Power Deposition in Low Pressure, Capacitively Coupled RF Discharges

Abstract

Capacitively coupled rf discharges are routinely used to produce plasmas for etching and deposition in semiconductor device fabrication. For example, the deposition of thin films of amorphous silicon for solar panels is a well-developed technology based on plasma production in rf excited discharges. The current efforts to improve device fabrication technologies involve developing a better understanding of the plasmas produced and their interactions with the surfaces. This requires an understanding of the rf discharge itself and the mechanisms of electrical power deposition in the gas. Intensive efforts in modeling and diagnosing rf plasmas over the past ten years have led to considerable progress in the understanding of the power deposition mechanisms in these discharges. Models ranging from simple equivalent circuits to sophisticated particle simulation techniques have been used and a consistent picture is emerging from the various models and the experimental results which provides a basis for understanding and optimizing rf discharges to enhance certain plasma properties (see the recent issue of IEEE Transactions on Plasma Science edited by Kushner and Gravest for an overview of the ongoing research in this active area). In this article we present model results to illustrate the range of phenomena determining the power deposition which come into play in these discharge conditions.