New materials for multilayer mirrors in the extreme ultraviolet region

Persistent Link:
http://hdl.handle.net/10150/279973
Title:
New materials for multilayer mirrors in the extreme ultraviolet region
Author:
Hiller, Uli
Issue Date:
2002
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Near normal incidence multilayer mirrors are optical elements that are suitable for the extreme ultraviolet wavelength (EUV) region where applications include lithography, astronomy, and microscopy. Multilayer mirrors are made from alternating layers of two materials, called the "absorber" and "spacer," with the thickness of the layers designed such that reflections from each interface add in phase resulting in a large overall reflectivity. The criteria I used for the selection of six new material pairs included achieving the maximum theoretical reflectivity while taking into consideration the possible structural properties of the interfaces based on binary phase diagrams. The pairs were: C-Cu, B₄C-Ag, B₄C-Sn, Y-Pd, Be-Mo, and Be-Y. My experimental results on sputtered C-Cu and B₄C-Ag multilayers showed that they are not suitable as mirror materials due to the formation of discontinuous layers of Cu and Ag for small bilayer periods Λ. I also found it not possible to sputter tin films with small enough interfacial roughness values that would result in useful B₄C-Sn mirrors. My analysis of Y-Pd multilayers showed asymmetric alloying at the interfaces with an approximately 40 Å thick alloy region at the Y on Pd interface which would result in negligible mirror reflectivity. I used one of our molecular beam epitaxy (MBE) machines to attempt to grow single crystal Be-Mo mirrors. Although my attempts were unsuccessful to date, this combination cannot be excluded due to various problems with the MBE sample manipulator during the growth study. Finally I used the same MBE machine to grow Be-Y mirrors with up to 40 bilayers. These multilayers had extremely smooth interfaces (σ = 3.5-4.5 A) with a predicted mirror reflectivity larger than 65%. I found the stability of the Be-Y interfaces to be excellent under atmospheric long term storage. An X-ray photoelectron spectroscopy (XPS) annealing study I conducted also showed stable interfaces for temperatures of up to 200°C. Be-Y mirrors should be suitable for a variety of applications including EUV-lithography.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Physics, Condensed Matter.; Physics, Optics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Physics
Degree Grantor:
University of Arizona
Advisor:
Falco, Charles M.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleNew materials for multilayer mirrors in the extreme ultraviolet regionen_US
dc.creatorHiller, Ulien_US
dc.contributor.authorHiller, Ulien_US
dc.date.issued2002en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractNear normal incidence multilayer mirrors are optical elements that are suitable for the extreme ultraviolet wavelength (EUV) region where applications include lithography, astronomy, and microscopy. Multilayer mirrors are made from alternating layers of two materials, called the "absorber" and "spacer," with the thickness of the layers designed such that reflections from each interface add in phase resulting in a large overall reflectivity. The criteria I used for the selection of six new material pairs included achieving the maximum theoretical reflectivity while taking into consideration the possible structural properties of the interfaces based on binary phase diagrams. The pairs were: C-Cu, B₄C-Ag, B₄C-Sn, Y-Pd, Be-Mo, and Be-Y. My experimental results on sputtered C-Cu and B₄C-Ag multilayers showed that they are not suitable as mirror materials due to the formation of discontinuous layers of Cu and Ag for small bilayer periods Λ. I also found it not possible to sputter tin films with small enough interfacial roughness values that would result in useful B₄C-Sn mirrors. My analysis of Y-Pd multilayers showed asymmetric alloying at the interfaces with an approximately 40 Å thick alloy region at the Y on Pd interface which would result in negligible mirror reflectivity. I used one of our molecular beam epitaxy (MBE) machines to attempt to grow single crystal Be-Mo mirrors. Although my attempts were unsuccessful to date, this combination cannot be excluded due to various problems with the MBE sample manipulator during the growth study. Finally I used the same MBE machine to grow Be-Y mirrors with up to 40 bilayers. These multilayers had extremely smooth interfaces (σ = 3.5-4.5 A) with a predicted mirror reflectivity larger than 65%. I found the stability of the Be-Y interfaces to be excellent under atmospheric long term storage. An X-ray photoelectron spectroscopy (XPS) annealing study I conducted also showed stable interfaces for temperatures of up to 200°C. Be-Y mirrors should be suitable for a variety of applications including EUV-lithography.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectPhysics, Condensed Matter.en_US
dc.subjectPhysics, Optics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorFalco, Charles M.en_US
dc.identifier.proquest3050338en_US
dc.identifier.bibrecord.b42728113en_US
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