Optimization of SiC Cleaning Process Based on Zeta Potential

Abstract

This The SiC is a polar semiconductor that is easy to adsorb particles due to the surface charges, which results in that the RCA process commonly used for silicon cleaning is not good for SiC cleaning, and the technique should be optimized. To check the surface charge of SiC wafers during the cleaning process, this work investigated the adsorption of polystyrene spheres (PS) on SiC epitaxial wafers at different pH values and measured the Zeta potential of the SiC wafers. We analyzed the mechanisms by which the Zeta potential in alkaline (SC1) and acidic (SC2) cleaning solutions affects the adsorption of particles on SiC epitaxial wafers surface. The results showed that both the SiC epitaxial wafers and the particles had a negative Zeta potential in the SC1 cleaning solution and there was an electrostatic repulsion between them. In contrast, in the SC2 cleaning solution, the SiC epitaxial wafers and particles had opposite Zeta potentials, which caused attraction between the wafers and particles. Therefore, based on the analysis of Zeta potential, we proposed an optimized the SiC cleaning process that use SC2 cleaning before SC1 cleaning. We successfully reduced the number of particles attached to the surface of SiC epitaxial wafers by 80.4% than RCA cleaning process by the optimized cleaning process. The optimized cleaning process would have a practical value due to the reduction on the consumption of time and chemical reagents.