As the microelectronics industry continues to follow Moore's law, the demand to print ever smaller features continues. Figure 1.1 shows a roadmap of lithographic technologies from the past, as well as possible technologies of the future. The microelectronics industry has progressed from 365-nm (i-line) to 193-nm (ArF) lithography. Currently, both âdryâ and immersion 193-nm lithography are being used to manufacture today's fastest integrated circuits. For several years (~2000â2004), the development of 157-nm lithography was pursued but eventually was abandoned. Although EUV lithography is capable of printing high-resolution images, advances in supporting technology (source power, resists, masks) have been slow and EUV lithography is not yet ready for high-volume manufacturing. Immersion 193-nm lithography (193i) has emerged as the successor to 193-nm dry imaging and is the subject of this book. The rise of 193i actually pushed 157-nm lithography off the roadmap. Double patterning of immersion 193-nm images will most likely follow 193i single patterning.
The immersion technique was first introduced by Carl Zeiss in the 1880s to increase the resolving power of the optical microscope. Introduction of the immersion technique into modern lithography was suggested in 1980s.