Measurement on helium excitation temperature in the vicinity of substrate during helium plasma irradiation

Excitaion temperature of helium atom in the vicinity of substrate in an ECR helium plasma was measured based on multi-thermal equilibrium (MTE). In the case of no substrate in the plasma, clear atomic line spectra of excited helium were not observed. The intensities of line spectra increased with the negative voltage biased at the substrate and the discharge pressure. The intensities were also strong at the position close to the substrate. From the Boltzmann plot, an excitation temperature of approximately 4000 K for helium atom was obtained. This temperature was a little higher in the case of lower pressure and farther from the substrate. (author)