Preface ...................................................... xiii
Introduction ................................................. xvii
List of Contributors .......................................... xix
List of Abbreviations ......................................... xxi
Chapter 1 EUV Lithography: An Historical Perspective .......... 1
Hiroo Kinoshita and Obert Wood
1.1 Introduction .............................................. 1
1.2 The Early Stage of Development—1981 to 1992 ............... 3
1.3 The Second Stage of Development—1993 to 1996 ............. 10
1.4 Other Developments in Japan and Europe ................... 18
1.5 The Development of Individual Technologies ............... 20
1.6 EUVL Conferences ......................................... 40
1.7 Summary .................................................. 42
Acknowledgments ................................................ 44
References ..................................................... 46
Chapter 2 EUV LLC: An Historical Perspective ................. 55
Chuck Gwyn and Stefan Wurm
2.1 Introduction ............................................. 56
2.2 Formation of the LLC ..................................... 59
2.3 Program Structure ........................................ 66
2.4 Program Results .......................................... 72
2.5 Retrospective Observations ............................... 79
2.6 Status of EUV Development at the End of LLC .............. 84
2.7 Summary .................................................. 85
Appendix A: Major Accomplishments of the EUV LLC Program ....... 87
Appendix B: EUV LLC Program Patents ............................ 92
Acknowledgments ................................................ 96
References ..................................................... 99
Chapter 3 EUV Source Technology ............................. 103
Vivek Bakshi
3.1 Introduction ............................................ 104
3.2 EUV Source Requirements ................................. 106
3.3 DPP and LPP Source Technologies ......................... 109
3.4 EUV Source Performance .................................. 112
3.5 Summary and Future Outlook .............................. 126
References .............................................. 127
Chapter 4A Optics and Multilayer Coatings for EUVL Systems ... 133
Regina Soufli, Saša Bajt, Russell M. Hudyma
and John S. Taylor
4A.1 Introduction ............................................ 133
4A.2 Properties of EUVL Systems .............................. 133
References .............................................. 134
Chapter 4B Projection Systems for Extreme Ultraviolet
Lithography ....................................... 135
Russell M. Hudyma and Regina Soufli
4B.1 General EUVL Optical Design Considerations .............. 135
4B.2 EUV Microsteppers ....................................... 138
4B.3 Engineering Test Stand (ETS) ............................ 147
4B.4 Six-Mirror EUVL Projection Systems ...................... 149
Acknowledgments ............................................... 156
References .................................................... 157
Chapter 4C Specification, Fabrication, Testing, and
Mounting of EUVL Optical Substrates ............... 161
John S. Taylor and Regina Soufli
4C.1 Introduction ............................................ 161
4C.2 Specification ........................................... 162
4C.3 Projection Optics ....................................... 163
4C.4 Effect of Substrate Errors on Imaging Performance ....... 164
4C.5 Low-Frequency (Figure) Errors ........................... 165
4C.6 Mid-Spatial-Frequency Errors ............................ 169
4C.7 High-Spatial-Frequency Errors ........................... 170
4C.8 Influence of Coatings on Roughness Specification ........ 171
4C.9 Calculation of Surface Errors .......................... 171
4C.10 Uniformity .............................................. 173
4C.11 Substrate Materials ..................................... 173
4C.12 Fabrication ............................................. 174
4C.13 Metrology ............................................... 176
4C.14 Mounting and Assembly ................................... 177
4C.15 Alignment ............................................... 179
4C.16 Condenser Optics ........................................ 179
Acknowledgments ............................................... 181
References .................................................... 181
Chapter 4D Multilayer Coatings for EUVL ...................... 187
Regina Soufli and Saša Bajt
4D.1 Overview and History of EUV Multilayer Coatings ......... 187
4D.2 Choice of ML Materials and Wavelength Considerations .... 188
4D.3 Multilayer Deposition Technologies ...................... 189
4D.4 Theoretical Design ...................................... 190
4D.5 High Reflectivity, Low Stress, and Thermal Stability
Considerations .......................................... 191
4D.6 Optical Constants ....................................... 192
4D.7 Multilayer Thickness Specifications for Imaging and
Condenser EUVL Mirrors .................................. 193
Acknowledgments ............................................... 197
References .................................................... 197
Chapter 5 EUV Optical Testing ............................... 205
Kenneth A. Goldberg
5.1 Introduction ............................................ 205
5.2 Target Accuracy ......................................... 207
5.3 Techniques for Angstrom-scale EUV Wavefront
Measurement Accuracy .................................... 208
5.4 Intercomparison ......................................... 218
5.5 Future Directions ....................................... 219
References .................................................... 222
Chapter 6A Optics Contamination .............................. 227
Saša Bajt
6A.1 Introduction ............................................ 227
6A.2 Fundamentals of Optics Contamination .................... 234
6A.3 Optics Contamination Control ............................ 241
6A.4 Summary and Future Outlook .............................. 250
References .................................................... 251
Chapter 6B Grazing Angle Collector Contamination ............. 261
Valentino Rigato
6B.1 Introduction ............................................ 261
6B.2 Collector Lifetime Status and Challenges ................ 269
6B.3 Summary ................................................. 281
Acknowledgments ............................................... 281
References .................................................... 281
Chapter 6C Normal Incidence (Multilayer) Collector
Contamination ..................................... 285
David N. Ruzic and Shailendra N. Srivastava
6C.1 Introduction ............................................ 285
6C.2 Overview of Normal-Incidence Collector Mirrors .......... 287
6C.3 Collector Performance ................................... 290
6C.4 Summary ................................................. 317
Acknowledgments ............................................... 318
References .................................................... 318
Chapter 7 EUV Mask and Mask Metrology ....................... 325
Han-Ku Cho and Jinho Ahn
7.1 Introduction ............................................ 326
7.2 EUV Mask Structure and Process Flow ..................... 327
7.3 Mask Substrate .......................................... 328
7.4 Mask Blank Fabrication .................................. 332
7.5 Absorber Stack and Backside Conductive Coating .......... 349
7.6 Mask Patterning ......................................... 355
7.7 Mask Cleaning ........................................... 361
7.8 Advanced Mask Structure ................................. 363
7.9 Summary and Future Outlook .............................. 372
Acknowledgments ............................................... 373
References .................................................... 373
Chapter 8 Photoresists for Extreme Ultraviolet
Lithography ....................................... 383
Robert L. Brainard
8.1 Introduction ............................................ 384
8.2 Earliest EUV Resist Imaging ............................. 385
8.3 Absorption Coefficients of EUV Photoresists ............. 391
8.4 Multilayer Resists and Pattern Transfer ................. 394
8.5 Resist Types ............................................ 403
8.6 PAGs and Acids .......................................... 426
8.7 Line Edge Roughness ..................................... 428
8.8 Summary and Future Outlook .............................. 435
Acknowledgments ............................................... 435
References .................................................... 437
Chapter 9 High-Resolution EUV Imaging Tools for Resist
Exposure and Aerial Image Monitoring .............. 449
Malcolm Gower
9.1 Introduction ............................................ 450
9.2 EUV Tool Design Considerations .......................... 450
9.3 EUV Microstepper ........................................ 453
9.4 Reticle Imaging Microscope .............................. 470
9.5 Summary and Future Outlook .............................. 488
Acknowledgments ............................................... 490
References .................................................... 490
Chapter 10 Fundamentals of EUVL Scanners ..................... 493
Kazuya Ota
10.1 Introduction ............................................ 494
10.2 Illumination Optics ..................................... 494
10.3 Projection Optics ....................................... 498
10.4 Stages .................................................. 502
10.5 Sensors ................................................. 506
10.6 Handling Systems ........................................ 508
10.7 Vacuum and Environment System ........................... 508
10.8 Budgets ................................................. 509
10.9 Summary ................................................. 511
Acknowledgments ............................................... 511
References .................................................... 512
Chapter 11 EUVL System Patterning Performance ................ 515
Patrick Naulleau, John E. Bjorkholm, and Manish
Chandhok
11.1 Introduction: The Benefits of EUV Imaging ............... 516
11.2 Imaging with the 0.1 -NA ETS Optic ...................... 517
11.3 Imaging with the 0.3-NA MET Optic ....................... 530
11.4 System Contributors to Line Edge Roughness .............. 539
11.5 Flare in EUVL Systems ................................... 551
11.6 Summary ................................................. 576
Acknowledgments ............................................... 577
References .................................................... 577
Chapter 12 Lithography Cost of Ownership ..................... 585
Phil Seidel
12.1 Cost of Ownership Overview .............................. 586
12.2 Lithography: Historical Cost and Price Trends ........... 599
12.3 Major Lithography CoO Parameter and Productivity
Drivers ................................................. 604
12.4 General Observations on Lithography Cell and CoO
Improvements (Past Decade) .............................. 622
12.5 CoO Considerations for Future Lithography
Technologies ............................................ 629
12.6 Summary ................................................. 635
12.7 Appendix: Example Case Studies of Lithography CoO
Calculations ............................................ 635
Acknowledgments ............................................... 638
References .................................................... 639
Appendix Reference Data for the EUV Spectral Region .......... 643
Eric M. Gullikson and David Attwood
A.1 Introduction ............................................ 643
Table A.1 Optical constants and absorption data for
extreme ultraviolet wavelengths ............... 643
Table A.2 Physical constants ............................ 652
Table A.3 Electron binding energies in electron volts
for the elements in their natural forms ....... 653
Table A.4 Photon energies in electron volts of
principal K- and L-shell emission lines ....... 659
References .................................................. 663
Index ......................................................... 665
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