Generation of droplet‐free high‐power pulsed sputtering (HPPS) glow plasma with several tens of kilowatts

Abstract

AbstractA droplet free metallic plasma source is promising for enhanced adhesion of films with a smooth coating surface. This paper concerns a highly ionized metallic plasma source using a pulsed Penning discharge. A high‐power pulsed sputtering (HPPS) glow discharge plasma is generated using electric‐ and magnetic‐field interactions. The metallic species are sputtered by the energetic argon ion bombardment, followed by their ionization in as short as approximately 3 μs. The plasma source is compact in size (approximately 60 × 60 × 60 mm3) and the plasma is arc‐free. The glow plasma is generated at a gap with a length of 10 mm. The magnetic field at the gap is approximately 0.3 T. A pulsed power source with a rectangular‐shaped voltage‐output is used. Fundamental electrical and optical characteristics are obtained. The glow voltage and current are approximately –0.43 kV and 37 A at 30 μs, respectively, which corresponds to a peak power of approximately 16 kW, where the applied voltage –1.2 kV and a current limiting series resistance is 20 Ω. The consumed energy is approximately 0.41 J, which corresponds to an average power of 250 W at a repetition rate of 625 Hz. The power and energy are changed by circuit conditions. In order to increase the consumed power, the current limiting‐resistance is decreased to be 3 Ω, the peak power is increased to approximately 70 kW with a power density of 2.9 kW/cm2, where a current density is 4.5 A/cm2. The ambient gas is argon at a pressure of 2 Pa. In the emission spectra, singly‐ and doubly‐ionized titanium ions are observed, following the generation of argon ions, which shows the ionization of sputtered titanium species. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)