Advanced technology for extending optical lithography

This paper discusses the technological consequences of extending optical lithography down to 50 nm. A total systems approach is used to define the overall error budgets on CD and overlay. The feasibility of extremely high NA optics is studied. With extremely high-NA optics, Depth of Focus decreases and focus control becomes more critical. Using a Step and Scan system, the potential of system dynamics is evaluated. Mask issues are briefly reviewed. Experimental data on field extension with butting is included. As well as being technically feasible, the lithography step for the future technology nodes must be cost effective. It is concluded that optical extension should preferably be supported by reduced field, large magnification scanners. The transition to Next Generation Lithography will be pushed to at least the 50 nm node.