Yutaka ICHIHARA

Core Technology Head Quarters, Nikon Corporation, Yokohama 244-0843, Japan

(Received August 23, 2014; Accepted September 1, 2014)

The development of high-resolution projection optics for semiconductor lithography is briefly described and is enabled by precise wavefront measurement. Then, the evolution of the interferometer for the measurement of the wavefront aberration of these optics is described together with the development of the interferometer for the measurement of the surface errors of the element lenses. The measurement of subnanometer accuracy is achieved in mass production.

Key words: lithography, projection optics, resolution, interferometer, wavefront, aberration, aspheric surface distortion, point diffraction interferometer