Mechanism and kinetics of tetrachlorosilane reactions in an argonhyphen;hydrogen microwave plasma

摘要

The dissociation mechanism of silicontetrachloride to silicon by plasma with argon or in mixtures of argon and hydrogen was investigated by sampling the microwave induced plasma and its chemical components by (i) electrostatic double floating probe system (DFPS), (ii) quadrupole mass spectrometry (QMS), and (iii) electron spin resonance (ESR). Plasma diagnostics, i.e., determination of mean electron energy and positive ion density, were performed by DFPS. The reaction rate for chlorosilane fragmentation, polymerization, and silicon formation, in the plasma state were evaluated by QMS sampling of the plasma along the gas flow. ESR was used to investigate the amounts of free radicals adsorbed on solid alumina from different regions of the plasma. Comparing the two plasmas lcub;SiCl4+Arrcub; to lcub;SiCl4+Ar+H2rcub; it was found that the dissociation of SiCl4to Si in the argon plasma is mainly controlled by an ionhyphen;molecule mechanism while the dissociation in the presence of H2is mainly controlled by the radical mechanism.