Patent ID: 8175831

Claim:
A method for creating a dynamic sampling scheme for a process during which measurements are performed on wafers, comprising: performing the measurements on all of the wafers in at least one lot at all measurement spots on the wafers; and determining an optimal sampling scheme, an enhanced sampling scheme, a reduced sampling scheme, and thresholds for the dynamic sampling scheme for the process based on results of the measurements, wherein the thresholds correspond to values of the measurements at which the optimal sampling scheme, the enhanced sampling scheme, and the reduced sampling scheme are to be used for the process, wherein the optimal sampling scheme, the enhanced sampling scheme, and the reduced sampling scheme comprise numbers of other wafers in other lots to be measured in the process by a measurement tool and one or more parameters of the measurements to be performed on each of the other wafers by the measurement tool during the process, wherein the one or more parameters of the measurements for at least two of the optimal sampling scheme, the enhanced sampling scheme, and the reduced sampling scheme are different and determined prior to use of the dynamic sampling scheme, and wherein said determining is performed using a computer system.