The use of aluminium ion implantation for power semiconductor devices

Abstract

Because of its high diffusivity in silicon, aluminium is best suited for the deep diffusions often required in high voltage power semiconductor devices. The ion implantation technique allows the reproducible low dosage doping necessary, e.g., for the new concepts of junction termination systems.The most important draw back of the use of aluminium as a p-type dopant in silicon is its low electrical activity after the anneal. The main problem therefore is the enhancement of the aluminium yield (the amount of electrically active Al with respect to the implanted dose). Sheet resistivity and spreading resistance measurements after various annealing processes are presented as well as a triple implant process, which allows to enhance the aluminium yield.