Analysis of Extreme Ultraviolet Induced Surface Defect Processes An Gao Ph.D. committee Chairman: Prof.dr.ir. J.W.M. Hilgenkamp University of Twente, TNW Secretary: Prof.dr.ir. J.W.M. Hilgenkamp University of Twente, TNW Promoter: Prof.dr. F. Bijkerk University of Twente, TNW Co-Promoter: Dr. C.J. Lee University of Twente, TNW Members: Prof.dr. A.P, Mosk University of Twente, TNW Prof.dr. J. Schmitz University of Twente, TNW Prof.dr. W. van der Zande Radboud University Nijmegen Prof.dr. M.W. Beijersbergen University of Leiden Prof.dr. J. Herek University of Twente, TNW Cover: An optical instrument built in this PhD project,which can serve Photoluminescence and Raman measurement. Photography by Dr. Lennino Cacace Analysis of Extreme Ultraviolet Induced Surface Defect Processes Ph.D Thesis, Unveristy of Twente, Enschede – Illustrated. With references – With summary in English and Dutch ISBN: 978-90-365-3985-2 Printed by Ridderprint BV, the Netherlands ANALYSIS OF EXTREME ULTRAVIOLET INDUCED SURFACE DEFECT PROCESSES PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Universiteit Twente, op gezag van de rector magnificus, prof. dr. H. Brinksma, volgens besluit van het College voor Promoties in het openbaar te verdedigen op donderdag 22 oktober 2015 om 12:45 uur door An Gao geboren op 25 Nov 1984 te Shandong, China Dit proefschrift is goedgekeurd door de promotor Prof.dr. F. Bijkerk en assistent promotor Dr. C.J. Lee This thesis is based on the following publications: Chapter 4: A. Gao, P. J. Rizo, L. Scaccabarrozi, C.J. Lee, V. Banine, F. Bijkerk, “Photoluminescence-based detection of particle contamination on Extreme Ultra-Violet reticles” Review of Scientific Instruments 86, 063109 (2015) Chapter 5: A. Gao, P.J. Rizo, E. Zoethout, L. Scaccabarozzi, C.J. Lee, V. Banine, F. Bijkerk, ” Extreme ultraviolet induced defects on few-layer graphene”, Journal of Applied. Physics 114, 044313 (2013) Chapter 6: A. Gao, E. Zoethout, J.M. Sturm, C.J. Lee, F. Bijkerk, ”Defect formation in single layer graphene under extreme ultraviolet irradiation”, Applied Surface Science, 317 . 745 - 751 (2014) Chapter 7: A. Gao, C.J. Lee, F. Bijkerk,”Graphene defect formation by extreme ultraviolet generated photoelectrons”, Journal of Applied Physics. 116, 054312 (2014) This work is part of the research programme ‘Controlling photon and plasma induced processes at EUV optical surfaces (CP3E)’ of the ‘Stichting voor Fundamenteel Onderzoek der Materie (FOM)’, which is financially supported by the ‘Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)’. The CP3E programme is co- financed by Carl Zeiss SMT and ASML. We also acknowledge financial support from Agentschap NL (EXEPT project). Table of Contents Chapter 1 Introduction ......................................................................... 1 1.1 Photolithography ..................................................................... 1 1.2 EUV reticles and reticle defects .............................................. 4 1.3 Particle contamination on reticles in EUVL ............................ 7 1.4 Inspection of particle contamination ....................................... 9 1.5 EUV Pellicle: prevention of particle contamination .............. 13 1.6 Outline of this thesis .............................................................. 15 1.7 References ............................................................................. 16 Chapter 2 Photoluminescence ............................................................ 20 2.1 Introduction ........................................................................... 20 2.2 Color centers .......................................................................... 26 2.3 Photoluminescence from particles in EUVL ......................... 28 2.4 References ............................................................................. 29 Chapter 3 Graphene............................................................................ 31 3.1 Introduction ........................................................................... 31 3.2 Graphene synthesis ................................................................ 32 3.3 Defects in graphene ............................................................... 36 3.4 Graphene characterization: Raman spectroscopy .................. 38 3.5 Reference ............................................................................... 44 Chapter 4 Photoluminescence-based detection of particle contamination on EUV reticles ............................................................. 48 4.1 Introduction ........................................................................... 48 4.2 Theory.................................................................................... 51 4.3 Experimental setup ................................................................ 53 4.4 Experiment procedure ........................................................... 55 4.5 Results and Discussion .......................................................... 56 [i] 4.6 Conclusion ............................................................................ 66 4.7 References ............................................................................. 67 Chapter 5 EUV induced defects in few-layer graphene .................... 70 5.1 Introduction ........................................................................... 70 5.2 Experimental ......................................................................... 71 5.3 Results and discussion .......................................................... 72 5.3.1 Raman analysis ............................................................. 72 5.3.2 XPS analysis ................................................................. 76 5.4 Conclusions ........................................................................... 78 5.5 References ............................................................................. 79 Chapter 6 Defects formation in single layer graphene under extreme ultraviolet irradiation ............................................................................ 82 6.1 Introduction ........................................................................... 82 6.2 Experiments .......................................................................... 84 6.3 Results and discussion .......................................................... 85 6.3.1 Photo-induced plasma of the residual water ................. 85 6.3.2 Photo-induced plasma of the adsorbed water ................ 88 6.3.3 Exposing graphene with hydrocarbon contamination ... 94 6.4 Conclusion ............................................................................ 97 6.5 Reference .............................................................................. 98 Chapter 7 Graphene defect formation by Extreme UV generated photoelectrons ..................................................................................... 101 7.1 Introduction ......................................................................... 102 7.2 Experiments ........................................................................ 103 7.3 Results and Discussion........................................................ 104 7.4 Conclusion .......................................................................... 112 7.5 Reference ............................................................................ 113 Chapter 8 Valorization ..................................................................... 116 [ii] 8.1 Inspection of EUV reticles .................................................. 116 8.2 Pellicle for the EUV reticle ................................................. 119 8.3 Conclusion ........................................................................... 124 8.4 References ........................................................................... 124 Chapter 9 Summary.......................................................................... 126 Acknowledgement ............................................................................... 132 Curriculum Vitae ................................................................................. 134 [iii] Introduction Chapter 1 Introduction 1.1 Photolithography Defect free imaging is of paramount importance for many optical systems. Photolithography, for instance, is a key process in semiconductor manufacturing, and a technology which requires ultimate imaging control. It transfers chip patterns from a photomask or reticle* to silicon wafers coated with a photo-sensitive lacquer, or resist. A simplified version of an optical lithography system, i.e. designed for the visible or near UV wavelength range, is shown in Figure 1-1. Light from a light source is collimated by a condenser lens; then the light passes through the reticle, where the light is partially blocked by an absorber pattern on the reticle, while the transmitted pattern is projected on the wafer by the projection optics. The smallest feature that can be patterned is often described as the critical dimension (CD) in semiconductor processing. Making the critical dimension smaller is the primary concern of the semiconductor industry, for two main reasons: 1) the number of devices per unit area can increase. Therefore, more devices (integrated circuits) will be produced per wafer, reducing the cost of a single device; 2) a smaller CD improves the performance of the device by allowing, for instance, a faster clock speed (frequency), and/or lower power consumption. The CD is given by Rayleigh’s equation: 1 * In the