A Method for Defect Delineation in Silicon Carbide Using Potassium Hydroxide Vapor

Defect evaluation of silicon carbide (SiC) wafers can be accomplished by potassium hydroxide (KOH) etching. The method described in this work employs etching by KOH in a vapor phase rather than in a liquid phase and this method allows reliable etching of both Si- and C-faces and furthermore it allows the delineation of defects on alternate orientation planes of SiC. Polished SiC wafers were etched in the temperature range from 700 to 1000°C at atmospheric air pressure. Etch pits were observed on (0001), (0001), (1120) and (1100) planes. The shape of the pits was found to be in accordance with the crystallographic symmetry. Activation energies for (0001) and (1120) planes were found to be ~17 kcal/mol and ~20 kcal/mol, respectively. It was demonstrated that the method of KOH vapor etching of SiC is simple for implementation having possibilities to reveal most of the important crystal defects.