Substrate processing apparatus and substrate processing method

A substrate processing apparatus comprising:

• a processing container configured to process a substrate using a processing fluid in a supercritical state;
• a processing fluid supply configured to supply the processing fluid to the processing container;
• and
• a controller,
• wherein the processing fluid supply includes:
• a first fluid ejector that ejects the processing fluid into the processing container,
• a second fluid ejector that ejects the processing fluid into the processing container,
• a first supply line that supplies the processing fluid to the first fluid ejector,
• a first opening/closing valve provided in the first supply line,
• a second supply line that supplies the processing fluid to the second fluid ejector,
• a second opening/closing valve provided in the second supply line, and
• a density adjustor that adjusts a density of the processing fluid present on an upstream side of the second opening/closing valve in the second supply line, and
• the controller is configured to control the substrate processing apparatus to execute:
• at least a first process in which the first opening/closing valve is opened and the second opening/closing valve is closed to supply the processing fluid to the first fluid ejector through the first supply line in a first period until a pressure in the processing container is increased and the processing fluid in the processing container reaches a supercritical state after supplying of the processing fluid to the processing container is started,
• at least a second process in which the first opening/closing valve is closed and the second opening/closing valve is opened to supply the processing fluid to the second fluid ejector through the second supply line at a flow rate larger than a flow rate of the processing fluid supplied to the first fluid ejector from the first supply line in the first period, in a second period after the processing fluid in the processing container has reached the supercritical state, and
• a density adjustment process in which after ending of the first process and before starting of the second process, the density adjustor makes a difference between an intra-line density and an intra-container density smaller than a predetermined threshold, the intra-line density being defined as a density of the processing fluid present in an upstream region of the second opening/closing valve in the second supply line, and the intra-container density being defined as a density of the processing fluid present in the processing container.