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High Temperature Material Processes (An International Quarterly of High-Technology Plasma Processes)

An International Journal

ISSN for PRINT: 1093-3611

Institutional price:	$604.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2006, Volume10

172 pages

DOI: 10.1615/HighTempMatProc.v10.i3

Issue price - $155.00

RF PLASMA PROCESS FOR HIGH PURITY SILICON

A. Soric
Laboratoire de Génie des Procédés Plasmas et Traitement de Surface − Université Pierre et Marie Curie − Paris 6 - ENSCP, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05, France

S. Rousseau
Laboratoire de Génie des Procédés Plasmas et Traitement de Surface − Université Pierre et Marie Curie − Paris 6 - ENSCP, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05, France.

M. Benmansour
Laboratoire de Génie des Procédés Plasmas et Traitement de Surface − Université Pierre et Marie Curie − Paris 6 - ENSCP, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05, France.

Daniel Morvan
Laboratoire de Génie des Procédés Plasmas et Traitement de Surface − Université Pierre et Marie Curie − Paris 6 - ENSCP, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05, France

Jacques Amouroux
Laboratoire de Génie des Procédés Plasmas et Traitement de Surface − Université Pierre et Marie Curie − Paris 6 - ENSCP, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05, France

ABSTRACT

The goal of this study is the metallurgical grade silicon purification in order to obtain photovoltaic grade silicon. The silicon purification process uses thermal plasma and an applied electrical field to the silicon liquid bath. The aim is to develop electrochemical reactions due to the interaction between the plasma bias and the liquid bath that leads to increase the kinetic of the purification. The solid silicon melted by RF thermal plasma (Argon, P = 20 kW) is under a bias DC current generated by the plasma or by independent electrical DC source. The experiments consist in the checking of the impurities extraction process on the liquid bath surface and the understanding of the role of the bath bias on this kinetic according to the nature of the impurity. Indeed, Optical Emission Spectroscopy permits to demonstrate, on line, the role of the sample positive biasing on the evaporation's kinetic of the cationic impurities of the melted silicon sample. Results show that for an applied polarization of 60 V (i = 900 mA), evaporation of calcium during the plasma treatment is increased by a factor 5 compared to a treatment without any current applied. Keywords: Plasma, Silicon, Purification, Electrochemistry, Spectroscopy