| AVS 57th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | V. Milosavljevic, Dublin City University, Ireland & University of Belgrade, Serbia |
| Authors: | V. Milosavljevic, Dublin City University, Ireland & University of Belgrade, Serbia A. Jasenko, Faculty of Pharmacy, Serbia Z. Simic, Astronomical Observatory, Serbia L.C. Popovic, Astronomical Observatory, Serbia |
| Correspondent: | Click to Email |
To decouple the optical contributions of surfaces in a process chamber to the plasma chemistry from those of other constituents present in the plasma is one of the most demanding tasks today. In this work oxygen spectral emission is used for purposes to increase understanding of plasmas such as those used in industry and particularly those used in semiconductor device manufacture, when plasma-surface interactions are of critical importance.
We analyze the intensity of forbidden oxygen lines at 630.0, 636.3, 297.23 and 557.73 nm as well as the (NLTE afflicted) oxygen triplet lines around 777.4 nm. The emission of forbidden spectral lines is used to establish a threshold for actinometry. Actinometry suffers from signal masking by molecular species due to molecular dissociation and trace gas emission. To establish the threshold for actinometry we monitor the emission of forbidden spectral lines and search for “phase transition” in the intensities of forbidden spectral lines (in most cases the upper energy levels of atomic forbidden lines are below the threshold for dissociation of any constituent molecule so that any sudden increase in the emission intensity of forbidden lines indicates molecular dissociation has occurred). Concurrently the forbidden spectral line is used for determination of the main plasma parameters too.
Radiative emission of the forbidden spectral lines follows a three level atomic model that characterize the radiative transfer processes, and can help to understand the contribution of molecular dissociation processes to the emission spectrum of atomic oxygen. This represents a major contribution to the current state of the art and eliminates the requirement for trace gas based actinometry which will overcome not only the molecular masking problem but the intrinsic problem of having a trace gas in the plasma discharge. Thus, this work develops the method based on OES as a non invasive technique for quantifying complex chemistry which has direct application in plasma processing in semiconductor and other industries. This approach enables greater understanding of complex processes allowing, optimization, fault detection, increased productivity and yields. The challenge in this case lies in the complex plasma chemistry that is commonly used in surface treatment and the constraint of applying intrusive sensors to industrial plasma reactors. These constraints make OES ideal for industrial use, however interpreting the spectra and extracting useful information is the challenge. This work is done with ICP 13.56 MHz RF plasma discharge at pure oxygen, as well at oxygen-argon-hydrogen mixture.