Semiconductor processing and manufacturing requires incredibly high precision operations, with the highest precision devices having features on the order of nanometers (that’s 10-9 meters). In order for the finished product to work correctly, potential contaminants must be removed from the manufacturing system. This means removing as much of the atmosphere or gas present in the system, which requires that the processes be done under vacuum. The feature sizes only continue to get smaller over time (see Moore’s law), making vacuum more and more crucial to the semiconductor manufacturing process.
How are semiconductors manufactured? It’s a complicated process involving many steps where circuits are created on a wafer of semiconducting material (typically silicon) for a specific application (read more about an ASIC or Application Specific Integrated Circuit). An example is the processor (along with many other components) in your phone or computer that you’re using to read this article. There are various processes in semiconductor manufacturing that require vacuum, and they can generally be broken down into two categories; deposition and patterning or lithography.
Deposition is done in a variety of ways including PVD (physical vapor deposition), CVD (chemical vapor deposition), LPCVD (low pressure chemical vapor deposition), MBE (molecular beam epitaxy), and ALD (atomic layer deposition). While deposition involves adding materials to the surface of the semiconductor, lithography involves taking them away. Historically a photoresist material is added to the wafer and then etched away using various processes; you can read more about photoresist here.
Semiconductor fabs are huge; they can be the size of many football fields, producing millions of chips per day. This means that all of the equipment must be very reliable and accurate, because equipment failure can lead to huge financial losses. Additionally, the finished semiconductor products may be used in critical systems, for example on an airplane, and contaminants present in the manufacturing process could easily lead to premature failure of the component. All of this reiterates the importance of reliable, accurate vacuum gauges in these semiconductor manufacturing systems.
Historically semiconductor fabs used glass hot ion and nude hot ion vacuum gauges for a variety of reasons. These gauges are throw-away; there’s no maintenance (cleaning) that can be done as the gauges become contaminated over time other than a degassing procedure. Hot ion gauges are also much more prone to contamination because they’re a hot filament instead of a cold (or room temperature) operation gauge. More recently, semiconductor fabs have started adopting cold cathode vacuum gauges because they’re more contamination resistant and can be cleaned and put back into service.
The most common Televac vacuum gauging solution for semiconductor manufacturing is the MX200 controller along with the 4A convection vacuum gauge for rough vacuum from 1000 Torr to 10-3 Torr, and the 7FC cold cathode vacuum gauge for measurement of high vacuum from 10-2 to 10-11 Torr. The MX200 is a highly configurable vacuum controller, controlling up to 10 vacuum gauges and offering a variety of communication options to read vacuum measurements including 0 to 10 V analog outputs, RS-232/RS-485 communications, and EthernetIP communications. Remember that the cold cathode vacuum gauge can be cleaned, with gauges remaining in operation in certain cases for decades without being replaced.