Patent ID: 7286247

Claim:
A method for assessing a measurement system under test (MSUT), the method comprising the steps of: (a) providing a substrate having a plurality of structures; (b) measuring a dimension of the plurality of structures using a reference measurement system (RMS) to generate a first data set, and calculating an RMS uncertainty (U RMS ) from the first data set, where the RMS uncertainty (U RMS ) is defined as one of (i) an RMS precision; (ii) an independently determined RMS total measurement uncertainty (TMU RMS ); and (iii) V U RMS =V ST +V AG , wherein V U RMS is U RMS expressed as a variance, V ST is a short term precision variance, and V AG is an across grating variance; (c) measuring the dimension of the plurality of structures using the MSUT to generate a second data set, and calculating a precision of the MSUT from the second data set; (d) conducting a linear regression analysis of the first and second data sets to determine a corrected precision of the MSUT and a net residual error; (e) determining a total measurement uncertainty (TMU) for the MSUT by removing the RMS uncertainty (U RMS ) from the net residual error; and (f) outputting the TMU to a system capable of optimizing the MSUT.