Processing chamber cleaning method, cleaning attachment and substrate processing system

The processing chamber cleaning method for a supercritical processing system which includes:

• a wet processing apparatus for processing a substrate by supplying a processing liquid to the substrate;
• and
• a supercritical processing apparatus having a processing chamber for accommodating a supporting member supporting the substrate into a processing space of the processing chamber and processing the substrate by a processing fluid in a supercritical state in the processing space;
• the processing chamber cleaning method comprising:
• transporting a container from a container stocker storing the container to the wet processing apparatus, the container having a flat bottom surface and a side wall surface extending upward from an outer peripheral part of the flat bottom surface;
• storing a cleaning liquid in the container by the wet processing apparatus;
• conveying the container with the cleaning liquid from the wet processing apparatus into the processing chamber of the supercritical processing apparatus and supporting the container by the supporting member;
• and
• accommodating the supporting member into the processing space, filling the processing space within which the container and the cleaning liquid therein are present, with the processing fluid in the supercritical state so that at least part of the cleaning liquid is dissolved into the processing fluid and then discharging the processing fluid by the supercritical processing apparatus, thereby cleaning the processing chamber of the supercritical processing apparatus.