Vacuum chambers are built in a variety of shapes and sizes. The most frequently utilized designs include spherical chambers, boxes, cylinders, bell jars, and D-shaped. Additional components used in the fabrication of the chambers are endplates, service wells, and feedthrough collars.
Austenitic stainless steels are the most common choice of materials for high vacuum and ultra-high vacuum systems. They are mechanically strong, easy to machine weld and polish, have a magnetic permeability close to 1, possess good corrosion resistance, and can be outgassed by baking. 304L/304 is the most commonly used grade. 304L/304 and 316L/316 are used for ultra-high vacuum systems. 321H/321 is selected when low magnetic permeability is needed. 303, the free machining variation of 304L/304, is not suitable for use in these applications because its sulfur content tends to outgas.
Semi-conductor chips are manufactured by a multi-step process involving chemical vapor deposition, photolithography, chemical stripping, and other processes to create an engineered structure on the surface of a specially prepared silicon wafer. For components in gas delivery systems for semi-conductor manufacturing, 316L/316 is the alloy of choice.