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Title: Surface science applied to the development of novel sensors and methods for EUV mirror remediation
Author: Davis, D. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
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This thesis provides a surface science approach to the study of a fundamental obstacle associated with the implementation of extreme ultraviolet (EUV) lithography: specifically, the degradation of highly intricate and expensive ruthenium-capped multilayer mirrors used in this process. These mirrors have an exceptionally low tolerance to carbon contamination which reduces their reflectivity. Accordingly, this thesis seeks to understand and counteract such issues, and is composed of three inter-linked themes. First is the identification and characterisation of contaminants, that under EUV irradiation, deposit carbon on ruthenium-capped multilayer mirrors. A Ru(0001) single crystal was used to model the ruthenium-capped multilayer mirrors and EUV radiation was simulated using electron irradiation. The rate of carbon deposition from a number of hydrocarbons was investigated using x-ray photoelectron spectroscopy (XPS). The next stage was the development of techniques to monitor levels of hydrocarbon contaminants which were found to deposit carbon at significant rates on Ru(0001) under electron irradiation. Initially hydrocarbon uptakes were performed on a polycrystalline platinum substrate in an attempt to model the behaviour of a platinum electrode on an electrochemical device. The properties of the surface(s) were engineered (by forming surface alloys with gold) to provide adsorption properties resembling those of the Ru(0001) sample under electron irradiation. Following these model studies, the principles were transferred to a solid state electrochemical device where in situ XPS measurements allowed correlation between sensor output and surface composition of the sensing electrode. Finally, methodologies were investigated for counteracting the effects of the poisonous hydrocarbons defined by the studies on Ru(0001). In a real processing environment, such procedures could be initiated when altered by the hydrocarbon monitoring system.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available