AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuA

Paper PS2-TuA1
Plasma Study in Modulated Pulse Power (MPP) Magnetron Sputtering with Different Magnetron Configurations

Tuesday, October 19, 2010, 2:00 pm, Room Galisteo

Session: Plasma Sources
Presenter: D.N. Ruzic, University of Illinois at Urbana-Champaign
Authors: D.N. Ruzic, University of Illinois at Urbana-Champaign
L. Meng, University of Illinois at Urbana-Champaign
S. Jung, University of Illinois at Urbana-Champaign
M.J. Neumann, University of Illinois at Urbana-Champaign
Correspondent: Click to Email
As a derivative of high power pulsed magnetron sputtering (HPPMS), modulated pulse power (MPP) technology is used to apply arbitrary voltage waveforms to the cathode. It not only retains the distinctive features of HPPMS as the intense pulsed plasma density and potentially high ionization fraction of metal atoms, but also offers high degree of freedom for additional process control. In a 1000 cm2 circular planar magnetron, discharges were initiated using a 10 kW average power MPP generator (capable of a pulse peak power up to 147 kW). To optimize the MPP discharge for the future applications, the effects of pulse waveforms and other discharge parameters on the plasma were studied first using a time-resolved triple Langmuir probe. A typical electron temperature (Te) of 10 eV and an electron density (ne) close to 1012 cm-3 during the pulses were determined. Higher pulse current, lower pulse repetition frequency, higher gas pressure and closer to the target were revealed to exhibit higher ne, while Te was also affected. The ion fluxes were then measured using an electrostatic gridded energy analyzer, showing typical ion energies of about 10 eV. Combined with a quartz crystal microbalance, the analyzer was further employed to measure the ionization fractions of sputtered metal atoms under various conditions. Finally, the effects of magnetron configurations were investigated using a specially-designed magnet pack in which both the positions and the strengths of the magnets were fully adjustable. Several configurations showed obvious superiorities to the normal balanced DC magnetron configuration, maintaining a higher pulse current and consequently a higher plasma density. A qualitative plasma model was proposed to explain the observed results and further understand the underlying mechanisms of the MPP discharge.