CHEMOMECHANICAL POLISHING OF SILICON-CARBIDE

In an effort to improve silicon carbide (SIG) substrates surfaces prio r to epitaxial growth, two chemomechanical polishing (CMP) techniques were investigated and the results were compared with a mechanical poli shing procedure involving various grades of diamond paste. This work f ocused on silicon-terminated (0001) SiC surfaces. The two CMP techniqu es utilized (i) chromium oxide(lll) abrasives and (ii) colloidal silic a polishing slurry. The best surfaces were obtained after colloidal si lica polishing under conditions that combined elevated temperatures (s imilar to 55 degrees 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 sh owed a significant reduction in roughness compared to commercial diamo nd-polished wafers. Growth experiments following colloidal silica poli shing yielded a much improved film surface morphology.