NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Optical Computer Aided Tomography Measurements of Plasma Uniformity in an Inductively Coupled Discharge
Published
Author(s)
Eric C. Benck, J R. Roberts
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 from which optical emission measurements can be made of the plasma. The tomographic inversion problem with restricted optical access is being solved using Tikhonov regularization. The accuracy of this inversion process is investigated for sevral different observation geometries using theoretical test data generated from known distributions. Optical CAT is applied to an ICP-GEC plasma source, with all the measuremnts made through a single large 152 mm diameter window. Axially asymmetric plasma distributions are demonstrated as a function of gas flowrate and gas composition.
Citation
Characterization and Metrology for ULSI Technology Conference
Benck, E.
and Roberts, J.
(1998),
Optical Computer Aided Tomography Measurements of Plasma Uniformity in an Inductively Coupled Discharge, Characterization and Metrology for ULSI Technology Conference
(Accessed October 9, 2025)