A field-emission cathode in the electron gun of a scanning electron microscope provides narrower probing beams at low as well as high electron energy, resulting in both improved spatial resolution and minimized sample charging and damage. The JSM-7001F, Thermal Field Emission SEM, is the ideal platform for demanding analytical applications as well as those requiring high resolution and ease-of-use. The specimen stage is large, motorized, automated, and fully eucentric with 5-axis motion option (X, Y, Z, Tilt, and rotation). The specimen chamber handles specimens up to 200mm in diameter. Moreover, JSM-7001F model is equipped with unique features such as one-action specimen exchange airlock, small probe diameter at large probe current and low voltage. Also, the current model has two imaging modes (SEI and RBEI). Up to four live images can be simultaneously viewed, including signal mixing, and a single scan can record and store all four images at once. In addition, the current SEM is powered with two analytical detectors: Energy Dispersive X-ray Spectroscopy (EDS) and Electron Back Scattered Diffraction (EBSD).
Observation in the GB (Gentle Beam):
This mode can help lower the charging effect on the specimen by applying the bias voltage to the specimen stage. The ability to image non conductive samples at moderate to high kV and higher beam current can be performed without the need to coat the sample with metal or carbon for conductivity.
- FESEM produces clearer, less electrostatically distorted images with spatial resolution down to 1.5 nm. That's 3 to 6 times better than conventional SEM.
- Resolution (secondary electron image):
- Image modes:
- Accelerating voltage (Acc. V.):
Gentle Beam (GB-Lmode):
- Probe current: is order of 10-12 to 2 x 10-7 A.
- Smaller-area contamination spots can be examined at electron accelerating voltages compatible with Energy Dispersive X-ray Spectroscopy.
- Reduced penetration of low kinetic energy electrons probes closer to the immediate material surface.
- Need for placing conducting coatings on insulating materials is virtually eliminated.
- The In-Lens Thermal FEG, which is a combination of FEG and the first condenser lens, can produce ten times larger probe current than a conventional FEG and is sufficient for EDS and EBSD with the smallest objective lens aperture for high resolution imaging.
Example: EBSD Map showing both Ferrite (red) & Austenite (blue) phases in duplex steel
Principle of Operation:
As the electron beam of the SEM is scanned across the sample surface, it generates X-ray fluorescence from the atoms in its path. The energy of each X-ray photon is characteristic of the element that produced it. The EDS microanalysis system collects the X-rays, sorts and plots them by energy, and automatically identifies and labels the elements responsible for the peaks in this energy distribution.
The EDS data are typically compared with either known or computer-generated standards to produce a full quantitative analysis showing the sample composition.
Data output plots the original spectrum showing the number of X-rays collected at each energy level. Maps of element distributions over areas of interest and quantitative composition tables can also be provided as necessary.
EDS identifies the elemental composition of materials imaged in a Scanning Electron Microscope (SEM) for all elements with an atomic number greater than boron. Most elements are detected at concentrations on the order of 0.1%.
- Failure analysis
- Materials evaluation and identification
- Failure analysis
- Quality control screening
Electron Backscatter Diffraction (EBSD) is a technique which allows crystallographic information to be obtained from samples in the scanning electron microscope (SEM). In EBSD, a stationary electron beam strikes a tilted crystalline sample and the diffracted electrons form a pattern on a fluorescent screen. This pattern is characteristic of the crystal structure and orientation of the sample region from which it was generated. The diffraction pattern can be used to measure the crystal orientation, measure grain boundary misorientations, discriminate between different materials, and provide information about local crystalline perfection. When the beam is scanned in a grid across a polycrystalline sample and the crystal orientation measured at each point, the resulting map will reveal the constituent grain morphology, orientations, and boundaries. This data can also be used to show the preferred crystal orientations (texture) present in the material. A complete and quantitative representation of the sample microstructure can be established with EBSD.
- Mapping Speed:
- High Resolution CCD:
- Forescatter Detector (FSD):