| AVS 64th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Thursday Sessions |
| Session PS+VT-ThA |
| Session: | Plasma Diagnostics, Sensors and Control |
| Presenter: | Yaser Helal, The Ohio State University |
| Authors: | Y.H. Helal, The Ohio State University C.F. Neese, The Ohio State University F.C. De Lucia, The Ohio State University A. Niabati, Applied Materials, Inc. M. Johnson, Applied Materials, Inc. B. Craver, Applied Materials, Inc. P.J. Stout, Applied Materials, Inc. M.D. Armacost, Applied Materials, Inc. |
| Correspondent: | Click to Email |
Processing plasmas are at a similar pressure and temperature to the environment used to study atmospheric and astrophysical species in the terahertz (THz) spectral region. Many of the molecular neutrals, radicals, and ions present in processing plasmas have been studied in the laboratory and their absorption spectra have been cataloged or are in the literature for the purpose of astrophysical study. Recent developments in THz devices have made technology commercially available for applications outside of specialized laboratories. The methods developed over several decades in the THz spectral region for these laboratory studies are directly applicable to diagnostic measurements in the semiconductor manufacturing industry. In this work, a continuous wave, intensity calibrated THz absorption spectrometer was developed as a remote sensor of gas and plasma species. A major advantage of intensity calibrated rotational absorption spectroscopy is its ability to determine absolute concentrations and temperatures of molecular species from first principles without altering the plasma environment. An important part of this work was the design of the optical components which couple 500 – 750 GHz radiation through a commercial inductively coupled plasma (ICP) chamber. The measurement of transmission spectra was simultaneously fit for background and absorption signal. The measured absorption signal was used to calculate absolute densities and temperatures of polar species. Examples of measurements made in ICPs will be presented. Also, time resolved measurements were made and the time evolution of molecular densities will be discussed.