Abstract: A system and method of forming a thin film on a semiconductor wafer includes: a reaction tube adapted to provide a sealed space to process a wafer; dual wafer loading boats including a first wafer loading boat and a second wafer loading boat, the first wafer loading boat arranged within the sealed space of the reaction tube, the second wafer loading boat arranged adjacent to either an internal side or an external side of the first wafer loading boat; a gap adjusting unit arranged at a lower portion of the dual wafer loading boats; and a gas supplying unit adapted to supply at least one process gas to the reaction chamber.