Projection optical lithography

Projection optical lithography has had a remarkable history and, most probably, it will have an equally successful future for at least another decade. To date, it has met all the major challenges posed by the semiconductor industry roadmap. In order to do so, it has undergone important transformations, and has greatly expanded the frontiers of the science and engineering of optics. This paper will review the most recent developments, including transitioning to the short wavelengths of 193 nm and 157 nm, moving toward ultrahigh numerical apertures facilitated by liquid immersion, and incorporation of a range of resolution-enhancing techniques such as optical proximity correction and phase-shifting masks.