A Novel SiC Asymmetric Cell Trench MOSFET With Split Gate and Integrated JBS Diode

Abstract

A novel high performance SiC asymmetric cell trench MOSFET with split gate (SG) and integrated junction barrier schottky (JBS) diode (SGS-ATMOS) is proposed for the first time. The shielding effect provided by the SG structure not only reduces the gate-drain capacitance (C gd ) but also alleviates the electric field crowding in the dielectric layer at trench corner. The integrated trench JBS diode bypasses the PiN body diode while obtaining good double protection from the SG and p-type shielding region. Therefore, not only the MOSFET but also diode performance is significantly improved for the proposed structure. Numerical analysis results show that compared with the conventional asymmetric cell trench MOSFET (Con-ATMOS), the high frequency figure of merit (HFFOM 1 , R on • C gd ) is reduced by 92.5% and the Baliga figure of merit (BFOM, BV 2 /R on,sp ) is increased by 57.2%, respectively. In addition, the forward conduction voltage drop (V F ), reverse recovery charge (Q rr ) and peak reverse recovery current (I rrm ) of the diode are reduced from 3.10V, 1.95µC/cm 2 and 68.0A for the Con-ATMOS to 1.56V, 0.97µC/cm 2 and 35.9A for the proposed SGS-ATMOS, respectively. Compared with the Con-ATMOS, the turn-on loss (E on ) and turn-off loss (E off ) of the proposed device are reduced by 33.3% and 33.0%, respectively. The E on and E off of the proposed device are also 33.6% and 30.0% off compared with the Con-ATMOS with external JBS diode, respectively. The temperature characteristics of the SGS-ATMOS are also discussed and it is found that the proposed device exhibits good performance at high temperature.INDEX TERMS 4H-SiC, trench MOSFET, asymmetric cell, split gate, junction barrier Schottky (JBS), figure of merit (FOM), turn-on loss, turn-off loss.

A SiC asymmetric cell trench MOSFET with a split gate and integrated p+-poly Si/SiC heterojunction freewheeling diode

“…1(a). [30,31] Figure 1(b) shows a schematic cross-section view of the improved SGHJD-TMOS. To facilitate the comparison between the CA-TMOS and SGHJD-TMOS, except for the parameters of the spilt gate and heterojunction freewheeling diode, other configurable factors are consistent with the CA-TMOS.…”

Low Switching Loss Split-Gate 4H-SiC MOSFET With Integrated Heterojunction Diode

“…And it can also be seen that the switching speed of HJD-SG-MOS is much faster than Con-MOS. The turn-on energy loss and turn-off energy loss can be calculated by the integration of Ids×V ds and turn-on delay time or turn-off delay time, respectively [15]. Fig.…”

“…However, the use of SG MOSFET will usually increase the resistance of the device under the same cell size [11]- [13], and make the electric field crowding in the gate oxide under high voltage [26], which will affect the reliability of the device for long-term use. The values of HF-FOM (Crss×Ron,sp) and HF-FOM 2 (Qgd×Ron,sp) are usually compared to measure the performance of the device under high-frequency operation [14]- [15]. These values are not only related to the Crss and Qgd, but also related to the specific on-resistance (Ron,sp).…”

Low switching loss and increased short-circuit capability split-gate SiC trench MOSFET with p-type pillar

“…Yang et al [19] investigated a novel SiC UMOSFET by using a deep p + shielded region and current spreading layer. Besides, the stepped oxide, [20][21][22] split-gate (SG), [23][24][25] and thick bottomoxide structure [26][27][28] have been proposed to further improve the compromise relationship between E ox and R on,sp .…”