Investigation of unusual mobile ion effects in thermally grown SiO₂ on 4H-SiC(0001) at high temperatures

Understanding and controlling bias-temperature instability in SiC metal-oxide-semiconductor devices induced by unusual generation of mobile ions

“…13 In addition, with physical analyses such as dynamic secondary ion mass spectrometry (D-SIMS) and x-ray photoelectron spectroscopy (XPS), we were unable to detect such a small number of mobile ion species in the oxide. At present, we believe that carbon-related complexes exhibiting positive fixed charge in the gate oxide induce structural changes in SiC-MOS interfaces to increase D it .…”

“…These results coincide well with those obtained in our previous study. 13 Figures 2(b) and 2(c) show typical bidirectional C-V curves of SiC-MOS capacitors that received BTS and slope etching. In both cases, the estimated electrical oxide thickness, i.e., the equivalent oxide thickness (EOT) of the remaining oxide, was 26 nm.…”

“…More recently, we have reported unusual generation of mobile ions in thermally grown SiC-MOS structures. 13 Our systematic study revealed that the mobile ions (other than extrinsic metal contaminations) are self-generated by dry oxidation of SiC substrates, and that carrying out POA under a diluted hydrogen ambient, the socalled forming gas annealing (FGA) at around 800 C also causes mobile ion generation in SiC-MOS devices, although the interface property is improved by hydrogen passivation. Since BTI induced by unusual mobile ions in thermal oxides was definitely found to be an intrinsic problem for SiC-MOS structures, it is essential to acquire a deep understanding of the mechanism of self-generated mobile ions.…”

“…As we previously demonstrated, while a reference Si-MOS device that received identical thermal budget in the same furnace did not exhibit mobile-ion-induced BTI, intrinsic mobile ions were selfgenerated in the thermal oxide grown on the SiC substrate. 13 In order to investigate the nature of the mobile ions in detail, slope-shaped oxides (see Fig. 1) were prepared by wet etching after applying positive or negative bias-temperature stress (PBTS or NBTS).…”

Reduction of interface state density at SiO2/InAlN interface by inserting ultrathin Al2O3 and plasma oxide interlayers

“…Although the frequency dispersion is less than that in other samples, the hysteresis was increased to $1 V (not shown). However, the hysteresis for the plasma oxide interlayer sample was counterclockwise, which most likely resulted from the mobile ions and not from the interface state charge [30,31]. Although the origin of the mobile ions is not clear, they might have originated from the intermingling of extrinsic contamination during the surface chemical treatment prior to the interface formation.…”