Langmuir probe measurements of plasma parameters in a planar magnetron with additional plasma confinement

Langmuir probe measurements have been carried out in a planar magnetron spu ttering system with an additional plasma confinement which can be operated at low argon pressures (down to 3.4 x 10(-2) Pa) when target utilization gr eater than 80% can be achieved. The electron density, electron temperature, relative densities of low- and high-energy groups of electrons and the dif ference between the plasma and floating potential have been determined in v arious positions between the target and a substrate at the argon pressures in the range from 0.05 to 5 Pa. It has been proved that the additional magn etic field results, particularly in larger distances from the target at low er pressures, in the formation of structured electron energy distributions with a substantial contribution from a high-energy group of electrons, whic h is responsible for enhanced gas ionization and relatively high values obs erved for the difference between the plasma and the floating potential. (C) 1999 Elsevier Science Ltd. All rights reserved.