US Patent 7964042 Substrate processing apparatus and substrate processing method

After the rinsing processing is completed, the rotation speed of the substrate is reduced from 600 rpm to 10 rpm to form a puddle-like DIW liquid film. After the supply of DIW is stopped, the control unit waits for a predetermined time (0.5 seconds) so that the film thickness t1 of the puddle-like liquid film becomes approximately uniform. Then, IPA is discharged to a central part of the surface of the substrate at a flow rate of 100 (mL/min) for instance. By the supply of IPA, DIW is replaced with IPA at the central part of the surface of the substrate to form a replaced region. Further, after three seconds of IPA supply, the rotation speed of the substrate is accelerated from 10 rpm to 300 rpm. This causes the replaced region to expand in a radial direction of the substrate so that the entire surface of the substrate is replaced with the low surface-tension solvent.