Method for forming oxide thin film and the treatment of silicon substrate

A method for forming an oxide thin film in the form of an epitaxial film of a composition:

• Zr.sub.1-x R.sub.x O.sub.2-.delta. wherein R is a rare earth metal inclusive of yttrium, x is a number of 0 to 0.75, and .delta. is a number of 0 to 0.5 on a single crystal substrate of silicon, comprising the steps of:
• initially evacuating a vacuum chamber to a vacuum of .ltoreq.1.times.10.sup.-5 Torr,
• heating a single crystal substrate of silicon in the evacuated condition,
• then evaporating at least zirconium among metal elements including zirconium and at least one rare earth metal (inclusive of yttrium) concurrently from distinct evaporation sources at a controlled ratio of Zr and the rare earth metal, thereby supplying the metal(s) to the surface of the single crystal substrate,
• introducing an oxidizing gas into said vacuum chamber at the same time as the supply of the metal(s) or after a delay time from the supply of the metal(s), thereby setting at least the atmosphere in proximity to the single crystal substrate in the vacuum chamber at a pressure of 1.times.10.sup.-4 to 1.times.10.sup.-2 Torr, and
• allowing an oxide thin film to form on the surface of said single crystal substrate by epitaxial growth.