UHF Power transistors fabricated by double ion implantation

Because of its higher accuracy and reproducibility of impurity doping, ion implantation is favorable for constructing both the emitter and base junctions of transistors, especially narrow base structures like UHF or microwave transistors. It is also important in this case to minimize the emitter dip effect which appears in the double diffused transistors and often causes emitter-collector reach-through. To meet these requirements, a new process using double ion implantation has been developed for UHF power transistors designed for cable television, mobile radio transmitters, etc.