A new trench base-shielded bipolar transistor

In order to satisfy the conflicting requirements of narrow base width for high current gain and high cut-off frequency, and wide base width for high collector-emitter breakdown voltage that exist in conventional bipolar power transistors (BPTs), a new bipolar power transistor called the trench base-shielded bipolar transistor (TBSBT) is proposed. In this structure, p⁺ poly-Si trenches are incorporated in the base of a conventional BPT. With the base shielded effectively by a pair of p⁺ poly-Si trenches, the transistor base width can be made very narrow for high current gain and high cut-off frequency, but still provide high collector-emitter breakdown voltage. Experimental results show that significant improvement of BV _CEO, current gain h_FE, cut-off frequency f_T , turn-on time, turn-off time, current density, collector-emitter saturation voltage (V_CES), and SOA over the gate associate transistor (GAT) and conventional BPT are obtained