A source gas-supplying unit may include a chamber for receiving a liquid source. A first pipe may extend into the chamber to dip into the liquid source. The first pipe may provide a carrier gas to bubble through the liquid source to generate a vapor source. A second pipe may be connected to the chamber. The vapor source and the carrier gas may be supplied by the second pipe to a process chamber in which a semiconductor-manufacturing process may be carried out. A blocking structure may be provided in the sealed chamber. The blocking structure may block the liquid source that may be splashed toward the second pipe due to the bubbling.