| 摘要 |
PURPOSE:To make it possible to remove dislocation, cracks and the like in a film having a required thickness, by setting the temperature of a single cyrstal silicon substrate at a first temperature, at which a film can be formed, in the initial forming period of a single crystal calcium fluoride film, and thereafter setting a second temperature, which is lower than said first temperature and at which a film can be further formed. CONSTITUTION:A single crystal calcium fluoride film 6 is formed on a single crystal silicon substrate 5 by a molecular-beam epitaxial growing method at the substrate temperature of 700 deg.C at the initial film growing period and at a jetting cell temperature of 1200 deg.C. The growing is stopped at the film thickness of 500Angstrom . Then the substrate temperature is decreased to 400 deg.C. Thereafter, a single crystal calcium fluoride film 7 is formed under the condition of a jetting cell temperature of 1,200 deg.C. Thus the single crystal fluoride calcium fluoride films can be formed under an excellent condition of lattice alignment.
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