Control of Ion Energy for Low-Damage Plasma Processing in RF Discharge

A new control technique for ion energy is based on the external electron injection into the capacitively coupled rf plasma using an auxiliary plasma source. The externally injected electrons replace the plasma electrons carrying the rf current and then reconstruct the rf sheath in which ions are accelerated. The experiment is carried out by using a parallel-plate rf plasma device with a magnetron discharge plasma source mounted behind the mesh grounded electrode. The experimental results show that the energies of ions are continuously controlled by varying the amount of injected electrons in a wide range from ≃(1/2)e V rf to ≃T e, and this result agrees with that derived from our simple model.