Substrate processing apparatus, substrate processing method, and storage medium

A substrate processing apparatus for processing a substrate using a processing fluid in a supercritical state, the apparatus comprising:

• a processing container that accommodates the substrate and has a first end and a second end opposite the first end;
• a supply line configured to feed the processing fluid in the supercritical state from a fluid supply source to the processing container through at least one nozzle;
• a discharge line that discharges the processing fluid from the processing container through a discharge port positioned at the first end of the processing container;
• a discharge flow rate regulator that regulates a flow rate of the processing fluid discharged from the processing container to the discharge line;
• and
• a controller that controls an operation of the discharge flow rate regulator,
• wherein during at least part of a time period for increasing a pressure inside the processing container from a pressure lower than a critical pressure of the processing fluid to a pressure higher than the critical pressure, the controller controls the discharge flow rate regulator such that the increasing is performed by supplying the processing fluid into the processing container from the fluid supply source through the supply line while simultaneously discharging the processing fluid from the processing container to the discharge line at a discharge flow rate.