一种积累型槽栅超势垒二极管

An Accumulated Trench-gate Super Barrier Diode

提出了一种积累型槽栅超势垒二极管,该二极管采用N型积累型MOSFET,通过MOSFET的体效应作用降低二极管势垒。当外加很小的正向电压时,在N+区下方以及栅氧化层和N-区界面处形成电子积累的薄层,形成电子电流,进一步降低二极管正向压降;随着外加电压增大,P+区、N-外延区和N+衬底构成的PIN二极管开启,提供大电流。反向阻断时,MOSFET截止,PN结快速耗尽,利用反偏PN结来承担反向耐压。N型积累型MOSFET沟道长度由N+区和N外延区间的N-区长度决定。仿真结果表明,在相同外延层厚度和浓度下,该结构器件的开启电压约为0.23 V,远低于普通PIN二极管的开启电压,较肖特基二极管的开启电压降低约30%,泄漏电流比肖特基二极管小近50倍。

An accumulated trench gate super barrier diode has been proposed in the paper. It has a Ntype accumulation MOSFET, which reduces the barrier through MOSFET body effect. With tiny positive voltage applied, an accumulate electronic thin layer is produced under N＋heavy doped region as well as at the interface between gate oxide and Ntype light doped region, electron current can be produced to reduce the forward voltage of the diode. With the increase of applied voltage, the PIN diode which consist of P＋doped region, N-epitaxial layer and N＋substrate, is opened, and the PIN affords large current. When a reverse voltage is applied, the MOSFET is cut off and PN junction is depleted rapidly, so the PN junction undertakes the voltage drop and the leakage current is reduced. The channel length of Ntype accumulates MOSFET due to the length between N＋doped region and Ntype lightly doped region. The simulation results show, with the same thickness and concentration of epitaxial region, the onset voltage of the device is about 0. 23V, far lower than conventional PIN diode. Compared with Schottky diode, the onset voltage is reduced by 30%, and the leakage current is 50 times smaller than that of Schottky diode.