A split-gate trench IGBT with low Miller capacitance and d V /d t noise
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A split‑gate trench IGBT with low Miller capacitance and dV/dt noise Yitao He1,2 · Haihui Luo1,2 · Rongzhen Qin1,2 · Xiang Luo1,2 · Yao Yao1,2 · Gao Wen1,2 · Qiang Xiao1,2 · Canjian Tan1,2 Received: 22 June 2020 / Accepted: 9 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract A novel trench insulated gate bipolar transistor (IGBT) with a split-gate structure is proposed herein, where the polysilicon electrode in the trench is divided into two parts and insulated by the polysilicon oxide, thus decreasing the overlap between the gate electrode and n-drift region. Due to this split-gate structure, much lower Miller capacitance can be achieved. The performance of the proposed split-gate IGBT device, in particular the turn-on dV/dt controllability, is discussed. The simulation results show that the proposed split-gate IGBT can achieve a much better tradeoff between the maximum reverse-recovery dVKA/dt of the free-wheeling diode and the turn-on loss (Eon) of the IGBT compared with the conventional IGBT design. The reverse-recovery dVKA/dt can be decreased by 56% at the same Eon as in the IGBT. Moreover, a feasible manufacturing process for the split-gate structure is proposed. Keywords Split-gate structure · Miller capacitance · dV/dt controllability · Electromagnetic interference (EMI) noise
1 Introduction Trench insulated gate bipolar transistors ( IGBTs) have been widely used in high-power switching applications, e.g., in automotive drives, power supplies, railway traffic, industrial control, etc. [1–6]. As the current density of the IGBT increases, so does the trench density, leading to a higher Miller capacitance and turn-on loss (Eon), and limiting the application frequency. A lower gate resistance RG can speed up the turn-on process but also increases the dV/dt of the IGBT and results in high electromagnetic interference (EMI) noise [7–9]. A structure with low Miller capacitance would be a good solution to improve the tradeoff between the turn-on dV/dt and Eon of the IGBT. Indeed various IGBT structures have been proposed [10–15] based on this idea, including the trench shielded-gate IGBT [10], the side-gate high-conductivity IGBT (HiGT) [11], and the fin-shaped p-body IGBT [12, 13]. However, most of these structures are difficult to manufacture and not conducive to mass production. The split-gate structure, which is another approach to * Yitao He [email protected] 1
State Key Laboratory of Advanced Power Semiconductor Devices, Zhuzhou, China
Zhuzhou CRRC Times Semiconductor Co., Ltd., Zhuzhou, China
2
reduce the Miller capacitance, has been used in low-voltage power vertical double-diffused metal-oxide semiconductor (VDMOS) devices [15–19] but has not yet been reported for high-voltage IGBTs. A trench IGBT with a split-gate structure (split-gate IGBT) is proposed for the first time herein. Due to this splitgate structure, the Miller capacitance can be greatly reduced, which contributes to a better tradeoff between the reverserecovery dVKA/dt of the free-wheeli
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