Spatial distributions of ion-species in a large-volume inductively coupled plasma source

Distributions of plasma parameters, such as electron temperature and electron density have been studied for large-volume processing. In terms of precise study of large-volume plasma, ion-species distributions in plasma should be measured as well as those of plasma parameters. However, no method to measure the spatial distributions of ion species has been developed so far. In this study, we construct a new apparatus to measure the ion-species distribution by using a quadrupole mass spectrometer, which can be moved in vacuum perpendicularly to the beam extraction. Furthermore, we propose a new method to generate uniform plasma by introducing gas in pulse and generate pulsed plasma correspondently with the gas introduction. The results suggest that the ion-species distributions are not consistent with the electron-density distribution and spatial distributions of ion species can be improved by introducing gas in pulse and generating pulsed plasma. For further study towards the next-generation semiconductor fabrication, the ion-species distributions in large-volume plasma should be taken into account as well as those of the other plasma parameters.