Optical Computer Aided Tomography for Plasma Uniformity Measurements

Published

July 1, 1998

Author(s)

Eric C. Benck

Abstract

Optical Computer aided tomography (CAT) is being investigated as a potential in situ diagnostic for measuring plasma uniformity without making assumptions concerning the plasma symmetry. The presence of an opaque vacuum chamber wall severely limits the different directions optical emission measurements can be made of the plasma. The tomographic inversion problem with restrict4d optical access is being solved using Tikhonov regularization. The accuracy of the inversion process is investigated for several different observation geometries using theoretical test data generated from known distributions. Optical CAT is applied to an ICP-GEC plasma source for a variety of different plasma conditions, with all the measurements made from a single large 152 mm diameter window. Axially asymmetric plasma distributions are demonstrated as a function of gas flow rate and gas composition.

Proceedings Title

Proceedings of the Plasma Etch Users Group 4th International Workshop on Advanced Plasma Tools and Process Engineering

Conference Dates

May 26-27, 1998

Conference Title

International Conference on Advances in Plasma Tools and Process Engineering

Pub Type

Conferences

Keywords

computer aided tomography, GEC rf reference cell, inductively coupled plasma, optical emission, plasma uniformity

Citation

Benck, E. (1998), Optical Computer Aided Tomography for Plasma Uniformity Measurements, Proceedings of the Plasma Etch Users Group 4th International Workshop on Advanced Plasma Tools and Process Engineering (Accessed October 28, 2025)