High performance carrier stored trench bipolar transistor with dual shielding structure

We propose a novel high performance carrier stored trench bipolar transistor (CSTBT) with dual shielding structure (DSS-CSTBT). The proposed DSS-CSTBT features a double trench structure with different trench profiles in the surface, in which a shallow gate trench is shielded by a deep emitter trench and a thick oxide layer under it. Compared with the conventional CSTBT (con-CSTBT), the proposed DSS-CSTBT not only alleviates the negative impact of the shallow gate trench and highly doped CS layer on the breakdown voltage (BV), but also well reduces the gate-collector capacitance C_GC, gate charge Q_G, and turn-off loss E_OFF of the device. Furthermore, lower turn-on loss E_ON and gate drive loss E_DR are also obtained. Simulation results show that with the same CS layer doping concentration N_CS = 1.5 × 10¹⁶ cm⁻³, the BV increases from 1312 V of the con-CSTBT to 1423 V of the proposed DSS-CSTBT with oxide layer thickness under gate (T_og2) of 1 μm. Moreover, compared with the con-CSTBT, the C_GC at V_CE of 25 V and miller plateau charge (Q_GC) for the proposed DSS-CSTBT with T_og2 of 1 μm are reduced by 79.4% and 74.3%, respectively. With the V_GE increases from 0 V to 15 V, the total Q_G for the proposed DSS-CSTBT with T_og2 of 1 μm is reduced by 49.5%. As a result, at the same on-state voltage drop (V_CEON) of 1.55 V, the E_ON and E_OFF are reduced from 20.3 mJ/cm² and 19.3 mJ/cm² for the con-CSTBT to 8.2 mJ/cm² and 9.7 mJ/cm² for the proposed DSS-CSTBT with T_og2 of 1 μm, respectively. The proposed DSS-CSTBT not only significantly improves the trade-off relationship between the V_CEON and E_OFF but also greatly reduces the E_ON.