Process for fabricating a semiconductor device

A process for fabricating a semiconductor device basically includes forming a boron implanted layer intended to be a base region by implanting boron ions to a substrate through a first opening, implanting fluorine ions to the substrate through a second opening serving to define an emitter-inner base formation region beneath the second opening and in the boron implanted layer to lower the boron ion concentration of that region only thereby lowering the peak carrier concentration of an inner base region than that of an emitter region to be formed later, and doping the region defined by a third opening with arsenic ions to form the emitter region with the inner base region underlying.