Non-destructive and fast electrical profiling method for the active base regions of vertical BJT structures

The authors present an accurate, fast, and easy-to-use nondestructive electrical method for profiling the active base regions of vertical BJT (bipolar junction transistor) structures. The method is based on the modulation of a vertical BJT in the reverse operating region, known as the reverse Early effect. To perform the base profiling, the method requires the forced and measured DC voltages and currents at the BJT terminals, the device operating temperature during the electrical measurements, and the emitter area as inputs. The measured I(V) pairs of data are then processed through a computer program to calculate the active base profile, based on widely used and accepted physical formulations. It is shown that the calculated profiles are in good agreement with measured SIMS data as well as independent pinched base measurements performed on special test structures.<>