A semiconductor processing apparatus for processing a plurality of substrates is provided. In a preferred embodiment, the apparatus comprises a reaction chamber. The reaction chamber comprises a reaction space for receiving a substrate boat constructed and arranged for holding the plurality of substrates. The rection chamber further comprise a gas distributor for providing gas into the reaction space and a gas exhaust for removing gas from the reaction space. The boat, the gas distributor and the gas exhaust are constructed and arranged to at least partially enclose the substrates in the boat and to form a gas flow path, in use, from the gas distributor to the gas exhaust, wherein the gas flow path is substantially being directed in between the substrates.