Past FE-SEM could obtain a high resolution image, however its probe current was not sufficiently strong enough for analytical purpose.
We have developed a multi-purpose thermal field emission scanning electron microscope (JSM- 6500F), in which a new designed “In-Lens Thermal FEG” is installed.
Fig. 1 shows a cross section images of the In-Lens Thermal FEG, comparing with the past FEG. The In-Lens Thermal FEG consists of the thermal FEG and the 1st condenser lens. The emitter is located in the magnetic field produced by the 1st condenser lens, so that electrons emitted from the emitter are condensed effectively to produced a high probe current. The maximum probe current of 200 nA is attainable at the accelerating voltage of 15 kV, ten times larger than the maximum probe current of ordinary FE-SEMs. Therefore the WDS analysis can be performed by this newly FE-SEM.
The “aperture angle control lens” has been installed in the electron optics system, for improving the resolution at a large probe current. The resolution of 3.0nm at the analytical condition (at probe current 5nA, accelerating voltage 15kV, WD 10mm: fig.2).
The ultimate resolution of the microscope is 1.5nm at 15kV and 5nm at lkV. The objective lens is not an immersion type and does not leak magnetic fields on the specimen surface, therefore this equipment was suitable for observing or analyzing magnetic materials, and also suitable for the EBSD analysis. Fig.3 shows an example of the EBSD analysis.