Split-gate Resurf Stepped Oxide (RSO) MOSFETs for 25V applications with record low gate-to-drain charge

Abstract

This paper presents a split-gate version of the Resurf Stepped Oxide (RSO) MOSFET. Splitting the gate enables a drastic reduction of the gate-to-drain capacitance intrinsic to the RSO device concept while keeping all the benefits of the RESURF effect. We achieved a record on- resistance of 3.8mΩmm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and gate-to-drain charge of 0.9nC.mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> at a breakdown voltage of 35V for a pitch of 1.3μm (0.8μm trench width). The switching losses of our split-gate RSO MOSFET are 4 times better than the best published data in the same voltage range.