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Figure 3 Layer Thickness Values
| The layered structure is made from an electron transparent cross-sectional TEM sample made from a molecular beam epitaxy (MBE) -grown, single crystal semiconductor wafer. When the calibration structure is viewed by TEM, it appears as a series of light and dark layers where the layer thicknesses are very accurately known. The calibrated thickness measurements of these light (Si) and dark (SiGe alloy) layers are based on careful TEM measurements of the {111} lattice spacing of silicon which is visible on the calibration sample itself and are supported by x-ray diffraction measurements. Furthermore, the layer thickness variation across the entire silicon wafer has been verified to be less than 1%, allowing all samples prepared from the same wafer to have errors in the given layer thickness values of less than 1%. |
Click here for detailed picture Figure 3 Layer Thickness Values |
Figure 3 shows the extraordinary layer structure from which the calibration measurements can be made.
To improve accuracy when making measurements, always measure the largest distance clearly visible on the micrograph. For example, at the highest magnification ranges, measure the distance across the entire set of five dark layers and four light layers, instead of trying to measure an individual dark layer.
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