Silicon carbide (SiC) films have been grown on 4 in. diam (100) silicon wafers by atmospheric pressure chemical vapor deposition, using propane, silane, and hydrogen. X-ray photoelectron spectroscopy data confirm that the films are stoichiometric SiC, with no major impurities. X-ray diffraction and transmission electron microscopy (TEM) data indicate that the films are single-crystalline cubic polytype (3C) across the 4 in. substrates. With the exception of slip lines near the edge of the wafers, the films appear featureless when observed optically. The nitrogen concentration, as determined by secondary ion mass spectroscopy, is 4×1018 cm3. Cross-sectional TEM images show a fairly rough, void-free interface.

In an effort to improve silicon carbide (SIC) substrates surfaces prior to epitaxial growth, two chemomechanical polishing (CMP) techniques were investigated and the results were compared with a mechanical polishing procedure involving various grades of diamond paste. This work focused on silicon-terminated (0001) SIC surfaces.The two CMP techniques utilized (i) chromium oxide(lll) abrasives and (ii) colloidal silica polishing slurry. The best surfaces were obtained after colloidal silica polishing under conditions that combined elevated temperatures (-55°C) with a high slurry alkalinity (pH > 10) and a high solute content. Cross-sectional transmission electron microscopy showed no observable subsurface damage, and atomic force microscopy showed a significant reduction in roughness compared to commercial diamond-polished wafers. Growth experiments following colloidal silica polishing yielded a much improved film surface morphology.A pressing need in the development of SiC semiconductor technology is to improve the structural and surface quality of epitaxial films used in device fabrication. A flat and defect-free substrate surface is crucial for the epitaxial growth of thin films. Research on the epitaxial growth of 4H-and 6H-SiC has shown that processinduced defects on the substrate surface, such as scratches generated during lapping and polishing, are the primary contributors to unwanted polytype inclusions in the epi layer.14

Articles you may be interested inA method to determine fault vectors in 4H-SiC from stacking sequences observed on high resolution transmission electron microscopy images

The temperature dependence of hardness and microcracking in single-crystal 9.5-mol%-Y203-fully-stabilized cubicZr02 was studied as a function of orientation. Crack lengths increased with increased temperature up to 500°C; above 800°C, no cracks were found, indicating an indentation brittle-to-ductile transition of -800°C. The temperature dependence of hardness was reduced around 500°C. Etching studies to delineate the plastic zone around and below indents identified the operative slip systems. The role of dislocations and their interactions within the plastic zone on the hardness and indentation fracture behavior of cubic-ZrOz are discussed. [