Electrochemical Growth of Micrometer-Thick Oxide on SiC in Acidic Fluoride Solution

Abstract

Anodic polarization of SiC at modest potential in dilute fluoride solution of pH 3 surprisingly gives rise to the growth of micrometer-thick surface layers, clearly revealed with scanning electron microscopy. The reaction occurs at p-type SiC in the dark and at n-type SiC under (supra)bandgap illumination. The surface layer was shown by Rutherford backscattering spectrometry (RBS) to consist of silicon dioxide and to contain excess oxygen. Elastic recoil detection (ERD) indicated only a low level of carbon and fluoride in the layer but a considerable content of hydrogen. The growth kinetics was characterized in situ by spectroscopic ellipsometry and electrical impedance spectroscopy. The results suggest the formation of a duplex layer: a thin inner dielectric oxide and a thick hydrated outer oxide. The latter must have a considerable degree of porosity to allow diffusion/migration of reactants and products during oxide growth.

Charge Utilization Efficiency and Side Reactions in the Electrochemical Mechanical Polishing of 4H-SiC (0001)

“…Before the anodic oxidation of H 2 O and Cl − , anodic oxidation of SiC occurred preferentially, the SiC surface was covered by the generated oxide layer, which has a very high resistance of hundreds of kΩ. 36 As a result, when the anodic oxidation of H 2 O and Cl − occurred, most of the voltage was dropped on the oxide layer, resulting in large overpotentials.…”

Investigation of oxidation mechanism of SiC single crystal for plasma electrochemical oxidation

“…The anodic oxidation rate of SiC is very high, due to the loose and porous characteristics of its oxide layer, the depth of the oxide layer can reach micron level after continuous oxidation. 31 Fig. 7 shows the cross section of SiC oxide layer, an obvious layered structure can be observed.…”

“…3.3.3 Growth process of silicon dioxide. Based on the study of D. H. van Dorp that the oxide produced during oxidation is double-layered: thin internal dielectric oxide in solid state and thick hydrated outer oxide that has considerable porosity, 31 when the oxide layer is very thin, it is considered as a solid.…”

Surface Modification and Microstructuring of 4H-SiC(0001) by Anodic Oxidation with Sodium Chloride Aqueous Solution

“…On the other hand, the anodic oxidation rate of SiC is very high, and SiC can be continuously oxidized to a depth of micrometer order owing to the porosity of the oxide layer. 18 The MRRs of polishing techniques using anodic oxidation can reach 3−4 μm/h, 16,17 making anodic oxidation a very promising surface modification method for SiC. Investigation of the anodic oxidation properties of SiC is very important for its future applications.…”

“…Although the MRRs of these techniques (approximately 1 μm/h) are greater than that of CMP, the MRRs and technical maturity are still not satisfactory for practical industrial applications. On the other hand, the anodic oxidation rate of SiC is very high, and SiC can be continuously oxidized to a depth of micrometer order owing to the porosity of the oxide layer . The MRRs of polishing techniques using anodic oxidation can reach 3–4 μm/h, , making anodic oxidation a very promising surface modification method for SiC.…”