Abstract: A method and system of measuring waviness of a silicon wafer. A memory stores data representative of the shape of the wafer at a plurality of positions on the wafer and a processor processes the data to determine a waviness parameter. The processor defines an inspection surface as a function of the data and calculates deviations between the inspection surface and a first reference plane at a plurality of positions on the inspection surface. The processor further defines a plurality of localized sites on the wafer and calculates deviations between the inspection surface and a second reference plane at a plurality of positions on the inspection surface for each site. The second reference plane is a function of the calculated deviations between the inspection surface for each site and the first reference plane. The processor then defines a waviness parameter for each site as a maximum variance of the calculated deviations between the inspection surface and the second reference plane.