Sputtering magnetron experiments and modeling

Summary form only given. Global plasma behavior was characterized experimentally for a cylindrically symmetric planar magnetron with a Cu cathode located above a set of permanent magnets, yielding a trap with a major radius of 1.7 cm. It was found that the electron confinement time was ≈1 μs for argon and that this is regulated by the transit time of the ions across the plasma. A DC discharge has several distinct regimes of operation, revealed through the current-voltage-pressure relations, while a modulated discharge is dominated by transient gas recycling, i.e. thermal desorption of ions that were trapped in the cathode surface. Extensive in situ measurements of ions, using sub-Doppler laser induced fluorescence, and of electrons, using Langmuir probes, have also been made. It was also shown that the spatial distribution of ionization and the resulting efficiency of sputtering target utilization can be accurately predicted using a Monte Carlo simulation in which electrons born on the cathode due to secondary emission are followed individually. The average number of ionizations per electron was found to depend strongly on the magnetic field strength, up to about 400 G, but only weakly on the neutral gas pressure. The ion dynamics have been simulated in another Monte Carlo code in which argon ions are released from the sites predicted by the electron code discussed above. It is found that this model adequately predicts the LIF experimental data