| 摘要 |
PROBLEM TO BE SOLVED: To reduce the concentration of residual oxygen by evaporating a cryogen fed into a chamber through an orifice from a cryogen source in the chamber, and substantially purging the atmospheric air in the chamber. SOLUTION: An anneal process to be effected in a furnace 100 is effected in a controlled atmosphere. As for generally requested atmosphere, a substantial part of the peripheral oxygen is artificially purged, and the quantity of oxidation caused on a surface of a material to be treated is reduced. The artificial atmosphere is formed using a condition where the purge gas is liquefied at least locally. A cryogen source 114 to be used as a purge source is of low-pressure type, and the pressure in the tank is preferably about 20-40 psi. A suitable cryogen is an inert gas, which contains liquid nitrogen and argon. Since a limited space is filled by the very large volumetric expansion when the cryogen is changed from the liquid into the gas, a raw material necessary for the purge can be small.
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