Search

The performance of four cell topologies is compared for 2.3-kV 4H-SiC power MOSFETs fabricated in a commercial 6-in foundry. The devices were simultaneously manufactured with the same channel length (0.5 μm), JFET width (1.1 μm), and gate oxide thickness (55 nm) for comparison. In addition, an octagonal cell design with a JFET width of 1.5 μm was included for comparison. The square and hexagonal cell designs had the lowest specific ON-resistance, but their breakdown voltage was found to be reduced below 2.3 kV due to sharp cell corners. The smallest reverse transfer capacitance and gate charge were observed for the octagonal cell design with significantly larger (~5 ×) values for the square and hexagonal designs. The high-frequency figure-of-merit HF-FOM [RON* Crss] for the octagonal cell design was 3.5 × superior to the hexagonal and square cells and 1.5 × better than the linear cell. Its high-frequency figure-of-merit HF-FOM [RON* Qgd] was 1.5 × superior to the hexagonal and square cells and 1.2 × better than the linear cell. This work demonstrates that the square and hexagonal cells are the best for low-frequency applications, whereas the octagonal cell design is the most suitable for achieving the best high-frequency performance of 2.3-kV 4H-SiC power MOSFETs. [ABSTRACT FROM AUTHOR]

A 1.2-kV rated 4H-SiC split-gate octagonal cell MOSFET (SG-OCTFET) is proposed and successfully fabricated in a 6-in foundry for the first time. The measured results quantify the benefits of the SG-OCTFET structure: improvement in high-frequency figures of merit (HF-FOM) ($\text{R}_{ \mathrm{\scriptscriptstyle ON}}\times $ C $_{\text {gd}}$) by $1.8\times $ , HF-FOM ($\text{R}_{ \mathrm{\scriptscriptstyle ON}}\times $ Q $_{\text {gd}}$) by $1.6\times $ , and FOM ($\text{C}_{\text {iss}}/\text{C}_{\text {gd}}$) by $1.6\times $ compared with the optimized compact OCTFET design due to the reduced gate-to-drain overlap area. An important conclusion of this letter is that unlike commercially available 1.2-kV SiC power MOSFETs with linear cell topology, the 1.2-kV SG-OCTFET design can outperform commercially available 600-V Si super-junction devices. [ABSTRACT FROM AUTHOR]

The electrical characteristics of 1.2-kV-rated 4H-SiC accumulation (Acc) and inversion (Inv) channel MOSFETs with linear, square, hexagonal, and octagonal cell topologies fabricated using the same design rules and process flow in a 6-in foundry are compared for the first time. TCAD numerical simulations have been conducted to analyze the structures. For all the cell topologies, it was found that the Acc MOSFETs have lower specific ON-resistance (${R}_{ \mathrm{\scriptscriptstyle ON},\textsf {sp}}$) than the Inv counterparts due to higher channel mobility resulting in 1.3– $2.0\times $ smaller high-frequency figure-of-merit (HF-FOM[ ${R} _{ \mathrm{\scriptscriptstyle ON}} \times {Q}_{\textsf {gd}}$ ]), where ${Q} _{\textsf {gd}}$ is the gate-to-drain charge. It is observed that the square and hexagonal cell topologies with the same structural dimensions show similar electrical performance. When compared with the standard linear cell topology: 1) the hexagonal cell topology has $1.15\times $ better specific ON-resistance and $1.12\times $ worse HF-FOM[ $\text{R}_{ \mathrm{\scriptscriptstyle ON}} \times {Q}_{\textsf {gd}}$ ] and 2) the octagonal cell topology has $1.5\times $ worse specific ON-resistance and $1.4\times $ better HF-FOM[ $\text{R}_{ \mathrm{\scriptscriptstyle ON}} \times {Q}_{\textsf {gd}}$ ]. In addition, the octagonal cell topology has a much superior figure-of-merit (FOM[ ${C} _{\textsf {iss}}/{C} _{\textsf {rss}}$ ]), where ${C} _{\textsf {iss}}$ is the input capacitance and ${C} _{\textsf {gd}}$ is the reverse transfer capacitance. [ABSTRACT FROM AUTHOR]

This letter compares the measured electrical characteristics of 600 V planar-gate inversion-channel 4H-SiC power MOSFETs fabricated with four different cell topologies (Linear, Square, Hexagonal, and Octagonal) for the first time. The High-Frequency Figures-of-Merit (HF-FOMs) of these devices were compared with the commercially available SiC device and the Si CoolMOS product. It was found that the HF-FOMs of the 600-V SiC product and our fabricated conventional Linear cell device are much worse in comparison to the Si CoolMOS product. However, the 600 V SiC power MOSFET with comparable performance to the Si CoolMOS product could be achieved by using the Octagonal cell topology. [ABSTRACT FROM AUTHOR]

A 1.2 kV rated 4H-SiC OCTFET device with octagonal-cell topology is proposed and experimentally demonstrated for the first time. The device was first optimized using TCAD numerical simulations. Devices were then successfully fabricated in a 6-inch foundry. From the measured electrical characteristics, the OCTFET is demonstrated to have $\textsf {1.4}\times $ superior high frequency figures-of-merits (HF-FOM) [ $\textsf {R}_{\textsf {on}}\times \textsf {Q}_{\textsf {gd}}$ ], and $\textsf {2.1}\times $ superior HF-FOM [ $\textsf {R}_{\textsf {on}}\times \textsf {C}_{\textsf {gd}}$ ] compared with the conventional linear-cell MOSFET. [ABSTRACT FROM AUTHOR]