A Method for Deep Purification of Iodine for Semiconductor Applications

Abstract

We have developed a novel approach for purification of iodine relevant to semiconductor and optical materials applications. For the first time iodine has been purified via intermediate plasma-chemical formation of iodine oxides (mainly I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> ) followed by their thermal decomposition with formation of highly-pure iodine and oxygen. The process of iodine oxidation included direct interaction of iodine vapours with oxygen-argon plasma feed gas mixtures at a low pressure (0.1 Torr) in an inductively coupled non-equilibrium RF (13.56 MHz) plasma discharge. By the new method developed we were able to reduce both metal and carbon-containing impurities. A plausible mechanism for the impurities conversion during the purification process was suggested.