Mostly, microelectronics industry has the need of the cleanest microscope columns. For instance, after the semiconductor wafers, containing numerous microelectronic devices, are observed with SEMs, various fabrication processes will continue. Therefore, the wafers cannot be contaminated during SEM observation. The vacuum configuration of the microscopes for this application would probably have a scroll pump used to rough out and to back a turbomolecular pump for the specimen chamber. In addition, ion getter pumps are typically attached to the electron electron gun and the upper portion of the column. In this case, the three types of pumps can provide the cleanest SEM system.