Specific Process Knowledge/Characterization/Dektak XTA: Difference between revisions
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===Total Uncertainty=== | ===Total Uncertainty=== | ||
[[File:Error probability distributions rev.png|upright=2|alt=Four different probability distributions that contribute to the total error on measurements with the DektakXT 6.5 micron range. By far the widest distribution is the one from the error on the standard step, which is a Gaussian. The others are the non-Gaussian spread of the average measurement of the standard height, which cuts off at the QC limits, the resolution, which is a very narrow uniform distribution, and the spread of measurement values for a given step being measured, which is a Gaussian whose width depends on the step in question.|right|thumb|Figure 2: The probability distributions of the main sources of error that are convoluted to create the total error on a profiler measurement.]] | [[File:Error probability distributions rev.png|upright=2|350px|alt=Four different probability distributions that contribute to the total error on measurements with the DektakXT 6.5 micron range. By far the widest distribution is the one from the error on the standard step, which is a Gaussian. The others are the non-Gaussian spread of the average measurement of the standard height, which cuts off at the QC limits, the resolution, which is a very narrow uniform distribution, and the spread of measurement values for a given step being measured, which is a Gaussian whose width depends on the step in question.|right|thumb|Figure 2: The probability distributions of the main sources of error that are convoluted to create the total error on a profiler measurement.]] | ||
Apart from the error due to the standard step height's intrinsic uncertainty, there will be a contribution to the overall uncertainty from the deviation of the value that the profiler measures from the theoretical height of the standard step that could be called "QC error" (since we accept some variation in our quality control routine). In practice for the 917 nm standard this range is about ± 4 nm for the DektakXT and ± 8 nm for the P17, while for the large standard it ranges from about 0.06 µm on the DektakXT to about 0.15 µm on the P17. | Apart from the error due to the standard step height's intrinsic uncertainty, there will be a contribution to the overall uncertainty from the deviation of the value that the profiler measures from the theoretical height of the standard step that could be called "QC error" (since we accept some variation in our quality control routine). In practice for the 917 nm standard this range is about ± 4 nm for the DektakXT and ± 8 nm for the P17, while for the large standard it ranges from about 0.06 µm on the DektakXT to about 0.15 µm on the P17. | ||