Patent ID: 7144601

Claim:
A method of purging photoresist from semiconductor wafer coating equipment comprising first and second photoresist storage bottles, first and second supply pipes respectively connected to the first and second photoresist bottles, a supply line connected to the first and second supply pipes downstream thereof, and a spray nozzle disposed at an end of the supply line, the method comprising: after the first and second photoresist storage bottles are exchanged with photoresist storage bottles containing new photoresist, placing the first supply pipe in open communication with the supply line while preventing the second supply pipe from communicating with the supply line, thereby allowing new photoresist in the storage bottle connected to the first supply pipe to flow into the first supply pipe and photoresist in the supply line to issue from the spray nozzle; measuring off a first predetermined period of time beginning from when the first supply pipe is placed in open communication with said the supply line; once the first predetermined period of time has been measured off, preventing the first supply pipe from communicating with the supply line while placing the second supply pipe in open communication with the supply line, thereby allowing new photoresist in the storage bottle connected to the second supply pipe to flow into the second supply pipe and photoresist in the supply line to issue from the spray nozzle; measuring off a second predetermined period of time after the second supply pipe is placed in open communication with the supply line; and preventing photoresist from issuing from the spray nozzle once the second predetermined period of time has elapsed.