| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS1-TuA |
| Session: | Plasma Diagnostics, Sensors and Control |
| Presenter: | J.-P. Booth, LPP-CNRS, Ecole Polytechnique, France |
| Authors: | J.-P. Booth, LPP-CNRS, Ecole Polytechnique, France N. Sirse, LPP-CNRS, Ecole Polytechnique, France P. Chabert, LPP-CNRS, Ecole Polytechnique, France M. Foucher, LPP-CNRS, Ecole Polytechnique, France |
| Correspondent: | Click to Email |
Inductively-coupled plasmas (ICP) containing hydrogen bromide are widely used for conductor-etch applications, often using mixtures with Cl2 and O2. However, very few scientific studies (whether theoretical, simulation or experimental) have been made of HBr plasmas [ 1, 2] . We have studied pure HBr plasmas in an industrial-scale ICP (diameter 550mm, height 100mm, excited at 13.56MHz by a 4-turn planar coil) adapted for advanced diagnostic techniques.
We have demonstrated the first detection of Br atoms by two-photon laser-induced fluorescence (TALIF). The relative variation of Br atoms was determined as a function of HBr pressure (5-90 mTorr) and RF power (20-500W). The Br density increases with pressure over this range, although the dissociation fraction (Br density divided by the total gas pressure) decreases with pressure. The Br density also increases with RF power up to about 100W, but then progressively saturates. This saturation could be attributed to complete dissociation of the HBr, or to the onset of gas heating leading to gas density reduction. Measurements of the Br decay rate in the afterglow of a pulsed plasma allow the surface reaction coefficient of Br to be estimated.
The electron density was determined using a microwave hairpin resonator[ 3] . With HBr pressure the electron density peaks at 10 mTorr, and it increases with RF power. This behaviour is very similar to that observed in pure Cl2, although the densities are about a factor 2 lower in HBr. The radial profiles of electron density are centre-peaked at low pressure, but at pressures above 50 mTorr the maximum is off-axis, peaking under the RF antenna coils.
This work was supported by Agence Nationale de la Recherche project INCLINE (ANR-09 BLAN 0019) and by the Applied Materials University Research Partnership Program. NS acknowledges the Ecole Polytechnique for a post-doctoral grant.
[1] Cunge G., Fouchier M., Brihoum M., et al., J Phys D Appl Phys, 2011, 44,
[2] Sasic O., Dujko S., Makabe T., et al., Chemical Physics, 2012, 398, 154-159
[3] Piejak R., Al-Khuzee J. and Braithwaite N. S., Plasma Sources Sci. Technol., 2005, 14, 734