US Patent 11574827 Substrate processing apparatus and substrate processing method

A substrate processing apparatus includes: a processing unit including a holder that holds a substrate and rotates the substrate, a nozzle that ejects a processing liquid, and a conductive piping unit that supplies the processing liquid to the nozzle; a controller that causes the processing unit to execute a liquid processing in which the substrate is processed by supplying the processing liquid from the nozzle to the substrate that is held and rotated by the holder, and a measuring unit that measures a flowing current generated by the processing liquid flowing through the piping unit. The controller monitors the liquid processing based on a measurement result by the measuring unit.