A Charge Plasma Based Dual Buried Gates Power MOSFET With Improved Figure of Merits

Abstract

Abstract In this work, we design and simulate a high performance electrostatically doped dual buried gates power MOSFET (EDDBGP-MOS) structure. The novelty of the proposed device is three folds. Firstly, the n + source and P + body regions of the device are realized using induced charge plasma by employing metal electrodes on the silicon film. The device thus reduces the risk of random doping fluctuations and the formation of highly abrupt junctions during fabrication. The high temperature processes involved in defining the doped regions are not required, thus providing low thermal budget. Secondly, the Gaussian hole plasma profile in the p body region allows increase in drift doping concentration from 5x1015/cm3 to 7x1015/cm3 resulting in Ron reduction to almost 24% of its uniformly doped counterpart structure, with only a slight reduction in breakdown voltage of the device. The proposed device thus provides 10% increase in the Baliga’s figure of merit (FOM1 = BV2/Rsp). Further, the linearly graded Gaussian profile at the source side reduces the source coupling with gate. The gate charge together with the reduced specific ON resistance value provides as good as 19% reduction in Baliga’s high frequency figure of merit FOM2 = Rsp.Qsp). As compared to the conventional trench MOSFET structure, the two buried gates in the proposed structure provides low gate drain coupling along with the suppression in parasitic BJT effect. A two-dimensional simulation study of the proposed EDDBGP-MOS device reveals that it outperforms the conventional trench MOSFET device in terms of the performance parameters of power devices, along with the reduced fabrication complexity.