Fabrication and characterization of 4H-SiC P-N junction diodes by selective-epitaxial growth using TaC as the mask

Abstract

Selective nitrogen doping of 4H-SiC by epitaxial growth using TaC as the hightemperature mask has been demonstrated. Nomarski optical microscopy and scanning electron microscopy (SEM) were used to characterize selective growth of SiC. In addition, 250-µm, square-shaped, p-n junction diodes by selective n-type epitaxial growth on a p-type epilayer were fabricated. The refilled fingers with different width were designed to vary the periphery/area (P/A) ratio. The effects of P/A ratio on the current-voltage (J-V) characteristics have been investigated. The ideality factor extracted from J-V characteristics is Ϸ2 at a temperature range of 25-275°C, which indicates that the ShockleyRead-Hall recombination is the dominant mechanism in the conduction region. The reverse leakage current does not show dependence on P/A ratio for trench-refilled diodes. The room-temperature reverse leakage-current density at 100 V is less than 3.5 ϫ 10 Ϫ7 A/cm 2 for all diodes. Also, the reverse leakage current does not increase significantly with temperature up to 275°C. The breakdown voltages measured at room temperature are about 450 V and 400 V for diodes without and with fingers, respectively.

Epitaxy and recrystallization kinetics of TaC thin films on SiC for high temperature processing of semiconductor devices

“…18 We also did this but discovered uneven formation of carbide surface and also the Ta reacted at with the SiC at 1600°C, as shown in Fig. For selective area growth of SiC, Ta mask has been formed by evaporating a Ta film onto the SiC substrate, patterning and etching it, and then carburizing it in a propane atmosphere.…”

“…18 One interesting possibility is that TaC could grow epitaxially on the SiC making it possible to use for SAE at high temperatures. For this to be done, the areas where growth should not occur must be covered by a material for which it is difficult for SiC to nucleate and grow on.…”

Integrated 4H-silicon carbide diode bridge rectifier for high temperature (773 K) environment

“…1. Different from the conventional vertical pn diodes [7], both electrodes of the 4H-SiC diodes were designed to be located on the top side of the chip to permit the integration of the four diodes. The top and cross-sectional views of the integrated 4H-SiC pn diode bridge rectifier layout are shown in Fig.…”

Epitaxial Growth of Silicon Carbide

“…It is reported that SiC pn junctions formed by embedded epitaxy exhibit lower leakage current when the sidewalls are {1120} rather than {1100} [212]. Selective embedded epitaxy by using carbon [213] or TaC [214] as masking materials has also been reported. Figure 4.39 shows a cross-sectional TEM image of SiC trenches filled by embedded epitaxy [211].…”