Abstract—In this brief, we propose a new stepped oxide heteromaterial trench power MOSFET with three sections in the trench gate (an N+ poly gate sandwiched between two P+poly gates) and having different gate oxide thicknesses (increasing from source side to drain side). The different gate oxide thickness serves the purpose of simultaneously achieving the following: 1) a good gate control on the channel charge and 2) a lesser gate-to-drain capacitance. As a result, we obtain higher transconductance as well as reduced switching delays, making the proposed device suitable for both RF ampliﬁcation and high-speed switching applications. In addition, the sandwiched gate with different work-function gate materials modiﬁes the electric ﬁeld proﬁle in the channel, resulting in an improved breakdown voltage. By using 2-D simulations, we have shown that the proposed device structure exhibits about 32% enhancement in breakdown voltage, 25% reduction in switching delays, 20% enhancement in peak transconductance, and 10% reduction in ﬁgure of merit (product of ON- resistance and gate charge) as compared to the conventional trench-gate MOSFET.
Index Terms—Breakdown voltage, gate charge, ON-resistance,
power MOSFET, switching speed, transconductance, trench gate.
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