Specific Process Knowledge/Characterization/Stylus Profiler Measurement Uncertainty: Difference between revisions
| Line 44: | Line 44: | ||
Note that the step determination will usually be better than the noise of the underlying scan. In the DektakXT we regularly measure shadow masked metal films made by e-beam evaporation that are around 100 nm thick. We have found good agreement between our measurements with the DektakXT of a 500 µm wide step compared to XRR measurements of films of the same thickness. Probably this is because we level the scan close to the step, so only the curvature in an 800 µm range in x is important, and since we average the thickness across approx. 400 µm across the top of the step compared to 50 µm intervals nearby where the average height is set to zero, the variation comes out much smaller than what is seen across a full 2000 µm. | Note that the step determination will usually be better than the noise of the underlying scan. In the DektakXT we regularly measure shadow masked metal films made by e-beam evaporation that are around 100 nm thick. We have found good agreement between our measurements with the DektakXT of a 500 µm wide step compared to XRR measurements of films of the same thickness. Probably this is because we level the scan close to the step, so only the curvature in an 800 µm range in x is important, and since we average the thickness across approx. 400 µm across the top of the step compared to 50 µm intervals nearby where the average height is set to zero, the variation comes out much smaller than what is seen across a full 2000 µm. | ||
In practice we have found the step heights around 100 nm can be measured with higher accuracy in the DektakXT than the P17: We tend to get a measurement with the DektakXT within a few nm of the XRR measurement while the measurement with the P17 is off by around 10 We don't yet have a good explanation for this - nor do we have enough data to prove it's a general trend. | In practice we have found the step heights around 100 nm can be measured with higher accuracy in the DektakXT than the P17: We tend to get a measurement with the DektakXT within a few nm of the XRR measurement while the measurement with the P17 is off by around 10 nm. We don't yet have a good explanation for this - nor do we have enough data to prove it's a general trend. | ||
===How flat is a "flat" scan?=== | ===How flat is a "flat" scan?=== | ||