Substrate cleaning apparatus, polishing apparatus, buffing apparatus, substrate cleaning method, substrate processing apparatus, and machine learning apparatus

A substrate cleaning apparatus comprising:

• a substrate holder configured to hold and rotate a substrate;
• a cleaning tool configured to clean the substrate by rubbing the rotating substrate in a presence of a cleaning liquid;
• a surface-property measuring device configured to obtain surface data in a non-contact manner, the surface data being indicative of a surface property which corresponds to a degree of deterioration and a degree of contamination of the cleaning tool;
• and
• a controller coupled to the surface-property measuring device and configured to determine a replacement time of the cleaning tool based on the surface data,
• wherein the surface-property measuring device is configured to obtain surface data of the cleaning tool at at least two measurement points of the cleaning tool each time a predetermined number of substrates are scrubbed, and
• the controller is configured to determine the replacement time of the cleaning tool based on a comparison between a difference in the surface data obtained at the at least two measurement points and a predetermined threshold value for the difference in the surface data stored in advance.