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Abstract: This paper reports on influences of reactive oxygen (O2) or nitrogen (N2) addition on ionization characteristics of sputtered titanium (Ti) atoms in an argon (Ar)-based novel droplet-free metal ion sources. Although Ti atoms had a pressure dependence of ionization characteristics similar to copper ones in a pure Ar discharge, the ionization characteristics of Ti atoms were affected by adding reactive N2 and O2 gases into the Ar plasma. Especially, the reactive gas addition significantly reduced fluxes of Ti atoms and Ti+ ions probably due to target-poisoning effect caused by chemical reactivity of Ti. Even adding the reactive gases, the source will still work as a droplet-free metal ion source since the ionization fraction of Ti atoms reached over ∼90%. Optimization of discharge conditions and reactive gas provision will be necessary from a metal ion process point of view. [Copyright &y& Elsevier]

Abstract: This paper reports on ionization fraction in sputter-based copper ion sources for plasma immersion ion implantation (PIII). Deposition rate of copper thin film on a silicon substrate was measured, and A Cu+ ion flux fraction to overall Cu species was obtained from the effects of the substrate bias on the deposition rate. The ion flux fraction increased with Ar pressure and the fraction reached ∼100%. The fraction was also compared with that obtained from quadrupole mass spectroscopy (QMS) and Langmuir probe measurements; and these results showed a fairly good agreement. The ionization fraction increased with the discharge pressure and a flight length of the sputtered copper atoms in the plasma column, suggesting that a long interaction time of the copper atoms with the plasma is a crucial condition for the enhancement of the ionization fraction. [Copyright &y& Elsevier]

Abstract: This paper reports on ionization of sputtered zirconium (Zr) atoms in inductively coupled argon discharge. A Zr+ ion flux fraction to overall Zr species mainly was obtained by deposition measurements with the retarding bias method, and the fraction approximately reached ∼100%. The Zr+ ion fraction was affected by the discharge pressure, and hardly dependent on the discharge power corresponding to an electron density. This result suggested that the Zr+ ions were generated with ionization process other than electron impact such as Penning effect. There was an optimal pressure to produce the Zr+ ions, and the Zr+ ion density estimated from the deposition measurement was consistent with that obtained from a combination of Langmuir probe measurements and mass spectroscopic measurements. [Copyright &y& Elsevier]