A new trench base-shielded bipolar transistor

In this paper a new power bipolar transistor structure called the trench ba se-shielded bipolar transistor (TBSBT) is proposed and experimentally demon strated. This structure incorporates deep p(+) poly-Si trenches into the ba se of a conventional bipolar transistor. With the base shielded effectively by the p(+) trenches, the base of the TBSBT can be made very narrow to ach ieve high current gain h(FE) and high cut-off frequency f(T) without compro mising on the breakdown voltage. Experimental results show that the on-stat e and switching characteristics of the TBSBT are significantly better than those of the existing power bipolar transistors.