Patent ID: 7020981

Claim:
A reactor that defines a reaction chamber for processing a substrate, the reactor comprising: A first inlet for providing a first reactant and to the reaction chamber; A second inlet for a second reactant to the reaction chamber; A first exhaust outlet for removing gases from the reaction chamber; A second exhaust outlet for removing gases from the reaction chamber; A flow control system configured to alternately constrict flow through the first and second exhaust outlets Wherein a first flow restriction divides the first inlet and first exhaust outlet from the reaction chamber and a second flow restriction divides the second inlet and the second exhaust outlet from the reaction chamber and wherein the reactor is configured such that when the first exhaust outlet is in an un-constricted condition and the second exhaust outlet is in a constriction condition, flow from the second inlet is directed through the reaction chamber, over the substrate to the first exhaust outlet and forms a diffusion barrier at least partially within the first flow restriction between the first inlet and the substrate.