Patent ID: 7809474

Claim:
A protection gas control method for a non-sealed process chamber, comprising steps of: (A) activating a protection gas control apparatus while coupling a protection gas to a plurality of throttle valves; (B) defining an opening time for each of the throttle valves; (C) setting up a first target value and a second target value related to the oxygen concentration in the non-sealed process chamber; (D) heating up the non-sealed process chamber; (E) determining whether a processing apparatus is in operation and performing step (F) if the processing apparatus is in operation, and otherwise performing step (M); (F) determining whether an inlet/outlet for the non-sealed process chamber is opened and performing step (G) if the inlet/outlet for the non-sealed process chamber is opened, and otherwise performing step (H); (G) opening all the throttle valves for a pre-determined period of time and performing step (E); (H) closing at least one of the throttle valves; (I) determining whether the oxygen concentration in the non-sealed process chamber is smaller than or equal to the first target value, and performing step (J) if the oxygen concentration in the non-sealed process chamber is smaller than or equal to the first target value, and otherwise performing step (E); (J) determining whether the oxygen concentration in the non-sealed process chamber is smaller than or equal to the second target value, and performing step (K) if the oxygen concentration in the non-sealed process chamber is smaller than or equal to the second target value, and otherwise performing step (L); (K) closing at least one of the throttle valves and performing step (E); (L) keeping the number of throttle valves that are opened and performing step (E); and (M) stopping supplying the protection gas when the temperature of the non-sealed process chamber is lower than a pre-determined temperature.