The repeatability of wafer uniformity measurements can be increased by
taking spatially averaged measurements of wafer response. By increasing
the time over which measurements are obtained, the amount of noise can be
significantly reduced, thereby improving the repeatability of the
measurements. These measurements can be taken at several locations on the
wafer to ensure wafer uniformity. In order to get a stable and repeatable
assessment of the wafer process, addressing uncertainties related to
damage relaxation or incomplete anneal, an anneal decay factor (ADF)
characterization can be performed at a distance away from the TW
measurement boxes. From the ADF measurement and the spatially averaged
measurements of wafer response, a repeatable assessment of the wafer
process can be obtained.