Sophisticated vacuum systems are required for modern growth, deposition and etching processes, and analytical techniques. These systems have been developed to the point where they are available with optional pumping packages, system designs, and procedures. We discuss the applications of high and ultrahigh vacuum pumping systems and procedures used for device fabrication. Plasma processing in the medium vacuum range is attractive because it is fast, economical, and does not require especially clean vacuum technique. It is now clear that certain device structures must be fabricated under ultraclean plasma conditions. We discuss the current state of ultraclean high flow processing. © 1983, American Vacuum Society. All rights reserved.