An investigation of moisture and oxygen contamination in a vacuum loadlock single-wafer cluster tool

Vacuum loadlocked cluster tools have allowed significant improvement in reactor ambient control to be realized for low-pressure chemical vapor deposition relative to equipment configurations which expose the reaction chamber to cleanroom ambient impurities each time wafers are processed. We found, however, that substantial moisture and oxygen contamination can still be introduced into the cluster platform via the vacuum loadlock. Residual gas analysis was used to identify the wafer cassettes as the major source of impurities. Equipment operating procedures were developed to minimize migration of these contaminants from the loadlocks to the process chamber.