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Title: Etching mechanism of niobium in coaxial Ar/Cl{sub 2} radio frequency plasma

The understanding of the Ar/Cl{sub 2} plasma etching mechanism is crucial for the desired modification of inner surface of the three dimensional niobium (Nb) superconductive radio frequency cavities. Uniform mass removal in cylindrical shaped structures is a challenging task because the etch rate varies along the direction of gas flow. The study is performed in the asymmetric coaxial radio-frequency (rf) discharge with two identical Nb rings acting as a part of the outer electrode. The dependence of etch rate uniformity on pressure, rf power, dc bias, Cl{sub 2} concentration, diameter of the inner electrode, temperature of the outer cylinder, and position of the samples in the structure is determined. To understand the plasma etching mechanisms, we have studied several factors that have important influence on the etch rate and uniformity, which include the plasma sheath potential, Nb surface temperature, and the gas flow rate.
Authors:
; ; ;  [1] ; ;  [2]
  1. Department of Physics, Center for Accelerator Science, Old Dominion University, Norfolk, Virginia 23529 (United States)
  2. Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)
Publication Date:
OSTI Identifier:
22399298
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 11; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ASYMMETRY; CHLORINE; CONCENTRATION RATIO; CYLINDRICAL CONFIGURATION; ELECTRODES; ETCHING; GAS FLOW; HIGH-FREQUENCY DISCHARGES; MODIFICATIONS; NIOBIUM; PLASMA POTENTIAL; PLASMA SHEATH; RADIOWAVE RADIATION; SUPERCONDUCTING CAVITY RESONATORS; SURFACES; THREE-DIMENSIONAL LATTICES