• ETRI Journal
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• v.34 no.6
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• pp.962-965
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• 2012

In this letter, we propose a new RESURF stepped oxide (RSO) process to make a semi-superjunction (semi-SJ) trench double-diffused MOSFET (TDMOS). In this new process, the thick single insulation layer ($SiO_2$) of a conventional device is replaced by a multilayered insulator ($SiO_2/SiN_x/TEOS$) to improve the process and electrical properties. To compare the electrical properties of the conventional RSO TDMOS to those of the proposed TDMOS, that is, the nitride_RSO TDMOS, simulation studies are performed using a TCAD simulator. The nitride_RSO TDMOS has superior properties compared to those of the RSO TDMOS, in terms of drain current and on-resistance, owing to a high nitride permittivity. Moreover, variations in the electrical properties of the nitride_RSO TDMOS are investigated using various devices, pitch sizes, and thicknesses of the insulator. Along with an increase of the device pitch size and the thickness of the insulator, the breakdown voltage slowly improves due to a vertical field plate effect; however, the drain current and on-resistance degenerate, owing to a shrinking of the drift width. The nitride_RSO TDMOS is successfully fabricated, and the blocking voltage and specific on-resistance are 108 V and $1.1m{\Omega}cm^2$, respectively.

• Journal of IKEEE
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• v.23 no.3
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• pp.832-838
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• 2019

In this paper, 4H-SiC MOSFET, the next generation power semiconductor device, was studied. In particular, Semi-SJ MOSFET structures with improved electrical characteristics than conventional DMOSFET structures were proposed in the class of 3300V, and static characteristics of conventional and proposed structures were compared and analyzed through TCAD simulations. Semi-SuperJunction MOSFET structure is partly structure that introduces SuperJunction, improves Electric field distribution through the two-dimensional depletion effect, and increases breakdown voltage. Benefit from the improvement of breakdown voltage, which can improve the on resistance as high doping is possible. The proposed structure has a slight reduction in breakdown voltage, but has an 80% decrease in on resistance compared to the conventional DMOSFET structure, and a 44% decrease in on resistance compared to the Current Spreading Layer(CSL) structure that improves the conventional DMOSFET structure.