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.
© 2000 Optical Society of America
(120.3940) Instrumentation, measurement, and metrology : Metrology
(120.4630) Instrumentation, measurement, and metrology : Optical inspection
(220.1010) Optical design and fabrication : Aberrations (global)
(220.3740) Optical design and fabrication : Lithography
(220.4840) Optical design and fabrication : Testing
Hiroshi Nomura, Kazuo Tawarayama, and Takuya Kohno, "Aberration Measurement from Specific Photolithographic Images: A Different Approach," Appl. Opt. 39, 1136-1147 (2000)