Self aligned process for BJT fabrication

Methods for forming a SiC BJT having a low base resistance and minimal emitter width are provided. The methods incorporate a plated shadow metal layer overhanging the emitter mesa. The mushroom-shaped shadow metal layer can then act as either a deposition shadow mask or an ion implantation mask in subsequent steps for forming base contacts. In this way, base contacts can be formed with a variable and controllable distance from the emitter mesa defined by the lateral extent of overhang of the shadow metal layer. The same shadow masking effect can also be used to form self-aligned emitter and base wiring metals for reduction of resistance. Plating of the emitter contact layer allows avoiding subsequent photolithography steps on the top of emitter mesa; thus emitter mesa width could be minimized.