On three different ways to quantify the degree of ionization in sputtering magnetrons

Butler, AlexandreUniv Paris Saclay, LPGP, UMR CNRS 8578, Univ Paris Sud, F-91405 Orsay, France. (author)

QC 20181106
Funding Agencies|Svensk-Franska Stiftelsen; Icelandic Research Fund [130029]; Swedish Government Agency for Innovation Systems (VINNOVA) [2014-04876]
Quantification and control of the fraction of ionization of the sputtered species are crucial in magnetron sputtering, and in particular in high-power impulse magnetron sputtering (HiPIMS), yet proper definitions of the various concepts of ionization are still lacking. In this contribution, we distinguish between three approaches to describe the degree (or fraction) of ionization: the ionized flux fraction F-flux, the ionized density fraction F-density, and the fraction a of the sputtered metal atoms that become ionized in the plasma (sometimes referred to as probability of ionization). By studying a reference HiPIMS discharge with a Ti target, we show how to extract absolute values of these three parameters and how they vary with peak discharge current. Using a simple model, we also identify the physical mechanisms that determine F-flux, F-density, and a as well as how these three concepts of ionization are related. This analysis finally explains why a high ionization probability does not necessarily lead to an equally high ionized flux fraction or ionized density fraction.

Brenning, NilsLinköpings universitet,KTH,Rymd- och plasmafysik,Univ Paris Saclay, LPGP, UMR CNRS 8578, Univ Paris Sud, F-91405 Orsay, France.; Linkoping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linkoping, Sweden.,Plasma och ytbeläggningsfysik,Tekniska fakulteten,Univ Paris Saclay, France; KTH Royal Inst Technol, Sweden(Swepub:liu)nilbr83 (author)
Raadu, Michael A.KTH,Rymd- och plasmafysik,KTH Royal Inst Technol, Sweden(Swepub:kth)u1ajzw7w (author)
Gudmundsson, Jon Tomas,1965-KTH,Rymd- och plasmafysik,Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.,KTH Royal Inst Technol, Sweden; Univ Iceland, Iceland(Swepub:kth)u1q27a34 (author)
Minea, TiberiuUniv Paris Saclay, LPGP, UMR CNRS 8578, Univ Paris Sud, F-91405 Orsay, France. (author)
Lundin, DanielUniv Paris Saclay, LPGP, UMR CNRS 8578, Univ Paris Sud, F-91405 Orsay, France. (author)
Univ Paris Saclay, LPGP, UMR CNRS 8578, Univ Paris Sud, F-91405 Orsay, France.Rymd- och plasmafysik (creator_code:org_t)

In:Plasma sources science & technology: IOP PUBLISHING LTD27:100963-02521361-6595

By the author/editor: Butler, Alexandr ...; Brenning, Nils; Raadu, Michael A ...; Gudmundsson, Jon ...; Minea, Tiberiu; Lundin, Daniel

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Fusion Plasma an ...

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