When a substrate coated with a coating solution which oxidizes at high temperatures is heat-treated, an oxygen concentration of a treatment atmosphere is lowered when the temperature is low. Poly containing ferrocene is prepared by dissolving ferrocene corresponding to 1 to 3 wt % on the iron atomic basis in furfuryl alcohol, adding hydrochloric acid thereto as a polymerization initiator, and then polymerizing them in the air at 70\xb0 C. The control system includes an atmosphere valve selectively operable to provide atmospheric communication between the enclosure and the CA room or to isolate the enclosure from the CA room.