A process gas line (255) for carrying WF6 gas for nucleation, a process gas line (259) for carrying WF6 gas for film deposition after nucleation are joined at a single joint (280) to a carrier gas line (256). A gas line (270) is connected to the joint (280) to carry a mixed gas of the carrier gas and WF6 gas to a processing chamber defined by a processing vessel. Sections of the carrier gas line (256) and the gas line (270) extending on the opposite sides of the joint (280) extend along a straight line, and the process gas lines (255, 259) are perpendicular to the gas line (270).