@article {58925, title = {Drifting Ionization Zone in DC Magnetron Sputtering Discharges at Very Low Currents}, journal = {IEEE Transactions on Plasma Science}, volume = {42}, year = {2014}, month = {10/2014}, pages = {2578 - 2579}, abstract = {

Discharges with crossed electric and magnetic fields are known to develop instabilities that are crucial in the transport of charged particles. Sputtering magnetrons are no exception. While most recent studies focused on traveling ionization zones in high power impulse magnetron sputtering, we show here fast camera images of magnetron discharges at very low current. A single drifting ionization zone is always present, even down to the threshold current of about 10 mA.

}, issn = {0093-3813}, doi = {10.1109/TPS.2014.2334601}, author = {Andr{\'e} Anders and Pavel A Ni and Joakim Andersson} } @article {58924, title = {Drifting potential humps in ionization zones: The {\textquotedblleft}propeller blades{\textquotedblright} of high power impulse magnetron sputtering}, journal = {Applied Physics Letters}, volume = {103}, year = {2013}, month = {10/2013}, pages = {144103}, abstract = {

Ion energy distribution functions measured for high power impulse magnetron sputtering show features, such as a broad peak at several 10\ eV with an extended tail, as well as asymmetry with respect to E {\texttimes} B, where E and B are the local electric and magnetic field vectors, respectively. Here it is proposed that those features are due to the formation of a potential hump of several 10\ V in each of the traveling ionization zones. Potential hump formation is associated with a negative-positive-negative space charge that naturally forms in ionization zones driven by energetic drifting electrons.

}, keywords = {Electric fields, ionization, plasma ionization, sputter deposition, sputtering}, issn = {00036951}, doi = {10.1063/1.4823827}, author = {Andr{\'e} Anders and Matjaž Panjan and Robert Franz and Joakim Andersson and Pavel A. Ni} } @article {58927, title = {Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas}, journal = {Applied Physics Letters}, volume = {103}, year = {2013}, month = {07/2013}, pages = {054104}, abstract = {

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side-on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

}, keywords = {Aluminium, ionization, Ionizing radiation, plasma ionization, visible spectra}, issn = {00036951}, doi = {10.1063/1.4817257}, author = {Joakim Andersson and Pavel A Ni and Andr{\'e} Anders} } @article {11918, title = {High quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition}, journal = {Thin Solid Films}, year = {2009}, abstract = {

Aluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide (ITO). In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on the growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200{\textdegree}C, have resistivities in the low to mid 10-4Ω cm range with a transmittance better than 85\% in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method.

}, author = {Andr{\'e} Anders and Sunnie H.N. Lim and Kin Man Yu and Joakim Andersson and Johanna Ros{\'e}n and Mike McFarland and Jeff Brown} } @article {11897, title = {Gasless sputtering: Opportunities for ultraclean metallization, coatings in space, and propulsion}, journal = {Applied Physics Letters}, volume = {92}, year = {2008}, pages = {221503}, abstract = {

Pulsed magnetron sputtering was demonstrated in high vacuum: no sputter gas was used at any time. Sustained selfsputtering was initiated by multiply charged ions from a short vacuum arc. Copper ion currents to an ion collector in excess of 30 A were measured, implying a plasma density of about 6 x1018 m-3. This technology may prove useful for metal coatings free of noble gas inclusions and suggests that magnetrons could operate in the vacuum of space. In addition to coating objects in space, the momentum of the sputtered atoms and ions may be utilized in space thrusters.

}, author = {Joakim Andersson and Andr{\'e} Anders} } @article {12123, title = {Observation of Ti4+ ions in a high power impulse magnetron sputtering plasma}, journal = {Applied Physics Letters}, volume = {93}, year = {2008}, month = {08/2008}, pages = {71504}, abstract = {

Multiply charged titanium ions including Ti4+ were observed in high power impulse magnetron sputtering discharges. Mass/charge spectrometry was used to identify metal ion species. Quadruply charged titanium ions were identified by isotope-induced broadening at mass/charge 12. Due to their high potential energy, Ti4+ ions give a high yield of secondary electrons, which in turn are likely to be responsible for the generation of multiply charged states.

}, doi = {10.1063/1.2973179}, author = {Joakim Andersson and Arutiun P. Ehiasarian and Andr{\'e} Anders} } @article {12244, title = {Self-sputtering far above the runaway threshold: an extraordinary metal ion generator}, journal = {Physical Review Letters}, year = {2008}, abstract = {

When self-sputtering is driven far above the runaway threshold voltage, energetic electrons are made available to produce excess plasma far from the magnetron target. Ionization balance considerations show that the secondary electrons deliver the necessary energy to the remote zone. Thereby, such a system can be an extraordinarily prolific generator of useable metal ions. Contrary to other known sources, the ion current to a substrate can exceed the discharge current. For gasless self-sputtering of copper, the useable ion current scales exponentially with the discharge voltage.

}, author = {Joakim Andersson and Andr{\'e} Anders} } @conference {1731, title = {Physics of High Power Impulse Magnetron Sputtering}, booktitle = {ISSP2007: The 9th International Symposium on Sputtering \& Plasma Processes}, year = {2007}, abstract = {

High power impulse magnetron sputtering is characterized by discharge pulses whose target power density exceeds conventional sputtering power densities by two orders of magnitude or more; the goal is to provide a large flux of ionized sputtered material. The processes of pulse evolution are briefly reviewed, including secondary electron emission, self-sputtering, and rarefaction. Using a pulse power supply capable of providing constant voltage for target peak power densities up to 5 kW/cm2, the evolution of the current-voltage characteristics was investigated for copper and titanium. It is shown that the characteristic cannot be reduced to value pairs. Rather, a strong but reproducible development exists. The details depend on the argon pressure and applied voltage. Each target material exhibits a distinct and sharp transition to a high current regime that appears to be dominated by metal plasma. Despite the higher sputter yields for copper, the transition to the high current regime occurs much earlier and stronger for titanium, which may be attributed to a higher secondary electron yield and hence a higher density of electrons confined in the magnetron structure. At high currents, the closed-drift Hall current generates a magnetic field that weakens plasma confinement, thereby enabling large ion currents to reach a biased substrate.

}, author = {Andr{\'e} Anders and Joakim Andersson and David Horwat and Arutiun P. Ehiasarian} }