Non-Local Electron Transport in Inductively Coupled Plasmas

University Of Houston, Houston TX

Investigators

Abstract

This project uses analytical methods and numerical simulations to understand the near-collisionless electron transport in inductively coupled plasmas (ICPs) at low pressures - below 10 mTorr. Collisionless heating and the anomalous skin effect are studied with emphasis on the influence of the oscillatory magnetic field induced by the RF current and an externally applied static magnetic field. Since the efficiency of power deposition profiles are important issues in the use of ICP discharges, particular attention is paid to resonances between the applied discharge frequency and the bounce frequency of electrons in the self-generated potential well, or the cyclotron frequency in the case of the applied static magnetic field. In the latter case, low-intensity static magnetic fields are studied in an effort to contour the power deposition profiles. The non-local approach, a powerful method for analyzing low-pressure plasmas, is extended to cover the near-collisionless regime in both electropositive (argon) and electronegative (chlorine) plasmas. The insight from these studies of electron kinetics and transport are incorporated into self-consistent simulations of ICPs at very low pressures. The models and simulations are tested experimentally by measurement of electromagnetic fields and electron distribution functions in well-characterized ICP reactors. Methodology is stressed so that the approach can be extended to other high-density, low-pressure plasmas such as electron cyclotron resonance (ECR) and helicon plasma tools. Low-pressure, high-density plasmas, including inductively coupled plasmas (ICPs) are necessary to maintain uniformity when processing large-area surfaces, a paramount goal of the microelectronics industry. They also have relevance for materials processing, fluorescent lighting, and other plasma applications. This project includes collaborations with Osram Sylvania, the Princeton Plasma Physics Laboratory, the Korea Advanced Institute of Science and Technology, and the University of Saskatchewan.