Novel Si/SiC Heterojunction Lateral Double-Diffused Metal Oxide Semiconductor With SIPOS Field Plate by Simulation Study

Abstract

A novel Si/SiC heterojunction Lateral Double-diffused Metal Oxide Semiconductor with the Semi-Insulating Polycrystalline Silicon field plate (SIPOS Si/SiC LDMOS) is proposed in this paper for the first time. The innovative terminal technology of Breakdown Point Transfer (BPT) had been applied on Si/SiC MOSFETs. This creative technology improved Breakdown Voltage (BV) of the proposed device, compared with the conventional Si LDMOS (Cov. LDMOS). In order to optimize the trade-off between BV and Specific On-Resistance ( $\text{R}_{\mathrm{ ON,SP}}$ ), the SIPOS field plate is applied on Si/SiC LDMOS for the first time in this paper. At On-State, due to the internal electric field of SIPOS filed plate, the majority carriers accumulation layer is formed on the surface of the drift region for the proposed SIPOS Si/SiC LDMOS, which means $\text{R}_{ON,SP}$ will be reduced. Meanwhile, the electric field modulation effect of SIPOS field plate can make the surface electric field distribute evenly, which leads to an increase of BV. In addition, due to the high-thermal conductivity of SiC substrate, the heat-dissipation efficiency of the proposed device is significantly improved. The simulation results show that the BV of SIPOS Si/SiC LDMOS is 428.4V, which increased by 78.4% in comparison with Cov. LDMOS (BV of 240.0V) with the same structure parameters. The $\text{R}_{\mathrm{ ON,SP}}$ of SIPOS Si/SiC LDMOS is decreased from $33.2{\mathrm{ m}}\Omega \cdot {\mathrm{ cm}}^{2}$ of Cov. LDMOS to $24.0{\mathrm{ m}}\Omega \cdot {\mathrm{ cm}}^{2}$ , decreased by 27.7%. Furthermore, the figure-of-merit (FOM = BV2/ $\text{R}_{\mathrm{ on,sp}}$ ) of SIPOS Si/SiC LDMOS reaches 7.6MW/cm2, which means SIPOS Si/SiC LDMOS has enough performance to break the Silicon limit.

Keywords

• Si/SiC heterojunction
• SIPOS
• breakdown point transfer
• breakdown voltage
• specific on-resistance
• figure-of-merit