Characterization of oxygen plasma with a fiber optic catalytic probe and determination of recombination coefficients

Summary form only given. Oxygen plasmas are used in several advanced technologies including the plasma etching, drilling, oxidation, cleaning, ashing and surface activation. Different technologies require application of plasma with different parameters. The density of neutral oxygen atoms can be measured by different means including a variety of optical emission and absorption spectroscopy methods, NO titration, and catalytic probes. Recently, it was shown that fiber optic catalytic probes (FOCP) have some advantages over the other methods. The main advantage is a low cost and the ability for real time measurement of the O density, as well as immunity to EM fields. FOCP are also very good for determination of recombination coefficients for different materials. The fiber optic catalytic probes were used to measure the neutral oxygen density in a post-glow of plasma reactor made from a pyrex tube. Plasma was excited with an inductively coupled RF generator with the frequency of 27.12MHz and the power of 700W. Plasma density was measured with a double Langmuir probe, while the density of neutral oxygen atoms was measured with 4 different fiber optic catalytic probes (Ni, Fe, Co, Nb), where the Ni FOCP was calibrated with NO titration. The measurements were performed at different pressure from 10 to 400 Pa. The results of neutral O density, gas dissociation and recombination coefficients were explained by accommodation and recombination on the FOCP surface, taking into account collision phenomena in ionized gases.