Substrate processing apparatus and method for determining deterioration degree of conductive pipe

A method for determining a deterioration degree of conductivity of a conductive pipe in a substrate processing apparatus, the substrate processing apparatus including:

• a substrate holder configured to hold and process a substrate;
• a nozzle configured to eject a processing liquid to the substrate held by the substrate holder;
• the conductive pipe connected to the nozzle and configured to supply the processing liquid to the nozzle;
• a ground line that connects the conductive pipe and a reference potential;
• a liquid receiver provided around the substrate holder and configured to receive the processing liquid ejected from the nozzle,
• an electrode provided close to the liquid receiver, and
• a voltage source configured to apply a voltage to the electrode,
• the method comprising:
• imparting a potential difference between a liquid contact surface of the liquid receiver and the reference potential by applying the voltage to the electrode;
• supplying the processing liquid to the conductive pipe thereby ejecting the processing liquid from the nozzle to the liquid receiver;
• when the processing liquid is ejected from the nozzle to the liquid receiver, measuring a current value of a current flowing through a charge moving path established via the measurement liquid between the liquid contact surface of the liquid receiver and the ground line;
• and
• determining a deterioration degree of the conductive pipe based on a relationship between the voltage applied to the electrode by the voltage source and the measured current value.