Method of forming single crystalline magnesia spinel film

DETAILED DESCRIPTION The present invention has been achieved in order to solve the above described problem.
For a method of forming a single crystalline magnesia spinel film of the present invention, a first single crystalline magnesia spinel layer containing Mg at nearly stoichiometric compositional ratio is epitaxially grown on a single crystalline silicon substrate in a vapor-phase and then a second single crystalline magnesia spinel layer containing Mg at ratios which decrease upward is epitaxially grown in a vapor-phase on the resulting first single crystalline magnesia spinel layer.
Accordingly, it is a first object of the present invention to provide a method capable of forming, on a single crystalline Si substrate, a single crystalline magnesia spinel film wherein a concentration of Mg atoms which react more actively upon Si out of atoms of Mg and Al taken in the Si film at the first growth stage of the Si film, which is an upper layer, is greatly reduced in comparison with the conventional method.
It is a second object of the present invention to provide a method of forming, on a single crystalline Si substrate, a single crystalline magnesia spinel film wherein a reaction of Si upon Mg is suppressed and whereby the Si film, which is an upper layer, is prevented from deteriorating its quality.
It is a third object of the present invention to provide a method of forming a single crystalline magnesia spinel film capable of obtaining a SOI film of superior quality and improving characteristics of various kinds of devices.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.