Arsenic-Spike epilayer technology applied to bipolar transistors

For the first time, epilayers with an arsenic-doped spike of 50 nm width ha ve been grown and used in silicon bipolar junction transistors (BJTs). The epilayer has been optimized such that the collector-base junction of the BJ T is formed within the arsenic spike. The counterdoping of boron out-diffus ion by arsenic strongly reduces the basewidth. The portion of the spike tha t is not counterdoped increases the total amount of n-type doping in the co llector without reducing BVceo. The increased collector-doping allows a 60% higher collector current prior to f(T) fall-off. Arsenic has a low diffusi vity so very few constraints are put on the thermal budget of the final pro cess. This high flexibility makes the presented epilayer technology a promi sing candidate to enhance a bipolar process significantly.