Power VDMOS transistor with the step oxide trench breaks the limit line of silicon

摘要

A power vertical double-diffusion metal-oxide-semiconductor (VDMOS) transistor is designed with the step oxide trench based on the oxide-nbypassed concept proposed by Liang and co-workers. It is suitable for breakdown voltage below 300 V to obtain ultra-low specific on-resist-nance. The electric field of the drift region is modulated because of the new electric field peak introduced by the various thicknesses of sidewallnoxide. As a result, the breakdown voltage was increased no less than 20% because of more uniform electric field distribution in the drift region,nwhile the specific on-resistance was reduced by 40–60% resulting from the step oxide trench compared with the oxide-bypassed structure. Thenlimit line of the silicon has been broken because the trade-off is improved between the breakdown voltage and the specific on-resistance. Thenlow Ron,sp of 15.0 mV mm2nwith the breakdown voltage (BV) of 150 V and 28.0 mV mm2nwith the BV of 230 V in the proposed step oxidentrenchMOS are improved greatly compared to the Ron,sp of 163.4 mV cm2nwith the BV of 150 V and 475.75 mV mm2nwith the BV of 230 V innthe conventional VDMOS.