The Simulation Study On 4h-SiC Trench MOSFET With Integrated SBD

With the development of the power electronics industry,traditional silicon power devices are gradually unable to meet increasingly demanding application requirements.Silicon carbide(Si C)has received widespread attention due to the superior material properties.Among 4H-Si C devices,metal-oxide-semiconductor field-effect transistor(MOSFET)has developed rapidly due to their simple driving and fast switching speed.The 4H-Si C trench MOSFET has bacome the focus of 4H-Si C MOSFET due to the elimination of the JFET region of the VDMOSFET,which leads to a lower on-state resistance and a lower cell size of the device.Because the bipolar degradation effect results from the conduction of the parasitic Pi N diode and the poor reverse recovery characteristics,an external SBD is anti-paralleled with the 4H-Si C MOSFET as a freewheeling diode to suppress the conduction of parasitic Pi N diode.However,the external SBD will increase the area of the overall circuit module,and introduce additional parasitic inductance.Therefore,many institutions have studied the new MOSFET structures with integrated SBD.However,the currently proposed trench MOSFET with integrated SBD still have some shortcomings.Integrated SBD will increase the cell size of the device,and the effect of temperature on device characteristics after integrated SBD has not been fully paid attention to.In view of the above problems,this paper studys on a new4H-Si C trench MOSFET with integrated SBD.The main work is as follows:At first,this paper discusses the static and dynamic characteristics of 4H-Si C trench MOSFET,Pi N diode,and SBD,theoretically.The effect of integrated SBD on MOSFET device performance is analyzed Simultaneously.Subsequently,the parameter,static and dynamic characteristics of the Cool Si C^TM MOSFET(Cool-MOSFET)proposed by Infineon and the Proposed-MOSFET with integrated SBD is discussed in this paper.Based on the Cool-MOSFET,the Proposed-MOSFET utilizes an extended source metal ground the P+shield region under the bottom of gate oxide.At the same time,a Schottky barrier diode is formed with the metal and the N-type Si C current spread layer.A thick oxide layer is used to isolate the gate polysilicon from the Schottky metal.Simulation results show that the static characteristics of Proposed-MOSFET are not degraded compared to the Cool-MOSFET.At the same time,the integrated SBD of Proposed-MOSFET suppresses the conduction of the parasitic Pi N diode effectively.In terms of dynamic characteristics,due to the thick oxide layer between the Schottky metal and the gate polysilicon,the input capacitance C_iss and the characteristic gate charge Q_g,sp of Proposed-MOSFET is reduced by 36.7%and 26.7%respectively.in comparion of Cool-MOSFET.In terms of reverse recovery characteristics,at normal temperature,the reverse recovery charge Q_rr and reverse recovery peak current I_rr-peak of the Proposed-MOSFET are reduced by 64.4%and 66.3%respectively compared to the Cool-MOSFET.At 450 K,the Q_rr and I_rr-peak are reduced by 82.83%and 80.34%respectively.Finally,this paper analyzes the power consumption of the Proposed-MOSFET and Cool-MOSFET.In the process of single MOSFET switching,Proposed-MOSFET has reduced its switching power consumption by 19.05%compared to Cool-MOSFET due to the reduction of gate-source capacitance C_gs.When the Cool-MOSFET and Proposed-MOSFET form the half-bridge module,the power consumption of switching MOSFET of Proposed-MOSFET half-bridge module has decreased by 37.2%compared to the Cool-MOSFET due to the improvement of the reverse recovery characteristics of the SBD.With the increase of the switching frequency,the power consumption of Proposed-MOSFET switching MOSFET has decreased more than that of Cool-MOSFET switching MOSFET.The results show that the Proposed-MOSFET is more suitable for high-frequency power applications than the Cool-MOSFET.