Published May 10, 2011 | Version v1
Miscellaneous Open

Multidimensional particle modeling of non equilibrium low pressure discharges excited by electromagnetic fields

Creators

Description

The aim is to develop a particle model in the case of a multidimensional geometry to analyse the kinetic and energetic behaviours of the reactive plasma generated by low pressure RF discharges excited by electric field and confined by a crossed magnetic field. A better understanding of the properties of such plasmas as a function of operating parameters is essential for new nano-electronic applications using thin film deposition from cathode sputtering. The particle model is based on Monte Carlo simulation for the treatment of collisions including the optimization of the free path calculations and comparisons with the free time of flight calculations. The coupling of the kinetics of charged particles with the calculation of the space charge electric field has also been also optimized. The validation of the particle model was first performed from the coherent results obtained in Ar RF discharge and from comparisons with literature measurements of electron densities in Ar RF discharges. The model is then applied to a cylindrical configuration with plate parallel electrodes in asymmetrical geometry taking into account the self-bias voltage. In the case of Ar/O2 mixtures, the ion-gas collision cross sections have been supplemented by calculations based on interaction potentials and validated from comparisons with measurements of transport coefficient as a function of reduced electric field. Then, the energetic and electrical properties of RF discharges at 13.56 MHz were analyzed according to the partial pressure of O2 in Ar for pressures between 50 and 100 mTorr and also for various amplitudes of the crossed magnetic field from 0 to 50 Gauss. The confinement at the center of discharge and the increasing of the plasma density which is 10 times greater at 50 Gauss were clearly shown. The energy distribution of different ions near the cathode was also analyzed due to their specific roles in the sputtering process. (author)

Abstract (French)

L'objectif est de developper un modele particulaire en geometrie multidimensionnelle pour l'etude energetique et cinetique des plasmas froids reactifs formes dans les decharges excitees par un champ electrique RF et confines par un champ magnetique croise. Une meilleure comprehension des proprietes de ces plasmas en fonction des parametres operatoires est indispensable aux nouvelles applications en nanoelectronique utilisant les depots de couches minces par pulverisation cathodique. Le modele est base sur la methode de Monte Carlo pour le traitement des collisions en optimisant notamment la technique de calcul du libre parcours. Le couplage de la cinetique des particules chargees avec le calcul du champ de charges d'espace a egalement fait l'objet d'optimisations specifiques. La validation du modele particulaire a ete d'abord effectuee par comparaison avec les mesures de densites electroniques de la litterature dans les decharges RF dans l'argon. Le modele est applique a un reacteur cylindrique avec des electrodes planes et paralleles dans une configuration symetrique puis asymetrique en tenant compte de la tension d'auto-polarisation. Dans le cas du melange Ar-O2 etudie, les sections efficaces de collision notamment ion-gaz ont ete completees par des calculs bases sur les potentiels d'interaction et validees par des comparaisons avec des mesures de coefficient de transport en fonction du champ reduit. Ensuite, les proprietes energetiques et electriques de la decharges RF a 13,56 MHz ont ete analysees en fonction de la pression partielle de O2 dans Ar pour des pressions du melange entre 50 et 100 mTorr et surtout en fonction de l'amplitude du champ magnetique croise allant de 0 a 50 Gauss. Le confinement au centre de la decharge et l'augmentation de la densite plasma qui est 10 fois plus grande a 50 Gauss ont ete clairement montres. Les distributions en energie des differents ions a proximite de la cathode a egalement fait l'objet d'analyses specifiques en raison de leurs roles dans les processus de pulverisation. (auteur)

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Additional details

Additional titles

Original title (French)
Modelisation particulaire et multidimensionnelle des decharges hors equilibre a basse pression excitees par champs electromagnetiques

Publishing Information

Imprint Pagination
189 p.
Report number
FRNC-TH--14131

INIS

Country of Publication
France
Country of Input or Organization
France
INIS RN
54044049
Subject category
S70: PLASMA PHYSICS AND FUSION TECHNOLOGY;
Resource subtype / Literary indicator
Thesis
Descriptors DEI
ALGORITHMS; ARGON; CATHODE SPUTTERING; COLD PLASMA; COLLISIONS; COMPUTERIZED SIMULATION; CROSS SECTIONS; ELECTRIC DISCHARGES; ELECTRODES; ELECTROMAGNETIC FIELDS; ELECTRON DENSITY; MEAN FREE PATH; MONTE CARLO METHOD; PLASMA DENSITY; POISSON EQUATION; RF ION SOURCES; SPACE CHARGE; TIME-OF-FLIGHT METHOD
Descriptors DEC
CALCULATION METHODS; DIFFERENTIAL EQUATIONS; ELEMENTS; EQUATIONS; FLUIDS; GASES; ION SOURCES; MATHEMATICAL LOGIC; NONMETALS; PARTIAL DIFFERENTIAL EQUATIONS; PLASMA; PLASMA ION SOURCES; RARE GASES; SIMULATION; SPUTTERING

Optional Information

Notes
88 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses