VHS 4

Diffusion pumps are vacuum pumps used to produce high vacuum. Diffusion pumps are support equipment rather than direct wafer-processing tools. Diffusion pumps are commonly integrated into vacuum systems that need a low-pressure environment for scientific or industrial work.

Diffusion pumps operate by heating a low-vapor-pressure pump fluid and directing the resulting vapor through jet stages inside the pump body. Diffusion pumps transfer momentum from the vapor jet to gas molecules and drive that gas toward the foreline, where a backing pump removes it from the system. Diffusion pumps require cooled pump walls so the working fluid condenses and returns to the boiler region for repeated circulation.

A diffusion pump sits in the vacuum utility portion of a tool or laboratory vacuum station rather than at the point of material handling. A diffusion pump is used after rough pumping to bring a chamber from preliminary vacuum into a higher-vacuum regime. A diffusion pump normally works with a backing pump and foreline hardware as part of a multi-stage vacuum system.

Diffusion pumps are used wherever high vacuum is needed for laboratory or industrial processes. Diffusion pumps can support vacuum chambers used for thin-film work, surface analysis, beam-line service, and general vacuum experimentation. Diffusion pumps are also used in support systems where the main requirement is sustained evacuation rather than in-chamber process actuation.