Why new superjunction developments are delivering cooler, more efficient MOSFETs

Why new superjunction developments are delivering cooler, more efficient MOSFETs

Superjunction MOSFETs have become favoured solutions for energy-conscious designers. Through semiconductor process advances, modern devices allow smaller die sizes for the same MOSFET on-resistance, enabling designers to reduce circuit size and increase current density.

Improved fabrication processes, such as the single-epitaxial fabrications enabled by deep trench filling, give greater freedom to optimise N- and P-channel aspect ratios thereby minimising on-resistance and reducing MOSFET size.

Why new superjunction developments are delivering cooler, more efficient MOSFETs

Toshiba’s fourth-generation DTMOS IV family takes advantage of single epitaxy to reduce on-resistance per die area by 30%. The latest DTMOS V is also based on the deep trench process, with additional cell structure improvements.

The single-epitaxial process enables superjunction MOSFETs to deliver more stable performance over the entire temperature change, addressing the efficiency reduction often experienced at higher operating temperatures. Single EPI devices can offer a 12% lower on-resistance (RDS(ON)) than multi EPI at 150°C. The resistance curve is also flatter, demonstrating more consistent performance.

The fifth-generation DTMOS V devices also display a well-balanced ratio of lower noise performance and switching performance, achieved through a modified gate structure and patterning.

Other substantial benefits to designers of power electronics include a figure-of-merit (FoM) of resistance x chip size that shows a 30% improvement over DTMOS III, leading to chips with lower values of RDS(ON) in the same package size.

DTMOS IV solutions with fast body diode offer recovery times in the region of 140ns, even at high temperature. This results in lower power losses, less heat generation and a more thermally efficient design. The superjunction process also reduces the output capacitance, COSS, by 12%, leading to a reduction in the waste energy being stored in the device (that has to be dissipated during each and every switching cycle). Which is why DTMOS is ideal for the fast-switching and resonant topologies commonly found in power designs.

Ultimately, the latest single epitaxy DTMOS devices simply generate less heat at the same performance levels as earlier devices. As less heat is generated, less heat has to be dissipated, thereby saving cost, space and weight by allowing for less stringent heat management requirements.

To learn more about the consistent and efficient performance of Toshiba's latest deep-trench MOSFETs, please click here.

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