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Title: Characterization of Niobium Oxide Films Deposited by High Target Utilization Sputter Sources

Abstract

High quality, refractory metal, oxide coatings are required in a variety of applications such as laser optics, micro-electronic insulating layers, nano-device structures, electro-optic multilayers, sensors and corrosion barriers. A common oxide deposition technique is reactive sputtering because the kinetic mechanism vaporizes almost any solid material in vacuum. Also, the sputtered molecules have higher energies than those generated from thermal evaporation, and so the condensates are smoother and denser than those from thermally-evaporated films. In the typical sputtering system, target erosion is a factor that drives machine availability. In some situations such as nano-layered capacitors, where the device's performance characteristics depends on thick layers, target life becomes a limiting factor on the maximizing device functionality. The keen interest to increase target utilization in sputtering has been addressed in a variety of ways such as target geometry, rotating magnets, and/or shaped magnet arrays. Also, a recent sputtering system has been developed that generates a high density plasma, directs the plasma beam towards the target in a uniform fashion, and erodes the target in a uniform fashion. The purpose of this paper is to characterize and compare niobia films deposited by two types of high target utilization sputtering sources, a rotating magnetron andmore » a high density plasma source. The oxide of interest in this study is niobia because of its high refractive index. The quality of the niobia films were characterized spectroscopically in optical transmission, ellipsometrically, and chemical stoichiometry with X-ray photo-electron spectroscopy. The refractive index, extinction coefficients, Cauchy constants were derived from the ellipsometric modeling. The mechanical properties of coating density and stress are also determined.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
908100
Report Number(s):
UCRL-CONF-227700
TRN: US0703617
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: International Conference on Metallurgical Coatings and Thin Films (ICMCTF), San Diego, CA, United States, Apr 23 - Apr 27, 2007
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; MECHANICAL PROPERTIES; NIOBIUM OXIDES; OXIDES; PLASMA; REFRACTIVE INDEX; REFRACTORY METALS; SPUTTERING; TARGETS; THIN FILMS; METALLURGY; SPECTROSCOPY

Citation Formats

Chow, R, Ellis, A D, Loomis, G E, and Rana, S I. Characterization of Niobium Oxide Films Deposited by High Target Utilization Sputter Sources. United States: N. p., 2007. Web.
Chow, R, Ellis, A D, Loomis, G E, & Rana, S I. Characterization of Niobium Oxide Films Deposited by High Target Utilization Sputter Sources. United States.
Chow, R, Ellis, A D, Loomis, G E, and Rana, S I. Mon . "Characterization of Niobium Oxide Films Deposited by High Target Utilization Sputter Sources". United States. doi:. https://www.osti.gov/servlets/purl/908100.
@article{osti_908100,
title = {Characterization of Niobium Oxide Films Deposited by High Target Utilization Sputter Sources},
author = {Chow, R and Ellis, A D and Loomis, G E and Rana, S I},
abstractNote = {High quality, refractory metal, oxide coatings are required in a variety of applications such as laser optics, micro-electronic insulating layers, nano-device structures, electro-optic multilayers, sensors and corrosion barriers. A common oxide deposition technique is reactive sputtering because the kinetic mechanism vaporizes almost any solid material in vacuum. Also, the sputtered molecules have higher energies than those generated from thermal evaporation, and so the condensates are smoother and denser than those from thermally-evaporated films. In the typical sputtering system, target erosion is a factor that drives machine availability. In some situations such as nano-layered capacitors, where the device's performance characteristics depends on thick layers, target life becomes a limiting factor on the maximizing device functionality. The keen interest to increase target utilization in sputtering has been addressed in a variety of ways such as target geometry, rotating magnets, and/or shaped magnet arrays. Also, a recent sputtering system has been developed that generates a high density plasma, directs the plasma beam towards the target in a uniform fashion, and erodes the target in a uniform fashion. The purpose of this paper is to characterize and compare niobia films deposited by two types of high target utilization sputtering sources, a rotating magnetron and a high density plasma source. The oxide of interest in this study is niobia because of its high refractive index. The quality of the niobia films were characterized spectroscopically in optical transmission, ellipsometrically, and chemical stoichiometry with X-ray photo-electron spectroscopy. The refractive index, extinction coefficients, Cauchy constants were derived from the ellipsometric modeling. The mechanical properties of coating density and stress are also determined.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 29 00:00:00 EST 2007},
month = {Mon Jan 29 00:00:00 EST 2007}
}

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  • High quality RF-sputtered MgO films are used as tunnel barriers to fabricate small area, niobium nitride Josephson tunnel junctions. A magnesium oxide barrier deposited as a single layer, or as a multilayer film, results in devices with similar characteristics. Annealing trilayers at temperatures in excess of 250/sup 0/C for several hours decrease junction current density and improve device quality presumably by increasing barrier heights through reducing resonant tunneling states. A self-aligned process utilizing only two mask levels is used to produce junctions as small as 0.5 ..mu..m/sup 2/ with excellent critical current uniformity. These junctions exhibit energy gaps of 5.1more » mV and low subgap currents at current densities in excess of 1000 A/cm/sup 2/ which make them suitable for a variety of applications such as SIS mixers and logic circuits.« less
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