Method of reducing particulate contaminants in a chemical-vapor-deposition system

In a chemical-vapor-deposition system, a method of reducing particulate contamination in a reaction chamber, wherein a gas inlet conduit connects said reaction chamber to a source of reactive gas for filling said reaction chamber, wherein a gas outlet conduit having a cross-sectional area connects said reaction chamber to a means for producing a pressure differential in said outlet conduit for exhausting said gas from said reaction chamber, said method comprising the steps of:

• filling, via said inlet conduit, said reaction chamber with a reactive gas from said gas source;
• exhausting the reactive gas from said reaction chamber using said pressure differential producing means;
• isolating said reaction chamber from said pressure differential producing means to cease exhausting the reaction chamber;
• backfilling, via said inlet conduit, said reaction chamber with said reactive gas from said gas source;
• and
• preventing, during said backfilling step, generation of eddy currents within a portion of said outlet conduit by providing a particle restrictor within said outlet conduit, wherein said particle restrictor contains a baffle extending transversely across said outlet conduit, said baffle defines an aperture therethrough, said aperture having a cross-sectional area less than said cross-sectional area of said outlet conduit, said baffle having a convex face that faces into said outlet conduit.