Lateral Resolution of EDX Analysis with Ultra Low Acceleration Voltage SEM

The spectral imagings were performed in order to examine the lateral resolution of the EDX analysis which is attached in an ultra low acceleration voltage SEM. The spectral imagings were performed for the cross section of the Ni coating on Al, which was cut using microtome, and the cross section of GaAs/AlAs super-lattice, which was cleavaged, using a ultra-low-acceleration-voltage SEM and EDX. The line scan of Al and Ni across the interface of the Ni coating and the Al substrate shows that the lateral resolution measured under the acceleration voltage of 7 kV is less than 100 nm. All of four layers with a thickness of about 25 nm of the GaAs/AlAs super-lattice are apparently observed in the spectral mapping of Ga and Al, which is measured under the acceleration voltage of 3 kV. This high lateral resolution of the EDX analysis can be resulted from the followings: (1) The area of the characteristic x-rays generation becomes small for low acceleration voltage of the primary electron. (2) The electron beam with the small diameter and the high current is obtained even under the ultra low acceleration voltage using an optimum electron optics.