The base region ofNPNtransistors was fabricated using a 0.2 μm beam diameter (maskless) of 75 keV B focused ion beam (FIB), and on the same wafer a broad beam (with mask) of 75 keV B ions with conventional ion implantation. Transistor properties were compared using electrical characteristics, microbeam Rutherford backscattering spectroscopy (RBS), and scanning Auger microscopy (SAM). No significant differences were found between the transistors fabricated with FIB and with conventional ion implantation. Lateral doping profiles were implanted using the FIB system. Bipolar transistors with lateral active base profiles implanted with FIB were shown to have normal device characteristics. While the main intent was to assess the feasibility of fabricating the devices, the expected relationships between lateral profile and base resistance and current gain were observed. The results indicate that FIB can be used to study the impact of lateral profiles on device performance.