Computational study of plasma dynamics and reactive chemistry in a low-pressure inductively coupled CF4/O2 plasma

Abstract

Plasma etching continues to play a central role in microelectronics manufacturing. As the semiconductor industry continues to shrink critical feature sizes and improves device performance, etch challenges continue to increase due to the requirement of processing smaller features along with new device structures. With their high density and high-aspect ratio features, these structures are challenging to manufacture and have required innovation in multiple areas of wafer processing. Innovations in this technology are increasingly reliant on comprehensive physical and chemical models of plasma etch processes. In the present paper, we develop a new mechanism of plasma chemical reactions for a low-pressure CF4/O2 plasma. We validate this mechanism against available experimental data using the self-consistent axisymmetric fluid model of inductively coupled plasma discharge. We show that this mechanism is in reasonable agreement with the results of experiments both quantitively and qualitatively. Using this mechanism, we analyze the influence of oxygen fraction in the feed gas mixture on the kinetics of the ion species and the fluorine and oxygen atom yield.