Patent ID: 7189434

Claim:
A method of controlling the operation of photoresist supply apparatus in coating eguipment adapted to perform a coating operation in which a substrate is coated with a solution of photoresist comprising: supplying the solution of photoresist to a nozzle via a third photoresist supply pipe commonly connected to first and second tank traps, the first and second trap tanks being connected respectively to first and second bottles via first and second photoresist supply pipes: sensing the level of the photoresist solution in the first and the second trap tanks; generating an alarm when the sensed level of the photoresist solution in either one of the first and second trap tanks falls below a first level: and generating an interlock signal that stops the progress of the coating operation when the sensed level of the photoresist solution in either one of the first and second trap tanks falls below a second level, lower than the first level: wherein supplying solution of photoresist from the first and second bottles comprises: switchably introducing N, gas into the first bottle via a first gas supply pipe by operating a first solenoid valve disposed thereon, and switchably introducing a source of N, gas into the second bottle via a second gas supply pipe by operating a second solenoid valve disposed thereon: wherein introduction of the N, gas into the first bottle causes the photoresist solution to be supplied via a first photoresist supply pipe to the nozzle, and introduction of the N, gas into the second bottle causes the photoresist solution to be supplied via a second photoresist supply pipe to the operating a third solenoid valve disposed on a first discharge pipe connected to the first trap tank and sensing discharge of the photoresist solution through the first discharge pipe using a first drain sensor, and operating a fourth solenoid valve disposed on the second discharge pipe connected to the second trap tank and sensing discharge of the photoresist solution through the second discharge pipe using a second drain sensor: operating the first and third solenoid valves and sensing discharge of the photoresist solution from the first discharge pipe via the first drain valve in response to a first purge start key signal generated by manipulation of a first purge start button; and, operating the second and fourth solenoid valves and sensing discharge of the photoresist solution from the second discharge pipe via the second drain valve in response to a second purge start key signal generated by manipulation of a second purge start button.