Current rash of wafer handling faults seems to be caused by the loadlock vacuum valve slamming close during wafer transfer. The vibration it generates causes the wafer to shift on the lift pins. The change in position of the wafer is picked up by the capacitive sensor on the robot arm.
- Need to rebuild the load lock vacuum valve.
- Ch.A and C are runable but there is a good chance that the wafer might shift during the unload. Please run it only when staff or a super user is available to recover the wafer.
-Ch.B is down. It seems to be more sensitive to the vibrations.
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