High Temporal Resolution Ion Energy Distribution Functions in HIPIMS Discharges

Mishra, Anurag; Clarke, Gregory; Kelly, Peter; Bradley, James W.

doi:10.1002/ppap.200931601

Cited by 12 publications

(5 citation statements)

References 17 publications

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“…It has been reported that the time-averaged IEDF can be fitted using the sum of two Maxwellian distributions with different effective ion temperatures originating from the on and off phase of the discharge [127]. Furthermore, the time-resolved measurements show that during the pulse, a Thompson-like high-energy tail distribution of the target material IEDF with energies up to 100 eV has been reported, whereas after the pulse the target material IEDF comprises a main low-energy peak and a high-energy tail [127][128][129]. Several contributions showed that by increasing the working gas pressure, the highenergy tail of the IEDF was reduced and the low-energy peak of the IEDF increased and narrowed as a result of thermalization [124][125][126][127][128][129][130][131][132][133][134][135].…”

Section: Ion Energy Distribution Functions-speciesmentioning

confidence: 99%

“…The temporal resolution is limited to 10 µs. Time-resolved measurements were performed in a HIPIMS discharge [125,[127][128][129] where ionization of the sputtered material is up to 80% [156]. Hecimovic et al utilized 20 µs acquisition time to observe the temporal evolution of IEDF of Cr + ions showing dynamic evolution of the ion energies during and after the pulse, figure 19.…”

Section: Time-resolved Measurementsmentioning

confidence: 99%

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Quadrupole mass spectrometry of reactive plasmas

Benedikt¹,

Hecimovic²,

Ellerweg³

et al. 2012

J. Phys. D: Appl. Phys.

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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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Section: Ion Energy Distribution Functions-speciesmentioning

confidence: 99%

Section: Time-resolved Measurementsmentioning

confidence: 99%

Quadrupole mass spectrometry of reactive plasmas

Benedikt¹,

Hecimovic²,

Ellerweg³

et al. 2012

J. Phys. D: Appl. Phys.

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“…Therefore Ti neutrals with only a few volts of forward kinetic energy, ionized outside the trap can readily reach the substrate (grounded or negatively biased). It is these ions that form the bulk of the deposit in HiPIMS and have been detected by energy-resolved mass spectrometry [29][30][31].…”

Section: The Axial Distribution In V Pmentioning

confidence: 99%

The evolution of the plasma potential in a HiPIMS discharge and its relationship to deposition rate

Mishra

Kelly

Bradley

2010

Plasma Sources Sci. Technol.

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122

113

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An electron-emitting probe has been used to measure the temporal evolution of the plasma potential V p along a line from target (Ti) to substrate above the racetrack in a high-power impulse magnetron sputtering discharge pulsed at 100 Hz. The 20 ns time-resolution of the probe allowed us to observe the highly dynamic nature of V p as the discharge voltage waveform develops, with large negative V p values (−210 V) and strong potential gradients existing in the magnetic trap region in the first 6 to 8 µs. After 55 to 60 µs, V p is elevated towards ground potential (0 V) and the bulk electric field collapses. Outside the magnetic trap, i.e. on the open field lines, V p reveals much smaller axial and temporal variations, similar to those observed in conventional pulsed dc magnetrons.At standard conditions (Ar pressure of 0.54 Pa and 650 W average power), the results show that for over 50% of the 100 µs plasma 'on-time' the spatial structure of V p provides a large potential barrier for the sputtered post-ionized species so impeding their transport and deposition at the substrate. This barrier is reduced markedly (by 50%) through a small reduction in the magnetic field strength (33% at the target) so increasing the deposition rate by a factor of 6 at a typical position of the substrate (z = 100 mm). The structure of V p is marginally sensitive to changes in pressure (over the range 0.54 to 1.08 Pa), but more strongly dependent on the applied power (over the range 650 to 950 W).

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“…IV D. With a mass spectrometer that faces the target Vlček et al observed copper ions that have energies of up to 45 eV, 170 and titanium ions that have energies of up to 50 eV, 171 at 0.6 Pa, and zirconium ions with energies up to 100 eV at 1 Pa. 172 They find Cu þ ions to be up to 80%-95% of the total ion flux to the substrate. 173 Mishra et al 174 also have the mass spectrometer facing the race track region of the target 10 cm from a titanium target. They find Ti þ ions having a high energy tail extending up to 100 eV.…”

Section: B Ion Flux Energy and Compositionmentioning

confidence: 99%

High power impulse magnetron sputtering discharge

Guðmundsson¹,

Brenning²,

Lundin³

et al. 2012

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

623

446

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The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

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High Temporal Resolution Ion Energy Distribution Functions in HIPIMS Discharges

Cited by 12 publications

References 17 publications

Quadrupole mass spectrometry of reactive plasmas

Quadrupole mass spectrometry of reactive plasmas

The evolution of the plasma potential in a HiPIMS discharge and its relationship to deposition rate

High power impulse magnetron sputtering discharge

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