CPC H01L 22/20 (2013.01) [G03F 7/70633 (2013.01); G03F 9/7003 (2013.01); H01L 22/12 (2013.01)] | 9 Claims |
1. An apparatus comprising:
an optical metrology tool that includes:
an optical illumination source;
optical elements;
a processing unit configured to:
select a plurality of measurement setups for a corresponding plurality of wafer regions, wherein the wafer regions are pre-determined or determined on-the-fly;
send instructions to carry out metrology measurements with one of the selected measurement setups for each corresponding wafer region using the optical metrology tool, wherein the metrology measurements are on a plurality of metrology targets on one or more wafers;
symmetrize pixel values in pupil images of the wafer regions;
modify at least one pixel value according to an average of neighboring pixel values thereby reducing noise in the pupil images;
concatenate pixels from the metrology measurements using a different one of the measurement setups;
determine metrology metric values from the concatenated pixels;
weight the concatenated pixels; and
determine measurement stability by comparing results from concatenations of different sub-sets of the metrology measurements.
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