Plasma cathode oxygen‐ion source

• Published in: Review of scientific instruments 1991-12, Vol.62 (12), p.2890-2894
• Main Author: Shibuya, Takehisa
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma devices
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/1.1142177

A plasma cathode ion source has been developed to attain a long lifetime in oxygen‐ion production. In this ion source, a plasma of a nonreactive gas serves as a cathode in place of a thermionic tungsten hot cathode used in the conventional Kaufman ion source. An anode ring with an annular slit mounted on the top of the ion source contributes to raising spatial uniformity in the ion current density. At 15 cm from the top of the ion source, a current density of 680 μA/cm2 was obtained with a value of 0.85 for the uniformity (defined as the ratio of the lowest density to the highest) in an area of 15 cm diameter. Mass spectrometry results show that considerable amounts of O+ and O2 + ions, especially of O+ ions, as well as Ar+ ions, are contained in ion beams produced by this source. In an oxygen‐ion production test, the ion source could continuously be operated for 61 h. It was confirmed that the ion energy distribution in the beam can be well controlled by the anode ring voltage. In an experiment of oxygen‐ion‐assisted deposition performed with this ion source, a film having a stoichiometric composition very close to SiO2 was successfully produced from a starting material of SiO.