No abstract

The surface preparation of 4H-SiC substrate plays a crucial role for the epitaxial growth. In the present work, the Hydrogen etching influence on 4H-SiC surface of substrate before the growth process was studied. The epi-layer was grown .with a commercial low-pressure, hot-wall Chemical Vapor Deposition (CVD) reactor by Tokyo Electron Limited. The etching time of the surface was increased until three time (x3) respect with the normal value usually adopted for the growth. Photoluminescence and optical inspection analyses show a clear relationship between the etching time and the defectivity. Atomic Force Microscope (AFM) measurements also show an increase of step bunching with the etching time.

Doping incorporation and good uniformity along the wafer it is a mandatory for application in high voltage electronic devices. In this work the effect of the Hydrogen (H) flux position inside the reaction chamber on homo-epitaxial 4H-SiC growth process has been studied. Capacitance-Voltage and FT-IR analyses show as the different position of the gas injector affect the doping and thickness uniformity and profile. On the other hand, By Candela and AFM analyses no morphological or surface influence by Hydrogen flux position has been observed.

3C-SiC devices are hampered by a high crystal defect density due to the hetero-epitaxial growth of these films, which results in the presence of stacking faults (SF). In this paper high growth rate CVD processes have been used to try to reduce the SF density in 3C-SiC films. In a first step a high growth rate (30 μm/h) has been used to grow 50 μm thick 3C-SiC layer on (100) Si. Then the silicon substrate was removed via etching and a further 3C-SiC growth was performed with a higher growth rate (90 μm/h) at a higher temperature (1600 °C) to obtain a final thickness of 150 μm. The SF presence and density were evaluated by TEM analysis performed on as-grown samples and SEM analysis on KOH etched samples with various thicknesses. A decrease of SF density was observed with an increase of 3C-SiC film thickness, with the best results (500/cm) obtained for the thickest sample. The 3C-SiC film quality and orientation was evaluated by XRD are correlated with film thickness and SF density.

A study of the carbonization process and of a low temperature buffer layer on the Cubic Silicon Carbide (3C-SiC) epitaxial growth has been reported in this work. From this study it has been evidenced the importance of the C/H2 ratio and of the buffer layer process on the voids formation at the 3C-SiC/Si interface. From our study, the influence of the voids the wafer curvature is highlighted. It has been observed that decreasing the density of these voids, decreases the stress of the 3C-SiC film; consequently, the wafer curvature is reduced.