A semiconductor substrate processing apparatus is provided with a cleaning process chamber containing a semiconductor substrate for performing a cleaning process on the semiconductor substrate. Connected to the cleaning process chamber is a cleaning liquid feeding pipe for supplying a cleaning liquid to the semiconductor substrate. A gas dissolving unit is provided in the midpoint of the cleaning liquid feeding pipe for dissolving a prescribed gas in ultrapure water. An inert gas or a reducing gas is dissolved as a prescribed gas in ultrapure water. A control unit is provided having a function of supplying the cleaning liquid with the prescribed gas dissolved therein to the semiconductor substrate subjected to the cleaning process before performing a dry process. Therefore, the surface of the semiconductor substrate is free from stains. Moreover, a metal interconnection does not elude.