A Power Bipolar Integrated Device with Schottky Extension of Anode

In this paper, a structure named Schottky extension of anode (SEA) is proposed for BJT/diode power bipolar integrated devices. With BE reverse biased, it can serve as isolation between the main transistor and the internal diode of the integrated device and depress the hole injection from p-anode toward the region near or under the p-base, thus improve the reverse recovery of the internal diode. On the other hand, the forming method of this structure is completely compatible with the conventional processing of power bipolar devices, and no additional processing steps, difficulties and chip areas are needed. Therefore, this structure, while performing its good function, completely retains the low-cost and simple-processing advantages of power bipolar devices. Experimental results show that with the structure parameters given in this paper, an internal diode with the SEA structure can achieve an improvement of about 20%, compared with a conventional structure, in terms of resistive and inductive reverse recovery.