Spatial profiles of a planar inductively coupled discharge in argon

The spatial profiles of the plasma density and plasma potential are important for plasma applications like semiconductor etching because they determine the particle fluxes to the discharge boundaries and the energy distribution of the particles reaching the walls. Langmuir probe measurements have been performed to get information on the electron distribution function (EDF), the plasma density and potential at different positions in the discharge. At low-pressure operation a non-local behaviour of the electrons has been observed; nevertheless, significant differences between the measured spatial profiles and the predictions of non-local theory have been found. Surprisingly, at higher pressures, when strong deviations of the EDF from non-locality occur, the spatial profiles conform to a non-local scenario. These experimental observations could be reproduced by a self-consistent kinetic plasma model.