Development of a FEM, FIM-AP system for studying gridded vacuum microelectronic devices

We have modified a conventional FIM-AP system specifically for studying vacuum microelectronic (VME) devices, which includes facilities for field emission microscopy (FEM), field ion microscopy (FIM) atom probe microanalysis (AP) and current-voltage measurements. This is the first integrated experimental system for the characterisation of VME devices on the atomic scale. In this paper the behaviour of a typical gridded field emitter in different operation modes is discussed using a simple simulation model, and is compared with that of a conventional FIM tip. The simulation shows that gridded emitters still preserve the projection geometry of FIM and FEM which is essential to the interpretation of FIM and FEM images. The design considerations for an ideal FIM/FEM/AP system for studying VME devices are also discussed. A wide view angle detector and low voltage operation are the two key elements. Our system has been tested on silicon-based VME devices. The results show that in-situ chemical analysis and FIM images with atomic resolution are achieved. The geometrical field factor k of the tested VME devices is found to be in the range of 1–2. This confirms that gridded VME devices have much better field enhancement factors than conventional field emitters.