If the image is measured digitally or on the film negative as being 1.10 cm (1.10*10-2 m), compute the calibrated magnification: Table 1: Magnification Calibration 250 keV, Philips EM430 TEM, December, 2006.Įxample: Suppose that a feature that is known to be 1.00 micrometer (1.00 *10-6 m) in length is imaged, and the Nominal (instrument) Magnification is given as 10,000X. STEP 7: Make up a table of calibration values similar to Table 1 below, recording the Nominal Magnification (the magnification given on the TEM) with the Calibrated Magnification (the actual magnification determined by comparing the measured feature size from your micrograph or digital image, and the actual feature size, as taken from the attached sheet labeled “Layer Thickness Values”). Note that measurements must be made perpendicular to the (111) planes, since the planes viewed from this zone do not meet at right angles. The lines marked parallel to the upper two sides of the diamond shape indicate (111) planes, with an interplanar spacing of 0.3135428 nm. 5: Lattice image of Si viewed down the zone axis, recognizable by the central diamond shape formed by the rows and columns of Si atoms. This gives the measurement on the micrograph or digital image that corresponds to the (111) lattice spacing of Si (0.3135428 nm.).įig. Measure the perpendicular distance across a large number of (111) lattice fringes, then divide this length by the number of fringes. STEP 6: The most accurate calibrations at the highest magnification ranges (>400,000) can be accomplished by forming a lattice image of the Si material below the layered structure (Fig. The measured length on the micrograph or digital image can then be compared to the calibrated values on the attached sheet labeled “Layer Thickness Values”. A series of micrographs or digital images at all magnification ranges should be taken starting at the highest magnification range and working down to the lowest. 3 at the highest magnification range available. STEP 5: Focus the microscope on the region shown in fig. When the electron diffraction pattern is centered anywhere along this band, the electron beam will be parallel to the layered structure, and result in accurate layer thickness values. The broad horizontal band in the center of this figure is between the Kikuchi lines. 1: Kikuchi pattern of single crystal silicon viewed down the zone axis. It may be necessary to translate the standard to slightly thicker or thinner regions to get a clear Kikuchi pattern.įig. The standard should be tilted to move the Kikuchi pattern so that the central “intersection” in this diagram (where the largest number of bands intersect) is centered on the brightest (zero order) diffraction spot in the electron diffraction pattern (adjust the intensity control back and forth). The intensity control can be adjusted so that either a diffraction spot pattern or a Kikuchi pattern can be observed. These Kikuchi bands are formed by elastic Bragg scattering of previously inelastically scattered electrons. Put the TEM into diffraction mode, choose the smallest camera length, and adjust the intensity control (condenser control) back and forth to find the proper value of over-focus that forms the striking pattern called a Kikuchi pattern, similar to Fig. Translate the standard to bring into view the calibration marks close to the thin edge near the perforation in the center of the sample (arrows, Fig. To take advantage of these attributes, mount the standard in the TEM sample holder with the epoxy line of the standard parallel to the stem of the TEM sample holder (see Fig.2, next page). The MAG*I*CAL ™ Calibration Standard is made from a single crystal of silicon, and therefore has many very useful attributes as a TEM standard. MAG*I*CAL™ Calibration Standard for TEM EMS Catalog # 80069 Aligning the Reference Standard
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