Patent ID: 7063981

Claim:
A method for determining changes in a reactant supply system that is designed to supply repeated pulses of a vapor phase reactant to a reaction chamber, the method comprising: providing a reactant source; providing a gas conduit system to connect the reactant source to the reaction chamber; providing a valve positioned in the gas conduit system such that switching of the valve induces vapor phase reactant pulses from the reactant source to the reaction chamber; repeatedly switching the valve to induce repeated vapor phase reactant pulses; providing a first sensor that is in communication with the conduit system at a point upstream of the reaction chamber and downstream of the reactant source, the first sensor providing a first signal indicative of a first characteristic parameter of the reactant pulses as a function of time; generating a first curve having a shape from the first signal for the repeated reactant pulses; and monitoring the shape of the first curve to determine changes in the shape of the first curve over time, the changes in the shape of the first curve being indicative of changes in a supply of repeated reactant pulses to the reaction chamber.