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Spie Press Book

Extreme Ultraviolet Lithography
Author(s): Harry J. Levinson
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Book Description

This book covers the many aspects of lithographic technology that needed to be addressed in order to make EUV lithography ready for high-volume manufacturing: exposure tools, light sources, masks, resists, process control, metrology, and computational lithography. Lithography costs, which have often influenced the areas of technical focus, are discussed. Potential improvements to current EUV technology and extensions to future nodes are also covered. Each topic is approached from the perspective of a practicing lithographer in a wafer fab, in either manufacturing or development, and there are many references at the end of each chapter.

Book Details

Date Published: 26 October 2020
Pages: 245
ISBN: 9781510639393
Volume: PM326

Table of Contents
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Table of Contents


1 Introduction
1.1 Historical Background
1.2 Components of Lithographic Technology
1.3 Material Considerations and Multilayer Reflectors
1.4 General Issues

2 Sources of EUV Light
2.1 Laser-Produced Plasma Light Sources
2.2 Discharge-Produced Plasma Sources
     2.2.1 Z-pinch light sources
     2.2.2 Electrode-based DPP sources
2.3 Free-Electron Lasers

3 EUV Exposure Systems
3.1 Lithography in Vacuum
3.2 Illumination Systems
3.3 Projection Optics
3.4 Alignment Systems
3.5 Stages in EUV Lithography Systems
3.6 Focus Systems

4 EUV Masks
4.1 Structure of EUV Masks
4.2 Multilayer and Mask Substrate Defects
4.3 Mask Flatness and Roughness
4.4 EUV Mask Fabrication
4.5 EUV Pellicles
4.6 Reticle Pods for EUV Masks
4.7 Alternative EUV Absorbers and Mask Architectures

5 EUV Resists
5.1 Exposure Mechanisms of Chemically Amplified EUV Resists
5.2 Stochastic Effects in EUV Lithography
5.3 New Concepts for Chemically Amplified Resists
5.4 Metal-Oxide EUV Resists
5.5 Scissioning Resists
5.6 Vacuum-Deposited Resists
5.7 Underlayers

6 Computational Lithography for EUV
6.1 Conventional OPC Considerations
6.2 The 3D Aspects of EUV Masks
6.3 Resist Physics
6.4 Imaging Optimization for EUV Lithography

7 Process Control for EUV Lithography
7.1 Overlay
7.2 Critical Dimension Control
7.3 Yield

8 Metrology for EUV Lithography
8.1 Mask Blank Defect Inspection
8.2 EUV Mask Qualification Tools
8.3 Tools for Qualifying Fabricated Masks
8.4 Tools for Material Testing

9 EUV Lithography Costs
9.1 Wafer Costs
     9.1.1 Capital costs
     9.1.2 Maintenance costs
     9.1.3 Operating costs
     9.1.4 Metrology costs
     9.1.5 Wafer cost summary
9.2 Mask Costs

10 Extending EUV Lithography
10.1 How Low k1 Can Go
10.2 Higher NA
10.3 Shorter EUV Wavelengths
10.4 EUV Multiple Patterning
10.5 The Future of EUV Lithography



While writing the chapter on EUV lithography for Principles of Lithography, I found myself challenged with covering many key topics while limiting the length of the chapter to something appropriate for a book that surveyed all major aspects of lithography. It seemed that a book fully dedicated to EUV lithography might be useful. Although there are already a number of fine books that survey the various aspects of EUV lithography, these books are generally compilations of chapters written by multiple experts in individual subjects. I thought that it might be useful to have a book where every chapter is written from a single perspective: that of the practicing lithographer in a wafer fab.

To bring EUV lithography to full readiness for high-volume manufacturing, considerable development (and a fair amount of research) was needed in nearly facet of lithographic technology - equipment, resists, masks, metrology, and computational methods. Each of these topics is discussed in this book, with an emphasis on those aspects that are unique to EUV lithography.

It is assumed that the reader has familiarity with optical lithography, since many of the concepts relevant to EUV lithography were developed and brought to maturity in the context of lithography at optical wavelengths. For many years, it has been my privilege and a pleasure to have worked with numerous outstanding and inspiring engineers and scientists on EUV lithography. Many of these people were co-workers at Advanced Micro Devices (AMD), the Advanced Mask Technology Center (AMTC), and GLOBALFOUNDRIES, while I engaged with others through consortia, such as Sematech, the EUV LLC, INVENT, and Imec. I also benefitted from interactions with engineers, managers, and executives from companies who supply equipment or materials for lithography. Much of the material in this book originated with colleagues and co-workers whose names appear in the references. I hope that this book does justice to their work.

Numerous people provided material for this book, many through their publications, while others were kind enough to provide figures specifically for this book. I would like to thank the following people who provided figures and gave permission for their use: Dr. Bruno La Fontaine of ASML (Figs. 1.1 and 1.3); Mr. Kevin Nguyen and Ms. Shannon Austin of SEMI (Fig. 1.7); Mr. Athanassios Kaliudis and Mr. Florian Heinig of Trumpf GmbH (Fig. 2.4); Dr. Torsten Feigl of optiX fab GmbH (Fig. 2.6); Dr. Hakaru Mizoguchi of Gigaphoton, Inc. (Fig. 2.8); Dr. Igor Fomenkov of ASML (Fig. 2.12); Dr. Anthony Yen of ASML (Figs. 2.13, 4.25, and 4.26); Dr. Patrick Naulleau of Lawrence Berkeley National Laboratory (Figs. 2.14 and 4.18); Mr. Toru Fujinami and Mr. Sam Gunnell of Energetiq (Fig. 2.18); Dr. Erik Hosler (Figs. 2.25 and 2.28); Dr. Winfried Kaiser of Carl Zeiss (Figs. 3.4 and 3.5); Dr. Yulu Chen of Synopsys, Inc. (Fig. 3.7); Dr. Sudhar Raghunathan (Fig. 3.9); Dr. Carlos A. Duran of Corning, Inc. (Figs. 3.11 and 3.12); Dr. David Trumper of MIT and Dr. Won-Jon Kim of Texas A&M University (Fig. 3.17); Dr. Obert Wood (Fig. 4.6); Dr. Uzodinma Okoroanyanwu of Univ. of Massachusetts (Fig. 4.22); Mr. Preston Williamson of Entegris (Fig. 4.31); Prof. Takahiro Kozawa of Osaka University (Fig. 5.1); Prof. Takeo Watanabe of Hyogo University (Fig. 5.11); Dr. Timothy Weidman of Lam Research, Inc. (Fig. 5.23); Dr. Lieve Van Look of Imec (Fig. 6.13); Dr. Peter De Bisschop of Imec (Fig. 6.18); Dr. Jan Van Schoot of ASML (Fig. 7.5); Dr. Yuya Kamei of Tokyo Electron Ltd. (Fig. 7.7); Mr. Masashi Sunako of Lasertec USA, Inc. (Fig. 8.4); Ms. Anna Tchikoulaeva of Lasertec USA, Inc. (Fig. 8.5); Dr. Klaus Zahlten of Carl Zeiss SMT GmbH (Fig. 10.7); and Dr. Vadim Vanine of ASML (Fig. 10.12).

Finally, I would like to thank my wife, Laurie, for her enduring patience.

Harry J. Levinson
August 2020

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