This paper reports the preparation and characterization of field emitter tips for use in a scanning tunneling microscope aligned field emission (SAFE) microprobe system. With the tip being at close proximity to the extraction electrode, new demands are imposed on the emitter tips: (1) a low extraction voltage, (2) a well‐defined emission pattern, preferably a single lobe emission, and (3) a high angular emission density. A combined field ion–field electron emission microscope equipped with a special stage for mounting a small aperture in close proximity to the emitter tip, which was used to simulate the first element of the electro‐optical system of the SAFE microprobe, was used to analyze different tip preparation techniques. A low‐temperature field‐assisted thermal annealing process has been developed to routinely produce sharp W 〈111〉 tips well suited for SAFE operation. Tips having an effective tip radius of less than 500 Å, an emission half cone angle of less than 10°, and a peak angular emission density of 7 μA/sr at a total emission current of 1 μA were successfully prepared and used in the SAFE microprobe system.

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