Abstract: A microelectronic fabrication system that includes a service area, a process area in the service area where microelectronic devices are processed, and a transfer area in the service area where microelectronic devices are transferred to and from the process area, is cleaned by maintaining higher pressure in the process area than in the transfer area, to thereby reduce particle flow from the transfer area to the process area. It has been found that conventional microelectronic fabrication system cleaning methods and systems can allow air to flow backward to the wafer process area. By allowing backward flow of air to the wafer process area, air may be induced from a place where a lower degree of cleanliness is maintained to a place where a higher degree of cleanliness should be maintained. Due to the backward flow of air, particles contained in the transfer area, that may be generated by the transfer system, may flow onto the wafer that is being processed in the process area.