Low voltage superjunction power MOSFET: An application optimized technology

Abstract

A detailed analysis of the power loss mechanisms in synchronous DC-DC converters has been undertaken to identify the critical MOSFET parameters that require improving to ensure that system efficiencies and power densities continue to increase. The analysis shows that the commonly used figures of merit (FOMs) based on Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> and Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GD</sub> (i.e. R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</sub> ×Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</sub> ×Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GD</sub> ) are no longer sufficient when developing power MOSFET technologies, and if followed religiously, can lead to non-optimal technology choices. The insights gained from this work have been employed to define a set of FOMs that were then used to develop a new low voltage power MOSFET technology. The resulting 30V technology, based on the superjunction concept, is ideally suited for DC-DC conversion and in contrast to competing technologies such as lateral and split-gate trench MOSFETs, this approach simultaneously offers low specific R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</sub> , Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> , Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GD</sub> , Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OSS</sub> , and high gate-bounce immunity.