Photoresists for EUV Lithography

Abstract

Extreme ultraviolet lithography (EUVL) has advanced dramatically since its inception in 1986. Progress in EUV research has required an interdisciplinary approach involving partnerships of scientists and engineers within both industry and academics. Contributions from the fields of physics, optics, computer science, business, materials science, and chemistry have been critical to all phases of EUV technical advances. One of the most important components of EUVL is the technological advancement of photoresists. Although EUV photoresist performance has made dramatic advances over the years, resist requirements are extremely demanding. Since the first edition of this book came out in 2008, several technical challenges have been met in all areas of technology to advance EUVL for use in high-volume manufacturing (HVM) fabs. Most notable have been the improvements in source power, reliability and uptime of sources, defect-free masks, and the development and sale of full-field exposure tools. For details, readers are referred to other chapters in this edition of the book that cover these developments. Equally remarkable has been the development of photoresists for use in EUVL. This review starts by describing the history of the first resists imaged by EUV light, skips several of the important resist accomplishments from 1995 to 2008 since they are well covered in the first edition of this book, and focuses on the accomplishments of resist chemists from 2008 to 2017. The development of photoresists has occurred through the successful collaboration of industry and academia. Typically, the best-performing resists come from industry; however, most industrial research is proprietary, so technical details are generally not publicly disclosed. Fortunately, the role played by academics lends balance to the industry by advancing and evaluating new chemical approaches and publishing the results. This review will cover contributions from both industry and academia, but will primarily emphasize publications that reveal the most information available during each period of research.