Tracking electron-induced carbon contamination and cleaning of Ru surfaces by Auger electron spectroscopy
17 May 2012-Journal of Vacuum Science and Technology (American Vacuum Society)-Vol. 30, Iss: 4, pp 041401
TL;DR: In this paper, the growth of carbon and oxygen desorption was investigated on a Ru surface by Auger electron spectroscopy (AES) in the presence and absence of additional photoelectrons (PEs) from a focusing Ru mirror.
Abstract: Extreme ultraviolet (EUV) radiation induced growth of carbon and oxygen desorption were investigated on a Ru surface by Auger electron spectroscopy (AES) in the presence and absence of additional photoelectrons (PEs) from a focusing Ru mirror. A decrease in EUV reflectivity with carbon growth in the presence of additional PEs has been observed. Conversely, a carbonaceous Ru surface was cleaned in sequential AES, and discussed in terms of secondary electron assisted dissociation of residual hydrocarbons and water molecules, followed by a chemical reaction between adsorbed carbon and oxygen atoms.
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TL;DR: In this paper, modifications in structural, stoichiometry, and optical properties of Cadmium zinc telluride (CdZnTe) crystals due to 1 keV Ar+ ion irradiation as a function of ion fluence, using ion flux of 1.7 × 1017 ions cm−2 s−1.
Abstract: In this paper, we report on modifications in structural, stoichiometry, and optical properties of cadmium zinc telluride (CdZnTe) crystals due to 1 keV Ar+ ion irradiation as a function of ion fluence, using ion flux of 1.7 × 1017 ions cm−2 s−1. The CdZnTe crystals were irradiated at normal incidence, using fluence range of 8 × 1017–3 × 1019 ions cm−2. Atomic force microscopy studies show sequential change in surface structure as a function of ion fluence, from homogeneously populated nano-hole to micron sized holes on the entire CZT crystal surface. These holes are well geometrically defined and most of them are rectangular in shape. X-ray photoelectron spectroscopy studies show a reduction in Zn at % while Raman and photoluminescence studies show almost complete depletion of Te inclusions and slight red shifts, respectively, due to ion irradiations. Schottky diode radiation detectors fabricated from such defect free CZT crystals will show significantly higher energy resolution.
10 citations
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TL;DR: In this article, the primary electron energy (Ep) dependent change in target current was studied on a grounded Au film in the range of 40 to 3500 eV and the current jumped suddenly from a negative to a positive value at ∼650 eV with increasing Ep, while it disappeared in reverse sweep and with increasing substrate temperature.
Abstract: Primary electron energy (Ep) dependent change in target current was studied on a grounded Au film in the range of 40 to 3500 eV. The current jumped suddenly from a negative to a positive value at ∼650 eV with increasing Ep, while it disappeared in reverse sweep and with increasing substrate temperature. Detailed analysis suggests that Ep dependent surface charging plays a pivotal role in flashover. Prior to critical Ep in the forward sweep, a gradual shift of a double peak-like structure towards high kinetic energy region in the secondary electron spectra also confirms surface charging effect.
2 citations
References
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TL;DR: In this article, a new and thorough examination of secondary electron (SE) yield as a function of primary energy (EPE) and atomic number Z for the 44 elements in the database is made.
Abstract: A new and thorough examination of secondary electron (SE) yield as a function of primary energy (EPE) and atomic number Z for the 44 elements in the database1 is made. The principles of the semiempirical universal law for the SE yield are described and a template for Monte Carlo (MC) simulation is produced accordingly. Both universal curve fitting and MC simulation are made for the 44 elements. The resulted maximum SE yield δm, corresponding primary energy , SE excitation energy e, and effective escape depth λ are tabulated and plotted as a function of atomic number Z. It is found that similarities exist in the profiles of e and λ, δm and , and all of these parameters seem to have characteristics associated with atomic shell filling. Copyright © 2005 John Wiley & Sons, Ltd.
229 citations
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TL;DR: In this paper, a theory of secondary electron emission from metals is formulated on the basis of the Sommerfeld free-electron model, momentum transfer between electrons and lattice being included by introducing a finite mean free path for elastic scattering.
Abstract: A theory of secondary electron emission from metals is formulated on the basis of the Sommerfeld free-electron model, momentum transfer between electrons and lattice being included by introducing a finite mean free path for elastic scattering. The approach to the problem is similar to that of Kadyschewitsch, but the development is simpler and comparison with experiment is made in more detail. An understanding is reached of the influence of work function and the width of the conduction band, making it clear why, on the average, metals with large work function might be expected to be the best emitters. The observed effect of changing the work function of a given metal by surface layers of foreign atoms is interpreted, an inverse relationship between emission and work function being obtained which is in qualitative agreement with experiment. The theory also accounts for the velocity distribution of the secondaries, giving the general shape of the curve and determining the approximate position of the maximum, and is consistent with the observed angular distribution of the secondaries. The investigation is not carried far enough to give new theoretical information concerning the variation of secondary emission with primary energy. However, the relation of the present theory to some work of Bruining is indicated, and attention directed to an important empirical relationship.
182 citations
Book•
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01 Jan 1998
TL;DR: In this article, the authors used spectroscopic and spectrometric techniques for analysis of surfaces and interfaces, core-level binding energies, Auger kinetic energies and modified Auger parameters for some chemical elements in various compounds, documentary standards in surface analysis.
Abstract: Elements of problem-solving how to use this book spectroscopic and spectrometric techniques - x-ray photoelectron spectroscopy (ISS) compositional analysis by Auger electron and x-ray photoelectron spectroscopy ion beam techniques - surface mass spectrometry in-depth analysis - methods for depth profiling ion beam effects in thin surface films and interfaces surface modification by ion implantation introduction to scanned probe microscopy metallurgy microelectronics and semiconductors minerals, ceramics and glasses composites corrosion and surface analysis - an approach involving spectroscopic and electrochemical methods problem-solving methods in tribology with surface specific techniques catalyst characterization adhesion science and technology archaeomaterials appendices - physical constants and conversion factors, data for the elements and isotopes, less commonly used techniques for analysis of surfaces and interfaces, core-level binding energies, Auger kinetic energies and modified Auger parameters for some chemical elements in various compounds, documentary standards in surface analysis - the way of the future?.
153 citations
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TL;DR: In this article, the authors summarize the thermal and radiation-induced surface chemistry of bare Ru exposed to gases; the emphasis is on H2O vapor, a dominant background gas in vacuum processing chambers.
Abstract: One of the most promising methods for next generation device manufacturing is extreme ultraviolet (EUV) lithography, which uses 13.5 nm wavelength radiation generated from freestanding plasma-based sources. The short wavelength of the incident illumination allows for a considerable decrease in printed feature size, but also creates a range of technological challenges not present for traditional optical lithography. Contamination and oxidation form on multilayer reflecting optics surfaces that not only reduce system throughput because of the associated reduction in EUV reflectivity, but also introduce wavefront aberrations that compromise the ability to print uniform features. Capping layers of ruthenium, films ∼2 nm thick, are found to extend the lifetime of Mo/Si multilayer mirrors used in EUV lithography applications. However, reflectivities of even the Ru-coated mirrors degrade in time during exposure to EUV radiation. Ruthenium surfaces are chemically reactive and are very effective as heterogeneous catalysts. In the present paper we summarize the thermal and radiation-induced surface chemistry of bare Ru exposed to gases; the emphasis is on H2O vapor, a dominant background gas in vacuum processing chambers. Our goal is to provide insights into the fundamental physical processes that affect the reflectivity of Ru-coated Mo/Si multilayer mirrors exposed to EUV radiation. Our ultimate goal is to identify and recommend practices or antidotes that may extend mirror lifetimes.
115 citations