AVS 52nd International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoM

Paper PS-MoM8
Modified Actinometry for Monitoring Atomic Radicals in Molecular Gas Discharge

Monday, October 31, 2005, 10:40 am, Room 302

Session: Plasma Diagnostics
Presenter: T. Ishijima, Nagoya University, Japan
Authors: T. Ishijima, Nagoya University, Japan
T. Okada, Nagoya University, Japan
Y. Tanabe, Nagoya University, Japan
H. Sugai, Nagoya University, Japan
Correspondent: Click to Email
Actinometry technique has widely been used for detecting radicals in processing plasmas owing to its simplicity. There are many arguments on its reliability, especially from a viewpoint of electron-impact excitation processes. For example, one often encounters a serious difficulty in detecting atomic radical X in a discharge in diatomic molecule gas X@sub 2@: the dissociative excitation of X@sub 2@ induces the same optical emission line with the direct excitation of X, so that a standard actinometry taking the optical intensity ratio between actinometer (say, Ar) and the radical does not give the direct information of the radical density. Here we propose a method to discriminate a direct excitation component in the actinometry. This method is successfully applied to monitoring the N atom and the O atoms in high-density plasma nitridation and oxidation of silicon surface at low temperatures, respectively. The relative atomic densities obtained in the modified actinometry are compared with the absolute densities measured by appearance mass spectrometry. Preliminary measurements were applied in the the microwave excited plasmas of 2.45 GHz at 0.3 - 1.0 kW. The relative N atom densities are evaluated with N@super 4@P intensity (821 nm) normalized by Ar@super 2@P intensity (750 nm). When the pressure increases from 50 mTorr to 300 mTorr, both the absoulte N atom density and relative atomic densities increase monotonously in the same condition for input power and mixing ratio of Ar/N@sub 2@=9/1. Correlation with the measured atomic densities with the surface analysis data is discussed.