Abstract

The capability of lenses for microlithography has doubled every few years, surpassing the expectations of the experts and postponing the introduction of more exotic technologies. Semiconductor lithography requirements place demands on optical design and performance that go well beyond the classical criteria of diffraction limited performance. The reduction in wavelength and the increase in numerical aperture and image field size have increased the required complexity, size, component count, and accuracy to unprecedented levels in the optical industry. The special­ized metrology and manufacturing processes have kept pace with these industry requirements. It is likely that capabilities will continue to improve through the year 2000 and be consistent with future requirements of reflective optical components needed for 0.1 μm lithography projection lenses in the extreme ultraviolet or soft x-ray region at 13 nm. The accuracy of components for this regime will need to be five times greater than for today’s lenses—i.e., about 1 nm. In addition, these surfaces will likely need to be aspheric. The tools and techniques needed for current and future lithographic components will be discussed.

© 1992 Optical Society of America