Ultralow specific ON-resistance high-k LDMOS with vertical field plate

Abstract

An ultralow specific on-resistance high-k LDMOS with vertical field plate (VFP HK LDMOS) is proposed. The high-k dielectric trench and highly doped interface N+ layer are made in bulk silicon to reduce the surface field of the drift region in the VFP HK LDMOS. The gate vertical field plate (VFP) pinning in the high-k dielectric trench can modulate the bulk electric field. The high-k dielectric not only provides polarized charges to assist depletion of the drift region, so that the drift region and high-k trench maintain charge balance adaptively, but also can fully assist in depleting the drift region to increase the drift doping concentration and reshape the electric field to avoid premature breakdown. Compared with the conventional structure, the VFP HK LDMOS has the breakdown voltage of 629.1 V at the drift length of 40 μm and the specific on-resistance of 38.4 mΩ·cm2 at the gate potential of 15 V. Then the power figure of merit is 10.31 MW/cm2.

Study of ultra-low specific on-resistance and high breakdown voltage SOI LDMOS based on electron accumulation effect

“…There are more electrons attached to the gates in the on-state, making R on,sp lower. Reference [21] proposed a field plate with highly doped N-layer beneath the oxide trench, which formed two electron accumulation layers in the on-state. Also, [22] proposed a novel multi-dimensional accumulation gate to attract more electrons, which very effectively reduced R on,sp .…”