Optical emission spectroscopy diagnostic of discharge plasma in a hollow-cathode sputtering source

Experimental results of the characterization of a cavity hollow-cathode post-discharge sputtering source by optical emission spectroscopy are presented. The discharge parameters are similar to those currently used in sputter-deposited ferromagnetic (Ni, Fe) and nonferromagnetic targets (Cu, Ti): Ar pressures, 6 x 10(-2)-1 x 10(-1) mbar and discharge currents, 5-60mA. The spatial distribution of the relative electron density in front of the cathode nozzle was determined from the radial distribution of light intensity by applying the Abel transformation. Therefore, the optical data could be correlated with the electrical diagnostic results obtained under low-density plasma conditions. The radial and axial distributions of the emission spectra were also mapped in the 340 to 650 nm wavelength range for Ar and metal (Ni, Ti, Cu) species.