Huang, S;
Volynets, V;
Hamilton, JR;
Lee, S;
Song, I-C;
Lu, S;
Tennyson, J;
(2017)
Insights to scaling remote plasma sources sustained in NF3 mixtures.
Journal of Vacuum Science & Technology A
, 35
(3)
, Article 031302. 10.1116/1.4978551.
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Abstract
Remote plasma sources (RPSs) are being developed for low damage materials processing during semiconductor fabrication. Plasmas sustained in NF3 are often used as a source of F atoms. NF3 containing gas mixtures such as NF3/O2 and NF3/H2 provide additional opportunities to produce and control desirable reactive species such as F and NO. In this paper, results from computational investigations of RPS sustained in capacitively coupled plasmas are discussed using zero-dimensional global and two-dimensional reactor scale models. A comprehensive reaction mechanism for plasmas sustained in Ar/NF3/O2 was developed using electron impact cross sections for NF2 and NF calculated by ab initio molecular R-matrix methods. For validation of the reaction mechanism, results from the simulations were compared with optical emission spectroscopy measurements of radical densities. Dissociative attachment and dissociative excitation of NFx are the major sources of F radicals. The exothermicity from these Franck–Condon dissociative processes is the dominant gas heating mechanism, producing gas temperatures in excess of 1500 K. The large fractional dissociation of the feedstock gases enables a larger variety of end-products. Reactions between NFx and O atom containing species lead to the formation of NO and N2O through endothermic reactions facilitated by the gas heating, followed by the formation of NO2 and FNO from exothermic reactions. The downstream composition in the flowing afterglow is an ion–ion plasma maintained by, in oxygen containing mixtures, [F−] ≈ [NO+] since NO has the lowest ionization potential and F has the highest electron affinity among the major neutral species.
| Type: | Article |
|---|---|
| Title: | Insights to scaling remote plasma sources sustained in NF3 mixtures |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1116/1.4978551 |
| Publisher version: | http://doi.org/10.1116/1.4978551 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Technology, Physical Sciences, Materials Science, Coatings & Films, Physics, Applied, Materials Science, Physics, KINETIC-DATA EVALUATION, ION-MOLECULE REACTIONS, ELECTRON-IMPACT IONIZATION, DOWNSTREAM ETCH SYSTEMS, TOTAL CROSS-SECTIONS, GAS-PHASE REACTIONS, ATMOSPHERIC CHEMISTRY, IUPAC SUBCOMMITTEE, PHOTOCHEMICAL DATA, RATE-CONSTANT |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1551289 |
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