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 semiconductor processes (100 sccm, 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 beam using an aerodynamic lens. The flow containing the aerosol beam was drawn through vacuum system components. The size of the beam was measured upstream and downstream of these components by collecting the aerosol on a filter and observing the deposition pattern. Very little mixing phenomenon was observed. These results point to a potential limitation in the methods employed by the semiconductor industry for in-situ particle monitoring in vacuum systems. A simple solution to this flaw is suggested.