A 30 V Self-Aligned Metal/Poly-Si Replacement Gate Planar DMOS for DC/DC Converters

In this letter, a novel self-aligned metal/poly-Si gate planar double-diffused MOS (DMOS) is proposed and demonstrated for high-switching-speed and high-efficiency dc/dc converter applications. The self-aligned metal/poly-Si gate is realized by a replacement gate technology. The fabricated metal/poly-Si gate planar DMOS has a breakdown voltage of 36 V and a threshold voltage of 2.1 V. The gate sheet resistance of the metal/poly-Si gate is around 0.2 Omega/square, which is 50 times lower than that of the polysilicon gate. The low sheet resistance reduces the switching time as well as the power loss of the device during switching. For a device with a drain current of 69 A/cm
²
, the turn-on and turn-off times are reduced from 29 to 25 ns and from 36 to 31 ns, respectively. The turn-on and turn-off switching energy losses are reduced by 22% and 15%, respectively