Patent ID: 7037372

Claim:
An apparatus for growing a thin film onto a substrate according to the ALD method, the apparatus comprising: a reaction chamber in which the substrate is positioned; a reactant source in communication with the reaction chamber via a first conduit; means for vaporizing reactant from said reactant source; and a flow regulation system configured to regulate the flow of vaporized reactant via the first conduit into said reaction chamber to cause the vaporized reactant to enter the reaction chamber in the form of repeated vapor-phase pulses that alternated with repeated vapor-phase pulses of at least one other reactant to react with the surface of the substrate at a reaction temperature to form a thin film on said substrate; wherein the flow regulation system comprises: a source of inactive gas, which is in communication with the first conduit via a second conduit which is connected to the first conduit at a first connection point; a drain of gas, which is in communication with the first conduit via a third conduit which is connected to the first conduit at a second connection point upstream of the first connection point, the third conduit being at a temperature equal to or higher than the condensation temperature of the vapor-phase reactant; and a non-fully closing valve, which is arranged to provide choking of the reactant flow while still allowing a minimum flow of said reactant.