Previously, we have given a detailed description of the so-called Extended Nijboer-Zernike approach and its application to aberration measurements of the optical projection system in a wafer scanner in the case of a low or medium high-NA system. The Extended Nijboer-Zernike theory provides an analytical description of the through-focus intensity point-spread function in the presence of lens aberrations and defocus. Taking the Extended Nijboer-Zernike description for the electric field components in the case of a high-NA optical system as a starting point, we present an approach to aberration retrieval when the NA is very high. The experimental procedure involves the analysis of a focus-exposure matrix. The differences between aberration retrieval using the low-NA scalar model and the high-NA full vectorial model are discussed. The mathematical framework is shown and the experimental procedure to extract aberrations for a high-NA lens is demonstrated on modern 193 nm wafer scanners.
|Title of host publication||Proceedings Optical Microlithography XVIII, 1 - 4 March 2005, San Jose, California|
|Place of Publication||Bellingham|
|Publication status||Published - 2005|
|Name||Proceedings of SPIE|