Abstract: A plurality of jetting outlets having a jetting outlet shape of a Vincent Bach curve are disposed in a jetting part of a heat-treatment apparatus. An oxygen pipe, an air pipe, and an argon pipe are connected to the jetting part. A wafer supplied into a reaction tube is warmed and subjected to a heat treatment at a predetermined temperature. Thereafter, in cooling the wafer, a cooling gas containing oxygen is introduced from the jetting part into the reaction tube after the wafer is cooled to a predetermined temperature, whereby the wafer is further cooled. This restrains exfoliation of the film formed on the wafer.

Abstract: The present invention provides a heat exchanger having a coating with durability which causes neither adhesion of sludge nor separation of the coating within a short time. The surface of the heat exchanger is coated with a fluororesin having excellent chemical resistance and characteristics in that the hardness is R96 or more, the taper abrasion is less than 8.7 mg, the linear expansion coefficient is 7.5 to 8.0.times.10.sup.-5 /.degree.C., and the elongation is 223 to 280%. The fluororesin is preferably poly chloro tri fluoro ethylene with 1-2 weight percent cobalt.