Patent ID: 7067828

Claim:
Method of determining an average charge state, {overscore (q)}, of cluster ions in a cluster ion beam having a beam path within a reduced-pressure chamber, comprising the steps of: providing, within the reduced-pressure chamber, a cluster ion beam attenuator, a particle flow rate measurement means, and a cluster ion beam current measurement means; disposing the cluster ion beam attenuator within the path of said cluster ion beam to form an attenuated sample of the cluster ion beam; measuring, in turn, the particle flow rate, Γ, of the attenuated sample of the cluster ion beam and the cluster ion beam current, I, of the attenuated sample of the cluster ion beam; and calculating a measure of the average charge state, {overscore (q)}, of cluster ions in the cluster ion beam by using the equation q _ = α ⁢ ⁢ I β ⁢ ⁢ eΓ wherein α and β are calibration constants and e is the magnitude of the electronic charge.