Patent ID: 7853345
Filing Date: 2010-12-14
Classification: G01D,G06Q

Abstract:
1. A business method for determining an offset for each of a plurality of measurement systems, the business method comprising: managing a computer infrastructure that performs each of the following: obtaining a set of test measurements of an artifact on a monitor wafer for each of the plurality of measurement systems, and a current offset for each measurement system, measuring the artifact on a measurement system under test (MSUT) to obtain a new test measurement, adding the new test measurement to the set of test measurements for the MSUT, calculating an exponentially weighted moving average (EWMA) of each measurement system based on their respective sets of test measurements, calculating for each measurement system a prime value equal to the EWMA of a respective measurement system plus the current offset of the respective measurement system, calculating a median of the prime values for the plurality of measurement systems as a group, calculating for each measurement system, a delta-to-median value equal to the prime value for the respective measurement system minus the median, and resetting the current offset for each respective measurement system to a reset offset equal to the current offset for a respective measurement system minus the delta-to-median for the respective measurement system in response to the delta-to-median value for the respective measurement system exceeding a predetermined threshold; and receiving payment based on the managing.