Slang for a short pressure spike that comes and goes: gas escaping from a trapped pocket when a part moves, a liquid nitrogen trap shedding gas as it warms, or a valve stem or bellows flexing. Burps show up as spikes on the pressure log, and when they repeat at regular intervals they often point to a virtual leak, argon instability or a cycling valve.
Chamber burps every time the wafer lift moves, I think there's a trapped pocket under the lift bellows.
Also heard as
- pressure burst
- spike
Related terms
Virtual leak
Gas trapped in a hidden pocket inside the vacuum that bleeds out slowly and behaves like a small real leak.
Argon instability
Periodic pressure bursts in a diode ion pump as buried argon is released again from the cathodes.
Cold trap
Chilled surface in a pumping line that freezes out water and oil vapour before it reaches the chamber or the pump.
RGA
Residual gas analyzer: a small mass spectrometer that identifies which gases remain in a vacuum chamber.