Specific Process Knowledge/Characterization/Stylus Profiler Measurement Uncertainty: Difference between revisions
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Apart from the uncertainty described above, the underlying "shape" of the scan due to the instrument itself will influence the measurement accuracy for steps <1 µm. Although the stylus profilers use an optically flat surface as a reference, the basic underlying scan is never truly completely flat. We have in June 2025 found both random and repeatable scan bowing / noise in the range of 10-60 nm across a 2 cm (2000 µm) scan. This is enough to influence the measurement accuracy of steps <1 µm and especially <500 nm. | Apart from the uncertainty described above, the underlying "shape" of the scan due to the instrument itself will influence the measurement accuracy for steps <1 µm. Although the stylus profilers use an optically flat surface as a reference, the basic underlying scan is never truly completely flat. We have in June 2025 found both random and repeatable scan bowing / noise in the range of 10-60 nm across a 2 cm (2000 µm) scan. This is enough to influence the measurement accuracy of steps <1 µm and especially <500 nm. | ||
We therefore cannot recommend using the stylus profilers for measuring steps <100 nm and one must expect relatively large uncertainty on steps in the range of hundreds of nm. | We therefore cannot recommend using the stylus profilers for measuring steps <100 nm and one must expect relatively large uncertainty on steps in the range of hundreds of nm. See further discussion below. | ||
[[image:Si 6 in left_50umprsec_aveof2.png||right|thumb|Sample average of 2 scans of a blank, new 6" Si wafer made with the P17 Stylus Profiler.]] | [[image:Si 6 in left_50umprsec_aveof2.png||right|thumb|Sample average of 2 scans of a blank, new 6" Si wafer made with the P17 Stylus Profiler.]] | ||