Formation of magnesium vapor with high evaporation speed

Abstract

A Mg source 3 is received in a vessel 1 having an opening 8, and the vessel 1 is heated at 670.degree. C. or higher to effuse Mg vapor through the opening 8. Since the vessel 1 is filled with Mg vapor, Mg is evaporated from molten state under stable condition without fluctuations in evaporation speed. The Mg vapor is effectively consumed for vapor deposition. A reflector plate may be provided at the outlet of the opening 8, or a duct for introducing Mg vapor from the vessel to the surface of a substrate sheet may be provided. In order to evaporate Mg from stabilized molten state, operational conditions are preferably determined so as to satisfy the relationships of W.sub.1 /W.sub.2 <0.6.times.(P.sub.Mg /V.sup.3) and W.sub.1 /W.sub.2 <0.04.times.P.sub.Mg, wherein W.sub.1 represents the area (mm.sup.2) of the opening 8, W.sub.2 represents the evaporation surface area (mm.sup.2) of the Mg source 3, P.sub.Mg represents Mg vapor pressure (torr.) and V represents the degree of vacuum.

Dependencies are inferred from the claim text.