PURPOSE: To decrease the time and the amount of an organic solvent required for performing an organic treatment in an apparatus for organically treating semiconductor substrates within a closed chamber by means of vapor of the organic solvent, by providing a fan for stirring the atmosphere within the closed chamber.

CONSTITUTION: Vapor from an organic solvent reservoir 3 is introduced into a semiconductor substrate treating chamber 7 in which a substrate to be treated 8 is disposed. In the chamber 7, a fan 5 fitted to a fan driving motor 6 is provided for the purpose of creating flow of air to distribute the vapor all over the substrate. In this manner, the period of time required for performing the organic treatment can be shortened and, hence, the amount of the organic solvent to be used also can be decreased.