Substrate processing apparatus and substrate processing method

A substrate processing apparatus comprising:

• a processing container into which process fluid is supplied and a liquid film of drying liquid formed on a substrate is replaced with the process fluid in a supercritical state to execute a drying process on the substrate;
• a pressure detecting unit that detects a pressure of the process fluid in the processing container;
• a temperature detecting unit that detects a temperature of the process fluid in the processing container;
• and
• a controller, wherein
• the drying process includes:
• a pressure raising process for supplying the process fluid into the processing container to raise an internal pressure of the processing container up to a set pressure equal to or more than a critical pressure, and
• the controller includes:
• a first density calculating unit that calculates first density data indicating a time-dependent change in a density of the process fluid based on a first pressure detected by the pressure detecting unit and a first temperature detected by the temperature detecting unit in the pressure raising process of preprocessing that is the drying process executed in a state where a liquid film of the drying liquid is not formed on the substrate;
• a second density calculating unit that calculates second density data indicating a time-dependent change in a density of the process fluid based on a second pressure detected by the pressure detecting unit and a second temperature detected by the temperature detecting unit in the pressure raising process of a main process that is the drying process executed in a state where a liquid film of the drying liquid is formed on the substrate;
• a density difference calculating unit that calculates density difference data that is difference between the first density data and the second density data;
• and
• an appropriateness determining unit that determines, based on the density difference data and in the main process, appropriateness of the state of the liquid film of the drying liquid formed on the substrate.