The characteristics of near interface electron and hole traps in n-type 4H-SiC MOS capacitors with and without nitric oxide (NO) passivation have been systematically investigated. The hysteresis of the bidirectional capacitance-voltage (C-V) and the shift of flat band voltage (Vfb) caused by bias stress (BS) with and without ultraviolet light (UVL) irradiation are used for studying the influence of near interface electron traps (NIETs) and near interface hole traps (NIHTs). Compared with Ar annealed process, NO passivation can effectively reduce the density of NIETs, but induce excess NIHTs in the SiC MOS devices. What’s worse is that part of the trapped hole cannot be released easily from the NIHTs in the NO annealed sample, which may act as the positive fixed charge and induce the negative shift of threshold voltage.
Based on the theoretical analysis and the simulation results of the ion implantation process and the floating Junction structure, a 4H-SiC SBD with floating junction (FJ_SBD) is fabricated. Compared with the on-resistance 5.13 mΩ·cm2 of conventional SBD fabricated at the same time, the on-resistance of FJ_SBD with 3μm P+ buried box is only 6.29 mΩ·cm2. The breakdown voltage of the FJ_SBD reaches 950V which is much higher than the 430V of conventional SBD. According to the presented results, The BFOM of the FJ_SBD is 3 times higher than the value of the conventional SBD. It is proved that FJ-SBD has greater prospects for development.
P-type implanted metal oxide semiconductor capacitors (MOSCAPs) and metal oxide semiconductor field effect transistors (MOSFETs) have been fabricated. The characteristics of hole trapping at the interface of SiO2/SiC are investigated through capacitance-voltage (CV) measurements with different starting voltages. The negative shift voltage ∆Vshift and the hysteresis voltages ∆VH which caused by the hole traps in the MOSCAPs and MOSFETs are extracted from CV results. The results show that the hole traps extracted from MOSCAPs are larger than the that extracted from the threshold voltage shift in the MOSFETs. It suggests holes trapping are the primary mechanism contributing to the NBTI, but not all the holes work. Part of the hole traps are compensation by sufficient electrons in the MOSFET structure.
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