PARTICLE BEHAVIOR IN VACUUM-SYSTEMS - IMPLICATIONS FOR IN-SITU PARTICLE MONITORING IN SEMICONDUCTOR PROCESSING EQUIPMENT

The flow of aerosol in vacuum conditions representative of many semico nductor processes (100 seem, 1 Torr). was investigated. The study was performed using aerosols with highly nonuniform spatial distributions. An ideally nonuniform aerosol was produced by generating an aerosol b eam using an aerodynamic lens. The flow containing the aerosol beam wa s drawn through vacuum system components. The size of the beam was mea sured upstream and downstream of these components by collecting the ae rosol on a filter and observing the deposition pattern. Very little mi xing phenomenon was observed. These results point to a potential limit ation in the methods employed by the semiconductor industry for in-sit u particle monitoring in vacuum systems. A simple solution to this fla w is suggested.