Papers by Keyword: Halo-Carbon

Abstract: Low-temperature halo-carbon homoepitaxial growth is suitable for selective epitaxial growth of 4H-SiC using SiO2 mask. A possibility of achieving high values of doping in combination with the selective growth makes it an alternative to ion implantation for selective doping in SiC. In this work, TMA doping in situ during a blanket low-temperature epitaxial growth was utilized to produce heavily Al doped SiC layers for Ohmic contact formation to p-type SiC. Nearly featureless epilayer morphology with Al atomic concentration exceeding 3x1020 cm-3 was obtained after growth at 13000C with the growth rate of 1.5 µm/hr. Ni TLM contacts with a thin adhesion layer of Ti were formed. The as-deposited metal contacts were almost completely Ohmic even before annealing. The specific contact resistance of 2x10-2 Ohm-cm2 and 6x10-5 Ohms-cm2 was achieved without and with contact annealing respectively. The resistivity of the epitaxial layers better than 0.01 Ohm cm was measured for Al atomic concentration of 2.7x1020 cm-3.

Abstract: Dislocations were investigated in the halo-carbon low-temperature epitaxial growth and low-temperature selective epitaxial growth (LTSEG) conducted at 13000C. The origin of triangular defects was investigated in low-temperature epilayers grown at higher growth rates with HCl addition. Due to the conversion of substrates’ basal plane dislocations (BPD) into threading dislocations, the concentration of BPDs was about an order of magnitude lower than the concentration of threading dislocations at moderate growth rates. An additional order of magnitude conversion of BPDs into threading dislocations was observed at higher grow rates achieved with HCl addition. In LTSEG epilayers, dislocation concentration away from the mesa walls was comparable to the blanket (i.e., regular non-selective) growth. High concentrations of BPDs were found only at mesa edges located on the “upstream” side with respect to the step-flow direction. No substrate defects could be traced to the triangular defects. Instead, the disturbances causing the triangular defect generation are introduced during the epitaxial process.

Abstract: Chlorinated silicon precursor SiCl4 was investigated as a source of additional chlorine instead of or in combination with HCl during the low temperature (13000C) halo-carbon epitaxial growth. No Si cluster cloud was visible inside the hot-wall susceptor indicating negligible homogeneous gas-phase nucleation. The growth rate was significantly enhanced compared to the SiH4-case, but was relatively close to the SiH4+HCl case. Similar to the SiH4+HCl growth, the increase of the growth rate caused by suppressed cluster formation was less significant than expected. The depletion of the growth species by vigorous polycrystalline deposition upstream of the hot zone, which was earlier reported for the SiH4+HCl growth, was also significant in the SiCl4-based growth. Closer to the growth zone, carbon species also get incorporated in the polycrystalline deposits.

Abstract: In this work, the local-loading effect and its influence on the growth rate enhancement and the growth rate non-homogeneity is investigated during the halo-carbon low-temperature selective epitaxial growth (LTSEG) using an SiO2 mask. The average growth rate during the LTSEG can be more than three-times higher than in blanket epitaxy at the same growth conditions. Both the size of the LTSEG seed windows and the surrounding area covered with the mask determine the growth rate non-homogeneity. A model for predicting the growth rate distribution is suggested.

Abstract: In this work, nitrogen doping was investigated during the low-temperature halo-carbon epitaxial growth of 4H-SiC on Si- and C-faces. The dependencies of nitrogen incorporation on nitrogen flow rate, Si/C ratio, growth rate, and temperature were investigated. It was established that the efficiency of nitrogen incorporation for the C-face growth at 1300 °C is higher than that for the Si-face for a wide range of the growth conditions. Seeming deviation of the Si/C ratio dependence from the “site-competition” trend confirmed the critical role of the silicon vapor condensation during the low-temperature epitaxy. Opposite trends for the nitrogen doping dependence on the growth rate were observed on the Si- and C-faces. Finally, a complex temperature dependence of the nitrogen doping in the temperature range from 1300 to 1450 0C was observed.