Formation of Isotopically Enriched Silicon Film from Fluorosilane Produced by Isotopically Selective Infrared Multiphoton Dissociation

Abstract

  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 microwave 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.