Comparison of spatial distributions of atomic oxygen and hydrogen in ICP by means of catalytic probes and actinometry.

Low pressure inductively coupled plasma was investigated with a combination of two diagnostic techniques: catalytic probes and optical emission spectroscopy (actinometry). Three working gases were used: oxygen, oxygen–argon mixture and hydrogen. Concentrations of oxygen and hydrogen atoms were determined in a wide range of plasma parameters, with pressure ranging from 10 Pa to 70 Pa, applied power in the range from 50 to 250 W and at many different positions throughout the system (including the coil and afterglow in sample chamber). Concentrations of oxygen atoms were measured to be 1.3 × 10 15 cm −3 in the middle of the coil and 4 × 10 12 cm −3 in the regions of the chamber furthest from the coil. These spatially resolved concentrations are very important in plasma processing of materials, because radical concentrations over the sample determine plasma–material interactions. This work demonstrates that a relatively simple detection system can be practical and sufficiently successful in many plasma applications. [ABSTRACT FROM AUTHOR]