Wet chemical processing of (0001)(Si) 6H-SiC hydrophobic and hydrophilic surfaces

The wetting characteristics of polished or polished and thermally oxidized, on- and off-axis (0001)(Si) 6H-SiC [the silicon-terminated surface of SiC] surfaces in selected acids and bases have been determined and compared wit h that of (111)Si. Auger electron and Xray photoelectron spectroscopies and low energy electron diffraction were used to characterize the chemical sta te and order of these surfaces. The oxidized SiC surfaces were hydrophilic after oxide removal with a 10:1 HF solution and were terminated with approx imately a monolayer containing OH,CO, CH, and F species. The same effects w ere observed for the similarly treated (0001), [the carbon-terminated surfa ce of SiC], (11 (2) over bar 0), and (10 (1) over bar 0) surfaces. The as-p olished SiC surfaces were hydrophobic and covered with a thin (5-10 Angstro m) contamination layer composed primarily of C-C, C-F, and Si-F bonded spec ies. Removal of this layer using an RCA SCl etch or Piranha clean resulted in a disordered hydrophilic SiC surface. A 20 Angstrom amorphous Si capping layer both passivated the SiC surfaces and provided a better alternative t o the aforementioned contamination layer for producing hydrophobic surfaces on this material. (C) 1999 The Electrochemical Society. S0013-4651(98)08-0 67-7. All rights reserved.