Integration of automated cryopump safety purge
View Patent ↗A system and method is provided to control a purge valve during an unsafe condition associated with a cryopump. An electronic controller may be used to control the opening and closing of one or more purge valves during the unsafe condition. The purge valve can be a cryo-purge valve or exhaust purge valve. The purge valve can be a normally open valve. The electronic controller can release the normally open valve in response to the unsafe condition. The electronic controller can delay its response to the unsafe condition for a safe period of time. Attempts from other systems to control these valves during unsafe conditions can be preempted during unsafe conditions. A user can be inhibited from manually controlling the purge valve during unsafe conditions. A power failure recovery routine may be initiated in response to a restoration of power. The power failure recovery routine can respond to an unsafe condition even if the power failure recovery routine has been manually turned off by a user.
1. A method of controlling a cryopump, the method comprising:
monitoring a temperature sensor coupled to the cryopump to determine whether the temperature sensor is functioning;
determining a potentially unsafe condition in response to an inability to determine a reading from the temperature sensor coupled to the cryopump;
automatically responding to the inability to determine the temperature reading by initiating an automated safety purge routine that releases a normally open purge valve coupled to the cryopump to deliver purge gas to dilute potentially hazardous gas; and
preventing the safety purge routine from being aborted by maintaining the normally open purge valve open until the potentially unsafe condition changes to a safe condition.
2. The method according to claim 1 wherein the normally open purge valve is at least one of: a cryo-purge valve or an exhaust purge valve coupled to an exhaust line.
3. The method according to claim 1 wherein directing the normally open purge valve open further includes emitting purge gas inside a process chamber.
4. The method according to claim 3 wherein the cryopump is in situ, such that the cryopump includes cryopumping surfaces inside the process chamber.
5. The method according to claim 1 wherein preventing the safety purge routine from being aborted further includes preventing another system from closing the normally open purge valve.
6. The method according to claim 1 wherein preventing the safety purge routine from being aborted further includes preempting a host controller from closing the normally open purge valve.
7. The method according to claim 1 wherein the normally open purge valve is maintained open upon release using local electronics on the cryopump, the local electronics configured to prevent any other system from controlling operation of the normally open purge valve.
8. The method according to claim 7 wherein causing the normally open purge valve to deliver purge gas further includes delaying the safety purge routine by:
retaining the normally open purge valve closed for a safe period of time; and
after the safe period of time elapses, allowing the normally open purge valve to open.
9. A system for controlling a cryopump comprising:
an electronic controller configured to monitor a temperature sensor coupled to the cryopump to determine whether the temperature sensor is functioning;
the electronic controller configured to determine a potentially unsafe condition in response to an inability to determine a temperature from the temperature sensor coupled to the cryopump;
the electronic controller configured to automatically respond to the inability to determine a temperature from the temperature sensor by causing a normally open purge valve coupled to the cryopump to deliver purge gas to dilute potentially hazardous gas; and
the electronic controller preventing the safety purge routine from being aborted by maintaining the normally open purge valve open until the potentially unsafe condition changes to a safe condition.
10. The system according to claim 9 wherein the controller preventing the safety purge routine from being aborted further includes the controller preventing another system from closing the normally open purge valve.
11. The system according to claim 9 wherein the cryopump is in situ, such that the cryopump includes cryopumping surfaces inside the process chamber.
12. The system according to claim 9 wherein the electronic controller causing the normally open purge valve to deliver purge gas further includes the electronic controller causing the normally open purge valve to deliver purge gas inside a process chamber.
13. A cryopump comprising:
an electronic controller configured to monitor a temperature sensor coupled to the cryopump;
the electronic controller configured to determine a potentially unsafe condition in response to an inability to determine a temperature reading from the temperature sensor coupled to the cryopump;
the electronic controller configured to automatically respond to the potentially unsafe condition by initiating an automated cryopump safety purge routine that causes a normally open purge valve coupled to the cryopump to deliver gas to dilute potentially hazardous gas; and
the electronic controller configured to prevent the safety purge routine from being aborted by maintaining the normally open purge valve open until the potentially unsafe condition changes to a safe condition.
14. The method according to claim 3 wherein the process chamber is an ion implantation process chamber.
15. The system according to claim 11 wherein the process chamber is an ion implantation process chamber.
16. The method according to claim 1 wherein the normally open purge valve is maintained opened by activating an interlock.
17. The system according to claim 9 wherein the normally open purge valve is maintained opened by activating an interlock.
18. The cryopump according to claim 13 wherein the normally open purge valve is maintained opened by activating an interlock.