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Silicon carbide (SiC) super junction (SJ) JFETs fabricated by sidewall implantation with different mesa-widths (MWs) and termination designs are characterized in this article. The device with an MW of $1.8 \mu \text{m}$ and active area of 0.104 mm2 achieves a breakdown voltage of 1086 V and a specific ON-resistance of 0.98 $\text{m}\Omega \,\cdot $ cm2. The first-quadrant output and transfer characteristics are presented, from which the ON-resistance and pinch-off voltage are extracted and analyzed. The pinch-off voltage shows great stability against the variation of temperature. The forward blocking characteristics under different gate voltages and with different terminations are presented. The gate needs to be negatively biased below the hold-off voltage to prevent the premature breakdown caused by drain-induced barrier-lowering (DIBL) effect. The termination with narrow mesas in the ${x}$ -direction and trapezoidal mesas in the ${y}$ -direction is found to have the highest breakdown voltage, due to its optimized net charge distribution. The third-quadrant output characteristics are presented. Under forward-off gate voltage, the third-quadrant turn-on voltage is found to be determined by the difference of hold-off and pinch-off voltages, and there is a tradeoff between the absolute third-quadrant voltage drop ($\vert {V}_{\text{on}}\vert $) and the maximum current before gate junction turn-on (${J}_{\text{umax}}$). The third-quadrant performance can be improved by using forward-on gate voltage, a $\vert {V}_{\text{on}}\vert $ lower than 0.2 V (at 100 A/cm2) and a ${J}_{\text{umax}}$ larger than 500 A/cm2 are achieved. Finally, the whole output characteristics are modeled to facilitate the device design in different applications. [ABSTRACT FROM AUTHOR]

This paper studies the impact of the trench angle on SiC super-junction device performance through the numerical simulation. Devices with different structure parameter sets (mesa width, epi doping) targeting different voltage ratings have been considered. It is found that with the optimum epi doping, the highest Baliga's figure of merit (BFOM) is always achieved at the trench angle of 90°. The advantage of 90° trench angle can be further increased by reducing the mesa width (MW). However, the 90° trench is hard to be achieved through the current fabrication technology. Once the trench angle is reduced slightly, the device BFOM will decrease evidently especially for high voltage devices. At this condition, the reduction of mesa width does not necessarily produce higher BFOM. For example, at the trench angle of 89° and trench depth of 25 μm, the BFOM of the device with MW = 3 μm is substantially higher than that of the device with MW = 1 μm. Such a phenomenon is contrary to conventional theory, which is crucial for device design. Finally, in order to improve the performance of devices with non-90° trenches, the multi-epi structure is proposed. With such a novel structure, significant improvements have been observed in the simulation. The BFOM increments for 2 kV, 3.5 kV and 5 kV voltage rating devices are 27.4%, 60.8% and 102.6% respectively, demonstrating the superiority of the proposed multi-epi structure for SiC super-junction devices. [ABSTRACT FROM AUTHOR]

Termination design for 4H-SiC super-junction devices based on “trench-etching and implantation” technology, has been discussed through 3D numeric simulations and experiments. It is found that the existing design concept of super-junction termination extension (SJTE) structure is no longer capable of blocking high voltage due to the hole accumulation on the trench sidewall. In order to provide sufficient protection for the device edge, a novel device structure, i.e., hybrid termination of wide trench and SJTE (WT-SJTE), is proposed. With such WT-SJTE structure, the simulated device breakdown voltage can be improved from 700V to 800V. Furthermore, through the narrow termination mesa design, as predicted by numeric simulations, a noticeable improvement were measured, and a breakdown voltage of 960V was experimentally demonstrated. These results show the effectiveness of the WT-SJTE with such narrow termination mesa design. [ABSTRACT FROM AUTHOR]