Ion distribution measurements to probe target and plasma processes in electronegative magnetron discharges. II. Positive ions

Welzel, Th.; Naumov, S.; Ellmer, K.

doi:10.1063/1.3553847

Cited by 16 publications

(8 citation statements)

References 37 publications

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“…This agrees with an earlier finding from positive ions' IEDs. 28 For O À , Fig. 3 shows that a fixed relation to V T is existent for the peak below ÀeV T .…”

Section: B Origin Of the Negative Ionsmentioning

confidence: 92%

Negative oxygen ion formation in reactive magnetron sputtering processes for transparent conductive oxides

Welzel¹,

Ellmer²

2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Reactive d.c. magnetron sputtering in Ar/O2 gas mixtures has been investigated with energy-resolved mass spectrometry. Different metal targets (Mg, Ti, Zn, In, InSn, and Sn), which are of importance for transparent conductive oxide thin film deposition, have been used to study the formation of negative ions, mainly high-energetic O−, which are supposed to induce radiation damage in thin films. Besides their energy distribution, the ions have been particularly investigated with respect to their intensity in comparison of the different target materials. To realize the comparability, various calibration factors had to be introduced. After their application, major differences in the negative ion production have been observed for the target materials. The intensity, especially of O−, differs by about two orders of magnitude. It is shown that this difference results almost exclusively from ions that gain their energy in the target sheath. Those may gain additional energy from the sputtering process or reflection at the target. Low-energetic negative ions are, however, less affected by changes of the target material. The results concerning O− formation are discussed in term of the sputtering rate from the target and are compared to models for negative ion formation.

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“…This agrees with an earlier finding from positive ions' IEDs. 28 For O À , Fig. 3 shows that a fixed relation to V T is existent for the peak below ÀeV T .…”

Section: B Origin Of the Negative Ionsmentioning

confidence: 92%

Negative oxygen ion formation in reactive magnetron sputtering processes for transparent conductive oxides

Welzel¹,

Ellmer²

2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…The source of highenergy ions is the backscattered gas atoms that are converted to fast ions, by resonant charge exchange in the gas phase. Welzel et al [106] reported IEDFs of plasma constituents in reactive dc sputtering of a tungsten target in Ar and O 2 atmosphere. An unusual high-energy tail of Ar + , O + and O + 2 was observed.…”

Section: Ion Energy Distribution Functions-speciesmentioning

confidence: 99%

Quadrupole mass spectrometry of reactive plasmas

Benedikt¹,

Hecimovic²,

Ellerweg³

et al. 2012

J. Phys. D: Appl. Phys.

100

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Reactive plasmas are highly valued for their ability to produce large amounts of reactive radicals and of energetic ions bombarding surrounding surfaces. The non-equilibrium electron driven plasma chemistry is utilized in many applications such as anisotropic etching or deposition of thin films of high-quality materials with unique properties. However, the non-equilibrium character and the high power densities make plasmas very complex and hard to understand. Mass spectrometry (MS) is a very versatile diagnostic method, which has, therefore, a prominent role in the characterization of reactive plasmas. It can access almost all plasma generated species: stable gas-phase products, reactive radicals, positive and negative ions or even internally excited species such as metastables. It can provide absolute densities of neutral particles or energy distribution functions of energetic ions. In particular, plasmas with a rich chemistry, such as hydrocarbon plasmas, could not be understood without MS. This review focuses on quadrupole MS with an electron impact ionization ion source as the most common MS technique applied in plasma analysis. Necessary information for the understanding of this diagnostic and its application and for the proper design and calibration procedure of an MS diagnostic system for quantitative plasma analysis is provided. Important differences between measurements of neutral particles and energetic ions and between the analysis of low pressure and atmospheric pressure plasmas are described and discussed in detail. Moreover, MS-measured ion energy distribution functions in different discharges are discussed and the ability of MS to analyse these distribution functions with time resolution of several microseconds is presented.

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“…It was found that the decrease in the island density was caused by the completion of island coalescence between the pulses for low frequencies while island growth by addition of atoms at higher frequencies impedes coalescence. sputtering [187][188][189][190]. We suggest that the high plasma density in HiPIMS discharges might lead an increase of the degree of ionization of these high energy ions which in combination with a substrate bias might have detrimental effects on growing films.…”

Section: Nucleation and Growth Of Polycrystalline Thin Filmsmentioning

confidence: 99%

Fundamental processes in thin film growth: The origin of compressive stress and the dynamics of the early growth stages

Mangfält¹

2014

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The fundamental mechanisms behind the generation of compressive stresses in polycrystalline thin films, the effects of pulsed deposition fluxes on the dynamics of the early growth stages as well as the generation of energetic Ar + ions in high power impulse magnetron sputtering (HiPIMS) discharges has been studied in this thesis. It was found that compressive film stresses in Mo films deposited using energetic vapor fluxes are correlated with high film densities while only a slight lattice expansion compared to relaxed Mo was found. This implies that the stress is caused by grain boundary densification and not defect creation in the grain bulk. The compressive stress magnitude should scale with the grain boundary length per unit area, or the inverse grain size, if the stress originates in the grain boundaries. This was found to be the case for dense Mo films confirming that the observed compressive stresses originate in the grain boundaries. Similarly to what has been suggested for conditions where adatoms are highly mobile we suggest that atom insertion into grain boundaries is the cause of the compressive stresses observed in the Mo films. Working on a thesis is not a lonely task and I have gotten a lot of inspiration from people around me. I would like to thank everyone (listed or not) who have contributed with seeds of ideas and knowledge. I could not have done this without you. • Ulf Helmersson for taking me on as a student and giving me freedom to define my own work. • Kostas Sarakinos for all long discussions about experiments, confusing results and non-work related science. • Gregory Abadias for a good cooperation and a nice and productive albeit rainy visit in Poitiers. • Viktor Elofsson and Bo Lü for all diffusion and coalescence discussions it all seems a lot more clear now. • Former and present members of the Plasma and Coatings Physics group for all lunches, coffee breaks and trips. Life is more fun when it is slightly absurd... • Colleagues and friends in the Thin Film Physics and Nanostructured Materials groups for Friday cake discussions about work and everything else and for creating a great working environment. • Min familj och vänner för allt stöd och uppmuntran.

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Ion distribution measurements to probe target and plasma processes in electronegative magnetron discharges. II. Positive ions

Cited by 16 publications

References 37 publications

Negative oxygen ion formation in reactive magnetron sputtering processes for transparent conductive oxides

Negative oxygen ion formation in reactive magnetron sputtering processes for transparent conductive oxides

Quadrupole mass spectrometry of reactive plasmas

Fundamental processes in thin film growth: The origin of compressive stress and the dynamics of the early growth stages

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