LITHOGRAPHY Will new technical solutions help lithographers in the future?

摘要

Comparing the new 2003 edition of ITRS Lithography Chapter with the year 2002 Update, it becomes apparent that the largest differences are related to the narrowing of potential solutions for near-term nodes and to the introduction of novel techniques for mid-and long-term nodes. The main purpose of these further options is to guarantee device geometrical specifications on time; additionally, extending the lifetime of already used and known techniques is also predicted. The choice for the 90nm half-pitch node, forecast in 2004, is a 193nm scanner with "hard" resolution enhancement technology (RET) and phase shifting on the most critical layers. Looking at the future, so-called "immersion" lithography, in which the volume between the wafer and the scanner objective lens is filled with a liquid (e.g., deionized water in the case of 193nm wavelength), looks like a promising technique. Immersion allows a larger NA and thus better ultimate resolution without exchanging the overall manufacturing infrastructure in the cleanroom. Its feasibility for the 65nm node will be assessed by the middle of next year. Immersion might also enable safe wafer processing for the 45nm node, where EUVL technology might otherwise first be used.