Inductively coupled plasmas play an important role in the manufacture of computer chips through etching and deposition processes. This relies on established system pressures and power values in order to generate and sustain the required reactive species density. Oxygen and hydrogen plasmas are routinely used in this industry and will therefore be at the centre of this study.
This research focuses on the development of a diagnostic procedure that resolves the plasma-surface interface by analysing stimulated plasma emission induced by a tailored voltage waveform (Pulse induced Optical Emission Spectroscopy (PiOES)). These measurements are generated in an area of the plasma that doesn't benefit from plasma emission produced via the inductive coil but does have great significance for industrial processes. The aim is to find a pulse regime that has minimal impact on electron and ion properties in the plasma-surface region, while producing enough emission to analyse the reactive chemistry and calculate atomic species densities.
PiOES-ERA, HPEM and TALIF techniques have been compared and show good agreement in the measurement and simulation of atomic oxygen density in a low pressure E-mode plasma. This was achieved through the development of a tailored voltage waveform design and novel implementation within the GEC. The final result is a configurable pulse application that allows the operator to analyse different regions of the plasma, that were previously unobtainable.
In both hydrogen and oxygen plasmas the E-H mode transition is found to be key in influencing the atomic species densities. In oxygen this is confirmed through the use of PROES measurements and HPEM simulations. The H-mode plasma measurements highlight additional excitation and/or de-excitation processes that are currently not considered in the ERA model, therefore more research into these processes is required to fully resolve them
