Chemical vapor deposition chamber

A semiconductor wafer-processing chamber comprises a substrate support platform having a centrally disposed recess and a substrate support assembly disposed over the centrally disposed recess of the support platform. At least one platform arm extends radially from the substrate support platform to a sidewall of said processing chamber. A pair of fluid line conduits, a RF cable conduit, a temperature probe conduit, and a backside gas supply line conduit having a pair of fluid lines, a RF cable, a temperature probe cable, and a backside gas supply line respectively, are disposed diagonally to define a negative slope through the at least one platform arm and communicate with the centrally disposed recess. The centrally disposed recess serves as a sump for drainage of unwanted fluids and contaminants through such conduits.