Dry vacuum pumps for semiconductor processes: Guidelines for primary pump selection

Each of the many processes used for the production of ultralarge scale integrated devices or flat panel displays has its own chemical and physical requirements. Many require a vacuum environment that may range from slightly below atmospheric pressure to ultrahigh vacuum. Requirements for system cleanliness often dictate an oil-free pumping system. This article discusses each of the process classes which require a dry primary vacuum pump and offers guidelines for the selection of the proper pump type. There are three classes of pump needed depending on the severity of the process—clean, moderate, and harsh—with escalating complexity and cost for pumps made for the harsher environments. In addition to reviewing some of the latest developments in materials and vacuum design, particular attention is paid to operating experience with the very harshest processes—dielectric deposition and metal etch.