Image-based EUVL aberration metrology

Kate Gleason College of Engineering Rochester Institute of Technology Degree: Doctor of Philosophy Program: Microsystems Engineering Authors Name: Germain L. Fenger Advisors Name: Dr. Bruce W. Smith Dissertation Title: Image-Based EUVL Aberration Metrology A significant factor in the degradation of nanolithographic image fidelity is optical wavefront aberration. As resolution of nanolithography systems increases, effects of wavefront aberrations on aerial image become more influential. The tolerance of such aberrations is governed by the requirements of features that are being imaged, often requiring lenses that can be corrected with a high degree of accuracy and precision. Resolution of lithographic systems is driven by scaling wavelength down and numerical aperture (NA) up. However, aberrations are also affected from the changes in wavelength and NA. Reduction in wavelength or increase in NA result in greater impact of aberrations, where the latter shows a quadratic dependence. Current demands in semiconductor manufacturing are constantly pushing lithographic systems to operate at the diffraction limit; hence, prompting a need to reduce all degrading effects on image properties to achieve maximum performance. Therefore, the need for highly accurate insitu aberration measurement and correction is paramount. In this work, an approach has been developed in which several targets including phase wheel, phase disk, phase edges, and binary structures are used to generate optical images to detect and monitor aberrations in extreme ultraviolet (EUV) lithographic systems. The benefit of using printed patterns as opposed to other techniques is that the lithography system is tested under standard operating conditions. Mathematical models in conjunction with iterative lithographic simulations are used to determine pupil phase wavefront errors and describe them as combinations of Zernike polynomials. ACKNOWLEDGMENTS I would like first thank my advisor, Dr. Bruce W. Smith, specifically for guiding me when needed, but giving me the confidence and room to think independently and critically. I would also like to thank my committee members Dr. Karl D. Hirschman, Dr. Zoran Ninkov, and Dr. Obert R. Wood II for guiding me through the PhD process. I would like to especially acknowledge and thank Obert, without his support much of this work would not have been possible. I would like to acknowledge and thanks KLA Tencor for the use of PROLITH TM , GLOBALFOUNDRIES for the fabrication of a phase-shifting reticle and processing support, the IBM alliance and partners for use of the cleanroom facilities including scanner and SEM tool time, Dr. Lena Zavyalova for her many discussions, Luke Orsini, Dr. Lei Sun, and Dr. Sudhar Raghunathan for help with exposures. I would also like to thank and acknowledge my fellow graduate students for their encouragement and support, Burak Baylav, Dr. Monica Sears, Andrew Estroff, Chris Maloney, Dr. Neal Lafferty and Dr. Peng Xie. I would also like to the U.S. Department of Education Graduate Assistance in Areas of National Need (GAAN) program and the Semiconductor Research Corporation (SRC/GRC) for their support. Table of