Specific Process Knowledge/Characterization/Profiler: Difference between revisions
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====Influence of calibration standard uncertainty==== | ====Influence of calibration standard uncertainty==== | ||
Nanolab staff check the instrument's measurement accuracy with a standard step height of | Nanolab staff check the instrument's measurement accuracy with a standard step height of 917 nm for the 65 kÅ range and 24.925 µm for the larger ranges. The 95 % confidence intervals for the standards are 17 nm for the 9160 Å standard and 0.072 µm for the 24.925 µm standard. If the control measurement is beyond the limit set in our Quality Control procedure, the instrument is calibrated and the users informed (see LabManager for details on the [http://labmanager.dtu.dk/d4Show.php?id=2493&mach=304 control instruction] and the [https://labmanager.dtu.dk/view_binary.php?type=data&mach=304 control measurement data]). | ||
The size of the calibration standard confidence intervals mean that the measurement uncertainty is much more significant for very shallow steps below 500 | The size of the calibration standard confidence intervals mean that the measurement uncertainty is much more significant for very shallow steps below 500 nm than for steps in the micron range: The 95 % confidence interval in the 65 kÅ range is obviously at least ± 17 nm, so measuring a 100 nm step will have a large error percentage-wise. Note that this error (from the calibration standard) is systematic. The random error associated with repeated measurements is usually smaller (perhaps ± 5 nm). One can therefore measure shallow steps to compare samples even if the absolute numbers are not totally reliable. | ||
====Total uncertainty==== | ====Total uncertainty==== | ||