title: Aberration measurement from specific photolithographic images: a different approach.
abstract: Techniques for measurement of higher-order aberrations of a projection optical system in photolithographic exposure tools have been established. Even-type and odd-type aberrations are independently obtained from printed grating patterns on a wafer by three-beam interference under highly coherent illumination. Even-type aberrations, i.e., spherical aberration and astigmatism, are derived from the best focus positions of vertical, horizontal, and oblique grating patterns by an optical microscope. Odd-type aberrations, i.e., coma and three-foil, are obtained by detection of relative shifts of a fine grating pattern to a large pattern by an overlay inspection tool. Quantitative diagnosis of lens aberrations with a krypton fluoride (KrF) excimer laser scanner is demonstrated.
authors.affiliation: Microelectronics Engineering Laboratory, Semiconductor Company, Toshiba Corporation, 8, Shinsugita-cho, Isogo-ku, Yokohama 235-8522, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nomura
authors.forename: K
authors.initials: K
authors.lastname: Tawarayama
authors.forename: T
authors.initials: T
authors.lastname: Kohno