Abstract: A baking apparatus for manufacturing a semiconductor device remarkably enhances the uniformity of the CD (Critical Dimension) of a wafer by creating a uniform temperature distribution. The apparatus includes a processing having an open upper part, a hot plate disposed in the chamber and on which a wafer is to be mounted, a cover covering the upper part of the chamber; and a thin film made of material having a low emissivity extending over the inner surface of the cover. The inventive structure prevents the emission of heat to the outside so that the temperature within the processing chamber can be rapidly stabilized.