Abstract: This disclosure is directed to an ion-implanted self-aligned transistor device including the fabrication method therefor wherein the emitter region and a pair of heavily doped base contact regions are spaced in a self-aligned manner from the periphery of the emitter region in order to precisely align the base contact regions at a predetermined distance from the periphery of the emitter region. Silicon nitride and silicon dioxide insulating layers are used together with an undercutting etching operation to precisely align the pair of spaced heavily doped base contact regions with respect to the periphery of the emitter region. The final completed semiconductor structure utilizes a single base metal contact electrode which makes contact to all of the spaced heavily doped base contact regions. A single emitter metal contact electrode is provided to the emitter regions located outside the periphery of the inner spaced heavily doped base contact regions.