| AVS 64th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | Vladimir Nagorny, Mattson Technology, Inc. |
| Authors: | V.P. Nagorny, Mattson Technology, Inc. V.V. Olshansky, Kharkiv Institute of Physics and Technology, Ukraine S. Ma, Mattson Technology, Inc. |
| Correspondent: | Click to Email |
Inductively coupled plasma (ICP) sources have been used in plasma processing for more than two decades, and will be used in a foreseen future. For a photoresist (PR) strip direct plasma interaction with a wafer is undesirable and plasma is used mainly for modification of a gas composition and creating chemically active radicals for processing the wafers. To achieve high ash rates strip tools usually operate at very high flows since a PR strip rate directly relates to the flux of radicals to the surface of the wafer.
Typical fluxes in strip sources are about or exceed 5slm per head and the gas pressure varies in the range of 0.5-5 Torr. At these high gas pressures, electron energy relaxation length for high energy electrons is very short and these electrons can only be in equilibrium with the local effective electric field Eeff rather that with other electrons. That strongly affects both the distribution of energy deposition into plasma, rates of kinetic processes and the field penetration into the plasma volume. A high plasma density, high gas temperature (low gas density N) region is formed near the coil, where reduced electric field Eeff/N is high enough to sustain the ICP discharge in a wide range of process gas pressures and flows, while outside of this region Eeff/N is low and ionization is negligibly small.
In this presentation we compare results of plasma simulations in ICP strip source from the common model with drift-diffusion approximation for both electrons and ions and Maxwellian EEDF for electrons with similar simulations using a new model, where in the hot region the drift-diffusion approximation is used only for ions. As for electrons, they are considered in balance with the effective electric field, and the drift-diffusion approximation for them is used only outside the hot region.