Drying treatment method and apparatus

A drying treatment apparatus for drying cleaned semiconductor wafers comprises drying gas producing means (41) connected to a drying treating unit (30) through a drying gas supplying pipe line (32). A flowrate controlling diaphragm pump (50) is provided in an isopropyl alcohol (IPA) supplying pipe line (32) that connects an IPA tank (48) and the drying gas producing means (41). An N2 gas supply source (52) is provided for supplying nitrogen gas into the drying gas producing means (41), and a heater (44) is disposed within the drying gas producing means to produce a drying gas. As a result of this, the amount of the IPA supplied to the drying gas producing means (41) by the diaphragm pump (50) is controllable, thus enabling the concentration of the IPA contained in the drying gas to be maintained at a value within a range of from 3% to 80%, inclusive, and enabling the temperature of the drying gas to be maintained at a value within a range of from 80° to 150°, inclusive, due to the heating by the heater (44). The above feature enables improvement of the drying efficiency and reduction in the amount of consumption of the drying gas.