Formation of isotopically enriched silicon film from fluorosilane produced by isotopically selective infrared multiphoton dissociation

Fabrication of isotopically enriched silicon thin film by plasma-enhanced chemical vapor deposition (PE-CVD) has been performed with source gas mixtures of SiF4, H2 and Ar. Enriched SiF4 gases with 30Si exceeding 25% were obtained from isotopically selective infrared multiphoton dissociation of hexafluorodisilane. The crystalline silicon films were successfully grown by a remote type micro-wave PE-CVD system on a quartz glass and Si wafers at substrate temperature of 623-1023 K. Secondary ion mass spectroscopy and energy-dispersive X-ray spectroscopy analyses indicated that the films had small impurity contents. The isotopic fraction of the grown Si film almost coincided with that of source gas. (author)