produce a pattern were also in play, such as nanoimprint lithography which stamps out circuit patterns.