Interactions between arrayed hollow cathodes

An array of novel hollow cathode plasma sources of 4 mm diameter and driven by up to 500 W of 13.56 MHz rf power was constructed. It was investigated using spatially resolved Langmuir probe measurements in the plasma expansion region. Initial results suggest the plasma observed downstream is the combination of a diffusion from the exit orifice of the 30 mm long cylindrical source region and a uniform plasma created in the expansion region. By measuring the ion density of the plasma plumes produced by two or more active hollow cathode sources, their mutual interaction has been inferred with the aim of determining whether a much larger array of sources could be envisioned. The effectiveness of the plasma in dissociating reactive species was tested using SF₆ and measuring etch rates on unbiased silicon wafers. The results have been modelled and show that it is possible to produce a uniform spread of ±5%.