Any roughing or backing pump that compresses gas without sealing fluid in the swept volume: scroll, screw, claw, multi-stage Roots and diaphragm designs. Semiconductor fabs put multi-stage screw or Roots-claw dry pumps on almost every process tool because they cope with corrosive and particle-laden exhaust and add no hydrocarbons to the line. They cost more than oil-sealed pumps and often need nitrogen purge and cooling water.
Dry pump on etch 4 tripped on high current again, probably process byproducts caking in the stages.
Also heard as
- dry vacuum pump
- dry roughing pump
Do not mix it up with
- Rotary vane pump: A rotary vane pump needs oil to seal its clearances and counts as a wet pump, while a dry pump has no fluid in the gas path.
Related terms
Scroll pump
Dry pump that compresses gas between a fixed spiral and an orbiting spiral, with no oil in the gas path.
Rotary vane pump
Oil-sealed positive displacement pump in which sliding vanes sweep gas around an off-centre rotor.
Roughing pump
Pump that takes a chamber from atmosphere down to the pressure where the high vacuum pump can take over.
Backstream
Of pump oil or vapour, to flow the wrong way, from the pump back toward the chamber.