Heating-mode transition in the capacitive mode of inductively coupled plasmas

The evolution of the electron energy distribution function (EEDF) against pressure is investigated in the capacitive mode of inductively coupled plasma (ICP). A significant change in the EEDFs is observed: a bi-Maxwellian EEDF at low pressure (⩽10 mTorr) evolves into a Druyvestein-like EEDF at high pressure (⩾50 mTorr) in the capacitive mode (low-density mode) while the EEDFs in the inductive mode (high-density mode) does not evolve like in the capacitive mode due to high electron–electron collisions. This EEDF transition in the capacitive mode of ICP is similar to that in the capacitive coupled plasma (CCP) reported in literature [V. A. Godyak and R. B. Piejak, Phys. Rev. Lett. 65, 996(1990)] as pressure increases. This observation directly shows that the electron heating mechanism of the capacitive mode in the ICP is the same as that in the CCP, as expected.