Chemical Properties of Oxidized Silicon Carbide Surfaces upon Etching in Hydrofluoric Acid

Abstract

Hydrogen termination of oxidized silicon in hydrofluoric acid results from an etching process that is now well understood and accepted. This surface has become a standard for studies of surface science and an important component in silicon device processing for microelectronics, energy, and sensor applications. The present work shows that HF etching of oxidized silicon carbide (SiC) leads to a very different surface termination, whether the surface is carbon or silicon terminated. Specifically, the silicon carbide surfaces are hydrophilic with hydroxyl termination, resulting from the inability of HF to remove the last oxygen layer at the oxide/SiC interface. The final surface chemistry and stability critically depend on the crystal face and surface stoichiometry. These surface properties affect the ability to chemically functionalize the surface and therefore impact how SiC can be used for biomedical applications.

Fixed nitrogen atoms in the SiO2/SiC interface region and their direct relationship to interface trap density

“…This kind of chemical bonding may be formed during nitridation or HF etching. 13 For example, the formation of a perfect epitaxial monolayer of silicon oxynitride (SiON) on (0001) 6H-SiC surfaces after nitridation has been reported. 14 Because the proposed SiON structure lacks dangling bonds and survived after exposure to air for one month, 14 it may be possible that this special layer has chemical resistance to HF etching.…”

Characterization of Semiconductor Surfaces during Surface Conditioning and Functionalization

“…(67,74) Consequently, polarization studies are not useful and some information is missing (or greatly suppressed). (27) An intrinsic limitation of IR spectroscopy is the need for a reference sample or surface. In contrast to all other spectroscopic thechniques, the raw spectrum is a measure of the transmitted intensity and not the absorbed radiation.…”

“…However, removal of the oxide does not lead to hydrogenated or halogenated surfaces. For instance, HF etching leads to the formation of hydrophilic, hydroxylterminated surfaces, (27) that cannot be readily reacted with organic molecules. In contrast to silicon and silicon carbide, III-V semiconductors have poor native oxides and cannot be easily hydrogen-terminated in HF.…”

Investigation of Enhanced Leaching of Lithium from α-Spodumene Using Hydrofluoric and Sulfuric Acid

“…Various processes, including traditional acid or alkaline digestion, or the recently-proposed roasting using sodium or calcium salts via ion exchange, have been reported to successfully extract lithium from spodumene [9][10][11][12][13]. These extraction processes are generally divided into two modules Hydrofluoric acid, which is capable of dissolving many materials, is specially used for etching SiO2 or silicon compounds in the microelectronic industry [14][15][16]. The HF/HCl system (called mud acid) is usually employed for acidizing in the petrochemical industry [17][18][19].…”

“…This HF/H2SO4 method achieved an efficient leaching of lithium without calcination, and also has no strict requirements on ore grade and deserves intensive investigation. Hydrofluoric acid, which is capable of dissolving many materials, is specially used for etching SiO 2 or silicon compounds in the microelectronic industry [14][15][16]. The HF/HCl system (called mud acid) is usually employed for acidizing in the petrochemical industry [17][18][19].…”